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2021-02-21 11:14 武汉大学 Java

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1 介绍

学习视频：https://www.bilibili.com/video/BV1aE41167Tu
Spring:IOC和AOP必须掌握
SpringMVC:执行流程必须掌握
官网：https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html

1.1 什么是MVC？

Model：数据模型，提供要展示的数据，因此包含数据和行为，可以认为是领域模型或JavaBean组件（包含数据和行为），不过现在一般都分离开来：Value Object（数据Dao）和服务层（行为Service）。也就是模型提供了模型数据查询和模型数据的状态更新等功能，包括数据和业务。
View:负责进行模型的展示，一般就是我们见到的用户界面，客户想看到的东西。
Controller（调度员）：接收用户请求，委托给模型进行处理（状态改变），处理完毕后把返回的模型数据返回给视图，由视图负责展示。也就是说控制器做了个调度员的工作。
最常用的MVC：（Model）Bean +（view） Jsp +（Controller） Servlet

1.2 Model1时代

分为：视图层V和模型层M；由视图层的view来控制分发数据并展示给用户
缺点：JSP职责不单一，过重，不便于维护

1.3 Model2时代（MVC延续至今）

流程：分为了Contrller,Model,View
访问流程：

用户发请求
Servlet接收请求数据，并调用对应的业务逻辑方法
业务处理完毕，返回更新后的数据给servlet
servlet转向到JSP，由JSP来渲染页面
响应给前端更新后的页面

1.4 回顾Servlet创建

创建maven,父工程：pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ssl</groupId>
    <artifactId>SpringMVC</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <!--父工程导入依赖-->
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.4.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.10.0</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.62</version>
        </dependency>

    </dependencies>

    <!--资源过滤器，防止导入资源失败问题，最好在父子pom.xml里都加入一下代码-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>

            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

</project>

创建子工程，idea右键Add Framwork Support添加web支持

实现HelloServlet继承HttpServlet接口，并创建/WEB-INF/jsp/test.jsp

public class HelloServlet extends HttpServlet {

 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
     //1 获得参数
     //2 调用业务层
     //3 视图转发或者重定向
     req.getRequestDispatcher("/WEB-INF/jsp/test.jsp").forward(req, resp);
 }

 @Override
 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
     super.doPost(req, resp);
 }
}

web.xml中注册HelloServlet,测试跳转：http://localhost:8080/springmvc_01_servlet//helloServlet

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>HelloServlet</servlet-name>
        <servlet-class>com.ssl.web.HelloServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>HelloServlet</servlet-name>
        <url-pattern>/helloServlet</url-pattern>
    </servlet-mapping>
</web-app>

2 第一个SpringMVC

概念：SpringMVC是Spring框架中的一个分支，是基于Java实现MVC的轻量级Web框架
核心：Spring的web框架围绕DispatcherServlet [ 调度Servlet ] 设计的。

2.1 执行原理

SpringMVC底层工作原理：

DispatcherServlet表示前置控制器，是整个SpringMVC的控制中心。用户发出请求，DispatcherServlet接收请求并拦截请求。
1. 假设url为 : http://localhost:8080/SpringMVC/hello
2. 服务器域名：http://localhost:8080
3. web站点：/SpringMVC
4. hello表示控制器：/hello
5. 通过分析，如上url表示为：请求位于服务器localhost:8080上的SpringMVC站点的hello控制器。
HandlerMapping为处理器映射。DispatcherServlet调用HandlerMapping,HandlerMapping根据请求url查找Handler。
HandlerExecution表示具体的Handler,其主要作用是根据url查找控制器，如上url被查找控制器为：hello。
HandlerExecution将解析后的信息传递给DispatcherServlet,如解析控制器映射等。
HandlerAdapter表示处理器适配器，其按照特定的规则去执行Handler。
Handler让具体的Controller执行。
Controller将具体的执行信息返回给HandlerAdapter,如ModelAndView。
HandlerAdapter将视图逻辑名或模型传递给DispatcherServlet。
DispatcherServlet调用视图解析器(ViewResolver)来解析HandlerAdapter传递的逻辑视图名。
视图解析器将解析的逻辑视图名传给DispatcherServlet。
DispatcherServlet根据视图解析器解析的视图结果，调用具体的视图。
最终视图呈现给用户。

2.2 不使用注解开发

了解具体的执行过程=面试谈资。虽然开发中不会这么麻烦的使用，但必须看完-理解-继续学习

1 配置web.xml

完成DispatcherServlet，关联resource配置文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <!--配置DispatcherServlet:SpringMVC核心-->
    <servlet>
        <servlet-name>SpringMvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--关联一个SpringMvc的resource配置文件-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springMvc_servlet.xml</param-value>
        </init-param>
        <!--启动级别-->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!--匹配所有的请求： / :只匹配请求，不包含所有的.jsp
                      /*:匹配所有的请求，包括jsp页面
    -->
    <servlet-mapping>
        <servlet-name>SpringMvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

2 配置springMvc_servlet.xml

获得视图解析器、映射器、适配器，绑定跳转url

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:c="http://www.springframework.org/schema/c"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--处理器映射器HandlerMapping:查找访问的url控制器-->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
    <!--处理器适配器HandlerAdapter：controller将处理好的数据返回给HandlerAdapter-->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
    <!--视图解析器ViewResolver：将后端处理好的数据和视图传给DispatchServlet，DS再交给ViewResolver先解析一遍，确认无误再传给前端
        必须熟悉，以后还要学模版引擎Thymeleaf/Freemarker...
        1 获取ModeAndView的数据
        2 解析ModeAndView的视图名字
        3 拼接视图名字，找到对应的视图 WEB-INF/jsp/hello.jsp
    -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
    </bean>
    <!--BeanNameUrlHandlerMapping处理器：绑定跳转的url=页面访问的网址-->
    <bean id="/hello" class="com.ssl.controller.HelloController"/>
</beans>

3 /WEB-INF/jsp/hello.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>hello</title>
</head>
<body>
<%--接受传递的参数--%>
${msg}
</body>
</html>

4 HelloController实现Controller

访问：http://localhost:8080/springmvc_02_hellomvc/hello

public class HelloController implements Controller {
    @Override
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        //1 创建modelAndView
        ModelAndView mv = new ModelAndView();
        //2 调用业务层，这里没有，就不写
        //3 封装对象，放在mv中添加
        mv.addObject("msg", "Hello SpringMvc");
        //4 封装要跳转的视图，WEB-INF/jsp/hello.jsp
        mv.setViewName("hello");
        return mv;
    }
}

==5 SpringMVC原理回顾==

反复观看，理解原理！

2.3 使用注解开发

1 web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
      <!--与前面一样-->
    <servlet>
        <servlet-name>springMvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springMvc_servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>springMvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

2 springMvc_servlet.xml

注解省略了映射器、适配器，专注于写视图解析器；跳转的Controller也不用配置进Spring

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
        xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <!--自动扫描包，让指定包下的注解生效，由IOC容器统一管理-->
    <context:component-scan base-package="com.ssl.controller"/>
    <!--让SpringMvc不处理静态资源。让.css,.js等不进视图解析器-->
    <mvc:default-servlet-handler/>
    <!--注解加载映射器、适配器，不用之前那么麻烦配置了-->
    <mvc:annotation-driven/>
    <!--配置视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
    </bean>
</beans>

3 /WEB-INF/jsp/hello.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>hello</title>
</head>
<body>
${msg}
</body>
</html>

4 HelloController

简化了实现的接口，使用@注解配置映射器
访问：http://localhost:8080/springmvc_03_annotation/hello

@Controller
public class HelloController {
    /**
     * @param model 模型
     * @return 被视图解析器处理：访问"/WEB-INF/jsp/hello.jsp资源
     * 访问的url:RequestMapping("/hello")
     */
    @RequestMapping("/hello")
    public String hello(Model model) {
        //封装数据
        model.addAttribute("msg", "Hello SpringMvc_annotation");
        //被视图解析器处理：访问"/WEB-INF/jsp/hello.jsp资源
        return "hello";
    }

3 Controller和RestFul

配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <servlet>
        <servlet-name>springMvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring_mvc_servlet.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>springMvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

   <!-- <filter>
        <filter-name>encode</filter-name>
        <filter-class>com.ssl.filter.EncodeFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>encode</filter-name>
        <url-pattern>/</url-pattern>
    </filter-mapping>-->
    <filter>
        <filter-name>encode</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encode</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

spring_mvc_servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <!--自动扫描包，让指定包下的注解生效，由IOC容器统一管理-->
    <context:component-scan base-package="com.ssl.controller"/>
    <!--让SpringMvc不处理静态资源。让.css,.js等不进视图解析器-->
    <mvc:default-servlet-handler/>
    <!--注解加载映射器、适配器，不用之前那么麻烦配置了-->
    <mvc:annotation-driven/>
    <!--以上的是定死的代码，
        以下是配置视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
    </bean>
    <!--不使用注解开发的适配器：/demo1,注意点是id需要配置/-->
    <bean id="/demo" class="com.ssl.controller.ControllerDemo1"/>
</beans>

3.1 Controller

不使用注解，极其不推荐使用，因为：

配置麻烦：<bean id="/demo" class="com.ssl.controller.ControllerDemo1"/>，并且需要 implements Controller
不够灵活，太费力气，浪费时间

访问：http://localhost:8080/springmvc_04_controller/demo

public class ControllerDemo1 implements Controller {
@Override
public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
  ModelAndView modelAndView = new ModelAndView();
  modelAndView.addObject("demo1","demo1:Controller会返回一个modelAndView");
  modelAndView.setViewName("demo1");
  return modelAndView;
}
}

3.2 @Controller

使用注解开发，@Controller注册进Spring容器，如果返回值是String，并且有具体的页面可以跳转，那么就会被视图解析器解析

访问：http://localhost:8080/springmvc_04_controller/demo2

@Controller
public class ControllerDemo2 {
 @RequestMapping("/demo2")
 public String test1(Model model) {
     model.addAttribute("demo2", "demo2");
     return "demo2";
 }
}

3.3 @RequestMapping

可以在类和方法上配置url访问路径

访问：http://localhost:8080/springmvc_04_controller/controller/demo3

@Controller
@RequestMapping("/controller")
public class ControllerDemo3 {
  @RequestMapping("/demo3")
  public String test1(Model model) {
      model.addAttribute("demo3", "demo3");
      return "demo3";
  }
}

3.4 RestFul风格

优点：
- 最大的优势是安全，看不出源代码的参数和意义
- 实现地址复用，使得get和post访问url相同，框架会自动进行类型转换
- 高效：支持缓存
缺点：
- 不像原生的url见名知意，url理解不直观
实现方式：
- 1：url @GetMapping("/addRest/{a}/{b}") + 参数@PathVariable int a, @PathVariable int b
  - 访问：http://localhost:8080/springmvc_04_controller/addRest/1/2
- 2：url @PostMapping("/addRest/{a}/{b}") + 参数不变@PathVariable int a, @PathVariable int b
  - 使用Postman中的post访问：http://localhost:8080/springmvc_04_controller/addRest/1/2

@Controller
public class RestFulController {

    /**
     * 原生的url：http://localhost:8080/springmvc_04/add?a=1&b=1
     */
    @RequestMapping("/add")
    public String getAdd1(int a, int b, Model model) {
        int result = a + b;
        model.addAttribute("add", "原生的url：结果为" + result);
        return "add";
    }

    /**
     * RestFul方式一：method = get
     * RequestMapping("/addRest/{a}/{b}" method=requestMethod.GET) = @GetMapping()
     * http://localhost:8080/springmvc_04/addRest/1/1
     */
    @GetMapping("/addRest/{a}/{b}")
    public String getAdd2(@PathVariable int a, @PathVariable int b, Model model) {
        int result = a + b;
        model.addAttribute("add", "Rest的url：结果为" + result);
        return "addRest";
    }

    /**
     * 复用相同的url
     * RestFul方式二：method=post，使用RestFul的话，请求的url和GET就一样了
     */
    @PostMapping("/addRest/{a}/{b}")
    public String getAdd3(@PathVariable int a, @PathVariable int b, Model model) {
        int result = a + b;
        model.addAttribute("add", "Rest的url：结果为" + result);
        return "addRest";
    }
}

3.5 重定向和转发

可以使用原生的request转发或者response重定向

推荐使用SpringMvc的return “forward:xxx”/"redirect:xxx"

@Controller
public class ModelTest1 {
  //原生的转发：返回值是void，没有经过视图解析器；原生的重定向同样如此，都不走视图解析器，直接重定向
  @RequestMapping("/test1")
  public void test1(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      String id = request.getSession().getId();
      System.out.println(id);
      request.getRequestDispatcher("index.jsp").forward(request,response);
  }
  //SpringMvc转发：测试结果是不走视图解析器，url没变是转发
  @RequestMapping("/test2")
  public String test2(Model model) {
      model.addAttribute("demo1","这是test2中的Spring转发");
      return "forward:/WEB-INF/jsp/demo1.jsp";
  }
  //SpringMvc重定向：测试结果是不走视图解析器
  @RequestMapping("/test3")
  public String test3() {
      System.out.println("跳转回首页index.jsp");
      return "redirect:index.jsp";
  }
}

3.6 接受请求参数和数据回显

前端提交的name和后端映射器接受的形参名一样，则直接接受
前端提交的name和后端映射器接受的形参名不用一样，再形参前@RequestParam("xxx")更改名称一致
- 养成习惯：无论是否一样，都必须加上@RequestParam
后端参数封装如果成一个pojo，前端传过来的name会自动pojo中的成员属性，不匹配的属性=null/0

如何解决中文乱码问题？请看下节！

@Controller
public class UserController {
  /** http://localhost:8080/springmvc_04/t1?id=1&name=abc&age=18
   * @param user SpringMvc 会自动封装数据到参数里的pojo，不匹配的属性=null/0
   */
  @GetMapping("/t1")
  public String getUser(User user){
      System.out.println(user);
      return "test1";
  }
}

3.7 Model，ModelAndView等

Model：精简版，适合初学者，大多数情况封装参数，设置转发视图层就够用
ModelMap：继承了LinkedHashMap，有它的方法和特性
ModelAndView：可以在存储数据的同时，可以进行设置返回的逻辑视图，进行控制展示层的跳转
怎么学习：用80%的时间学号基础，18%时间研究框架，2%学点英文，剩下不会的看官方文档

4 乱码问题

方法一：web.xml里面配置的SpringMvc自带的过滤器CharacterEncodingFilter

<url-pattern>/*</url-pattern>：因为要跳转到xxx.jsp页面，所以url是/*(≠/)

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
   version="4.0">
<!--配置SpringMVC-->
<servlet>
  <servlet-name>springMvc</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:spring_mvc_servlet.xml</param-value>
  </init-param>
</servlet>
<servlet-mapping>
  <servlet-name>springMvc</servlet-name>
  <url-pattern>/</url-pattern>
</servlet-mapping>

<!--web容器解决中文乱码问题-->
<filter>
  <filter-name>encode</filter-name>
  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  <init-param>
      <param-name>encoding</param-name>
      <param-value>utf-8</param-value>
  </init-param>
</filter>
<filter-mapping>
  <filter-name>encode</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>

方法二：一劳永逸，但需要重启Tomcat服务器，修改Tomcat里面的server.xml配置文件：URIEncoding = "UTF-8"

<Connector port="8080" protocol="HTTP/1.1"
         connectionTimeout="20000"
         redirectPort="8443"
         URIEncoding = "UTF-8"/>
<!-- A "Connector" using the shared thread pool-->

5 JSON

5.1 前端初识Json

前端展示两者数据，学会js和json互相转换

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
  <title>json</title>
  <script type="text/javascript">
      //user是一个js对象
      var user = {
          name: "张三",
          age: 18,
          sex: "男"
      };
      //后端传的json其实是一个字符串，前端将后端传的json转换成js对象渲染在页面上
      //jsonUser:模拟后端传的json数据
      //js转换成json
      var jsonUser = JSON.stringify(user);
      console.log(jsonUser);
      //jsUser：js是一个对象
      //json转换成js
      var jsUser = JSON.parse(jsonUser);
      console.log(jsUser)
  </script>
</head>
<body>
</body>
</html>

5.2 Jackson Databind

使用 Jackson Databind可以快速生成json数据

1 导入依赖

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.10.0</version>
</dependency>

json=一个字符串，所以会有中文乱码问题，需要在springmvc.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:context="http://www.springframework.org/schema/context"
     xmlns:mvc="http://www.springframework.org/schema/mvc"
     xsi:schemaLocation="http://www.springframework.org/schema/beans
      https://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/context
      https://www.springframework.org/schema/context/spring-context.xsd
     http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
  <!--自动扫描包，让指定包下的注解生效，由IOC容器统一管理-->
  <context:component-scan base-package="com.ssl.controller"/>
  <!--让SpringMvc不处理静态资源。让.css,.js等不进视图解析器-->
  <mvc:default-servlet-handler/>

  <!--注解加载映射器、适配器，解决Json数据中文乱码问题-->
  <mvc:annotation-driven>
      <mvc:message-converters register-defaults="true">
          <bean class="org.springframework.http.converter.StringHttpMessageConverter">
              <constructor-arg value="UTF-8"/>
          </bean>
          <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
              <property name="objectMapper">
                  <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                      <property name="failOnEmptyBeans" value="false"/>
                  </bean>
              </property>
          </bean>
      </mvc:message-converters>
  </mvc:annotation-driven>

  <!--配置视图解析器，明确json数据不走数据解析器，直接传给前端-->
  <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
      <property name="prefix" value="/WEB-INF/jsp/"/>
      <property name="suffix" value=".jsp"/>
  </bean>
</beans>

2 编写Controller

@RestControoler:该类下所有方法不走视图解析器，返回一个json数据
@ResponseBody：该方法不走视图解析器，返回一个json数据
访问：http://localhost:8080/springmvc_05_json/t1，页面显示一个json数据，不经过视图解析器
回顾日期：new SimpleDateFormat("yyyy-MM-dd:HH:mm:ss")

@RestController
public class UserController {
    /*  概念：前后端分离的项目，后端代码不走视图解析器，后端传给前端的是json数据
        方法上：注解@ResponseBody指定该方法不走视图解析器，会直接返回一个String=json数据就是一个字符串
        类上：注解@RestController指定该类下的所有方法都不走视图解析器
        Json返回一个对象
     */
    @RequestMapping("/t1")
    public String json1() throws JsonProcessingException {
        User user = new User(1, "张三", 20);
        ObjectMapper jacksonMapper = new ObjectMapper();
        String str_user = jacksonMapper.writeValueAsString(user);
        //user.toString()是自己指定的String但是公司通常是允许的，通常是使用第三方工具来返回String
        //str_user有中文乱码问题，springMvc可以统一配置
        return str_user;
    }

    /**
     * Json返回一个List
     */
    @RequestMapping("/t2")
    public String json2() throws JsonProcessingException {
        User user1 = new User(1, "张三", 20);
        User user2 = new User(2, "张三", 21);
        User user3 = new User(3, "张三", 22);
        User user4 = new User(4, "张三", 23);
        List<User> list = new ArrayList<>();
        list.add(user1);
        list.add(user2);
        list.add(user3);
        list.add(user4);
        return new ObjectMapper().writeValueAsString(list);
    }

    /**
     *  json返回一个日期格式
     */
    @RequestMapping("/t3")
    public String json3() throws JsonProcessingException {
        //方式一：原始纯java日期转换：推荐使用
        // String date = new SimpleDateFormat("yyyy-MM-dd:HH-mm-ss").format(new Date());
        ObjectMapper objectMapper = new ObjectMapper();
        //方式二：使用mapper来制定日期格式，先关闭时间戳表示
        objectMapper.configure(SerializationFeature.WRITE_DATE_KEYS_AS_TIMESTAMPS, false);
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd:HH:mm:ss"));
        Date date = new Date();
        return objectMapper.writeValueAsString(date);
    }

    @Test
    public void DateTest1() {
        //传统的java日期格式转换
        String date = new SimpleDateFormat("yyyy-MM-dd:HH:mm:ss").format(new Date());
        System.out.println(date);
    }
}

5.3 FastJson

阿里巴巴官方提供的，实现Json数据的另一个工具，比JackSon Databind更方便

1 导包

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.62</version>
</dependency>

2 编写Controller

比Jackson使用更方便

@RequestMapping("/t4")
  public String json4() throws JsonProcessingException {
      User user1 = new User(1, "张三", 20);
      User user2 = new User(2, "张三", 21);
      User user3 = new User(3, "张三", 22);
      User user4 = new User(4, "张三", 23);
      List<User> list = new ArrayList<>();
      list.add(user1);
      list.add(user2);
      list.add(user3);
      list.add(user4);
      String jsonString = JSON.toJSONString(list);
      return jsonString;
  }

6 SSM整合

6.1 环境

IDEA+Mysq5.7+Tomca5.7+Maven3.6
数据库

create database `ssmbuild`;
use `ssmbuild`;
CREATE TABLE `books` (
  `bookId` int(10) NOT NULL AUTO_INCREMENT COMMENT '书id',
  `bookName` varchar(100) NOT NULL COMMENT '书名',
  `bookCounts` int(11) NOT NULL COMMENT '数量',
  `detail` varchar(200) NOT NULL COMMENT '描述',
  KEY `bookId` (`bookId`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ssl</groupId>
    <artifactId>ssmbuild</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!--依赖:junit,数据库驱动，连接池，Servlet，jsp，mybatis,mybatis-mvc,Spring,SpringMVC-->
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.4.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.0.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>
    </dependencies>


    <!--Maven资源过滤设置-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>

            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>
</project>

6.2 开发流程

需求分析+设计数据库+业务+传给前端页面
整体效果：

6.3 整合Mybatis

mybatis-config.xml

数据库连接交给Spring-dao.xml配置

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
    PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--核心配置文件-->
<configuration>
<settings>
    <setting name="logImpl" value="STDOUT_LOGGING"/>
</settings>
<!--配置数据源，交给Spring去做-->
<!--取别名-->
<typeAliases>
    <!--resultMap:默认类名小写为使用id-->
    <package name="com.ssl.pojo"/>
</typeAliases>
<mappers>
    <mapper class="com.ssl.dao.BookMapper"/>
</mappers>
</configuration>

# db.properties配置文件
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/ssmbuild?useSSL=false&amp;useUnicode=true&amp;characterEncoding=utf-8
username=root
password=123456

6.4 整合Spring

1 spring-dao.xml

数据库连接读取db.properties有bug，手动连接jdbcurl和user

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xmlns:mvc="http://www.springframework.org/schema/mvc"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
    https://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    https://www.springframework.org/schema/context/spring-context.xsd
   http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!--1 关联数据库配置文件-->
<context:property-placeholder location="classpath:db.properties"/>
<!--2 连接池 这次使用c3p0的连接池.常见的数据库：
dbcp:半自动操作，不能自动连接
c3p0：自动化操作，并且可以配置到对象中
druid,hikari(SpringBoot)-->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
    <property name="driverClass" value="${driver}"/>
    <property name="jdbcUrl" value="${url}"/>
    <property name="user" value="${username}"/>
    <property name="password" value="${password}"/>
    <!--c3p0的私有属性-->
    <property name="maxPoolSize" value="30"/>
    <property name="minPoolSize" value="10"/>
    <!--关闭连接后，不自动commit-->
    <property name="autoCommitOnClose" value="false"/>
    <property name="checkoutTimeout" value="10000"/>
    <property name="acquireRetryAttempts" value="2"/>
 </bean>
<!--3 sqlSessionFactory-->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <!--绑定数据库-->
    <property name="dataSource" ref="dataSource"/>
    <!--绑定Mybatis的配置文件-->
    <property name="configLocation" value="classpath:mybatis-config.xml"/>
</bean>
<!--4 配置dao接口扫描包，动态的实现了dao接口可以注入到Spring容器中,不用写mapperImpl.xml-->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <!--注入sqlSessionFactory-->
    <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
    <!--扫描要扫描的dao的包-->
    <property name="basePackage" value="com.ssl.dao"/>
</bean>
</beans>

2 spring-service.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:context="http://www.springframework.org/schema/context"
     xmlns:mvc="http://www.springframework.org/schema/mvc"
     xsi:schemaLocation="http://www.springframework.org/schema/beans
      https://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/context
      https://www.springframework.org/schema/context/spring-context.xsd
     http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
  <!--1 扫描service下的包-->
  <context:component-scan base-package="com.ssl.service"/>
  <!--2 将我们的所有业务类，注入到Spring,这里使用bean配置，平时是使用注解-->
  <bean id="BookServiceImpl" class="com.ssl.service.BookServiceImpl">
      <property name="bookMapper" ref="bookMapper"/>
  </bean>
  <!--3  声明式事务配置-->
  <bean  id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
      <property name="dataSource" ref="dataSource"/>
  </bean>
  <!--4 AOP横切事务，这里用不到-->
</beans>

3 application.xml
- 导入其他配置进spring主配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <import resource="classpath:spring-dao.xml"/>
    <import resource="classpath:spring-service.xml"/>
    <import resource="classpath:spring-mvc.xml"/>
</beans>

6.5 整合SpringMVC

增加web项目的支持

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
       version="4.0">
  <!--SpringMVC配置-->
  <!--1 DispatcherServlet-->
  <servlet>
      <servlet-name>springMVC</servlet-name>
      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
      <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>classpath:application.xml</param-value>
      </init-param>
      <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
      <servlet-name>springMVC</servlet-name>
      <url-pattern>/</url-pattern>
  </servlet-mapping>
  <!--2 乱码过滤-->
  <filter>
      <filter-name>encodingFilter</filter-name>
      <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
      <init-param>
          <param-name>encoding</param-name>
          <param-value>utf-8</param-value>
      </init-param>
  </filter>
  <filter-mapping>
      <filter-name>encodingFilter</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>
  <!--3 Session过期时间-->
  <session-config>
      <session-timeout>15</session-timeout>
  </session-config>

``` - **spring-mvc.xml** ```xml <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd"> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> </bean> </beans> ```

6.6 dao层

BookMapper接口和BookMapperMapper.xml

public interface BookMapper {
    //增加一本书
    int addBook(Books books);

    //删除一本书
    int deleteBookById(@Param("bookId") int id);

    //修改一本书
    int updateBook(Books books);

    //查询一本书根据id
    Books queryBookById(@Param("bookId")int id);

    //查询全部书
    List<Books> queryAllBook();

    Books queryBookByName(@Param("bookName") String bookName);
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--核心配置文件-->
<mapper namespace="com.ssl.dao.BookMapper">
    <insert id="addBook" parameterType="Books">
        insert into ssmbuild.books(bookName, bookCounts, detail)
        values (#{bookName},#{bookCounts},#{detail});
    </insert>
    <delete id="deleteBookById" parameterType="int">
        delete from ssmbuild.books where bookId = #{bookId}
    </delete>
    <update id="updateBook" parameterType="Books">
        update ssmbuild.books set
        bookName=#{bookName},
        bookCounts=#{bookCounts},
        detail=#{detail}
        where bookId=#{bookId};
    </update>
    <select id="queryBookById" parameterType="int" resultType="Books">
        select * from ssmbuild.books where bookId = #{bookId};
    </select>
    <select id="queryAllBook" resultType="Books">
        select * from ssmbuild.books;
    </select>

    <select id="queryBookByName" parameterType="String" resultType="Books">
         select * from ssmbuild.books where bookName=#{bookName}
    </select>
</mapper>

6.7 service层

public interface BookService {
    //增加一本书
    int addBook(Books books);

    //删除一本书
    int deleteBookById(int id);

    //修改一本书
    int updateBook(Books books);

    //查询一本书根据id
    Books queryBookById(int id);

    //查询全部书
    List<Books> queryAllBook();

    Books queryBookByName(String bookName);
}

public class BookServiceImpl implements BookService {
    //注入Dao层
    private BookMapper bookMapper;
    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }

    @Override
    public int addBook(Books books) {
        return bookMapper.addBook(books);
    }

    @Override
    public int deleteBookById(int id) {
        return bookMapper.deleteBookById(id);
    }

    @Override
    public int updateBook(Books books) {
        return bookMapper.updateBook(books);
    }

    @Override
    public Books queryBookById(int id) {
        return bookMapper.queryBookById(id);
    }

    @Override
    public List<Books> queryAllBook() {
        return bookMapper.queryAllBook();
    }

    @Override
    public Books queryBookByName(String bookName) {

        return bookMapper.queryBookByName(bookName);
    }
}

6.8 controller层

@Controller
@RequestMapping("/book")
public class BookController {

    @Autowired
    @Qualifier("BookServiceImpl")
    private BookService bookService;

    //查询全部的书籍，并且返回到一个书籍展示页面
    @RequestMapping("/allBook")
    public String list(Model model) {
        List<Books> books = bookService.queryAllBook();
        model.addAttribute("list", books);
        return "allBook";
    }

    //跳转到增加书籍页面
    @RequestMapping("/toAddBook")
    public String toAddBook() {
        return "addBook";
    }

    //添加书籍
    @RequestMapping("/addBook")
    public String addBook(Books books) {
        int result = bookService.addBook(books);
        if (result > 0) {
            System.out.println("添加书籍成功");
        }
        return "redirect:/book/allBook";
    }

    @RequestMapping("/toUpdateBook")
    public String toUpdate(int bookId, Model model) {
        Books books = bookService.queryBookById(bookId);
        model.addAttribute("book", books);
        return "updateBook";
    }

    /*
        没有提交事务操作，更新会失败
     */
    @RequestMapping("/updateBook")
    public String updateBook(Books books) {
        int result = bookService.updateBook(books);
        if (result > 0) {
            System.out.println("修改书籍成功");
        }
        return "redirect:/book/allBook";
    }

    /*
        删除书籍，回顾RestFul风格
     */
    @RequestMapping("/deleteBook/{bookId}")
    public String deleteBook(@PathVariable("bookId") int bookId) {
        int result = bookService.deleteBookById(bookId);
        if (result > 0) {
            System.out.println("删除书籍成功");
        }
        return "redirect:/book/allBook";
    }

    @RequestMapping("/queryBook")
    public String queryBook(String queryBookName, Model model) {
        Books books = bookService.queryBookByName(queryBookName);
        //复用，这样就显示一个
        List<Books> list = new ArrayList<>();
        list.add(books);
        if (books == null) {
            list= bookService.queryAllBook();
            model.addAttribute("errMsg","未查任何书籍");
        }
        model.addAttribute("list", list);
        return "allBook";
    }
}

6.9 前端页面

index.xml

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>
    <style>
        /*消除字体蓝色下划线*/
        a {
            text-decoration: none;
            color: black;
            font-size: 18px;
        }

        h3 {
            width: 180px;
            height: 38px;
            margin: 100px auto;
            text-align: center;
            line-height: 38px;
            background: deepskyblue;
            border-radius: 5px;
        }
    </style>
</head>
<body>
<h3>
    <a href="${pageContext.request.contextPath}/book/allBook">进入书籍展示页面</a>
</h3>
</body>
</html>

WEB-INF/jsp/addBook.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <%--BootStrap美化界面--%>
    <link href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    <div class="row clearfix">
        <%--屏幕分成12列--%>
        <div class="col-md-12 column">
            <div class="page-header">
                <h1>
                    <small>新增书籍</small>
                </h1>
            </div>
        </div>
    </div>
    <%--BootStrap官网拿"表单"数据  name属性保证pojo属性名称一致 required保证必须提交--%>
    <form action="${pageContext.request.contextPath}/book/addBook" method="post">
        <div class="form-group">
            <label for="bName">书籍名称:</label>
            <input type="text" name="bookName" class="form-control" id="bName" required>
        </div>
        <div class="form-group">
            <label for="bCount">书籍数量：</label>
            <input type="text" name="bookCounts" class="form-control" id="bCount" required>
        </div>
        <div class="form-group">
            <label for="bDesc">书籍描述：</label>
            <input type="text" name="detail" class="form-control" id="bDesc" required>
        </div>
        <div class="form-group">
            <input type="submit" class="form-control" value="添加">
        </div>

    </form>
</head>
<body>

</body>
</html>

WEB-INF/jsp/allBook.jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
  Created by IntelliJ IDEA.
  User: 宋林
  Date: 2020/3/31
  Time: 20:50
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>书籍展示页面</title>
    <%--BootStrap美化界面--%>
    <link href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">

</head>
<body>

<div class="container">
    <div class="row clearfix">
        <%--屏幕分成12列--%>
        <div class="col-md-12 column">
            <div class="page-header">
                <h1>
                    <small> 书籍列表——————————显示所有书籍</small>
                </h1>
            </div>
        </div>
        <div class="row">
            <div class="col-md-4 column">
                <a class="btn btn-primary" href="${pageContext.request.contextPath}/book/toAddBook">新增书籍</a>
                <a class="btn btn-primary" href="${pageContext.request.contextPath}/book/allBook">显示全部书籍</a>
            </div>

            <div class="col-md-4 column"></div>

            <div class="col-md-8 column">
                <form action="${pageContext.request.contextPath}/book/queryBook" method="post" style="float: right">
                    <%--前端未传任何信息，就显示错误提示信息：未查任何书籍--%>
                    <span style="color: red;font-weight: bold">${errMsg}</span>
                    <%--class="form-inline"保证在同一行--%>
                    <input type="text" name="queryBookName" class="form-inline" placeholder="请输入要查询的书籍名称">
                    <input type="submit" value="查询" class="btn btn-primary">

                </form>
            </div>
        </div>

    </div>
    <div class="row clearfix">
        <div class="col-md-12 column">
            <table class="table table-hover table-striped">
                <thead>
                <tr>
                    <th>书籍编号</th>
                    <th>书籍名称</th>
                    <th>书籍数量</th>
                    <th>书籍详情</th>
                    <th>操作</th>
                </tr>
                </thead>
                <%--书籍从数据库中查询出来，从这个list中遍历出来，foreach--%>
                <tbody>
                <c:forEach var="book" items="${list}">
                    <tr>
                        <td>${book.bookId}</td>
                        <td>${book.bookName}</td>
                        <td>${book.bookCounts}</td>
                        <td>${book.detail}</td>
                        <td>

                            <a href="${pageContext.request.contextPath}/book/toUpdateBook?bookId=${book.bookId}">修改</a>
                            &nbsp; | &nbsp;
                            <a href="${pageContext.request.contextPath}/book/deleteBook/${book.bookId}">删除</a>
                        </td>
                    </tr>
                </c:forEach>
                </tbody>
            </table>
        </div>
    </div>
</div>
</body>
</html>

WEB-INF/jsp/updateBook.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <%--BootStrap美化界面--%>
    <link href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    <div class="row clearfix">
        <%--屏幕分成12列--%>
        <div class="col-md-12 column">
            <div class="page-header">
                <h1>
                    <small>修改书籍</small>
                </h1>
            </div>
        </div>
    </div>
    <%--BootStrap官网拿"表单"数据  name属性保证pojo属性名称一致 required保证必须提交--%>
    <form action="${pageContext.request.contextPath}/book/updateBook" method="post">
        <%--提交失败：没有回显：问题：
            1. 事务没有提交
            2. sql执行失败，没有提交BookId，需要前端的隐藏域
        --%>
        <%--添加bookId的隐藏域--%>
        <input type="hidden" name="BookId" value="${book.bookId}">
        <div class="form-group">
            <label for="bName">书籍名称:</label>
            <input type="text" name="bookName" class="form-control" id="bName" value="${book.bookName}" required>
        </div>
        <div class="form-group">
            <label for="bCount">书籍数量：</label>
            <input type="text" name="bookCounts" class="form-control" id="bCount" value="${book.bookCounts}"required>
        </div>
        <div class="form-group">
            <label for="bDesc">书籍描述：</label>
            <input type="text" name="detail" class="form-control" id="bDesc" value="${book.detail}" required>
        </div>
        <div class="form-group">
            <input type="submit" class="form-control" value="添加">
        </div>

    </form>
</head>
<body>

</body>
</html>

7 Ajax

7.1 概念

Ajax就是一个异步无刷新请求，无需更新整个页面就异步加载一些数据，交互性更强

模拟异步请求

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>模拟Ajax异步请求</title>
  <script>
      function go() {
          var url = document.getElementById("url").value;
          document.getElementById("iframe1").src = url;
      }
  </script>
</head>
<body>
<div>
  <p>请输入地址：</p>
  <p>
      <input type="text" id="url">
      <input type="button" id="button" value="提交" onclick="go()">
  </p>
</div>
<div>
  <iframe id="iframe1" style="width:100%;height: 500px">
  </iframe>
</div>
</body>
</html>

7.2 使用JQ使用Ajax

1 初试Ajax

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>
    <%--加载动态的JQ资源--%>
    <script src="https://code.jquery.com/jquery-3.4.1.js"></script>
    <script>
        /*
        AJax后盾必须懂的东西：
        url：后端接受的地址
        data：后端接受到的请求参数，json数据格式=前后端分离时候，后端传的数据便于前端接受就是json数据
        success:后端接受成功返回的函数
        error:后盾失败接受返回的函数
        */
        function username() {
            $.post({
                url: "${pageContext.request.contextPath}/a1",
                data: {"name": $("#username").val()},
                success: function (data, status) {
                    console.log("data:" + data);
                    console.log("status:" + status);
                }
            })
        }

    </script>
</head>
<body>
<%--实现Ajax异步请求
    1 绑定单击事件
    2 单击事件函数使用Jq：$.post({})
--%>
用户名:<input type="text" id="username" onclick="username()">
</body>
</html>

2 Ajax实现异步加载

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Ajax</title>

    <script src="https://code.jquery.com/jquery-3.4.1.js"></script>
    <script>
        /*页面加载完*/
        $(function () {
            /*绑定btn单击事件*/
            $("#btn").click(function () {
                /*JQ使用Ajax异步请求*/
                $.post("${pageContext.request.contextPath}/a2", function (data) {
                    // data接受返回的值
                    //console.log(data);
                    var html = "";
                    for (let i = 0; i < data.length; i++) {
                        html += "<tr>" +
                            "<td>" + data[i].name + "</td>" +
                            "<td>" + data[i].age + "</td>" +
                            "<td>" + data[i].sex + "</td>" +
                            +"<tr>"
                    }
                    $("#content").html(html);
                });
            });

        })
    </script>
</head>
<body>
<input type="button" id="btn" value="加载数据">
<table>
    <tr>
        <td>姓名</td>
        <td>年龄</td>
        <td>性别</td>
    </tr>
    <tbody id="content">

    </tbody>

</table>
</body>
</html>

3 实现登录验证

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>login</title>
    <script src="https://code.jquery.com/jquery-3.4.1.js"></script>
    <script>
        function nameFun() {
            $.post({
                url: "${pageContext.request.contextPath}/a3",
                data: {"name": $("#name").val()},
                success: function (data) {
                    //console.log(data);
                    if (data.toString() === "用户名成功") {
                        $("#userInfo").css("color", "green");
                    } else {
                        $("#userInfo").css("color", "red");
                    }
                    $("#userInfo").html(data);
                }
            })
        }

        function passwordFun() {
            $.post({
                url: "${pageContext.request.contextPath}/a3",
                data: {"password": $("#password").val()},
                success: function (data) {
                    if (data.toString() === "密码正确") {
                        $("#userPasswordInfo").css("color", "green");
                    }else {
                        $("#userPasswordInfo").css("color", "red");
                    }
                    $("#userPasswordInfo").html(data);
                }
            })
        }
    </script>
</head>
<body>
<p>
    用户名:<input type="text" id="name" onclick="nameFun()">
    <%--span提示信息--%>
    <span id="userInfo"></span>
</p>
<p>
    用户密码:<input type="password" id="password" onclick="passwordFun()">
    <span id="userPasswordInfo"></span>
</p>
</body>
</html>

appliacation.xml添加json乱码问题

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <!--1 自动扫描包，让指定包下的注解生效，由IOC容器统一管理-->
    <context:component-scan base-package="com.ssl.controller"/>
    <!--2 注解驱动-->
    <mvc:annotation-driven/>
    <!--  使用JQ，使用静态资源过滤需要引用，动态就不需要-->
    <mvc:default-servlet-handler/>
    <!--注解加载映射器、适配器，解决Json数据中文乱码问题-->
    <mvc:annotation-driven>
        <mvc:message-converters register-defaults="true">
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <constructor-arg value="UTF-8"/>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                        <property name="failOnEmptyBeans" value="false"/>
                    </bean>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
    <!--3 以上的是定死的代码，以下是配置视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

7.3 后端需要的前端知识

HTML+CSS+Js（超级熟练）
Js必会？：
- 函数闭包？
- DOM
  - id,name.tag
  - create,remove
- BOM：浏览器对象模型
  - window
  - document

8 拦截器

8.1 概念

数据独立性：Servlet中的是过滤器，而拦截器是SpringMVC框架独有的，独享request和response
拦截器只会拦***问的控制器方法，如果访问的是jsp/html/css等式不会拦截的

拦截器是基于AOP思想的，和AOP实现是一样的，在application.xml中配置

<!--拦截器配置-->
<mvc:interceptors>
  <mvc:interceptor>
      <!--
              /**是拦截之后所有的请求，比如/admin/a1/2131
          -->
      <mvc:mapping path="/**"/>
      <bean class="com.ssl.config.MyInterceptor"/>
  </mvc:interceptor>
</mvc:interceptors>

8.2 自定义拦截器

实现 HandlerInterceptor

public class MyInterceptor implements HandlerInterceptor {
  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
      //return true：执行下一个拦截器
      System.out.println("===========处理前,这里进行拦截处理=================");
      return true;
  }

  @Override
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
      System.out.println("===========处理后，通常进行日志管理=================");
  }

  @Override
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
      System.out.println("===========清洁中=================");
  }
}

applica.xml配置

<!--拦截器配置-->
<mvc:interceptors>
  <mvc:interceptor>
      <!--
              /**是拦截之后所有的请求，比如/admin/a1/2131
          -->
      <mvc:mapping path="/**"/>
      <bean class="com.ssl.config.MyInterceptor"/>
  </mvc:interceptor>
</mvc:interceptors>

8.3 登录验证判断

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HttpSession session = request.getSession();
        request.getRequestURL();
        //URL:http://localhost:8080/springmvc_07_interceptor/user//main
        System.out.println("URL:" + request.getRequestURL());
        //URI:/springmvc_07_interceptor/user//main
        System.out.println("URI:" + request.getRequestURI());

        if (session.getAttribute("username") == null || session.getAttribute("password") == null) {
            request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
        } else if (session.getAttribute("username").equals("admin") && session.getAttribute("password").equals("123456")) {
            return true;
        }
        if (request.getRequestURI().contains("ogin")) {
            return true;
        }
        request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
        return false;
    }
}

@Controller
@RequestMapping("/user")
public class LoginController {

    @RequestMapping("/main")
    public String main() {
        //沒登陸就不等進入首頁
        return "main";
    }

    @RequestMapping("/goLogin")
    public String goLogin() {
        return "login";
    }


    @RequestMapping("/login")
    public String login(String username, String password, HttpSession session, Model model) {
        session.setAttribute("username", username);
        session.setAttribute("password", password);
        model.addAttribute("username", username);
        return "main";
    }

    @RequestMapping("/outUser")
    public String outUser(HttpSession session) {
        session.removeAttribute("username");
        session.removeAttribute("password");
        return "main";
    }
}

9 文件上传

前端form添加enctype="multipart/form-data",method="post"

<form enctype="multipart/form-data" method="post" action="">

</form>

后端pom导包

<dependencies>
      <dependency>
          <groupId>commons-fileupload</groupId>
          <artifactId>commons-fileupload</artifactId>
          <version>1.4</version>
      </dependency>
      <!--导入高版本的api-->
      <dependency>
          <groupId>javax.servlet</groupId>
          <artifactId>javax.servlet-api</artifactId>
          <version>4.0.1</version>
      </dependency>
  </dependencies>

Spring自带的文件上传,application.xml配置

<!--4 文件上传配置-->
  <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
      <property name="defaultEncoding" value="utf-8"/>
      <!--最大上传大小：单位是1字节-->
      <property name="maxUploadSize" value="10485760"/>
      <property name="maxInMemorySize" value="40960"/>
  </bean>

```java
@RestController
public class FileController {
    @RequestMapping("/upFile")
    public String upFile(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        //设置文件保存路径
        String path = request.getServletContext().getRealPath("/upload");
        System.out.println("path:" + path);
        File realPath = new File(path);
        if (!realPath.exists()) {
            realPath.mkdir();
        }
        System.out.println("上传的文件地址：" + realPath);
        //CommonsMultipartFile的方法写文件，简化
        file.transferTo(new File(realPath + "/" + file.getOriginalFilename()));
        return "redirect:/index.jsp";
    }
}

10 文件下载

方式一：写方法下载

@RequestMapping(value = "/download")
  public String downLoad(HttpServletResponse response, HttpServletRequest request) throws IOException {
      //手动设置，要下载的图片地址
      String path = request.getServletContext().getRealPath("/upload");
      String fileName = "1.png";
      //设置响应头
      response.reset();//设置页面不缓存，清空buffer
      response.setCharacterEncoding("UTF-8");
      response.setContentType("multipart/form-data");//二进制传输数据
      response.setHeader("Content-Disposition", "attachment;fileName=" + URLEncoder.encode(fileName, "UTF-8"));
      File file = new File(path, fileName);
      //读取文件-输入流
      InputStream input = new FileInputStream(file);
      //写入文件-输出流
      OutputStream out = response.getOutputStream();
      byte[] buff = new byte[1024];
      int index = 0;
      while ((index = input.read(buff)) != -1) {
          out.write(buff,0,index);
          out.flush();
      }
      input.close();
      out.close();
      return "redirect:/index.jsp";
  }

方式二：标签直接web下静态获取

<a href="${pageContext.request.contextPath}/static/1.png">图片下载</a>

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腾讯_游戏客户端开发(准入职员工)

腾讯光子游戏客户端上岸，cpp秋招总结

引子文章是记录自己 2024.7~2024.11 秋招的情况，也是对自己大半年来努力的一个总结和收尾，也因为牛客上很多前辈和大佬的秋招感悟对我起到了很大的帮助，所以想记录一些内容供大伙参考（情况因人而异，可以辩证看待）。个人大致情况学历：本北邮软工硕华科计科专业成绩：排名10%到15%左右，保研比赛：略等于无论文：无项目：实验室工程项目（PCIE 驱动、动态库部分）、个人小项目实习：本科一段中厂 Java 后端、硕士一段华为武研所软开个人秋招投递/面试情况暑期在华为武研所实习，总体强度不大，因此从7月初开始参加秋招提前批，一边实习一边笔试面试。秋招主要投递的方向是 C++开发、嵌入式软件、操作...

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10-18 18:48

美团_到家_前端(准入职员工)

美团真开了？还是fake news

比去年还低？

斑驳不同：还为啥暴躁假的不骂你骂谁啊

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11-17 17:47

门头沟学院后端

第一家oc，太漫长了

终于拿到第一家oc了，一家游戏小厂，开的虽然不高，连暗号都对不了，不过好歹不加班，而且感觉上挺有技术，已经算是不错的选项了。虽然有大厂实习，有点心不甘，但已经有点面不动了，应该说，能开高点的游戏厂要么挂了，要么连面试都没给，太难了今年，本以为大厂实习是开始，没想到是巅峰。打算先签了，老老实实开始弄论文了，毕竟还有三座大山的压力，如果有大厂能愿意给面试的话，到时候再考虑抢救一下，不过游戏大厂基本全是995起步，都不知道自己这老年人能不能抗住。哎，算了，连面试都没有就开始幻想工作怎么样了，拿到oc就开始飘了吗，有点过于饥渴了，个人感觉，今年c++难度有点爆炸，除了劝退率极高的客...

独角兽内推__免笔试：同学，瞅瞅我司呀，我最新动态，绿灯直达，免笔试～

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