最近两天在学习java数据库，便写了这个示例，以后再加入界面吧。
package shujukv.nn;
/*
* java简单数据库验证登录及小功能
*/
import java.sql.Statement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;
public class Test1 {
static Connection con;
static Scanner p1=new Scanner(System.in);
static String url="jdbc:mysql://localhost:3306/userdemo2"; //相当于路径
static String username="root"; //登录名
static String password="1998";
static PreparedStatement p;
static ResultSet res;
static String sql;
static Scanner n=new Scanner(System.in);
static int i=0;
public static Connection getConnection() {
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("数据库正在连接");
}catch(Exception e) {
e.printStackTrace();
}
try {
// for(int i=0;i<6;i++)
// {
// Thread.sleep(600);
// System.out.print("# ");
// }
System.out.println();
con=DriverManager.getConnection(url, username, password);
System.out.println("数据库连接成功");
} catch (Exception e) {
e.printStackTrace();
}
return con;
}
//main函数
public static void main(String[] args) throws Exception {
getConnection();
int m=0;
while(m!=5) {
System.out.println("欢迎使用T.T租机！");
System.out.println("1.注册账户");
System.out.println("2.登录系统");
System.out.println("3.管理员登录");
System.out.println("4.找回密码");
System.out.println("5.退出");
System.out.println("请输入数字选择功能");
m=n.nextInt();
switch(m) {
case 1:zhuce();break;
case 2:denglu();break;
case 3:guanliyuan();break;
case 4:mhchaxun();break;
case 5:break;
}
}
}
//登录
public static void denglu() throws SQLException {
System.out.println("请输入你的账号:");
String a=n.next();
System.out.println("请输入你的密码:");
String b=n.next();
sql = "select username,password from user where username=? and password=?"; //预处理
p=con.prepareStatement(sql); //标记
p.setString(1, a);
p.setString(2, b);
res=p.executeQuery();
if(res.next()) {
System.out.println("登陆成功");
}
else {
i++;
if(i==3) {
Break(i);
}
System.out.println("登录失败,请重新登录！");
denglu();
}
}
public static void guanliyuan() throws SQLException {
System.out.println("请输入你的admin账号:");
String a=n.next();
System.out.println("请输入你的admin密码:");
String b=n.next();
sql = "select username,password from useradmin where username=? and password=?"; //预处理
p=con.prepareStatement(sql); //标记
p.setString(1, a);
p.setString(2, b);
res=p.executeQuery();
if(res.next()) {
System.out.println("登陆成功");
}
else {
i++;
if(i==3) {
Break(i);
}
System.out.println("登录失败,请重新登录！");
denglu();
}
}
//注册
public static void zhuce()throws SQLException, InterruptedException {
System.out.println("请输入你的新账号：");
String a=n.next();
sql="select username from user where username=?"; //预处理验证
p=con.prepareStatement(sql);
p=con.prepareStatement(sql);
p.setString(1, a);
res=p.executeQuery();
if(res.next()) {
System.out.println("此账号已注册,请重新输入");
zhuce();
}
else {
int k=0;
while(k==0){
System.out.println("请输入你的登录密码");
String b=n.next();
System.out.println("请再次输入你的确认密码");
String b22=n.next();
if(b.equals(b22)) {
//判断两次输入的密码是否相同
System.out.println("请输入你找回密码的问题:");
String b3=n.next();
System.out.println("请输入问题的答案:");
String b33=n.next();
String sql2="insert into user(username,password,userwt,userda) values(?,?,?,?)";
java.sql.PreparedStatement res3=con.prepareStatement(sql2);
res3.setString(1, a);
res3.setString(2, b);
res3.setString(3, b3);
res3.setString(4, b33);
res3.execute();
System.out.println("注册成功!");
k=1;
System.out.println("你的账号为:"+a);
System.out.println("你的密码为:"+b);
}
else {
System.out.println("两次输入的密码不一致，请重新输入");
}
}
}
}
//找密码
//预设问题提示回答验证
//根据账号 模糊查询
public static void mhchaxun() throws Exception {
System.out.println("请输入你的账号:");
String k=p1.next();
sql="select * from user where username=?";
p=con.prepareStatement(sql);
p.setString(1, k);
res=p.executeQuery();
if(res.next()) {
System.out.println(res.getString(4));
Thread.sleep(500);
System.out.println("请输入你的问题答案");
chazhao(k);
}
else {
mhchaxun();
}
}
//根据问题查找
public static void chazhao(String kk) throws Exception {
String k=p1.next();
p=con.prepareStatement("select * from user where userda=? and username=?");
p.setString(1, k);
p.setString(2, kk);
res=p.executeQuery();
if(res.next()) {
System.out.println("核对正确，请输入新密码:");
String k1=n.next();
xgpassword(k1,kk);
}else {
++i;
if(i==3) {
Break(i);
}
System.out.println("答案错误！,请重新输入");
chazhao(kk);
}
}
//强行退出提醒
public static void Break(int a) {
System.out.println("你已错误3次，已强行退出");
System.exit(0);
}
//修改密码
public static void xgpassword(String k1,String K2) throws Exception {
sql="update user set password=? where username=?";
p=con.prepareStatement(sql);
p.setString(1, k1);
p.setString(2, K2);
p.executeUpdate();
System.out.println("修改成功，即将返回登录界面————");
Thread.sleep(1000);
}
}