版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/huyande123/article/details/78459693
建User表
CREATE TABLE `user` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`name` VARCHAR(20) DEFAULT NULL,
`pwd` VARCHAR(20) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=INNODB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8
User对象(javaBean)
public class User {
private int id;
private String name;
private String pwd;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPwd() {
return pwd;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", pwd=" + pwd + "]";
}
}
数据库工具类
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
/**
* 连接数据的驱动类
* @author YandeHu
*
*/
public class DbUtil {
private static String driver="com.mysql.jdbc.Driver";
private static String url="jdbc:mysql://localhost:3306/db_demo";
private static String userName="root";
private static String password="123456";
public static Connection getCon()throws Exception{
//加载驱动类
Class.forName(driver);
//获取DriverManager
Connection con = DriverManager.getConnection(url, userName, password);
System.out.println("数据库连接成功");
return con;
}
public static void close(Connection con)throws Exception{
if(con!=null){
con.close();
}
}
public static void close(PreparedStatement pstmt,Connection con)throws Exception{
if(pstmt!=null){
pstmt.close();
}
if(con!=null){
con.close();
}
}
public static void close(ResultSet rs,PreparedStatement pstmt,Connection con)throws Exception{
if(rs!=null){
rs.close();
}
if(pstmt!=null){
pstmt.close();
}
if(con!=null){
con.close();
}
}
}
增删改查的方法
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Scanner;
import com.day.DbUtil.DbUtil;//连接数据库工具类的完整路径
public class DbMethod {
public static void showAll()throws Exception{
//连接数据库
Connection con=DbUtil.getCon();
String sql="select * from user";
//获取SQL预处理对象
PreparedStatement pstmt = con.prepareStatement(sql);
//执行SQL语句
ResultSet rs = pstmt.executeQuery();
while(rs.next()){
int id=rs.getInt("id");
String name=rs.getString("name");
String pwd=rs.getString("pwd");
System.out.println(id+" "+name+" "+pwd);
}
DbUtil.close(rs, pstmt, con);
}
public static void findUser(int id)throws Exception{
//连接数据库
Connection con = DbUtil.getCon();
//编写SQL语句
String sql="select * from user where id=?";
//获取SQL预处理对象
PreparedStatement pstmt = con.prepareStatement(sql);
//填坑
pstmt.setInt(1, id);
//执行SQL语句
ResultSet rs = pstmt.executeQuery();
if(rs.next()){
String name=rs.getString("name");
String pwd=rs.getString("pwd");
System.out.println(name+" "+pwd);
}
DbUtil.close(pstmt, con);
}
public static void addUser()throws Exception{
//获取数据库连接
Connection con = DbUtil.getCon();
//编写SQL语句
String sql="insert into user(id ,name,pwd) values(null,?,?)";
//获取预处理的SQL对象
PreparedStatement pstmt = con.prepareStatement(sql);
//填坑
System.out.println("请输入新的用户名");
Scanner sc =new Scanner(System.in);
String name=sc.nextLine();
System.out.println("请输入新的用户密码");
String pwd=sc.nextLine();
pstmt.setString(1, name);
pstmt.setString(2, pwd);
//执行SQL语句
int rows = pstmt.executeUpdate();
System.out.println("添加成功"+rows);
//关闭数据库
DbUtil.close(pstmt, con);
}
public static void deleteUser(int id )throws Exception{
//连接数据库
Connection con = DbUtil.getCon();
//编写SQL语句
String sql="delete from user where id=?";
//获取预处理对象
PreparedStatement pstmt = con.prepareStatement(sql);
//填坑
pstmt.setInt(1, id);
//执行SQL语句
int rows = pstmt.executeUpdate();
System.out.println("成功删除了"+rows+"个");
//关闭数据库
DbUtil.close(pstmt, con);
}
public static void updateUser(int id)throws Exception{
Connection con = DbUtil.getCon();
String sql="update user set name=? ,pwd=? where id=?";
System.out.println("输入新的名字");
Scanner sc=new Scanner(System.in);
String name=sc.nextLine();
System.out.println("输入新的密码");
String pwd=sc.nextLine();
//获取预处理的SQL语句
PreparedStatement pstmt = con.prepareStatement(sql);
pstmt.setString(1, name);
pstmt.setString(2, pwd);
pstmt.setInt(3, id);
int row = pstmt.executeUpdate();
System.out.println("更新成功"+row);
DbUtil.close(pstmt, con);
}
}
显示页面
import java.util.Scanner;
public class Demo01 {
public static void main(String[] args) throws Exception {
System.out.println("欢迎来到用户管理系统");
while(true){
System.out.println("--------0 显示所有用户信息---------");
System.out.println("--------1 添加用户信息------------");
System.out.println("--------2 修改用户信息------------");
System.out.println("--------3 删除用户信息------------");
System.out.println("--------4 查找用户信息------------");
System.out.println("--------5 退出系统---------------");
System.out.println("选择功能");
Scanner sc=new Scanner(System.in);
int choose=sc.nextInt();
switch(choose){
case 0:
DbMethod.showAll();
break;
case 1:
DbMethod.addUser();
break;
case 2:{
System.out.println("要修改对应的Id");
int id=sc.nextInt();
DbMethod.updateUser(id);
break;
}
case 3:{
System.out.println("要删除的Id");
int id=sc.nextInt();
DbMethod.deleteUser(id);
break;
}
case 4:{
System.out.println("要查找的Id");
int id=sc.nextInt();
DbMethod.findUser(id);
break;
}
case 5:
System.out.println("退出系统");
System.exit(0);
}
}
}
}