监听器和普通类获取springContext和context，从而获取springbean和application范围的对象

1、定义一个监听器[MyContextListener]，此类里最主要获取springContext和context

package my.request;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

/**
 * @author  chaox
 * @description 通过监听器获取springContext和context,此时普通类只需要提供get和set方法来获取springContext和context
 */
public class MyContextListener implements ServletContextListener
{
    private ServletContext context = null;
    
    // 获取spring注入的bean对象  
    private WebApplicationContext springContext = null;
    
    @Override
    public void contextDestroyed(ServletContextEvent event)
    {
        // Output a simple message to the server's console   
        System.out.println("The Simple Web App. Has Been Removed");
        this.context = null;
    }
    
    // 这个方法在Web应用服务做好接受请求的时候被调用。 
    @Override
    public void contextInitialized(ServletContextEvent event)
    {
        this.context = event.getServletContext();
        
        if (context == null)
        {
            System.out.println("获取ServletContext上下文失败!");
            return;
        }
        
        ApplicationContextHelper.setServletContext(context);
        //        context.setAttribute("xxxKey", "applicationScope");
        //        context.getAttribute("xxxKey");
        
        springContext = WebApplicationContextUtils.getWebApplicationContext(this.context);
        
        if (springContext != null)
        {
            // 获取制定的Sprign的beanId=xxxManager的对象
            // xxxManager = (XXXManager) springContext.getBean("xxxManager");
            ApplicationContextHelper.setContext(springContext);
        }
        else
        {
            System.out.println("获取应用程序上下文失败!");
            return;
        }
        
        //Output a simple message to the server's console   
        System.out.println("The Simple Web App. Is Ready");
    }
    
    public ServletContext getContext()
    {
        return context;
    }
    
    public void setContext(ServletContext context)
    {
        this.context = context;
    }
    
    public WebApplicationContext getSpringContext()
    {
        return springContext;
    }
    
    public void setSpringContext(WebApplicationContext springContext)
    {
        this.springContext = springContext;
    }
    
}

2、定义一个普通类[ApplicationContextHelper]，此类里最主要提供get和set方法来获取监听器中的springContext和context，从而获取springbean和application范围的对象

package my.request;

import javax.servlet.ServletContext;

import org.springframework.context.ApplicationContext;

public class ApplicationContextHelper
{
    private static ApplicationContext context = null;
    
    private static ServletContext servletContext = null;
    
    public static ApplicationContext getContext()
    {
        return context;
    }
    
    public static void setContext(ApplicationContext context)
    {
        ApplicationContextHelper.context = context;
    }
    
    public static ServletContext getServletContext()
    {
        return servletContext;
    }
    
    public static void setServletContext(ServletContext servletContext)
    {
        ApplicationContextHelper.servletContext = servletContext;
    }
}

3、web.xml配置，需要注意ContextLoaderListener配置的位置需要在自定义的MyContextListener前，否则springContext=null

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

    <!-- 配置获取springContext和context -->
    <listener>
        <listener-class>my.request.MyContextListener</listener-class>
    </listener>