随机生成验证码

import java.util.Random;
import java.util.Scanner;

public class UserLogin {
public static void main(String[] args) {
String username = getUsername();
String password = getPassword();
String code = generateRandomCode(4);

System.out.println("请输入验证码：" + code);
String inputCode = getInputCode();

if (inputCode.equalsIgnoreCase(code)) {
System.out.println("验证码正确，登录成功！");
} else {
System.out.println("验证码错误，登录失败！");
}
}

public static String getUsername() {
Scanner scanner = new Scanner(System.in);
System.out.print("请输入账号：");
return scanner.nextLine();
}

public static String getPassword() {
Scanner scanner = new Scanner(System.in);
System.out.print("请输入密码：");
return scanner.nextLine();
}

public static String generateRandomCode(int length) {
String characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
Random random = new Random();
StringBuilder code = new StringBuilder();

for (int i = 0; i < length; i++) {
int index = random.nextInt(characters.length());
char randomChar = characters.charAt(index);
code.append(randomChar);
}

return code.toString();
}

public static String getInputCode() {
Scanner scanner = new Scanner(System.in);
System.out.print("请输入验证码：");
return scanner.nextLine();
}
}