目录

1.效果展示

2.环境搭建

3.前端代码

4.后端代码 

5.创作不易，点个赞吧

效果展示

表

登入界面

注册界面

注册一个账号

登入该账号

1.尝试输入错误密码

2.输入正确密码

再次注册该账号

环境搭建

MySQL下载安装网上都有可以参考http://t.csdn.cn/czWMN

Eclipse搭载MySQLhttp://t.csdn.cn/NKXAh

这边说一点 javaWeb项目中无法驱动数据库 http://t.csdn.cn/jwKcA

tomcat下载安装 http://t.csdn.cn/EKMxB

Eclipse搭载tomcat http://t.csdn.cn/bCd6q

搭配过程中可能出现的问题：

1.设置里面没有Server  http://t.csdn.cn/LZCeq

2.以上办法出现无法安装 http://t.csdn.cn/nVlL9

其他的网上都有

前端代码

1.hello.html

 
 
LOGIN
 
 忘记密码?注册

2.signup.html

 
 
SIGN UP
 
 
  

内容我就不解释了html没怎么学，说一下前后端数据交互问题吧

form表单交互 

按钮type得是submit，会跳转

ajax交互

function testAjax(){ $.ajax({url: "HelloForm",    //请求的url地址dataType: "json",   //返回格式为jsonasync: true, //请求是否异步，默认为异步，这也是ajax重要特性data: {//数据"username": document.getElementById("no").value,"password": document.getElementById("pw").value},    //参数值type: "GET",  //方式//成功处理，我想这边的成功应该是接受到反馈的信息就算成功吧success: function(req) {var login=req[0].login;//登入成功if(login=="true"){ window.location.href="MainPage.html";}else {$("#loginFail").html("账号或者密码错误");}},error: function() {//请求出错处理//可能是返回的json格式出错alert("error");}});}

这时候按钮不需要submit就可以传输信息，登入界面我更喜欢用这个

注意需要引入包

而且在代码中最好放在 ajax方法之上

其他的不多说了.....

后端代码 

先看一下我的文件结构

User.java

package user;public class User {//用户IDint user_id;//用户昵称String user_name;  //账号密码String no;String password;//区分是否为管理员//所有页面注册的都是普通用户 管理员由后端指定 以0为普通用户 1为管理员int role_id=0;public User() {this.no="";this.password="";}public User(String no,String password) {this.no=no;this.password=password;}public User(String no,String password,String user_name) {this.no=no;this.password=password;this.user_name=user_name;}public void setUsername(String a) {this.no=a;}public void setPassword(String a) {this.password=a;}public void setUser_id(int id) {this.user_id=id;}
}

UserDao.java

package user;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;import database.Connect;public class UserDao {User user;Connect connect=new Connect();Connection connection=null;public void setUser(User u) {this.user=u;}//连接数据库public void getConnection() {connection=connect.getConnection();}//释放数据库public void deleteConnection() throws SQLException {if(connection!=null) {connection.close();} connection=null;}//用户登入是否成功public boolean checkUserLogin() {if(user==null)return false; try {PreparedStatement presta=connection.prepareStatement("select *"+ " from user where no like ? and password like ? ;");//同时验证账号密码presta.setString(1, user.no);presta.setString(2, user.password);boolean a=presta.executeQuery().next();presta.close();return a;} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return false;}//用户是否存在 用于注册页面判断public boolean checkUserExist() {if(user==null)return false;  try {Statement statement=connection.createStatement();//只需验证用户名是否存在String sql="select * from user where no = "+user.no+";";boolean a=statement.executeQuery(sql).next();statement.close();return a;} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return false;}//注册成功 应该在前端判断成功之后才调用此函数public void addUser() {//查找最大的用户ID 然后 此用户ID+1 特别注意线程安全（将来完善）int MaxUserId=-1; try {Statement statement=connection.createStatement();//String sql="select max(user_id) id from user";//是否是第一个用户  如果不是ID=MAXID+1 ResultSet rs=statement.executeQuery(sql);MaxUserId=rs.next()?rs.getInt("id")+1:0;//this.user.setUser_id(MaxUserId);String updateSql="insert into user values(?,?,?,?,?);";PreparedStatement presta=connection.prepareStatement(updateSql);presta.setInt(1, MaxUserId);presta.setString(2, user.no);presta.setString(3, user.user_name);presta.setString(4, user.password);presta.setInt(5, user.role_id);presta.executeUpdate();statement.close();presta.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}
}

 Connect.java

package database;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException; public class Connect {Connection con;public static String user;public static String password;public Connection getConnection() {try { // 加载数据库驱动类//记得在lib下面放jar包Class.forName("com.mysql.cj.jdbc.Driver");System.out.println("数据库驱动加载成功");} catch (ClassNotFoundException e) {e.printStackTrace();}user = "root";//数据库登录名password = "你自己的密码";//密码try { // 通过访问数据库的URL获取数据库连接对象con = DriverManager.getConnection("jdbc:mysql://localhost:3306/你自己的数据库?useUnicode=true&characterEncoding=utf-8",user, password);System.out.println("数据库连接成功");} catch (SQLException e) {e.printStackTrace();}return con; // 按方法要求返回一个Connection对象}  
}

 HelloForm.java

package com.servlets;import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import user.User;
import user.UserDao;/*** Servlet implementation class HelloForm*/
@WebServlet("/HelloForm")
public class HelloForm extends HttpServlet {private static final long serialVersionUID = 1L;UserDao user=new UserDao();/*** @see HttpServlet#HttpServlet()*/public HelloForm() {super(); System.out.println("HelloForm occur");// TODO Auto-generated constructor stub}/*** @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)*/protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 设置响应内容类型request.setCharacterEncoding("utf-8");response.setContentType("text/html;charset=utf-8");String name=request.getParameter("username");String password=request.getParameter("password");String login="false";System.out.println(name+" "+password);//验证  user.getConnection();user.setUser(new User(name,password));login=Boolean.toString(user.checkUserLogin());try {user.deleteConnection();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}//Json格式不能出错String buffer = "[{\"login\":"+"\""+login+"\"}]";  System.out.println(buffer);//写入回复中PrintWriter writer = response.getWriter();writer.write(buffer);writer.close(); }// 处理 POST 方法请求的方法public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request, response);}
}

register.java

package com.servlets;import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import user.User;
import user.UserDao;/*** Servlet implementation class register*/
@WebServlet("/register")
public class register extends HttpServlet {UserDao user=new UserDao();private static final long serialVersionUID = 1L;/*** @see HttpServlet#HttpServlet()*/public register() {super();System.out.println("register occur");// TODO Auto-generated constructor stub}/*** @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)*/protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stub// 设置响应内容类型request.setCharacterEncoding("utf-8");response.setContentType("text/html;charset=utf-8");String no=request.getParameter("no");String password=request.getParameter("password");String username=request.getParameter("username");  System.out.println(no+" "+password+" "+username);user.getConnection();user.setUser(new User(no,password,username));boolean usernoexist=user.checkUserExist();//用户不存在 添加到数据库if(!usernoexist) {user.addUser();}try {user.deleteConnection();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}//Json格式不能出错String buffer = "[{\"flag\":"+"\""+!usernoexist+"\"}]"; System.out.println(buffer);//写入回复中PrintWriter writer = response.getWriter();writer.write(buffer);writer.close(); }/*** @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoGet(request, response);}}

至此，就完成了简单的登入注册

关于使用servlet 我推荐菜鸟教程，哈哈哈哈哈哈，我也是刚看的，文件名还没换呢

 创作不易，点个赞吧

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