如何让springmvc在启动的时候执行特定的业务处理

时间：2022-11-02 19:58:31

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。

 

相关文章