java登录和身份验证系统。txt文件

Question

我正在尝试编写一个带有身份验证的简单登录系统。 我首先尝试给用户两种选择：登录或注册。 然后，如果用户选择注册，则信息将存储在中。然后使用txt文件与登录详细信息进行比较，以检查此用户是否存在或密码是否有效。 我遇到了一个问题，当我注册了两个或更多的“账户”时， 我可以登录除第一个帐户以外的其他帐户。 从“阅读”的角度来看，似乎缺少了一些东西。txt文件，查找数据

public static void main(String[] args) throws Exception {

    File file = new File("database.txt");
    PrintWriter output = new PrintWriter(new FileWriter(file, true));
    Scanner input = new Scanner(file);
    Scanner keyboard = new Scanner(System.in);
    Customers customer = new Customers();

    System.out.println("1. Login");
    System.out.println("2. Register");

    int option = keyboard.nextInt();

    switch (option) {
        case 1:
            System.out.println("LOGIN PAGE");
            System.out.println("Username: ");
            String inpUser = keyboard.next();

            if (input.next().equals(inpUser)) {
                System.out.println("Password: ");
                String inpPass = keyboard.next();
                if (input.next().equals(inpPass)) {
                    System.out.println("Login Succesful!");
                } else {
                    System.out.println("Password is incorrect.");
                }
            } else {
                System.out.println("Username is incorrect.");
            }
            break;

        case 2:
            System.out.println("REGISTRATION PAGE");
            System.out.println("Username: ");
            String username = keyboard.next();
            customer.setUsername(username);


            System.out.println("Password: ");
            String password = keyboard.next();
            customer.setPassword(password);

            System.out.println("You've successfully registered! You may login now.");

            output.println(customer.getUsername());
            output.println(customer.getPassword());

            output.close();
            break;

        default:
            System.out.println("1 OR 2 PLEASE");
    }
    keyboard.close();
    input.close();
}

客户代码

public Customers(){

}

public Customers(String username, String password) {
    this.username = username;
    this.password = password;
}

public String getUsername() {
    return username;
}

public String getPassword() {
    return password;
}

public void setUsername(String username) {
    this.username = username;
}

public void setPassword(String password) {
    this.password = password;
}

}

Answer 1

您只需要检查用户输入是否等于您的列表中的第一行。txt文件

if (input.next().equals(inpUser)){

你需要检查每个条目。为此，需要迭代文件中的每一行。像这样的东西应该可以

case 1:
System.out.println("LOGIN PAGE");
System.out.println("Username: ");
String inpUser =  keyboard.next();
boolean found = false;
while(input.hasNext() && !found) { // Add a loop here to chek for every entry in the file
    if (input.next().equals(inpUser)){
        System.out.println("Password: ");
        String inpPass = keyboard.next();
        if (input.next().equals(inpPass)){
            System.out.println("Login Succesful!");
            found = true;
            break;
        }
    } 
}
if(!found) {
    System.out.println("Login incorrect!");
}