xml:

<servlet>

<servlet-name>initparam</servlet-name><!-- 与servlet-mapping相对应 -->

<servlet-class>

com.servlet.InitParamServlet

</servlet-class>

<init-param><!-- 配置参数 -->

<param-name>ref</param-name>

<param-value>www.test.cn</param-value>

</init-param>

</servlet>

<servlet-mapping><!-- 映射路径 -->

<servlet-name>initparam</servlet-name><!-- 与servlet相对应 -->

<url-pattern>/InitParamServlet</url-pattern><!-- 页面的映射路径 -->

</servlet-mapping>

 

class文件：

package com.servlet;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.factory.DAOFactory;

import com.vo.User;

public class LoginServlet extends HttpServlet {

/**

* The doGet method of the servlet. <br>

*

* This method is called when a form has its tag value method equals to get.

*

* @param request the request send by the client to the server

* @param response the response send by the server to the client

* @throws ServletException if an error occurred

* @throws IOException if an error occurred

*/

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

String path = "login.jsp";

String userid = request.getParameter("userid"); // 接收userid内容

String userpass = request.getParameter("userpass"); //接收userpass内容

List<String> info = new ArrayList<String>(); // 保存所有返回信息

if (userid == null || "".equals(userid)) {//用户名为null

info.add("用户id不能为空!"); // 增加错误信息

}

if (userpass == null || "".equals(userpass)) {

info.add("密码不能为空!"); // 增加错误信息

}

if (info.size() == 0) { // 用户名和密码验证通过

User user = new User(); // 实例化VO

user.setUserid(userid);

user.setPassword(userpass);

try {

if (DAOFactory.getIUserDAOInstance().findLogin(user)) {//验证通过

info.add("用户登录成功，欢迎" + user.getName() + "光临！");

} else {

info.add("用户登录失败，错误的用户名或密码！");

}

} catch (Exception e) {

e.printStackTrace();

}

}

request.setAttribute("info", info);

request.getRequestDispatcher(path).forward(request, response);

}

/**

* The doPost method of the servlet. <br>

*

* This method is called when a form has its tag value method equals to post.

*

* @param request the request send by the client to the server

* @param response the response send by the server to the client

* @throws ServletException if an error occurred

* @throws IOException if an error occurred

*/

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

this.doGet(request, response);

}

}