Jsp+Dao+Jdbc+Servelet 用户完整登录总结

来源：互联网发布：出口退税明细数据录入编辑：程序博客网时间：2024/04/30 03:08

Index.jsp 实现用户登录页面，login_success.jsp实现用户登录成功的页面显示用户XX登录成功！错误则跳转到login_failure.jsp

用户填写好用户名和密码后发出登录请求给servlet（tomcat启动要加载web.xml文件，web.xml会根据index的action找到web.xml中的servlet，然后由servlet控制分发请求调用登录方法，

Index.jsp--àweb.xml---àservlet.java---àdao---àdaoImpl--àservlet--àlogin_success.jsp

Index.jsp页面如下：

<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%><%@page import="java.util.*"%><html> <head> <title>用户登录</title> </head> <body><%if(request.getAttribute("Error")!=null){// 有错误，要进行打印输出List all = (List)request.getAttribute("Error") ;Iterator iter = all.iterator() ;while(iter.hasNext()){%><li><%=iter.next()%><%}}%> <form action="servlet/loginServlet" method="Post"> <table align="CENTER"> <tr><td colspan="2" align="CENTER"><h3><font color="#0000ff"><strong>用户登录</strong></font></h3></td></tr> <tr> <td align="right">用户名：</td> <td><input type="text" name="username"/></td> </tr> <tr> <td>密码：</td> <td><input type="password" name="password"/></td> </tr> <tr> <td align="center"><input type="Submit" name="submit" value="提交"/></td> <td align="center"><input type="Reset" name="reset" value="重置"/></td> </tr> </table> </form> </body></html>

web.xml文件如下

<?xml version="1.0" encoding="gb2312"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>loginServlet</servlet-name> <servlet-class>com.lgy.servlet.loginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>loginServlet</servlet-name> <url-pattern>/servlet/loginServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>

注意

Web.xm中的<url-pattern>/servlet/loginServlet</url-pattern>

和index.jsp中的action=“servlet/loginServlet”必须一致

下面是javaBean 所谓的VO（POJO）主要负责对用户表进行描述，设置用户的各项信息，返回用户的各项信息

package com.lgy.vo;import java.util.List;public class login {private int id;private String username;private String password;private List errors;public boolean invalidate(){boolean flag=true;/** * 1.先验证输入不为空，在验证合法的输入格式。 * 如果输入不为空，那么进行下一项合法的格式的验证 */System.out.println("这是pojo得到的用户名********："+this.username);if(this.username==null||"".equals(this.username)){flag=false;errors.add("用户名不能为空！");}//合法格式的验证else{if(this.username.length()<3||this.username.length()>10){flag=false;errors.add("您应该输入合法的用户名，长度在3~10之间！");}}if(this.password==null||"".equals(this.password)){flag=false;errors.add("密码不能为空！");}else{if(this.password.length()<3||this.password.length()>10){flag=false;errors.add("您应该输入合法的密码，的长度在3~10之间！");}}return flag;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public List getErrors() {return errors;}public void setErrors(List errors) {this.errors = errors;}}

下面是数据库的链接类负责链接数据库

// 本类只用于数据库连接及关闭操作package com.lgy.db ;import java.sql.* ;public class MysqlConnection{// 属性// 定义数据库操作的常量、对象// 数据库驱动程序private final String DBDRIVER= "com.mysql.jdbc.Driver" ;// 数据库连接地址private final String DBURL= "jdbc:mysql://localhost:3306/test" ;// 数据库用户名private final String DBUSER= "root" ;// 数据库连接密码private final String DBPASSWORD= "root" ;// 声明一个数据库连接对象private Connection conn= null ;// 在构造方法之中连接数据库public MysqlConnection(){try{// 加载驱动程序Class.forName(DBDRIVER) ; // 连接数据库conn = DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD) ;}catch (Exception e){System.out.println(e) ;}}// 返回一个数据库连接public Connection getConnection(){/// 返回连接对象return this.conn ;}// 关闭数据库连接public void close(){try{this.conn.close() ;}catch (Exception e){}}

下面是servlet 控制处理用户发送来的请求

package com.lgy.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 javax.servlet.RequestDispatcher;import com.lgy.factory.DAOFactory;import com.lgy.vo.login;public class loginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {this.doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {List errors = new ArrayList() ;String path = "../index.jsp" ;String name=request.getParameter("username");System.out.println("这是页面上的用户名："+name);String pwd=request.getParameter("password");System.out.println("这是页面上的密码："+pwd);login lg=new login();lg.setUsername(name);lg.setPassword(pwd);lg.setErrors(errors);boolean b=lg.invalidate();System.out.println("判断输入格式的真假"+b); //下面的判断为如果输入的格式合法，那么我们进行数据库端得验证if(b){if(DAOFactory.getLoginDAOInstance().isLogin(lg)){System.out.println("进行数据库端得判断***********");path="../success.jsp";}else{errors.add("错误的用户名和密码！");}}request.setAttribute("Error", errors);request.setAttribute("Lg", lg);//request.getRequestDispatcher(path)request.getRequestDispatcher(path).forward(request, response);}}

下面是很据servlet的处理由具体实现类处理数据DAO

package com.lgy.dao;import com.lgy.vo.login;public interface loginDao {public boolean isLogin(login lg);}

DAOFactory

package com.lgy.factory;import com.lgy.dao.loginDao;import com.lgy.daoImp.loginDaoImp;public class DAOFactory {public static loginDao getLoginDAOInstance(){return new loginDaoImp() ;} }

DaoImpl

package com.lgy.daoImp;import com.lgy.dao.*;import com.lgy.vo.login;import com.lgy.db.*;import java.sql.*;import java.sql.PreparedStatement;import java.sql.Connection;import java.sql.ResultSet;public class loginDaoImp implements loginDao {public boolean isLogin(login lg) {boolean flag = false;PreparedStatement pstm = null;ResultSet rs = null;String sql = null;MysqlConnection mc = new MysqlConnection(); sql = "select username,password from login where username=? and password=?";try {System.out.println("这是要用到的sql………………："+sql);pstm=mc.getConnection().prepareStatement(sql);System.out.println("@@@@@@@@要查询的用户名："+lg.getUsername());pstm.setString(1, lg.getUsername());pstm.setString(2, lg.getPassword());rs = pstm.executeQuery();if (rs.next()) {flag = true;lg.setUsername(rs.getString("username"));}} catch (Exception ex) {ex.printStackTrace();} return flag;}}

至于如何连接数据我我就不讲了，只要把jar包导进去就行了。