如何讓springmvc在啟動的時候執行特定的業務處理

java 的 web服務器啟動時，經常會做一些特定的業務邏輯處理，比如數據庫初始化，

初始化系統參數，讀取配置文庫等。

很多web服務的中間件，可以 通過這樣的思路去實現。比如消息分發服務。

實現方法：

一、Web項目，非Spring

解決方法：實現【 ServletContextListener】 接口

(1)、把實現了ServletContextListener 的類配置到【 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)、加入自己的實現邏輯

1. public class StartInit implements ServletContextListener {
2. static final Logger logger = LoggerFactory.getLogger(StartInit.class);
3. // 系統初始化執行方法
4. public void contextDestroyed(ServletContextEvent e) {
5. logger.info("系統停止...");
6. }
8. public void contextInitialized(ServletContextEvent e) {
9. logger.info("系統初始化開始...");
11. // 獲取項目根目錄
12. String root_path = e.getServletContext().getRealPath("/");
13. logger.info("application path : {}",root_path);
15. // 初始化 ConfigFactorty
16. ConfigFactory.init(root_path);
17. // 初始化數據鏈接信息
18. DBManager.init();
19. // 初始化定時統計任務
20. TaskManager.init();
21. // 初始化用戶信息查詢位置
22. UserInfo.init();
24. logger.info("系統初始化結束...");
25. }
27. }

    public class StartInit implements ServletContextListener {  
        static final Logger logger = LoggerFactory.getLogger(StartInit.class);  
        // 系統初始化執行方法  
        public void contextDestroyed(ServletContextEvent e) {  
            logger.info("系統停止...");  
        }  
      
        public void contextInitialized(ServletContextEvent e) {  
            logger.info("系統初始化開始...");  
              
            // 獲取項目根目錄  
            String root_path  = e.getServletContext().getRealPath("/");  
            logger.info("application path : {}",root_path);  
              
            // 初始化 ConfigFactorty  
            ConfigFactory.init(root_path);  
            // 初始化數據鏈接信息  
            DBManager.init();  
            // 初始化定時統計任務  
            TaskManager.init();  
            // 初始化用戶信息查詢位置  
            UserInfo.init();  
              
            logger.info("系統初始化結束...");  
        }  
          
    }  

二、Spring項目

Spring-MVC的應用中，要實現類似的功能，主要是通過實現下面這些接口（任選一，至少一個即可）

1、ApplicationContextAware接口

1. package org.springframework.context;
3. import org.springframework.beans.BeansException;
4. import org.springframework.beans.factory.Aware;
5. import org.springframework.context.ApplicationContext;
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

1. package org.springframework.web.context;
3. import javax.servlet.ServletContext;
4. import org.springframework.beans.factory.Aware;
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

1. package org.springframework.beans.factory;
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

1. package org.springframework.context;
3. import java.util.EventListener;
4. import org.springframework.context.ApplicationEvent;
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代碼：

1. package test.web.listener;
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;
12. @Component
13. public class StartupListener implements ApplicationContextAware, ServletContextAware,
14. InitializingBean, ApplicationListener<ContextRefreshedEvent> {
16. protected Logger logger = LogManager.getLogger();
18. @Override
19. public void setApplicationContext(ApplicationContext ctx) throws BeansException {
20. logger.info("1 => StartupListener.setApplicationContext");
21. }
23. @Override
24. public void setServletContext(ServletContext context) {
25. logger.info("2 => StartupListener.setServletContext");
26. }
28. @Override
29. public void afterPropertiesSet() throws Exception {
30. logger.info("3 => StartupListener.afterPropertiesSet");
31. }
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. }
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");
        }
    }
 
}

運行時，輸出的順序如下：

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

註意：onApplicationEvent方法會觸發多次，初始化這種事情，越早越好，建議在setApplicationContext方法中處理。

如何讓springmvc在啟動的時候執行特定的業務處理