Spring MVC启动时初始化的几个常用方法

Spring-MVC的应用中，要实现类似的功能，主要是通过实现下面这些接口（任选一，至少一个即可）

一、ApplicationContextAware接口

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package org.springframework.context;   import org.springframework.beans.BeansException; import org.springframework.beans.factory.Aware; import org.springframework.context.ApplicationContext;   public interface ApplicationContextAware extends Aware {     void setApplicationContext(ApplicationContext var1) throws BeansException; }

二、ServletContextAware 接口

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package org.springframework.web.context;   import javax.servlet.ServletContext; import org.springframework.beans.factory.Aware;   public interface ServletContextAware extends Aware {     void setServletContext(ServletContext var1); }

三、InitializingBean 接口

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package org.springframework.beans.factory;   public interface InitializingBean {     void afterPropertiesSet() throws Exception; }

四、ApplicationListener<ApplicationEvent> 接口

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package org.springframework.context;   import java.util.EventListener; import org.springframework.context.ApplicationEvent;   public interface ApplicationListener<E extends ApplicationEvent> extends EventListener {     void onApplicationEvent(E var1); }

示例程序：

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package test.web.listener;   import org.apache.logging.log4j.*; import org.springframework.beans.*; import org.springframework.beans.factory.InitializingBean; import org.springframework.context.*; import org.springframework.context.event.ContextRefreshedEvent; import org.springframework.stereotype.Component; import org.springframework.web.context.ServletContextAware; import javax.servlet.ServletContext;   @Component public class StartupListener implements ApplicationContextAware, ServletContextAware,         InitializingBean, ApplicationListener<ContextRefreshedEvent> {       protected Logger logger = LogManager.getLogger();       @Override     public void setApplicationContext(ApplicationContext ctx) throws BeansException {         logger.info("1 => StartupListener.setApplicationContext");     }       @Override     public void setServletContext(ServletContext context) {         logger.info("2 => StartupListener.setServletContext");     }       @Override     public void afterPropertiesSet() throws Exception {         logger.info("3 => StartupListener.afterPropertiesSet");     }       @Override     public void onApplicationEvent(ContextRefreshedEvent evt) {         logger.info("4.1 => MyApplicationListener.onApplicationEvent");         if (evt.getApplicationContext().getParent() == null) {             logger.info("4.2 => MyApplicationListener.onApplicationEvent");         }     }   }

运行时，输出的顺序如下：

1 => StartupListener.setApplicationContext
2 => StartupListener.setServletContext
3 => StartupListener.afterPropertiesSet
4.1 => MyApplicationListener.onApplicationEvent
4.2 => MyApplicationListener.onApplicationEvent
4.1 => MyApplicationListener.onApplicationEvent

注意：onApplicationEvent方法会触发多次，初始化这种事情，越早越好，建议在setApplicationContext方法中处理。

最后一步别忘了，在spring-config.xml中加入自定义的bean，如下面的例子：

   <!--初始化操作的bean 在spring初始化完成的时候执行这个操作 -->
	<bean class="com.**.firm.fclient.web.listener.ApplicationContextListener"/>

此外还有一种方法：

写个BEAN，将要执行的操作写在构造函数里，在将这个类配置到XML里，比如配置到SPRING-MVC.XML里  <bean         class="com.test.xx"> 自己的类

不过不推荐使用这种方法