2月17-备孕春招40天-第35天

①leetcode

比特位计数 (根据剑指offer每次减1然后与运算。本题更优的解:当知道了i的比特数,就知道了2 * i和 2* i+1的比特数)

https://leetcode-cn.com/problems/counting-bits/submissions/

前k个高频元素

https://leetcode-cn.com/problems/top-k-frequent-elements/solution/leetcode-di-347-hao-wen-ti-qian-k-ge-gao-pin-yuan-/

字符串解码:

https://leetcode-cn.com/problems/decode-string/submissions/

每日温度(单调栈问题) 最大矩形和接雨水问题

https://leetcode-cn.com/problems/daily-temperatures/

回文子串个数:

https://leetcode-cn.com/problems/palindromic-substrings/submissions/

②ssm整合:

表现层,业务层,持久层 springMVC、spring、mybatis

使用spring整合springMVC和mybatis

创建web-app需要的属性(防止创建项目时下载耗时)

archetypeCatalog

internal

声明ssm的版本:(报错就换一下)

<properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <maven.compiler.source>1.8</maven.compiler.source>
  <maven.compiler.target>1.8</maven.compiler.target>
  <spring.version>5.3.12</spring.version>
  <slf4j.version>1.6.6</slf4j.version>
  <log4j.version>1.2.12</log4j.version>
  <shiro.version>1.2.3</shiro.version>
  <mysql.version>5.1.6</mysql.version>
  <mybatis.version>3.4.5</mybatis.version>
</properties>

在pom.xml中导入依赖:


<!-- spring -->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.6.8</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>

<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>

<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>

<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>

<!-- log start -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>

<!-- log end -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>

<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.3.0</version>
</dependency>

<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1.2</version>
<type>jar</type>
<scope>compile</scope>
</dependency>

提示:想在java文件夹下写测试方法(使用junit的@test注解),需要把pom.xml中junit范围设置为compile

创建java、resource文件夹

创建domain包下的实体类 (Serializable接口)

创建dao包下的dao接口

创建service包下的接口(和dao接口一样),并编写对应的

AccountServiceImpl实现类。

创建spring的配置xml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:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">

<!-- 配置 spring 创建容器时要扫描的包 -->
<context:component-scan base-package="com.itheima">
<!--制定扫包规则,不扫描@Controller 注解的 JAVA 类,其他的还是要扫描 -->
<context:exclude-filter type="annotation"
expression="org.springframework.stereotype.Controller" />
</context:component-scan>

<!--    spring整合mybatis框架-->
<!--    配置连接池-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql:///ssm"></property>
        <property name="user" value="root"></property>
        <property name="password" value="root"></property>
    </bean>
<!--    配置工厂对象-->
    <bean id="sqlSessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
<!--    配置接口所在包-->
    <bean id="mapperScanner" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.yan.dao"/>
    </bean>
</beans>

使用@Service注解,把业务层实现类放入IOC

把log4j配置文件放在resource文件夹下

至此spring搭建完成,下面整合MVC: 在web.xml中配置前端控制器、过滤器、监听器:


<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <!--  解决中文乱码-->
  <filter>
    <filter-name>characterEncodingFilter</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>characterEncodingFilter</filter-name>
    <url-pattern>/</url-pattern>
  </filter-mapping>

<!--  配置spring监听器,默认只加载WEB-INF目录下的applicationContext.xml配置文件-->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
<!--  设置配置文件的路径-->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext.xml</param-value>
  </context-param>

<!--  配置前端控制器-->
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--  加载springmvc.xml配置文件-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
<!--    启动服务器,创建该servlet-->
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  
</web-app>

编写springmvc.xml:


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<!--开启注解扫描,只扫描Controller注解-->
<context:component-scan base-package="com.yan">
    <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
</context:component-scan>


<!--配置视图解析器对象-->
<bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/pages/"/>
    <property name="suffix" value=".jsp"/>
</bean>


<!--过滤静态资源-->
    <mvc:resources location="/css/" mapping="/css/**"/> <!-- 样式 -->
    <mvc:resources location="/images/" mapping="/images/**"/> <!-- 图片 -->
    <mvc:resources location="/js/" mapping="/js/**"/> <!-- javascript -->


<!--开启springMVC注解支持-->
    <mvc:annotation-driven />


</beans>

至此可以编写index文件,编写并测试controller

spring整合springMVC原理:

alt

整合mybatis: 在dao接口使用注解编写sql语句:

alt

编写mybatis主配置文件(整合到spring后,这个配置文件里的信息都交给IOC管理了,可以删除这个配置文件): 在resources文件夹下新建SqlMapConfig.xml文件:


<?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">
<configuration>
<!--    配置环境-->
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/ssm"/><!--localhost:3306可以省略不写-->
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

<!--    引入映射文件-->
    <mappers>
<!--        <mapper class="com.yan.dao.AccountDao"></mapper>-->
        <package name="com.yan.dao"/>
    </mappers>

</configuration>

至此,进行mybatis整合的测试:


package com.yan.test;


import com.yan.dao.AccountDao;
import com.yan.domain.Account;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import java.io.InputStream;
import java.util.List;

public class TestMybatis {


    @Test
    public void run1() throws Exception{
        //加载配置文件
        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建SqlSessionFactory对象
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        //创建SqlSession对象
        SqlSession session = factory.openSession();
        //获取代理对象
        AccountDao dao = session.getMapper(AccountDao.class);
        //查询数据
        List<Account> list = dao.findAll();
        for(Account account : list){
            System.out.println(account);
        }
        //关闭链接
        session.close();
        in.close();
    }
}

spring整合mybatis框架(把mybatis的连接池、工厂、dao包放到IOC管理): spring的配置文件(applicationContext.xml)中编写代码(见上)。

在把dao接口使用@Repository交给IOC管理; 在业务层对应的实现类中,使用@Autowired注入这个接口(这个接口的实现类不用自己写)

alt

前端jsp文件:

<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %><%--设置为false,可以直接写java代码--%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><%--引入之后可以写下面的遍历代码--%>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h3>查询成功</h3>
${list}
<c:forEach items="${list}" var="account">
    ${account.name}
</c:forEach>
</body>
</html>

idea常用的快捷键

Alt+回车 导入包,自动修正

Ctrl+N 查找类

Ctrl+Shift+N 查找文件

Ctrl+Alt+L 格式化代码

Ctrl+Alt+O 优化导入的类和包

Alt+Insert 生成代码(如get,set方法,构造函数等)

Ctrl+E或者Alt+Shift+C 最近更改的代码

Ctrl+R 替换文本

Ctrl+F 查找文本

Ctrl+Shift+Space 自动补全代码

Ctrl+空格 代码提示

Ctrl+Alt+Space 类名或接口名提示

Ctrl+P 方法参数提示

Ctrl+Shift+Alt+N 查找类中的方法或变量

Alt+Shift+C 对比最近修改的代码

Shift+F6 重构-重命名

Ctrl+Shift+先上键

Ctrl+X 删除行

Ctrl+D 复制行

Ctrl+/ 或 Ctrl+Shift+/ 注释(// 或者/.../ )

Ctrl+J 自动代码

Ctrl+E 最近打开的文件

Ctrl+H 显示类结构图

Ctrl+Q 显示注释文档

Alt+F1 查找代码所在位置

Alt+1 快速打开或隐藏工程面板

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