标签：lis block 理解 getc gis 情况 rsh fail factory
http://blog.csdn.net/liaokailin/article/details/48186331
spring boot在启动过程中增加事件监听机制，为用户功能拓展提供极大的便利。
ApplicationStartedEvent
ApplicationEnvironmentPreparedEvent
ApplicationPreparedEvent
ApplicationFailedEvent
1.监听类实现ApplicationListener接口
2.将监听类添加到SpringApplication实例
ApplicationStartedEvent：spring boot启动开始时执行的事件
创建对应的监听类 MyApplicationStartedEventListener.java
package com.lkl.springboot.listener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.context.event.ApplicationStartedEvent;
import org.springframework.context.ApplicationListener;
/**
* spring boot 启动监听类
*
* @author liaokailin
* @version $Id: MyApplicationStartedEventListener.java, v 0.1 2015年9月2日 下午11:06:04 liaokailin Exp $
*/
public class MyApplicationStartedEventListener implements ApplicationListener<ApplicationStartedEvent> {
private Logger logger = LoggerFactory.getLogger(MyApplicationStartedEventListener.class);
@Override
public void onApplicationEvent(ApplicationStartedEvent event) {
SpringApplication app = event.getSpringApplication();
app.setShowBanner(false);// 不显示banner信息
logger.info("==MyApplicationStartedEventListener==");
}
}
在该事件中可以获取到SpringApplication对象，可做一些执行前的设置.
Application.java类
package com.lkl.springboot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import com.lkl.springboot.listener.MyApplicationStartedEventListener;
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication app = new SpringApplication(Application.class);
app.addListeners(new MyApplicationStartedEventListener());
app.run(args);
}
}
ApplicationEnvironmentPreparedEvent：spring boot 对应Enviroment已经准备完毕，但此时上下文context还没有创建。
MyApplicationEnvironmentPreparedEventListener.java
package com.lkl.springboot.listener;
import java.util.Iterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.context.event.ApplicationEnvironmentPreparedEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.MutablePropertySources;
import org.springframework.core.env.PropertySource;
/**
* spring boot 配置环境事件监听
* @author liaokailin
* @version $Id: MyApplicationEnvironmentPreparedEventListener.java, v 0.1 2015年9月2日 下午11:21:15 liaokailin Exp $
*/
public class MyApplicationEnvironmentPreparedEventListener implements
ApplicationListener<ApplicationEnvironmentPreparedEvent> {
private Logger logger = LoggerFactory.getLogger(MyApplicationEnvironmentPreparedEventListener.class);
@Override
public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
ConfigurableEnvironment envi = event.getEnvironment();
MutablePropertySources mps = envi.getPropertySources();
if (mps != null) {
Iterator<PropertySource<?>> iter = mps.iterator();
while (iter.hasNext()) {
PropertySource<?> ps = iter.next();
logger
.info("ps.getName:{};ps.getSource:{};ps.getClass:{}", ps.getName(), ps.getSource(), ps.getClass());
}
}
}
}
在该监听中获取到ConfigurableEnvironment后可以对配置信息做操作，例如：修改默认的配置信息，增加额外的配置信息等等~~~
ApplicationPreparedEvent:spring boot上下文context创建完成，但此时spring中的bean是没有完全加载完成的。
MyApplicationPreparedEventListener.java
package com.lkl.springboot.listener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.context.event.ApplicationPreparedEvent;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationListener;
import org.springframework.context.ConfigurableApplicationContext;
/**
* 上下文创建完成后执行的事件监听器
*
* @author liaokailin
* @version $Id: MyApplicationPreparedEventListener.java, v 0.1 2015年9月2日 下午11:29:38 liaokailin Exp $
*/
public class MyApplicationPreparedEventListener implements ApplicationListener<ApplicationPreparedEvent> {
private Logger logger = LoggerFactory.getLogger(MyApplicationPreparedEventListener.class);
@Override
public void onApplicationEvent(ApplicationPreparedEvent event) {
ConfigurableApplicationContext cac = event.getApplicationContext();
passContextInfo(cac);
}
/**
* 传递上下文
* @param cac
*/
private void passContextInfo(ApplicationContext cac) {
//dosomething()
}
}
在获取完上下文后，可以将上下文传递出去做一些额外的操作。
在该监听器中是无法获取自定义bean并进行操作的。
ApplicationFailedEvent:spring boot启动异常时执行事件 MyApplicationFailedEventListener.java
package com.lkl.springboot.listener;
import org.springframework.boot.context.event.ApplicationFailedEvent;
import org.springframework.context.ApplicationListener;
public class MyApplicationFailedEventListener implements ApplicationListener<ApplicationFailedEvent> {
@Override
public void onApplicationEvent(ApplicationFailedEvent event) {
Throwable throwable = event.getException();
handleThrowable(throwable);
}
/*处理异常*/
private void handleThrowable(Throwable throwable) {
}
}
在异常发生时，最好是添加虚拟机对应的钩子进行资源的回收与释放，能友善的处理异常信息。
在spring boot中已经为大家考虑了这一点，默认情况开启了对应的功能：
public void registerShutdownHook() {
if (this.shutdownHook == null) {
// No shutdown hook registered yet.
this.shutdownHook = new Thread() {
@Override
public void run() {
doClose();
}
};
Runtime.getRuntime().addShutdownHook(this.shutdownHook);
}
}在doClose()方法中进行资源的回收与释放。
spring boot提供的四种监听事件到这里就结束了，针对实际业务可添加自定义的监听器，下一节当中将会对spring boot中的监听源码进行分析，理解为什么是这样的。
标签：lis block 理解 getc gis 情况 rsh fail factory
原文地址：http://www.cnblogs.com/exmyth/p/7750770.html
