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jsp--MVC案例

日期：2021-05-20点击：498收藏

在这里插入图片描述

三层优化
1.加入接口
建议面向接口开发：先接口-再实现类
–service、dao加入接口
–接口与实现类的命名规范
接口：interface，起名 I实体类Service IStudentService
IStudentDao
实现类：implements 起名实体类ServiceImpl StudentServiceImpl
StudentDaoImpl
接口： I实体类层所在包名 IStudentService、IStudentDao
接口所在的包： xxx.service xx.dao

 实现类： 实体类层所在包名Impl StudentServiceImpl、StudentDaoImpl 实现类所在的包：xxx.service.impl xx.dao.impl 以后使用接口/实现类时，推荐写法： 接口 x = new 实现类(); IStudentDao studentDao = new StudentDaoImpl();

案例：实现用户登录验证
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"> </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> 登录成功！ </body> </html>

com.xdr.entity–Login.java

package com.xdr.entity; public class Login { private int id; private String uname; private String upwd; public Login() { } public Login(String uname, String upwd) { super(); this.id = id; this.uname = uname; this.upwd = upwd; } public Login(int id, String uname, String upwd) { super(); 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; } }

com.xdr.dao–loginDao.java

package com.xdr.dao; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import com.xdr.entity.Login; //模型层：用于处理登录（查询数据库） public class LoginDao { public static int login(Login login) {//登录 //boolean flag = false;//登录成功与否标识 int flag = -1; //-1系统异常 ，0用户名或密码有误 1登陆成功 int result = -1; Connection connection = null; PreparedStatement pstmt = null; ResultSet rs = null; try { Class.forName("com.mysql.jdbc.Driver"); connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/jsp01","root","123456"); 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) { return 1; }else { return 0;//登录失败（用户名或密码有误！） } }catch(ClassNotFoundException e) { e.printStackTrace(); return -1;//登录失败（系统异常！） }catch(SQLException e) { e.printStackTrace(); return -1; }catch(Exception e) { e.printStackTrace(); return -1; }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(); } } } }

com.xdr.servlet–LoginServlet.java

package com.xdr.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 com.xdr.dao.LoginDao; import com.xdr.entity.Login; //控制层：接受view请求，并分发给model public class LoginServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //处理登录 request.setCharacterEncoding("utf-8"); String name = request.getParameter("uname"); String pwd = request.getParameter("upwd"); Login login = new Login(name,pwd);//用户名，密码 //调用陪你过模型层的 登录功能 int result = LoginDao.login(login); if(result>0) {//成功 response.sendRedirect("welcome.jsp"); }else {//登录失败 response.sendRedirect("login.jsp"); } } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); } }