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  • 如何让springmvc在启动的时候执行特定的业务处理

    如何让springmvc在启动的时候执行特定的业务处理

            java 的 web服务器启动时，经常会做一些特定的业务逻辑处理，比如数据库初始化，

        初始化系统参数，读取配置文库等。

           很多web服务的中间件，可以 通过这样的思路去实现。比如消息分发服务。

    实现方法：

    一、Web项目，非Spring

    解决方法：实现【 ServletContextListener】 接口

           (1)、把实现了ServletContextListener 的类配置到【 web.xml】 文件中

          

    [html] view plain copy print?
    1. <?xml version="1.0" encoding="UTF-8"?>    
    2. <web-app version="2.5"     
    3.     xmlns="http://java.sun.com/xml/ns/javaee"     
    4.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     
    5.     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee     
    6.     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">    
    7.   <display-name></display-name>     
    8.   <welcome-file-list>    
    9.     <welcome-file>index.jsp</welcome-file>    
    10.   </welcome-file-list>    
    11.   <listener>    
    12.     <listener-class>com.chinaso.init.StartInit</listener-class>    
    13.   </listener>    
    14.   <filter>    
    15.     <filter-name>struts2</filter-name>    
    16.     <filter-class>    
    17.         org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter    
    18.     </filter-class>    
    19.   </filter>    
    20.   <filter-mapping>    
    21.     <filter-name>struts2</filter-name>    
    22.     <url-pattern>/*</url-pattern>    
    23.   </filter-mapping>    
    24.   </web-app>    
        <?xml version="1.0" encoding="UTF-8"?>  
    <web-app version="2.5"   
        xmlns="http://java.sun.com/xml/ns/javaee"   
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   
        http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  
      <display-name></display-name>   
      <welcome-file-list>  
        <welcome-file>index.jsp</welcome-file>  
      </welcome-file-list>  
      <listener>  
        <listener-class>com.chinaso.init.StartInit</listener-class>  
      </listener>  
      <filter>  
        <filter-name>struts2</filter-name>  
        <filter-class>  
            org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter  
        </filter-class>  
      </filter>  
      <filter-mapping>  
        <filter-name>struts2</filter-name>  
        <url-pattern>/*</url-pattern>  
      </filter-mapping>  
      </web-app>

     

       (2)、加入自己的实现逻辑

    [java] view plain copy print?
    1. public class StartInit implements ServletContextListener {    
    2.     static final Logger logger = LoggerFactory.getLogger(StartInit.class);    
    3.     // 系统初始化执行方法    
    4.     public void contextDestroyed(ServletContextEvent e) {    
    5.         logger.info("系统停止...");    
    6.     }    
    7.     
    8.     public void contextInitialized(ServletContextEvent e) {    
    9.         logger.info("系统初始化开始...");    
    10.             
    11.         // 获取项目根目录    
    12.         String root_path  = e.getServletContext().getRealPath("/");    
    13.         logger.info("application path : {}",root_path);    
    14.             
    15.         // 初始化 ConfigFactorty    
    16.         ConfigFactory.init(root_path);    
    17.         // 初始化数据链接信息    
    18.         DBManager.init();    
    19.         // 初始化定时统计任务    
    20.         TaskManager.init();    
    21.         // 初始化用户信息查询位置    
    22.         UserInfo.init();    
    23.             
    24.         logger.info("系统初始化结束...");    
    25.     }    
    26.         
    27. }    
        public class StartInit implements ServletContextListener {  
        static final Logger logger = LoggerFactory.getLogger(StartInit.class);  
        // 系统初始化执行方法  
        public void contextDestroyed(ServletContextEvent e) {  
            logger.info("系统停止...");  
        }  
      
        public void contextInitialized(ServletContextEvent e) {  
            logger.info("系统初始化开始...");  
              
            // 获取项目根目录  
            String root_path  = e.getServletContext().getRealPath("/");  
            logger.info("application path : {}",root_path);  
              
            // 初始化 ConfigFactorty  
            ConfigFactory.init(root_path);  
            // 初始化数据链接信息  
            DBManager.init();  
            // 初始化定时统计任务  
            TaskManager.init();  
            // 初始化用户信息查询位置  
            UserInfo.init();  
              
            logger.info("系统初始化结束...");  
        }  
          
    }



    二、Spring项目

    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）

    1、ApplicationContextAware接口

    [java] view plain copy print?
    1. package org.springframework.context;  
    2.    
    3. import org.springframework.beans.BeansException;  
    4. import org.springframework.beans.factory.Aware;  
    5. import org.springframework.context.ApplicationContext;  
    6.    
    7. public interface ApplicationContextAware extends Aware {  
    8.     void setApplicationContext(ApplicationContext var1) throws BeansException;  
    9. }  
    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;
}


    2、ServletContextAware 接口

    [java] view plain copy print?
    1. package org.springframework.web.context;  
    2.    
    3. import javax.servlet.ServletContext;  
    4. import org.springframework.beans.factory.Aware;  
    5.    
    6. public interface ServletContextAware extends Aware {  
    7.     void setServletContext(ServletContext var1);  
    8. }  
    package org.springframework.web.context;
 
import javax.servlet.ServletContext;
import org.springframework.beans.factory.Aware;
 
public interface ServletContextAware extends Aware {
    void setServletContext(ServletContext var1);
}



    3、InitializingBean 接口

       

    [java] view plain copy print?
    1. package org.springframework.beans.factory;  
    2.    
    3. public interface InitializingBean {  
    4.     void afterPropertiesSet() throws Exception;  
    5. }  
    package org.springframework.beans.factory;
 
public interface InitializingBean {
    void afterPropertiesSet() throws Exception;
}

     

    4、ApplicationListener<ApplicationEvent> 接口

    [java] view plain copy print?
    1. package org.springframework.context;  
    2.    
    3. import java.util.EventListener;  
    4. import org.springframework.context.ApplicationEvent;  
    5.    
    6. public interface ApplicationListener<E extends ApplicationEvent> extends EventListener {  
    7.     void onApplicationEvent(E var1);  
    8. }  
    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);
}


    java代码：

    [java] view plain copy print?
    1. package test.web.listener;  
    2.    
    3. import org.apache.logging.log4j.*;  
    4. import org.springframework.beans.*;  
    5. import org.springframework.beans.factory.InitializingBean;  
    6. import org.springframework.context.*;  
    7. import org.springframework.context.event.ContextRefreshedEvent;  
    8. import org.springframework.stereotype.Component;  
    9. import org.springframework.web.context.ServletContextAware;  
    10. import javax.servlet.ServletContext;  
    11.    
    12. @Component  
    13. public class StartupListener implements ApplicationContextAware, ServletContextAware,  
    14.         InitializingBean, ApplicationListener<ContextRefreshedEvent> {  
    15.    
    16.     protected Logger logger = LogManager.getLogger();  
    17.    
    18.     @Override  
    19.     public void setApplicationContext(ApplicationContext ctx) throws BeansException {  
    20.         logger.info("1 => StartupListener.setApplicationContext");  
    21.     }  
    22.    
    23.     @Override  
    24.     public void setServletContext(ServletContext context) {  
    25.         logger.info("2 => StartupListener.setServletContext");  
    26.     }  
    27.    
    28.     @Override  
    29.     public void afterPropertiesSet() throws Exception {  
    30.         logger.info("3 => StartupListener.afterPropertiesSet");  
    31.     }  
    32.    
    33.     @Override  
    34.     public void onApplicationEvent(ContextRefreshedEvent evt) {  
    35.         logger.info("4.1 => MyApplicationListener.onApplicationEvent");  
    36.         if (evt.getApplicationContext().getParent() == null) {  
    37.             logger.info("4.2 => MyApplicationListener.onApplicationEvent");  
    38.         }  
    39.     }  
    40.    
    41. }  
    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。

     

     
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  • 原文地址：https://www.cnblogs.com/wlsblog/p/7750202.html
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