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

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

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. public void contextInitialized(ServletContextEvent e) {
8. logger.info("系统初始化开始...");
9. // 获取项目根目录
10. String root_path  = e.getServletContext().getRealPath("/");
11. logger.info("application path : {}",root_path);
12. // 初始化 ConfigFactorty
13. ConfigFactory.init(root_path);
14. // 初始化数据链接信息
15. DBManager.init();
16. // 初始化定时统计任务
17. TaskManager.init();
18. // 初始化用户信息查询位置
19. UserInfo.init();
20. logger.info("系统初始化结束...");
21. }
22. }

    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

1. package org.springframework.context;
2. import org.springframework.beans.BeansException;
3. import org.springframework.beans.factory.Aware;
4. import org.springframework.context.ApplicationContext;
5. public interface ApplicationContextAware extends Aware {
6. void setApplicationContext(ApplicationContext var1) throws BeansException;
7. }

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

1. package org.springframework.web.context;
2. import javax.servlet.ServletContext;
3. import org.springframework.beans.factory.Aware;
4. public interface ServletContextAware extends Aware {
5. void setServletContext(ServletContext var1);
6. }

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

1. package org.springframework.beans.factory;
2. public interface InitializingBean {
3. void afterPropertiesSet() throws Exception;
4. }

package org.springframework.beans.factory;

public interface InitializingBean {
    void afterPropertiesSet() throws Exception;
}

4、ApplicationListener<ApplicationEvent> 接口

1. package org.springframework.context;
2. import java.util.EventListener;
3. import org.springframework.context.ApplicationEvent;
4. public interface ApplicationListener<E extends ApplicationEvent> extends EventListener {
5. void onApplicationEvent(E var1);
6. }

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：

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

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。