一个servlet 登录的小例子

一个servlet 登录的小例子

分类： j2ee 2008-06-29 23:44 4320人阅读 评论(1) 收藏 举报

servletstringurlhtmlusernull

1. 进入mysql，创建数据库和表：

   mysql>CREATE DATABASE demo;
   
   mysql>CREATE TABLE user(
   
                   id INT NOT NULL AUTO_INCREMENT,
   
                   username VARCHAR(50) NOT NULL,
   
                   password VARCHAR(20) NOT NULL,
   
                   PRIMARY KEY(id)
   
                   )ENGINE=INNODB;
   
   mysql>use demo;
   
   mysql>insert into user(id,username,password) values(default,'admin','admin');
   
   mysql>insert into user(id,username,password) values(default,'huzjtech','123456');
   
   

2. 创建验证用户的类UserValidation，他的功能是通过用户的输入数据到数据库中查找该用户是否存在：

   package huzj.login.jdbc;
   
   
   
   import java.sql.Connection;
   
   import java.sql.DriverManager;
   
   import java.sql.PreparedStatement;
   
   import java.sql.ResultSet;
   
   import java.sql.SQLException;
   
   
   
   public class UserValidation {
   
   
   
       private String username;
   
   
   
       public void setUsername(String username) {
   
           this.username = username;
   
       }
   
   
   
       public void setPassword(String password) {
   
           this.password = password;
   
       }
   
   
   
       private String password;
   
   
       public boolean validate() throws SQLException, ClassNotFoundException {
   
   
   
           boolean flag = false;
   
           Class.forName("com.mysql.jdbc.Driver");
   
   
   
           String url = "jdbc:mysql://localhost:3306/demo";
   
   
   
           Connection conn = DriverManager.getConnection(url, "root", "password");
   
   
   
           PreparedStatement ps = conn
   
                   .prepareStatement("select * from user u where u.username=? and u.password=?");
   
           ps.setString(1, username);
   
           ps.setString(2, password);
   
   
   
           ResultSet rs = ps.executeQuery();
   
   
   
           if (rs.next()) {
   
               flag = true;
   
           }
   
           return flag;
   
       }
   
   }

3. 创建一个servlet 完成分发LoginServlet；

   package huzj.login.control;
   
   
   
   import huzj.login.entity.User;
   
   import huzj.login.jdbc.UserValidation;
   
   
   
   import java.io.IOException;
   
   import java.sql.SQLException;
   
   
   
   import javax.servlet.ServletException;
   
   import javax.servlet.http.HttpServlet;
   
   import javax.servlet.http.HttpServletRequest;
   
   import javax.servlet.http.HttpServletResponse;
   
   
   
   import org.apache.commons.logging.Log;
   
   import org.apache.commons.logging.LogFactory;
   
   
   
   public class LoginServlet extends HttpServlet {
   
   
   
       public void service(HttpServletRequest request, HttpServletResponse response)
   
               throws ServletException, IOException {
   
   
   
           Log logger = LogFactory.getLog(getClass());
   
   
   
           logger.info("process this ....");
   
   
   
           String username = request.getParameter("username");
   
           String password = request.getParameter("password");
   
   
   
           UserValidation uv = new UserValidation();
   
   
   
           uv.setUsername(username);
   
           uv.setPassword(password);
   
   
   
           String url1 = "/loginsuccess.jsp";
   
           String url2 = "/login.jsp";
   
   
   
           try {
   
               if (uv.validate() == true) {
   
                   request.setAttribute("username", username);
   
                   getServletContext().getRequestDispatcher(url1).forward(request,
   
                           response);
   
               } else {
   
                   // response.sendError(404, "Loging failure...!");
   
                   getServletContext().getRequestDispatcher(url2).forward(request,
   
                           response);
   
               }
   
           } catch (SQLException e) {
   
               // TODO Auto-generated catch block
   
               e.printStackTrace();
   
           } catch (ClassNotFoundException e) {
   
               // TODO Auto-generated catch block
   
               e.printStackTrace();
   
           }
   
   
       }
   
   
   }

4. 配置web.xml文件：

   <?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>jdbc-first-app-login</display-name>
   
       <servlet>
   
           <servlet-name>userlogin</servlet-name>
   
           <servlet-class>huzj.login.control.LoginServlet</servlet-class>
   
       </servlet>
   
       <servlet-mapping>
   
           <servlet-name>userlogin</servlet-name>
   
           <url-pattern>/login</url-pattern>
   
       </servlet-mapping>
   
       <welcome-file-list>
   
           <welcome-file>login.jsp</welcome-file>
   
       </welcome-file-list>
   
   </web-app>

5. 创建一个登录login.jsp：

   <%@ page language="java" contentType="text/html; charset=UTF-8"
   
       pageEncoding="UTF-8"%>
   
   <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
   
   <html>
   
   <head>
   
   <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   
   <title>Insert title here</title>
   
   </head>
   
   <body>
   
   <form action="login">
   
       userName:<input type="text" name="username">
   
       userPassword:<input type="password" name="password">
   
       <input type="submit" value="Submit">
   
   </form>
   
   </body>
   
   </html>

6. 登录成功页面loginsuccess.jsp：

   <%@ page language="java" contentType="text/html; charset=UTF-8"
   
       pageEncoding="UTF-8"%>
   
   
   
   <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
   
   <html>
   
   <head>
   
   <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   
   <title>Insert title here</title>
   
   </head>
   
   <body>
   
   <h1>Login Success!</h1>
   
   <p>Hello,<b><%=request.getAttribute("username")%></b>!</p>
   
   </body>
   
   </html>

7. 结束。