三层架构：
package org.entity; public class Login { private int id; private String uname; private String upwd; public Login() { } public Login( String uname, String upwd) { this.uname = uname; this.upwd = upwd; } public Login(int id, String uname, String upwd) { this.id = id; this.uname = uname; this.upwd = upwd; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getUname() { return uname; } public void setUname(String uname) { this.uname = uname; } public String getUpwd() { return upwd; } public void setUpwd(String upwd) { this.upwd = upwd; } }
LoginDao.jsp
package org.dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.entity.Login;
//模型层，用于处理登录(查询数据)
public class LoginDao {
public static int login(Login login) {//登录
int flag=-1;//登录成功与否的标识 -1:系统异常，0：用户名或密码有误，1：登录成功
int result =-1;
Connection connection =null;
PreparedStatement pstmt =null;
ResultSet rs =null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
//Ctrl+1自动返回
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/login?serverTimezone=UTC&characterEncoding=utf-8","root","vayne");
String sql="Select count(*) from login where uname=? and upwd =?";
pstmt = connection.prepareStatement(sql);
pstmt.setString(1, login.getUname());
pstmt.setString(2, login.getUpwd());
rs = pstmt.executeQuery();
if(rs.next()) {
result =rs.getInt(1);
}
if(result>0) {//登录成功
flag= 1;
}else {
flag=0;//用户名或密码错误
}
}catch(ClassNotFoundException e) {
e.printStackTrace();
flag=-1;//系统异常
}catch(SQLException e) {
e.printStackTrace();
flag=-1;//系统异常
}catch(Exception e) {
e.printStackTrace();
flag=-1;//系统异常
}finally {
try {
if(rs!=null) rs.close();
if(pstmt!=null) pstmt.close();
if(connection!=null) connection.close();
}catch(SQLException e) {
e.printStackTrace();
}catch(Exception e) {
e.printStackTrace();
}
}
return flag;
}
}
View
login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>登录</title>
</head>
<body>
<form action="LoginServlet" method="post">
用户名:<input type="text" name="uname"><br/>
密码：<input type="password" name="upwd"><br/>
<input type="submit" value="登录"><br/>
</form>
</body>
</html>
welcome.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
登陆成功！！！
</body>
</html>
Controller
LoginServlet.java
package org.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.dao.LoginDao;
import org.entity.Login;
//控制器层：接受view层的请求，并分发给Model处理
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//处理登录请求
request.setCharacterEncoding("utf-8");
String name= request.getParameter("uname");
String pwd= request.getParameter("upwd");
Login login=new Login(name,pwd);
//调用模型层的登录功能
int result=LoginDao.login(login);
if(result>0) {
request.getRequestDispatcher("welcome.jsp").forward(request, response);
}else {//返回登录页，重新登录
request.getRequestDispatcher("login.jsp").forward(request, response);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}