getWebApplicationContext(arg0.getServletContext())为空的问题_webapplicationcontext.getservletcontext()报错-优快云博客

本文链接：https://blog.youkuaiyun.com/cs_ghy/article/details/8228070

在本文中，我们遇到了一个在Spring MVC应用中使用`WebApplicationContextUtils.getWebApplicationContext(arg0.getServletContext())`返回 null 的问题。这个问题发生在`contextInitialized()`方法中，当尝试从Servlet上下文中获取`WebApplicationContext`并进一步获取`DataSource`时。为了解决这个问题，文章可能涉及了在`web.xml`配置文件中正确设置监听器和上下文配置的步骤。

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package com;

import java.sql.PreparedStatement;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.sql.DataSource;

import org.apache.log4j.Logger;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

public class SystemListener implements ServletContextListener {

   private final static Logger logger = Logger.getLogger(SystemListener.class);

   public void contextDestroyed(ServletContextEvent arg0) {
       //System.out.println("this is contextDestroyed() !!!");
       logger.info("this is contextDestroyed() !!!");
   }

   public void contextInitialized(ServletContextEvent arg0) {
       //System.out.println("this is contextInitialized() !!!");
       logger.info("this is contextInitialized() !!!");
       try {
           WebApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(arg0.getServletContext());
           DataSource dataSource2 = (DataSource) ctx.getBean("dataSource");
           /*
           DataSourceUtil.setDataSource(dataSource2);
           //ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext-database.xml");
           ApplicationContext ac = new ClassPathXmlApplicationContext(new String[]{"applicationContext-database.xml"});
           DataSource dataSource2 = (DataSource) ac.getBean("dataSource");
           */

           logger.info("*******:"+dataSource2.getConnection().toString());
       } catch (Exception e) {
           logger.error(e);
       }
   }

}

以上代码中红色部分得到null ，在web.xml中加入以下代码：

<listener>
	<listener-class>
		org.springframework.web.context.ContextLoaderListener
	</listener-class>
</listener>