Servlet简单登陆验证实例

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林炳文Evankaka原创作品。转载请注明出处http://blog.csdn.net/evankaka

本文要实现Servlet简单登陆验证实例。结构如下

1、LoginCheck.java

package com.mucfc;import java.io.IOException;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class LoginCheck */@WebServlet("/LoginCheck")public class LoginCheck extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public LoginCheck() {        super();        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String username = request.getParameter("username");             String password = request.getParameter("password");                          //服务器端打印信息          System.out.println("username=" + username);          System.out.println("password=" + password);          if(username!=null&&password!=null && username.equals("linbingwen")&&password.equals("1234")){        //将数据存储在request对象中，传递给下一个servlet使用        request.setAttribute("username", username);        //进行数据的转发        RequestDispatcher dispatcher=request.getRequestDispatcher("Welcome");        dispatcher.forward(request, response);               }        else {response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,"用户名或密码错误");}}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  doGet(request, response);    }}

2、Welcome

package com.mucfc;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class Welcome */@WebServlet("/Welcome")public class Welcome extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public Welcome() {        super();        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String username = request.getParameter("username");   //设置编码格式          response.setContentType("text/html;charset=GB18030");                   //返回html页面          response.getWriter().println("<html>");          response.getWriter().println("<head>");             response.getWriter().println("<title>登录信息</title>");              response.getWriter().println("</head>");            response.getWriter().println("<body algin=center>");             response.getWriter().println("欢迎【" + username + "】用户登录成功！！！");            response.getWriter().println("</body>");            response.getWriter().println("</html>");  }/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  doGet(request, response);    }}

3、index.jsp

<%@ page language="java" contentType="text/html" pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><title>登录</title>  </head><body><form action="servlet/LoginCheck" method="POST">              用户：<input type="text" name="username" /><br/>              密码：<input type="password" name="password" /><br/>              <input type="submit" value="登录" />                   </form>  </body></html>

4、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" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <!-- 初始的页面 -->  <welcome-file-list>    <welcome-file>index.html</welcome-file>    <welcome-file>index.htm</welcome-file>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list>  <!-- 用户名和密码验证的servlet -->  <servlet>    <servlet-name>LoginCheck</servlet-name>    <servlet-class>com.mucfc.LoginCheck</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>LoginCheck</servlet-name>    <url-pattern>/servlet/LoginCheck</url-pattern>  </servlet-mapping>  <!-- 显示欢迎的servlet -->    <servlet>    <servlet-name>Welcome</servlet-name>    <servlet-class>com.mucfc.Welcome</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>Welcome</servlet-name>    <url-pattern>/servlet/Welcome</url-pattern>  </servlet-mapping>  </web-app>

运行后：

输入正确用户名（lingbingwen)和密码（1234）

输入错误

Servlet接口定义三个实现类，分别是FacesServlet， GenericServlet， HttpServlet。下面我们简单的介绍一下。

5、Servlet接口实现类

（1）FacesServlet是一个用于管理利用JSF（JavaServer Faces）构建用户界面的web应用程序请求处理生命周期的Servlet。（FacesServletis a servlet that manages the request processing lifecycle for web applications that are utilizing JavaServer Faces to construct the user interface.），大家如果想深入的学习，可以点这里。

（2）GenericServlet是HttpServlet的父类，包含了servlet的常用方法。GenericServlet使得程序员写servlets更加简单，它提供了初始化和销毁生命周期的方法，以及实现了写日志文件的方法。

（3）HttpServlet指能够处理HTTP请求的servlet。这是开发人员在编写Servlet时，通常应继承这个类即可。

对于这三个实现类，只为大家做一个简单的介绍，如果想深入的研究，直接看API就好。

林炳文Evankaka原创作品。转载请注明出处http://blog.csdn.net/evankaka

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