-07-01验证用户账号密码登录 三次输入错误要验证码

登录功能

如果登录失败的次数没到3次，登录时需要用户名和密码

如果登录失败的次数到达3次，登录时需要用户名、密码、验证码

验证码：4位，大小写字母和数字组成

root 1234 //正确的账号密码`package com.qf.test3;

import java.util.Random;import java.util.Scanner;public class TestOverload3 {public static void main(String[] args) {String s1 = "abc";String s2 = "ab3c";System.out.println(s1.equals(s2));/*登录功能如果登录失败的次数没到3次，登录时需要用户名和密码如果登录失败的次数到达3次，登录时需要用户名、密码、验证码验证码：4位，大小写字母和数字组成root 1234 //正确的账号密码*/Scanner sc = new Scanner(System.in);// 登录失败的次数int c = 0;for(;;){boolean b;if(c < 3){System.out.println("请输入用户名：");String username = sc.next();System.out.println("请输入密码：");String password = sc.next();b = login(username,password);}else{System.out.println("请输入用户名：");String username = sc.next();System.out.println("请输入密码：");String password = sc.next();String check = getCheckCode2();System.out.println("验证码："+check);System.out.println("请输入验证码：");String checkCode = sc.next();b = login(username,password,checkCode,check);}if(b){System.out.println("登录成功");break;}else{System.out.println("登录失败");c++;}}}public static boolean login(String username,String password){return username.equals("root") && password.equals("1234");}public static boolean login(String username,String password,String checkCode,String check){return username.equals("root") && password.equals("1234") && checkCode.equals(check);}public static String getCheckCode2(){Random r = new Random();String checkCode = "";for(int i = 1;i<=4;i++){int num = r.nextInt(3);// 0 1 2switch(num){case 0: // 65 90checkCode += (char)(r.nextInt(90 - 65 + 1) + 65);break;case 1: // 97 122checkCode += (char)(r.nextInt(122 - 97 + 1) + 97);break;case 2: // 48 57checkCode += (char)(r.nextInt(57 - 48 + 1) + 48);break;}}return checkCode;}public static String getCheckCode(){String s = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";Random r = new Random();String str = "";for(int i = 1;i<=4;i++){int index = r.nextInt(s.length());//0~61char c = s.charAt(index);str += c;}return str;}}