在Servlet中获取spring管理的bean详解编程语言

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>