SpringBoot系列之启动成功后执行业务的方法归纳

SpringBoot系列之启动成功后执行业务逻辑。在Springboot项目中经常会遇到需要在项目启动成功后，加一些业务逻辑的，比如缓存的预处理，配置参数的加载等等场景，下面给出一些常有的方法

实验环境

JDK 1.8
SpringBoot 2.2.1
Maven 3.2+
Mysql 8.0.26
开发工具
- IntelliJ IDEA
- smartGit

动手实践

ApplicationRunner和CommandLineRunner

比较常有的使用Springboot框架提供的ApplicationRunner和CommandLineRunner，这两种Runner可以实现在Springboot项目启动后，执行我们自定义的业务逻辑，然后执行的顺序可以通过@Order进行排序，参数值越小，越早执行

写个测试类实现ApplicationRunner接口，注意加上@Component才能被Spring容器扫描到

package com.example.jedis.runner;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Order(1)
@Component
@Slf4j
public class TestApplicationRunner implements ApplicationRunner {

    @Override
    public void run(ApplicationArguments args) throws Exception {
        log.info("TestApplicationRunner");
    }
}

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实现CommandLineRunner接口

package com.example.jedis.runner;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.CommandLineRunner;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Order(2)
@Component
@Slf4j
public class TestCommandLineRunner implements CommandLineRunner {


    @Override
    public void run(String... args) throws Exception {
        log.info("TestCommandLineRunner");
    }
}

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ApplicationListener加ApplicationStartedEvent

SpringBoot基于Spring框架的事件监听机制，提供ApplicationStartedEvent可以对SpringBoot启动成功后的监听，基于事件监听机制，我们可以在SpringBoot启动成功后做一些业务操作

package com.example.jedis.listener;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.context.event.ApplicationStartedEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class TestApplicationListener implements ApplicationListener<ApplicationStartedEvent> {

    @Override
    public void onApplicationEvent(ApplicationStartedEvent applicationStartedEvent) {
        log.info("onApplicationEvent");
    }
}

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SpringApplicationRunListener

如果要在启动的其它阶段做业务操作，可以实现SpringApplicationRunListener接口，例如要实现打印swagger的api接口文档url，可以在对应方法进行拓展即可

package com.example.jedis.listener;

import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.SpringApplicationRunListener;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;

import java.net.InetAddress;

@Slf4j
public class TestSpringApplicationRunListener implements SpringApplicationRunListener {

    private final SpringApplication application;
    private final String[] args;

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


    @Override
    public void starting() {
        log.info("starting...");
    }

    @Override
    public void environmentPrepared(ConfigurableEnvironment environment) {
        log.info("environmentPrepared...");

    }

    @Override
    public void contextPrepared(ConfigurableApplicationContext context) {
        log.info("contextPrepared...");
    }

    @Override
    public void contextLoaded(ConfigurableApplicationContext context) {
        log.info("contextLoaded...");
    }

    @Override
    public void started(ConfigurableApplicationContext context) {
        log.info("started...");
    }

    @SneakyThrows
    @Override
    public void running(ConfigurableApplicationContext context) {
        log.info("running...");
        ConfigurableEnvironment environment = context.getEnvironment();
        String port = environment.getProperty("server.port");
        String contextPath = environment.getProperty("server.servlet.context-path");
        String docPath = port + "" + contextPath + "/doc.html";
        String externalAPI = InetAddress.getLocalHost().getHostAddress();

        log.info("\n Swagger API: "
                        + "Local-API: \t\thttp://127.0.0.1:{}\n\t"
                        + "External-API: \thttp://{}:{}\n\t",
                docPath, externalAPI, docPath);
    }

    @Override
    public void failed(ConfigurableApplicationContext context, Throwable exception) {
        log.info("failed...");
    }
}

在/META-INF/spring.factories配置文件配置：

org.springframework.boot.SpringApplicationRunListener=\
  com.example.jedis.listener.TestSpringApplicationRunListener

在这里插入图片描述

源码分析

在Springboot的run方法里找到如下的源码，大概看一下就可以知道里面是封装了对Runner和SpringApplicationRunListener的调用

public ConfigurableApplicationContext run(String... args) {
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        ConfigurableApplicationContext context = null;
        Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList();
        this.configureHeadlessProperty();
        SpringApplicationRunListeners listeners = this.getRunListeners(args);
        // SpringApplicationRunListener调用
        listeners.starting();

        Collection exceptionReporters;
        try {
            ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
            ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
            this.configureIgnoreBeanInfo(environment);
            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();
            if (this.logStartupInfo) {
                (new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), stopWatch);
            }
			// SpringApplicationRunListener start
            listeners.started(context);
            // 调用所有的Runner
            this.callRunners(context, applicationArguments);
        } catch (Throwable var10) {
            this.handleRunFailure(context, var10, exceptionReporters, listeners);
            throw new IllegalStateException(var10);
        }

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