在Servlet中获取spring管理的bean

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>