SpringBoot几个重要的事件回调、监听机制

（1）、需要配置在META-INF/Spring.factories

　　1.ApplicationContextInitializer

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 package org.springframework.context;
 
 public interface ApplicationContextInitializer<C extends ConfigurableApplicationContext> {
     //监听ioc容器启动
     void initialize(C var1);
 }

　　2.SpringApplicationRunListener

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 package org.springframework.boot;
 
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.env.ConfigurableEnvironment;
 
 public interface SpringApplicationRunListener {
     //监听容器开始
     void starting();
     //SpringBoot环境准备好
     void environmentPrepared(ConfigurableEnvironment environment);
     //ioc容器准备好了
     void contextPrepared(ConfigurableApplicationContext context);
     //容器环境加载完成
     void contextLoaded(ConfigurableApplicationContext context);
 
     void started(ConfigurableApplicationContext context);
 
     void running(ConfigurableApplicationContext context);
     //SpringBoot创建完成
     void failed(ConfigurableApplicationContext context, Throwable exception);
 }

（2）、只需要放到ioc容器中即可

　　1.ApplicationRunner

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 package org.springframework.boot;
 
 @FunctionalInterface
 public interface ApplicationRunner {
     void run(ApplicationArguments args) throws Exception;
 }

　　2.CommandLineRunner

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 package org.springframework.boot;
 
 @FunctionalInterface
 public interface CommandLineRunner {
     void run(String... args) throws Exception;
 }