建立系统如下：
实现增减： 在src文件中创建一个名为 UserBean的文件 引入变量
package com; public class UserBean { private String username; private String password; private int gender; private int age; private int status; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public int getGender() { return gender; } public void setGender(int gender) { this.gender = gender; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public int getStatus() { return status; } public void setStatus(int status) { this.status = status; } }然后再在web中创建三个文件： 1 index.jsp
登陆界面
<%-- Created by IntelliJ IDEA. User: 113 Date: 2020/10/2 Time: 11:21 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>$Title$</title> </head> <body> <form method="post" action="register.jsp"> 用户名:<input type="text" name="username"><br> 密码: <input type="text" name="password"><br> 性别: <input type="text" name="gender"><br> 年龄: <input type="text" name="age"><br> <button type="submit">注册</button> </form> </body> </html>2 home.jsp 1>加载数据库却驱动 2>建立数据库连接 3>创建Statement对象 4>执行查询 返回结果集 5>遍历结果集数据
<%@ page import="java.sql.*" %><%-- Created by IntelliJ IDEA. User: 113 Date: 2020/10/6 Time: 14:14 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <% Class.forName("com.mysql.jdbc.Driver"); String url="jdbc:mysql://127.0.0.1:3306/submit?user=root&password=root"; Connection connection= DriverManager.getConnection(url); String sql="insert into user(userid,username,userpassword,usersex) values("+user.getUserid()+",'"+user.getUsername()+"','"+user.getUserpassword()+"',"+user.getUsersex()+")";//增加 //String sql="update user set username='离开' where userid=4";//修改 //String sql="delete from user where userid=1";//删除 //String sql="select * from user";//查询 Statement stmt=connection.createStatement(); int count=stmt.executeUpdate(sql); if (count==0) { out.print("失败"); } else { out.print("成功"); } %> </body> </html>3 register.jsp
<%@ page import="com.UserBean"%> <%@ page import="java.sql.Connection" %> <%@ page import="java.sql.DriverManager" %> <%@ page import="java.sql.Statement" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="username" class="com.UserBean" scope="application"></jsp:useBean> <jsp:setProperty name="username" property="*"></jsp:setProperty> <% Class.forName("com.mysql.jdbc.Driver"); String url="jdbc:mysql://localhost:3306/book"; Connection connection= DriverManager.getConnection(url,"root","root"); Statement stmt=connection.createStatement(); //String sql="insert into username(username,password,gender,age) values('"+username.getUsername()+"','"+username.getPassword()+"',2,11)"; //String sql="update user age= 42 where id=5"; String sql="delete from username where id=4"; int count=stmt.executeUpdate(sql); if(count>0){ out.print("删除成功"); }else { out.print("删除失败"); } %>