在Servlet中获取spring管理的bean

最新推荐文章于 2017-12-06 11:04:17 发布

最新推荐文章于 2017-12-06 11:04:17 发布 · 1.9k 阅读

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#spring #servlet

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本文介绍如何在Servlet中获取Spring管理的Bean。通过在web.xml中配置ContextLoaderListener，并使用WebApplicationContextUtils工具类，可以方便地获取到ApplicationContext上下文，进而获取到所需的Bean实例。

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在Servlet中获取spring管理的bean需要导入spring的web相关的jar包。spring-web-3.2.0.RELEASE.jar

在web.xml文件添加ContextLoaderListener
在Servlet中调用以下代码,获取ApplicationContext对象进而获取spring管理的bean。

ApplicationContext applicationContext = 
WebApplicationContextUtils.getWebApplicationContext(getServletContext());

代码示例：

HelloService.java

package com.my.service;

public class HelloService {
	
	public void sayHello(){
		System.out.println("hello，spring webxxx！");
	}

}

HelloServlet.java

package com.my.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

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

import com.my.service.HelloService;

public class HelloServlet extends HttpServlet {
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		doPost(req, resp);
	}
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		
		// 从spring容器 获得 HelloService 对象
		// ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		
		// ApplicationContext applicationContext = (WebApplicationContext) getServletContext().getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
		ApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(getServletContext());
		HelloService helloService = (HelloService) applicationContext.getBean("helloService");
		helloService.sayHello();

	}
	

}

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	   xmlns:p = "http://www.springframework.org/schema/p"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
		
	<bean id="helloService" class="com.my.service.HelloService"></bean>
	
</beans>

web.xml

<?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>
  <!-- spring 上下文监听器 -->
  <listener>
  	<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  
  <!-- 配置spring 配置文件位置 -->
  <context-param>
  	<param-name>contextConfigLocation</param-name>
  	<param-value>classpath:applicationContext.xml</param-value>
  </context-param>
  
  <servlet>
    <servlet-name>HelloServlet</servlet-name>
    <servlet-class>com.my.servlet.HelloServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>HelloServlet</servlet-name>
    <url-pattern>/hello</url-pattern>
  </servlet-mapping>	
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

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