package cn.itcast.service;public class UserService {public void sayHello(){System.out.println("Hello Spring web.....");     }
}

package cn.itcast.servlet;import java.io.IOException;
import java.io.PrintWriter;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.context.support.ClassPathXmlApplicationContext;*/
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import cn.itcast.service.UserService;@SuppressWarnings("serial")
public class UserServlet extends HttpServlet {
//每次启动Servlet都会加载Spring的环境.每次运行都需要加载Spring的环境.Spring配置环境中的东西如果多了,每次加载Servlet就加载Spring环境肯定不行.public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/*    ApplicationContext applicationContext  = new ClassPathXmlApplicationContext("applicationContext.xml");UserService userService =  (UserService) applicationContext.getBean("userService");userService.sayHello();*///得把代码改了,否则每次都是来获取Spring的环境.WebApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(getServletContext());//工具类WebApplicationContextUtilsUserService userService =  (UserService) applicationContext.getBean("userService");userService.sayHello();}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request,response);}}

<?xml version="1.0" encoding="UTF-8"?>
<!-- 别去schema,schema是文件,本地的文件,你得引那个头 --><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="userService" class="cn.itcast.service.UserService"></bean>
</beans>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"><display-name></display-name><!-- 配置监听器ContextLoaderListener --><listener><listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener><!-- 配置全局初始化参数 --><context-param><param-name>contextConfigLocation</param-name><param-value>classpath:applicationContext.xml</param-value></context-param><servlet><description>This is the description of my J2EE component</description><display-name>This is the display name of my J2EE component</display-name><servlet-name>UserServlet</servlet-name><servlet-class>cn.itcast.servlet.UserServlet</servlet-class></servlet><servlet-mapping><servlet-name>UserServlet</servlet-name><url-pattern>/userServlet</url-pattern></servlet-mapping><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list>
</web-app>