初学spring：web应用程序中使用Spring

简单web应用spring

1、创建Bean

package com.test.spring;public class MessageBean {private String message;public String getMessage() {return message;}public void setMessage(String message) {this.message = message;}}

2、Spring配置：applicationContext.xml(放在WEB-INF/目录下)

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN""http://www.springframework.org/dtd/spring-beans.dtd"><beans><!-- id指定bean 的访问名称，class指定bean的实现类 --><bean id="messageBean" class="com.test.spring.MessageBean"><property name="message"><!-- name指定bean实现类的属性 --><value>Spring framework web project test config file:applicationContext.xml!</value><!--指定了向bean属性注入的值 --></property></bean></beans>

注明：spring框架默认使用/WEB-INF/applicationContext.xml作为配置文件。

3、部署描述符文件:web.xml

<?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" id="WebApp_ID" version="2.5">
  <display-name>SpringTest</display-name>


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

  <servlet>
  <servlet-name>SpringWebTest</servlet-name>
  <servlet-class>com.test.spring.SpringWebTest</servlet-class>
  </servlet>
  
  <servlet-mapping>
  <servlet-name>SpringWebTest</servlet-name>
  <url-pattern>/SpringWebTest</url-pattern>
  </servlet-mapping>
</web-app>

通过上面的配置，ContextLoaderListener监听器默认查找/WEB-INF/applicationContext.xml文件。

如果要改变spring的配置文件名称或者位置，需要在web.xml中指定，如：

   <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/beans-config.xml</param-value>
  </context-param>

4、创建servlet类：

package com.test.spring;


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.web.context.support.WebApplicationContextUtils;


public class SpringWebTest extends HttpServlet{

/**
* serialVersionUID
*/
private static final long serialVersionUID = 1L;

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//super.doGet(req, resp);
this.doPost(request, response);
}


@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
//super.doPost(request, response);
PrintWriter out = response.getWriter();
ApplicationContext ac = WebApplicationContextUtils.getWebApplicationContext(this.getServletContext());
MessageBean bean = (MessageBean)ac.getBean("messageBean");
out.print(bean.getMessage());
out.close();//close
}
}

5、启动tomcat，显示结果。