Springboot启动流程分析

目录

  1. 先简单介绍一些SpringBoot 组件
  2. 介绍启动流程

参考资料

@SpringBootConfiguration的介绍

首先介绍以下@SpringbootConfiguration的作用

  1. 源码内含@Configuration ，也就是用@SpringbootConfiguration 的类就可以当配置类，如main方法也可以作为配置类 【可以参考 注解@SpringbootConfiguration 的源码】
  2. @SpringbootConfiguration会将当前类内声明的一个或多个用@Bean注解标记的方法的实例放到入到spring容器IOC中，并且实例名就是方法名。

接下来 通过springboot的启动，我们用代码的运行结果来说明上面的情况

  • 代码1 是Springboot启动类 也充当配置类

    @SpringBootApplication
public class SpringbootdemoApplication {
  public static void main(String[] args) {
      //在这里标明以下SpringApplication.run方法返回的是spring的IOC容器
      //ConfigurableApplicationContext 跟ClassPathXmlApplicationContext都是ApplicationContext实现类
      ConfigurableApplicationContext applicationContext = SpringApplication.run(SpringbootdemoApplication.class, args);
      System.out.println(applicationContext.getBean("getPerson"));
      System.out.println(applicationContext.getBean("student"));
  }

  @Bean
  public Person getPerson() {
      return new Person();
  }

  public static class Person { } //Person类
}

  • 代码2 自己写的配置类

    @Configuration   //同样Configuration也可以改为SpringBootApplication
public class MyConfig {
  @Bean
  public Student student(){
      return new Student();
  }
  public static class Student{}//Student类
}

  • 效果 两个类都放到了IOC容器中

    图片说明

springboot启动类的run真正的是

  • 代码
      SpringApplication.run(SpringbootdemoApplication.class, args);
||   进入run方法
\/  
  public static ConfigurableApplicationContext run(Class<?> primarySource, String... args) {
      return run(new Class[]{primarySource}, args);
  }
||  再次进入run方法
\/
  public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
      return (new SpringApplication(primarySources)).run(args);
  }
||
\/   再次进入的run方法是下面的ConfigurableApplicationContext 请继续看

这时候可以知道springboot基本的启动流程

  1. 创建new SpringApplication

  2. 调用run方法 .run

    也就是运行下面这一堆 这一堆也是springboot运行的底层启动流程代码 后面会更详细介绍

     public ConfigurableApplicationContext run(String... args) {
     StopWatch stopWatch = new StopWatch();
     stopWatch.start();//里面的代码实际就是System.currentTimeMillis();用来计时启动事件
     ConfigurableApplicationContext context = null; //IOC容器
     //exceptionReporters  异常的报告器
     Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList();
     this.configureHeadlessProperty();
     SpringApplicationRunListeners listeners = this.getRunListeners(args);
     listeners.starting();

     Collection exceptionReporters;
     try {
         ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
         ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
         this.configureIgnoreBeanInfo(environment);
//Banner 也就是spring的广告图 我们可以换成其他一些好玩的
         Banner printedBanner = this.printBanner(environment);
         context = this.createApplicationContext();
         exceptionReporters = this.getSpringFactoriesInstances(SpringBootExceptionReporter.class, new Class[]{ConfigurableApplicationContext.class}, context);
         this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
         this.refreshContext(context);
         this.afterRefresh(context, applicationArguments);
         stopWatch.stop();//跟上面的start对应 计时器
         if (this.logStartupInfo) {
             (new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), stopWatch);
         }

         listeners.started(context);
         this.callRunners(context, applicationArguments);
     } catch (Throwable var10) {
         this.handleRunFailure(context, var10, exceptionReporters, listeners);
         throw new IllegalStateException(var10);
     }

     try {
         listeners.running(context);
         return context;
     } catch (Throwable var9) {
         this.handleRunFailure(context, var9, exceptionReporters, (SpringApplicationRunListeners)null);
         throw new IllegalStateException(var9);
     }
 }

SpringApplication的初始化过程

  • 代码 做初始化

    //构造函数
  public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) { 
      this.sources = new LinkedHashSet();
      this.bannerMode = Mode.CONSOLE;
      this.logStartupInfo = true;
      this.addCommandLineProperties = true;
      this.addConversionService = true;
      this.headless = true;
      this.registerShutdownHook = true;
      this.additionalProfiles = new HashSet();
      this.isCustomEnvironment = false;
      this.lazyInitialization = false;
      this.resourceLoader = resourceLoader;
      Assert.notNull(primarySources, "PrimarySources must not be null");
//重点
// primarySources 接收启动器的args参数
      this.primarySources = new LinkedHashSet(Arrays.asList(primarySources));
      this.webApplicationType = WebApplicationType.deduceFromClasspath();
      this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
      this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
      this.mainApplicationClass = this.deduceMainApplicationClass();
  }

  • WebApplicationType ： 一般是得到SERVLET WebApplicationType应用类型
    可以干嘛呢？ 我们可以通过配置来设置是否使用Springboot内置的tomcat
    如：
    web-application-type:none 为none时 需要配置外部Tomcat执行
    为servlet时 用的是自身的Tomcat

      static WebApplicationType deduceFromClasspath() {
//下面是判断有没有对应的类 响应式编程需要webflux包 暂时没有
//isPresent的底层是用反射来生成传入的字符串  然后看看那些类必须有 那些类不能有
      if (ClassUtils.isPresent("org.springframework.web.reactive.DispatcherHandler", (ClassLoader)null) && !ClassUtils.isPresent("org.springframework.web.servlet.DispatcherServlet", (ClassLoader)null) && !ClassUtils.isPresent("org.glassfish.jersey.servlet.ServletContainer", (ClassLoader)null)) {
          return REACTIVE;//reactive : spring5的新特性 代表是否用响应式编程
      } else {
         //到了else 说明含有DispatcherServlet
          String[] var0 = SERVLET_INDICATOR_CLASSES;//SERVLET_INDICATOR_CLASSES的值看下面
// private static final String[] SERVLET_INDICATOR_CLASSES = new String[]{"javax.servlet.Servlet", "org.springframework.web.context.ConfigurableWebApplicationContext"};   查找又没有后面的类 有的√
//找出DispatchServlet
          int var1 = var0.length;
//遍历我们需要的类SERVLET_INDICATOR_CLASSES是否存在 不存在return NONE 
          for(int var2 = 0; var2 < var1; ++var2) {
              String className = var0[var2];
              if (!ClassUtils.isPresent(className, (ClassLoader)null)) {
                  return NONE;
              }
          }
          return SERVLET;
      }
  }

  • setInitializers 对容器一些初始化配置

    运行  this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));

其中getSpringFactoriesInstances的底层是 SpringFactoriesLoader 【去找META-INF/spring.factories】
this.getSpringFactoriesInstances(ApplicationContextInitializer.class)中的

ApplicationContextInitializer在以下找
META-INF/spring.factories文件对应的内容为
# Application Context Initializers
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer,\
org.springframework.boot.context.ContextIdApplicationContextInitializer,\
org.springframework.boot.context.config.DelegatingApplicationContextInitializer,\
org.springframework.boot.rsocket.context.RSocketPortInfoApplicationContextInitializer,\
org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer

//在springApplication中有SpringFactoriesLoader.loadFactoryNames 
//利用其去.properties文件中进行查找 【基本的配置文件♥】
  private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) {
      ClassLoader classLoader = this.getClassLoader();
      Set<String> names = new LinkedHashSet(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
      List<T> instances = this.createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
      AnnotationAwareOrderComparator.sort(instances);
      return instances;
  }
||
\/   SpringFactoriesLoader.loadFactoryNames(type, classLoader)的具体方法
  public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
  public static List<String> loadFactoryNames(Class<?> factoryType, @Nullable ClassLoader classLoader) {
      String factoryTypeName = factoryType.getName();
      return (List)loadSpringFactories(classLoader).getOrDefault(factoryTypeName, Collections.emptyList());
  }

  • setListeners：

  • mainApplicationClass：启动类

springbootApplication注解

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
        @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {
}

注解包装了SpringBootConfiguration【包含了Configuration 类似xml】、EnableAutoConfiguration、ComponentScan【default "*/.class" 当前文件路径会自动被扫描】

  • EnableAutoConfiguration的作用【auto配置文件 ♥】 -->DispatcherServlet(springmvc)
    @Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {}
    遍历所有的Auto配置文件里面的组件（如果一些没法添加 后来就没有加入IOC中）
    图片说明

springboot如何加载tomcat 和springmvc

tomcat

  • 从配置取出的类 已经是加载到了ioc中 该类通过ctrl+alt+shift+N找的 会加到springboot里面
    含有三个服务器的配置文件
@Import({ ServletWebServerFactoryAutoConfiguration.BeanPostProcessorsRegistrar.class,
      ServletWebServerFactoryConfiguration.EmbeddedTomcat.class,
      ServletWebServerFactoryConfiguration.EmbeddedJetty.class,
      ServletWebServerFactoryConfiguration.EmbeddedUndertow.class })
public class ServletWebServerFactoryAutoConfiguration {
  @Bean
  public ServletWebServerFactoryCustomizer servletWebServerFactoryCustomizer(ServerProperties serverProperties) {
      return new ServletWebServerFactoryCustomizer(serverProperties);
  }//注意后面的serverProperties
}
    ctrl + K 得知是开启tomcat
    图片说明 
    下面的类会读取自己写的yaml配置
@ConfigurationProperties(prefix = "server", ignoreUnknownFields = true)
public class ServerProperties {
  /**
   * Server HTTP port.
   */
  private Integer port;
}
    在tomcat工厂中是实现了new Tomcat(); 后面设置tomcat 然后启动mvc
    图片说明

DispatcherServletAutoConfiguration

  • 配置

    @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass(DispatcherServlet.class)//DispatcherServlet注入ioc中
@AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class)
public class DispatcherServletAutoConfiguration {

  public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";
  public static final String DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME = "dispatcherServletRegistration";

  @Configuration(proxyBeanMethods = false)
  @Conditional(DefaultDispatcherServletCondition.class)
  @ConditionalOnClass(ServletRegistration.class)
  @EnableConfigurationProperties({ HttpProperties.class, WebMvcProperties.class })
  protected static class DispatcherServletConfiguration {

      @Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
      public DispatcherServlet dispatcherServlet(HttpProperties httpProperties, WebMvcProperties webMvcProperties) {
      ...
          return dispatcherServlet;
      }

  • 自定义的配置

    @ConfigurationProperties(prefix = "spring.mvc")
public class WebMvcProperties {
   private Locale locale;
}

启动流程

SpringApplication -> run - > ConfigurableApplicationContext
博客运行流程
代码同上面的

下面也是SpringApplication的run方法
    public ConfigurableApplicationContext run(String... args) {
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();//实际就是System.currentTimeMillis()
        ConfigurableApplicationContext context = null; //IOC容器
        Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList();//记录错误日志
        this.configureHeadlessProperty();
        SpringApplicationRunListeners listeners = this.getRunListeners(args);
        listeners.starting();

        Collection exceptionReporters;
        try {
            ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
            ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
            this.configureIgnoreBeanInfo(environment);
//Banner 也就是spring的广告图 我们可以换成其他一些好玩的
            Banner printedBanner = this.printBanner(environment);
            context = this.createApplicationContext();
            exceptionReporters = this.getSpringFactoriesInstances(SpringBootExceptionReporter.class, new Class[]{ConfigurableApplicationContext.class}, context);
            this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
            this.refreshContext(context);
            this.afterRefresh(context, applicationArguments);
            stopWatch.stop();//跟上面的start对应 计时器
            if (this.logStartupInfo) {
                (new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), stopWatch);
            }

            listeners.started(context);
            this.callRunners(context, applicationArguments);
        } catch (Throwable var10) {
            this.handleRunFailure(context, var10, exceptionReporters, listeners);
            throw new IllegalStateException(var10);
        }

        try {
            listeners.running(context);
            return context;
        } catch (Throwable var9) {
            this.handleRunFailure(context, var9, exceptionReporters, (SpringApplicationRunListeners)null);
            throw new IllegalStateException(var9);
        }
    }
  • 自定义外部扩展文件
    利用底层的源代码 将my.properties放入springboot

总结启动流程

  1. 创建springApplication 对象 new SpringApplication ,Springboot容器初始化操作

  2. 获取当前应用启动类型 原理：判断classpath是否有加载我们的servlet类 返回servlet web启动方式

       this.webApplicationType = WebApplicationType.deduceFromClasspath();
类型：REACTIVE NONE SERVLET

  3. setInitializers：读取SpringBoot包下面的META-INF/spring.factories 获取对应的ApplicationContextInitializer装配到集合中

  4. setListeners ：读取SpringBoot包下面的META-INF/spring.factories 获取对应的ApplicationContextListener装配到集合中

  5. mainApplicationClass获取当前运行的主函数

  6. 调用springApplication的 run方法 也就是上面的方法ConfigurableApplicationContext run 实现启动

  7. StopWatch stopWatch = new StopWatch();记录我们springboot项目启动时间

  8. 运行下面的代码 getRunListeners读取我们的META-INF/spring.factories文件 如SpringApplicationRunListener

    SpringApplicationRunListeners listeners = this.getRunListeners(args);
||
\/
 private SpringApplicationRunListeners getRunListeners(String[] args) {
     Class<?>[] types = new Class[]{SpringApplication.class, String[].class};
     return new SpringApplicationRunListeners(logger, this.getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args));
 }
||
\/
getSpringFactoriesInstances ：读取spring.factories文件
||
\/
this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
 private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) {
     ClassLoader classLoader = this.getClassLoader();
     Set<String> names = new LinkedHashSet(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
     List<T> instances = this.createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
     AnnotationAwareOrderComparator.sort(instances);
     return instances;
 }
上面的代码经过核对跟上面获取 setInitializers  setListeners 一致
但是获取到的结果不应用 找的方式相同 上面返回的SpringApplicationRunListener类

this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));   
this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
其中的SpringFactoriesLoader到"META-INF/spring.factories"下找配置文件的内容

找到了 spring.factories下的
org.springframework.boot.SpringApplicationRunListener=\
org.springframework.boot.context.event.EventPublishingRunListener

    图片说明
    EventPublishingRunListener：作用是给我们springboot配置文件（application.yaml...）进行赋值 参数文件配置到容器中

  9. listeners.starting(); 循环调用start方法

    void starting() { //所有的***进行启动
    Iterator var1 = this.listeners.iterator();
    while(var1.hasNext()) {
        SpringApplicationRunListener listener = (SpringApplicationRunListener)var1.next();
        listener.starting();
    }
}

在EventPublishingRunListener的start方法
public void starting() {
    this.initialMulticaster.multicastEvent(new ApplicationStartingEvent(this.application, this.args));
}

    先插入讲一个运用场景
    图片说明
    自定义一个类SpringApplicationRunListener 

    文件路径--->main\resources\META-INF\spring.factories:
org.springframework.boot.SpringApplicationRunListener=\
com.project.springbootdemo.MySpringBootApplicationRunListener

//仿造 EventPublishingRunListener来编写代码
public class MySpringBootApplicationRunListener implements SpringApplicationRunListener {
//application、args、MySpringBootApplicationRunListener：必备的代码
private final SpringApplication application;
private final String[] args;

public MySpringBootApplicationRunListener(SpringApplication application, String[] args) {
    this.application = application;
    this.args = args;
}

@Override
public void starting() {
    System.out.println("---->>>starting");
}

//配置文件读取到程序中,需要自己将本地文件读取到程序中，然后再放入spring容器
@Override
public void environmentPrepared(ConfigurableEnvironment environment) {//environment是springboot提供的
    System.out.println("---->>>environmentPrepared");
    Properties properties = new Properties();
    try {
        //读取我们的配置文件
        properties.load(getClass().getClassLoader().getResourceAsStream("my.properties"));
        //读取名称
        PropertySource propertySource = new PropertiesPropertySource("person.name", properties);
        //将资源添加到Springboot项目中
        //取出environment的getPropertySources
        MutablePropertySources propertySources = environment.getPropertySources();
        // 通过该api接口可以将配置文件读取到springboot项目中
        propertySources.addLast(propertySource);
        System.out.println(propertySources.size());
    } catch (IOException e) {
        e.printStackTrace();
    }
}

@Override
public void contextPrepared(ConfigurableApplicationContext context) {
    System.out.println("---->>>contextPrepared");
}

@Override
public void contextLoaded(ConfigurableApplicationContext context) {
    System.out.println("---->>>contextLoaded");
}

@Override
public void started(ConfigurableApplicationContext context) {
    System.out.println("---->>>started");
}
}

    记载成功
    图片说明
    读取成功

    @RestController
public class TestController {
@Value("${person.name}")  //从environment里面取
private String value;
@RequestMapping("/hello")
public String hello(Map<String,Object>map){
    return value;
}
}

    图片说明

  10. 参数赋值 

    ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
||
\/
private ConfigurableEnvironment  prepareEnvironment(SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments) { 
// 运行***environmentPrepared 读取配置文件到springboot容器中 参考我们写的MySpringBootApplicationRunListener 
  listeners.environmentPrepared((ConfigurableEnvironment)environment);
}
||
\/
void environmentPrepared(ConfigurableEnvironment environment) {
    Iterator var2 = this.listeners.iterator();
    while(var2.hasNext()) {
        SpringApplicationRunListener listener = (SpringApplicationRunListener)var2.next();
//下面的方法是重点  我们重点研究EventPublishingRunListener
        listener.environmentPrepared(environment);
    }
}
||
\/  进入EventPublishingRunListener
public void environmentPrepared(ConfigurableEnvironment environment) {
    this.initialMulticaster.multicastEvent(new ApplicationEnvironmentPreparedEvent(this.application, this.args, environment));
}
||
\/
public void multicastEvent(ApplicationEvent event) {
    this.multicastEvent(event, this.resolveDefaultEventType(event));
}
||
\/
public void multicastEvent(ApplicationEvent event, @Nullable ResolvableType eventType) {
    ResolvableType type = eventType != null ? eventType : this.resolveDefaultEventType(event);
    Executor executor = this.getTaskExecutor();
    Iterator var5 = this.getApplicationListeners(event, type).iterator();
    while(var5.hasNext()) {
        ApplicationListener<?> listener = (ApplicationListener)var5.next();
        if (executor != null) {
            executor.execute(() -> {
                this.invokeListener(listener, event);
            });
        } else {
运行------>     this.invokeListener(listener, event);
        }
    }
}
||
\/
protected void invokeListener(ApplicationListener<?> listener, ApplicationEvent event) {
    ErrorHandler errorHandler = this.getErrorHandler();
    if (errorHandler != null) {
        try {
            this.doInvokeListener(listener, event);
        } catch (Throwable var5) {
            errorHandler.handleError(var5);
        }
    } else {
运行----->          this.doInvokeListener(listener, event);
    }
}
||
\/
private void doInvokeListener(ApplicationListener listener, ApplicationEvent event) {
    try {
运行 --->           listener.onApplicationEvent(event);//有很多事件 
    } catch (ClassCastException var6) {
        String msg = var6.getMessage();
        if (msg != null && !this.matchesClassCastMessage(msg, event.getClass())) {
            throw var6;
        }

        Log logger = LogFactory.getLog(this.getClass());
        if (logger.isTraceEnabled()) {
            logger.trace("Non-matching event type for listener: " + listener, var6);
        }
    }
}
listener.onApplicationEvent(event);EventPublishingRunListener找的是ConfigFileApplicationListener 
去默认配置的路径找 "classpath:/,classpath:/config/,file:./,file:./config/";
||
\/
public void onApplicationEvent(ApplicationEvent event) {
    if (event instanceof ApplicationEnvironmentPreparedEvent) {
        运行---->this.onApplicationEnvironmentPreparedEvent((ApplicationEnvironmentPreparedEvent)event);
    }

    if (event instanceof ApplicationPreparedEvent) {
        this.onApplicationPreparedEvent(event);
    }
}
||
\/
private void onApplicationEnvironmentPreparedEvent(ApplicationEnvironmentPreparedEvent event) {
    List<EnvironmentPostProcessor> postProcessors = this.loadPostProcessors();
    postProcessors.add(this);
    AnnotationAwareOrderComparator.sort(postProcessors);
    Iterator var3 = postProcessors.iterator();

    while(var3.hasNext()) {
        EnvironmentPostProcessor postProcessor = (EnvironmentPostProcessor)var3.next();
        运行--->postProcessor.postProcessEnvironment(event.getEnvironment(), event.getSpringApplication());//找到的是ConfigFileApplicationListener***
    }
}
||
\/
public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
    this.addPropertySources(environment, application.getResourceLoader());
}
||
\/
protected void addPropertySources(ConfigurableEnvironment environment, ResourceLoader resourceLoader) {
    RandomValuePropertySource.addToEnvironment(environment);
    (new ConfigFileApplicationListener.Loader(environment, resourceLoader)).load();    //Loader类读取一些配置文件 重点看load方法
}
||
\/
public void load(){}
||
\/
    private void load(ConfigFileApplicationListener.Profile profile, ConfigFileApplicationListener.DocumentFilterFactory filterFactory, ConfigFileApplicationListener.DocumentConsumer consumer) {
        this.getSearchLocations().forEach((location) -> {
            boolean isFolder = location.endsWith("/");
            Set<String> names = isFolder ? this.getSearchNames() : ConfigFileApplicationListener.NO_SEARCH_NAMES;
for循环            names.forEach((name) -> {
-->                  this.load(location, name, profile, filterFactory, consumer);
            });
        });
    }
||
\/   所有的配置路径会遍历一遍 除非找到目标文件
    private void load(String location, String name, ConfigFileApplicationListener.Profile profile, ConfigFileApplicationListener.DocumentFilterFactory filterFactory, ConfigFileApplicationListener.DocumentConsumer consumer) {
        if (!StringUtils.hasText(name)) {
            Iterator var13 = this.propertySourceLoaders.iterator();

            PropertySourceLoader loader;
            do {
                if (!var13.hasNext()) {
                    throw new IllegalStateException("File extension of config file location '" + location + "' is not known to any PropertySourceLoader. If the location is meant to reference a directory, it must end in '/'");
                }

                loader = (PropertySourceLoader)var13.next();
            } while(!this.canLoadFileExtension(loader, location));

            this.load(loader, location, profile, filterFactory.getDocumentFilter(profile), consumer);
        } else {
            Set<String> processed = new HashSet();
            Iterator var7 = this.propertySourceLoaders.iterator();

// PropertySourceLoader 分析得到他的继承类有两个properties yaml 其中子类实现的文件后缀有 properties xml yaml yml
            while(var7.hasNext()) {
                PropertySourceLoader loaderx = (PropertySourceLoader)var7.next(); 
                String[] var9 = loaderx.getFileExtensions();
                int var10 = var9.length;

                for(int var11 = 0; var11 < var10; ++var11) {
                    String fileExtension = var9[var11];
                    if (processed.add(fileExtension)) {
                        this.loadForFileExtension(loaderx, location + name, "." + fileExtension, profile, filterFactory, consumer);
                    }
                }
            }

        }
    }
||
\/
    private void loadForFileExtension(PropertySourceLoader loader, String prefix, String fileExtension, ConfigFileApplicationListener.Profile profile, ConfigFileApplicationListener.DocumentFilterFactory filterFactory, ConfigFileApplicationListener.DocumentConsumer consumer) {
        this.load(loader, prefix + fileExtension, profile, profileFilter, consumer);

}
||
\/
    private void load(PropertySourceLoader loader, String location, ConfigFileApplicationListener.Profile profile, ConfigFileApplicationListener.DocumentFilter filter, ConfigFileApplicationListener.DocumentConsumer consumer) {
        try {
            Resource resource = this.resourceLoader.getResource(location);
           else {
                    String name = "applicationConfig: [" + location + "]";

---->List<ConfigFileApplicationListener.Document> documents = this.loadDocuments(loader, name, resource);
                    if (CollectionUtils.isEmpty(documents)) {
                        if (this.logger.isTraceEnabled()) {
                            StringBuilder description = this.getDescription("Skipped unloaded config ", location, resource, profile);
                            this.logger.trace(description);
                        }

                    }
...
}
||
\/ 读取加载成功后 通过  this.addLoadedPropertySources();将文件记载到springboot中 如environment
    private void addLoadedPropertySources() {
        MutablePropertySources destination = this.environment.getPropertySources();
        List<MutablePropertySources> loaded = new ArrayList(this.loaded.values());
        Collections.reverse(loaded);
        String lastAdded = null;
        Set<String> added = new HashSet();
        Iterator var5 = loaded.iterator();
....
}

    图片说明

    去默认配置文件路径下找 file【直接编译前的配置文件】 classpath【读取编译后的配置文件】 默认读取application
    图片说明
    PropertySourceLoader 分析得到他的实现类有两个properties yaml 其中子类实现的文件后缀有 properties xml yaml yml每一种都会读取以下
    最后在对应的路径下找到了 然后在PropertySourceLoader 的实现类中解析
    图片说明

  11. 读取会覆盖 Order制定优先级（Event*** ）
    读取顺序properties xml yml yaml

  12. 打印springboot Banner图

  13. context = this.createApplicationContext(); 初始化AnnotationConfigServletWebServerApplicationContext（IOC）

    protected ConfigurableApplicationContext createApplicationContext() {
    Class<?> contextClass = this.applicationContextClass;
    if (contextClass == null) {
        try {
            switch(this.webApplicationType) {
            case SERVLET:
          --->      contextClass = Class.forName("org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext");
                break;

            }
        } catch (ClassNotFoundException var3) {
            throw new IllegalStateException("Unable create a default ApplicationContext, please specify an ApplicationContextClass", var3);
        }
    }

  14. 先做一些的提前准备 然后执行this.refreshContext(context);刷新上下文

           this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
       this.refreshContext(context);
||
\/
private void refreshContext(ConfigurableApplicationContext context) {
   this.refresh(context);
   if (this.registerShutdownHook) {
       try {
           context.registerShutdownHook();
       } catch (AccessControlException var3) {
       }
   }
}
||
\/
protected void refresh(ApplicationContext applicationContext) {
   Assert.isInstanceOf(AbstractApplicationContext.class, applicationContext);
   ((AbstractApplicationContext)applicationContext).refresh();
-->选择到ServletWebServerApplicationContext 
}
||
\/  
public final void refresh() throws BeansException, IllegalStateException {
   try {
       super.refresh();  springioc的创建方法
   } catch (RuntimeException var2) {
       this.stopAndReleaseWebServer();
       throw var2;
   }
}
||
\/ super.refresh 中有一个            
this.OnRefresh()
||
\/
this.createWebServer();
||
\/
private void createWebServer() {
   WebServer webServer = this.webServer;
   ServletContext servletContext = this.getServletContext();
   if (webServer == null && servletContext == null) {
       ServletWebServerFactory factory = this.getWebServerFactory();
//获得tomcat
       this.webServer = factory.getWebServer(new ServletContextInitializer[]{this.getSelfInitializer()});
   }
}

  15. 创建tomcat

    @Import({ ServletWebServerFactoryAutoConfiguration.BeanPostProcessorsRegistrar.class,

---->ServletWebServerFactoryConfiguration.EmbeddedTomcat.class,
    ServletWebServerFactoryConfiguration.EmbeddedJetty.class,
    ServletWebServerFactoryConfiguration.EmbeddedUndertow.class })
public class ServletWebServerFactoryAutoConfiguration {
...
}
||
\/
static class EmbeddedTomcat {

    @Bean
--->    TomcatServletWebServerFactory tomcatServletWebServerFactory(
            ObjectProvider<TomcatConnectorCustomizer> connectorCustomizers,
            ObjectProvider<TomcatContextCustomizer> contextCustomizers,
            ObjectProvider<TomcatProtocolHandlerCustomizer<?>> protocolHandlerCustomizers) {
        TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory();
        factory.getTomcatConnectorCustomizers()
                .addAll(connectorCustomizers.orderedStream().collect(Collectors.toList()));
        factory.getTomcatContextCustomizers()
                .addAll(contextCustomizers.orderedStream().collect(Collectors.toList()));
        factory.getTomcatProtocolHandlerCustomizers()
                .addAll(protocolHandlerCustomizers.orderedStream().collect(Collectors.toList()));
        return factory;
    }
||
\/
TomcatServletWebServerFactory 
public WebServer getWebServer(ServletContextInitializer... initializers) {
    Tomcat tomcat = new Tomcat();
}

    图片说明

  16. 开始加载springmvc

    @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass(DispatcherServlet.class)
@AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class)
public class DispatcherServletAutoConfiguration {
@Configuration(proxyBeanMethods = false)
@Conditional(DefaultDispatcherServletCondition.class)
@ConditionalOnClass(ServletRegistration.class)
@EnableConfigurationProperties({ HttpProperties.class, WebMvcProperties.class })
protected static class DispatcherServletConfiguration {

--->    @Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
    public DispatcherServlet dispatcherServlet(HttpProperties httpProperties, WebMvcProperties webMvcProperties) {
        DispatcherServlet dispatcherServlet = new DispatcherServlet();
        dispatcherServlet.setDispatchOptionsRequest(webMvcProperties.isDispatchOptionsRequest());
        dispatcherServlet.setDispatchTraceRequest(webMvcProperties.isDispatchTraceRequest());
        dispatcherServlet.setThrowExceptionIfNoHandlerFound(webMvcProperties.isThrowExceptionIfNoHandlerFound());
        dispatcherServlet.setPublishEvents(webMvcProperties.isPublishRequestHandledEvents());
        dispatcherServlet.setEnableLoggingRequestDetails(httpProperties.isLogRequestDetails());
        return dispatcherServlet;
    }
}
  1. 定义afterRefresh 是一个空方法
    让用户自定义编写
    protected void afterRefresh(ConfigurableApplicationContext context, ApplicationArguments args) {
}
  1. 调用started 告诉别人***启动成功
  2. listener.running()
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