简单的连接数据库的Web登录界面

xiaoxiao2021-02-28  10

简单的连接数据库的Web登录界面

一、需求分析

实现在登录界面输入用户名和密码,连接数据库,与数据库信息进行比对,若用户名和密码相互匹配,则显示登陆成功,若不正确,选择重新输入。

二、工具

1.MySql 2.Tomcat 3.Java EE 4.SQLyog或Navicat等,并配置好环境变量。

三、实现步骤

1.数据库建表

首先,创建数据库,并在数据库中创建数据表,表格如图所示:

2.新建项目

打开Eclipse Jee,File–new–Dynamic Web Project.

3.创建JSP、Class文件

1、新建login.jsp文件:

<%@ 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> <center> <h1 style="color:blue">登录</h1> <form id="indexform" name="indexForm" action="check.jsp" method="post"> <table border="0"> <tr> <td>账号:</td> <td><input type="text" name="username"></td> </tr> <tr> <td>密码:</td> <td><input type="password" name="password"></td> </tr> </table> <br> <input type="submit" value="登录"> </form> </center> </body> </html>

2、新建check.jsp

<%@ page import="java.sql.*" 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> <jsp:useBean id="db" class="Bean.DBBean" scope="page"/> <% request.setCharacterEncoding("UTF-8"); String username=(String)request.getParameter("username");//获取login页面输入的用户名和密码 String password=(String)request.getParameter("password"); String sql="select * from users where username="+"'"+username+"'";//定义一个查询语句 ResultSet rs=db.executeQuery(sql);//执行查询语句 if(rs.next()) { //将输入的密码与数据库密码相比对,执行相应操作 if(password.equals(rs.getObject("password"))){ response.sendRedirect("success.jsp"); } else{ out.print("<script language='javaScript'> alert('密码错误');</script>"); response.setHeader("refresh", "0;url=login.jsp"); } } else { out.print("<script language='javaScript'> alert('用户名错误,请重新输入');</script>"); response.setHeader("refresh", "0;url=login.jsp"); } %> </body> </html>

3、新建success.jsp 若用户名密码相比配,则显示此页面。

<%@ 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=ISO-8859-1"> <title>Insert title here</title> </head> <body style="text-align:center"> <h1>登录成功</h1> </body> </html>

4、创建DBBean.java文件 在该项目下,先创建名为Bean的package文件,然后创建DBBean.java文件:

package Bean; import java.sql.*; public class DBBean { private String driverStr = "com.mysql.jdbc.Driver"; private String connStr = "jdbc:mysql://localhost:3306/test"; private String dbusername = "root"; private String dbpassword = "root"; private Connection conn = null; private Statement stmt = null; public DBBean() { try { Class.forName(driverStr); conn = DriverManager.getConnection(connStr, dbusername, dbpassword); stmt = conn.createStatement(); } catch (Exception ex) { System.out.println(ex.getMessage()); System.out.println("数据连接失败!"); } } public int executeUpdate(String s) { int result = 0; System.out.println("--更新语句:"+s+"\n"); try { result = stmt.executeUpdate(s); } catch (Exception ex) { System.out.println("执行更新错误!"); } return result; } public ResultSet executeQuery(String s) { ResultSet rs = null; System.out.print("--查询语句:"+s+"\n"); try { rs = stmt.executeQuery(s); } catch (Exception ex) { System.out.println("执行查询错误!"); } return rs; } public void execQuery(String s){ try { stmt.executeUpdate(s); } catch (SQLException e) { System.out.println("执行插入错误!"); } } public void close() { try { stmt.close(); conn.close(); } catch (Exception e) { } } }

5、导入Mysql包 将mysql-connector-java-5.1.7-bin.jar拷贝到tomcat下lib目录即可。

四、运行结果

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