spring boot 源码分析(八) 事件机制 之 SpringApplicationEvent子类分析

1、前言

前面的文章咱们讲解了一下spring boot配置文件加载的相关源码分析，下面咱们将从源码角度讲解一下spring boot 相关的事件机制， 本章咱们将从 ApplicationEnvironmentPreparedEvent类分析一下spring boot 的事件机制。

2、类图

3、源码解析

ApplicationEnvironmentPreparedEvent

package org.springframework.boot.context.event;

import org.springframework.boot.SpringApplication;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;

//当springApplication启动而且环境第一次可用检查和修改的时候发布事件
@SuppressWarnings("serial")
public class ApplicationEnvironmentPreparedEvent extends SpringApplicationEvent {

	private final ConfigurableEnvironment environment;

	
	public ApplicationEnvironmentPreparedEvent(SpringApplication application,
			String[] args, ConfigurableEnvironment environment) {
		super(application, args);
		this.environment = environment;
	}

	
	public ConfigurableEnvironment getEnvironment() {
		return this.environment;
	}

}

ApplicationFailedEvent

package org.springframework.boot.context.event;

import org.springframework.boot.SpringApplication;
import org.springframework.context.ConfigurableApplicationContext;

//当SpringApplication启动失败时发布事件
@SuppressWarnings("serial")
public class ApplicationFailedEvent extends SpringApplicationEvent {

	private final ConfigurableApplicationContext context;

	private final Throwable exception;

	
	public ApplicationFailedEvent(SpringApplication application, String[] args,
			ConfigurableApplicationContext context, Throwable exception) {
		super(application, args);
		this.context = context;
		this.exception = exception;
	}

	
	public ConfigurableApplicationContext getApplicationContext() {
		return this.context;
	}

	
	public Throwable getException() {
		return this.exception;
	}

}

ApplicationPreparedEvent

package org.springframework.boot.context.event;

import org.springframework.boot.SpringApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.Environment;

//当SpringApplication启动后而且上下文充分准备但没刷新的时候发布事件，bean定义将会加载而且环境在这步已经准备好被使用
@SuppressWarnings("serial")
public class ApplicationPreparedEvent extends SpringApplicationEvent {

	private final ConfigurableApplicationContext context;

	
	public ApplicationPreparedEvent(SpringApplication application, String[] args,
			ConfigurableApplicationContext context) {
		super(application, args);
		this.context = context;
	}

	
	public ConfigurableApplicationContext getApplicationContext() {
		return this.context;
	}

}

ApplicationReadyEvent

package org.springframework.boot.context.event;

import org.springframework.boot.SpringApplication;
import org.springframework.context.ConfigurableApplicationContext;

//表示SpringApplication已经准备好为外面提供服务
@SuppressWarnings("serial")
public class ApplicationReadyEvent extends SpringApplicationEvent {

	private final ConfigurableApplicationContext context;

	
	public ApplicationReadyEvent(SpringApplication application, String[] args,
			ConfigurableApplicationContext context) {
		super(application, args);
		this.context = context;
	}

	
	public ConfigurableApplicationContext getApplicationContext() {
		return this.context;
	}

}

ApplicationStartedEvent

package org.springframework.boot.context.event;

import org.springframework.boot.ApplicationRunner;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.context.ConfigurableApplicationContext;


//一旦上下文刷新但在任何应用或命令行调用前都会被发布事件
@SuppressWarnings("serial")
public class ApplicationStartedEvent extends SpringApplicationEvent {

	private final ConfigurableApplicationContext context;

	
	public ApplicationStartedEvent(SpringApplication application, String[] args,
			ConfigurableApplicationContext context) {
		super(application, args);
		this.context = context;
	}

	
	public ConfigurableApplicationContext getApplicationContext() {
		return this.context;
	}

}

ApplicationStartingEvent 

package org.springframework.boot.context.event;

import org.springframework.boot.SpringApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationListener;
import org.springframework.core.env.Environment;

//当springApplication启动后发布事件
//但他是在Environment和ApplicationContext可用以前
//在ApplicationListeners注册以后。
@SuppressWarnings("serial")
public class ApplicationStartingEvent extends SpringApplicationEvent {

	
	public ApplicationStartingEvent(SpringApplication application, String[] args) {
		super(application, args);
	}

}