SpringBoot 监听机制

SpringBoot 监听机制

SpringBoot 在项目启动时，会对几个监听器进行回调，我们可以实现这些监听器接口，在项目启动时完成 一些操作

• ApplicationContextInitializer
• SpringApplicationRunListener
• CommandLineRunner
• ApplicationRunner

新建项目工程

创建类

MyApplicationContextInitializer

package com.xiang.listener;

import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.stereotype.Component;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/25 21:05
 */
@Component
public class MyApplicationContextInitializer implements ApplicationContextInitializer {
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {

        System.out.println("ApplicationContextInitializer.............. initialize()");
    }
}

MyApplicationRunner

package com.xiang.listener;

import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;

import java.util.Arrays;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/25 21:08
 */
@Component
public class MyApplicationRunner implements ApplicationRunner {
    @Override
    public void run(ApplicationArguments args) throws Exception {
        System.out.println("ApplicationRunner.........run");
        System.out.println("Arrays.asList(args.getSourceArgs())------->"+Arrays.asList(args.getSourceArgs()));
    }
}

MyCommandLineRunner

package com.xiang.listener;

import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

import java.util.Arrays;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/25 21:08
 */
@Component
public class MyCommandLineRunner implements CommandLineRunner {
    @Override
    public void run(String... args) throws Exception {
        System.out.println("CommandLineRunner....run");
        System.out.println("Arrays.asList(args)--------->"+Arrays.asList(args));
    }
}

MySpringApplicationRunListener

package com.xiang.listener;

import org.springframework.boot.ConfigurableBootstrapContext;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.SpringApplicationRunListener;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.stereotype.Component;

/**
 * Created by IntelliJ IDEA.
 * User: xiang
 * Date: 2021/10/25 21:06
 */
//@Component
public class MySpringApplicationRunListener implements SpringApplicationRunListener {

    public MySpringApplicationRunListener(SpringApplication application,String[] args) {
    }

    /**
     * springBoot 启动时会触发不同的事件；
     *
     * @param bootstrapContext
     */


    @Override
    public void starting(ConfigurableBootstrapContext bootstrapContext) {
        SpringApplicationRunListener.super.starting(bootstrapContext);
        System.out.println("starting..... 项目启动中");
    }

    @Override
    public void environmentPrepared(ConfigurableBootstrapContext bootstrapContext, ConfigurableEnvironment environment) {
        SpringApplicationRunListener.super.environmentPrepared(bootstrapContext, environment);
        System.out.println("environmentPrepared..... 环境对象开始准备");
    }

    @Override
    public void environmentPrepared(ConfigurableEnvironment environment) {
        SpringApplicationRunListener.super.environmentPrepared(environment);
        System.out.println("environmentPrepared..... 环境对象开始准备.........");
    }

    @Override
    public void contextPrepared(ConfigurableApplicationContext context) {
        SpringApplicationRunListener.super.contextPrepared(context);
        System.out.println("contextPrepared..... 上下文对象开始准备");
    }

    @Override
    public void contextLoaded(ConfigurableApplicationContext context) {
        SpringApplicationRunListener.super.contextLoaded(context);
        System.out.println("contextLoaded..... 上下文对象开始加载");
    }

    @Override
    public void started(ConfigurableApplicationContext context) {
        SpringApplicationRunListener.super.started(context);
        System.out.println("started..... 上下文对象加载完成");
    }

    @Override
    public void running(ConfigurableApplicationContext context) {
        SpringApplicationRunListener.super.running(context);
        System.out.println("running..... 项目启动完成，开始运行");
    }

    @Override
    public void failed(ConfigurableApplicationContext context, Throwable exception) {
        SpringApplicationRunListener.super.failed(context, exception);
        System.out.println("failed..... 项目启动失败");
    }
}

新建META-INF/spring.factories

org.springframework.context.ApplicationContextInitializer=\
  com.xiang.listener.MyApplicationContextInitializer
org.springframework.boot.SpringApplicationRunListener=\
  com.xiang.listener.MySpringApplicationRunListener

运行主程序 测试 SpringBootListenerApplication

package com.xiang;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootListenerApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootListenerApplication.class, args);
        /**
         * 控制台只走了 两个
         * ApplicationRunner.........run
         * CommandLineRunner....run
         */
    }

}

运行结果

starting..... 项目启动中
environmentPrepared..... 环境对象开始准备.........
environmentPrepared..... 环境对象开始准备

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.5.6)

ApplicationContextInitializer.............. initialize()
contextPrepared..... 上下文对象开始准备
2021-10-25 22:39:56.188  INFO 15652 --- [           main] com.xiang.SpringBootListenerApplication  : Starting SpringBootListenerApplication using Java 1.8.0_281 on DESKTOP-6K7C1EJ with PID 15652 (D:\ComprehensiveTraining\training\springBootDemo\spring-boot-listener\target\classes started by Xiang in D:\ComprehensiveTraining\training\springBootDemo)
2021-10-25 22:39:56.193  INFO 15652 --- [           main] com.xiang.SpringBootListenerApplication  : No active profile set, falling back to default profiles: default
contextLoaded..... 上下文对象开始加载
2021-10-25 22:39:57.209  INFO 15652 --- [           main] com.xiang.SpringBootListenerApplication  : Started SpringBootListenerApplication in 1.842 seconds (JVM running for 3.343)
started..... 上下文对象加载完成
ApplicationRunner.........run
Arrays.asList(args.getSourceArgs())------->[]
CommandLineRunner....run
Arrays.asList(args)--------->[]
running..... 项目启动完成，开始运行

Process finished with exit code 0