首先用一个JavaBean封装数据库操作,即mvc中的模型
JdbcBean.java
package data;
import java.sql.*;
public class JdbcBean {
private String DBDriver="com.mysql.jdbc.Driver";
private String DBUrl="jdbc:mysql://localhost:3306/test";
private String DBUser="root";
private String DBPassword="686175";
public Connection conn=null;
public ResultSet rs=null;
public ResultSet query(String sql)throws Exception{
try{
Class.forName(DBDriver);
conn=DriverManager.getConnection(DBUrl,DBUser,DBPassword);
Statement stmt=conn.createStatement();
rs=stmt.executeQuery(sql);
return rs;
}
catch(SQLException e){
System.out.println(e.getMessage());
}
return null;
}
public void update(String sql)throws Exception{
try{
Class.forName(DBDriver);
conn=DriverManager.getConnection(DBUrl,DBUser,DBPassword);
Statement stmt=conn.createStatement();
stmt.executeUpdate(sql);
stmt.close();
conn.close();
}
catch(SQLException e){
System.out.println(e.getMessage());
}
}
}
在src的data包中还有一个控制器Servlet,用于处理连接数据库的操作，此次工程用的数据库是MySQL
LoginServlet.java
package data;
import java.io.IOException;
import java.sql.ResultSet;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet {
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
String toJSP="";
request.setCharacterEncoding("gbk");
response.setContentType("text/html;charset=gbk");
String username=request.getParameter("username");
String password=request.getParameter("password");
String sql="select * from user where username='"+username+"'" +
"&&password='"+password+"'";
JdbcBean jdbc=new JdbcBean();
try{
ResultSet rs=jdbc.query(sql);
if(rs.next()){
toJSP="success.jsp";
}
else{
toJSP="error.jsp";
}
rs.close();
}
catch(Exception e){
System.out.println("发生查询异常");
}
RequestDispatcher rd=request.getRequestDispatcher(toJSP);
rd.forward(request, response);
}
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
}
接下来就是用jsp写的视图，显示页面操作
登录页面login.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<html>
<head>
<title>My JSP 'login.jsp' starting page</title>
<script>
function myFunction(){
if(myForm.username.value==""){
alert("用户名不能为空");
}
else if(myForm.password.value==""){
alert("密码不能为空");
}
else{
myForm.submit();
}
}
</script>
</head>
<body>
<form action="LoginServlet" method="post" name="myForm">
<center>
<table>
<tr>
<td>用户名</td>
<td><input type="text" name="username"></td>
<td>用户名不能为空</td>
</tr>
<tr>
<td>密码</td>
<td><input type="password" name="password"></td>
<td>密码不能为空</td>
</tr>
<tr>
<td></td>
<td><input type="submit" value="提交" onclick="myFunction()">
<input type="reset" value="取消"></td>
</tr>
</table>
</center>
</form>
</body>
</html>
登录成功页面success.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<html>
<head>
<title>My JSP 'success.jsp' starting page</title>
</head>
<body>
<%
out.println("登录成功!");
%>
</body>
</html>
如果登录的用户名和密码和存放在数据库的数据对不上，就显示登录错误页面error.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<html>
<head>
<title>My JSP 'error.jsp' starting page</title>
</head>
<body>
<%
out.println("用户名或密码错误，登录失败!");
%>
</body>
</html>
输入用户名ming,密码ming
输入用户名lin,密码li
完整代码包:http://download.csdn.net/detail/u011731233/8093745
时间： 2024-07-31 06:09:54