如何遍历文件以获取数据？

Question

我正在尝试进行基本登录并注册 c# 控制台应用程序，但是，我需要遍历我的文件以查看用户在登录时输入的用户名和密码是否匹配。如果用户输入用户名和密码, 我希望我的代码通过我的文件来检查它是否是现有的用户名和密码

这是我的代码：

[Serializable]
public class Users
{
    public string UserName;
    public string Password;

    public Users(string userName, string password)
    {
        UserName = userName;
        Password = password;
    }
}

public class SaveToFile
{
    public static void SerializeSignUpDetails(string userName, string password)
    {
        Users obj = new Users(userName, password);
        IFormatter formatter = new BinaryFormatter();
        Stream stream = new FileStream("SignUp.txt", FileMode.Append, FileAccess.Write);
        formatter.Serialize(stream, obj);
        stream.Close();
    }
    public static Users DeserializeSignUpDetails()
    {
        Stream stream = new FileStream("SignUp.txt", FileMode.Open, FileAccess.Read);
        IFormatter formatter = new BinaryFormatter();
        Users objnew = (Users)formatter.Deserialize(stream);
        stream.Close();
        return objnew;
    }
}

public static void Main(string[] args)
{
    Console.WriteLine("To Login Type 1, To Create a new account Type 2");
    int LogInOrSignUp;
    do
    {
        int.TryParse(Console.ReadLine(), out LogInOrSignUp);
    } while (LogInOrSignUp != 1 && LogInOrSignUp != 2);

    string userName = "";
    string password = "";
    bool successfull = false;
    Users userDetails = SaveToFile.DeserializeSignUpDetails();
    while (!successfull)
    {
        if (LogInOrSignUp == 1)
        {
            Console.WriteLine("Write your username:");
            userName = Console.ReadLine();
            Console.WriteLine("Enter your password:");
            password = Console.ReadLine();
            if (userName == userDetails.UserName && password == userDetails.Password)
            {
                Console.WriteLine("You have logged in successfully!");
                successfull = true;
                break;
            }
            if (!successfull)
            {
                Console.WriteLine("Your username or password is incorect, try again!");
            }
        }

        else if (LogInOrSignUp == 2)
        {
            Console.WriteLine("Enter a username:");
            userName = Console.ReadLine();

            Console.WriteLine("Enter a password:");
            password = Console.ReadLine();

            successfull = true;
            SaveToFile.SerializeSignUpDetails(userName, password);
        }
    }
}

我想使用 foreach 来遍历我的文件，但我不确定如何。

任何帮助表示赞赏！

Answer 1

要使用序列化保留多个条目的登录记录，您需要序列化对象列表。在您的情况下，您可以创建几个可序列化的类，User封装单个条目数据的Users类，以及包含List<User>对象和数据操作方法的类。

^{? 注意：根据您的喜好命名。}

? 要导入的命名空间

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

? 该用户类

[Serializable]
public class User
{
    public string UserName { get; set; }
    public string Password { get; set; }
    //More details...

    public User(string userName, string password)
    {
        UserName = userName;
        Password = password;
    }

    public override string ToString() => $"{UserName}, {Password}";
}

? 该用户类

[Serializable]
public class Users
{
    public readonly List<User> Accounts;

    public Users() => Accounts = new List<User>();

    public void Save(string filePath)
    {
        if (string.IsNullOrEmpty(filePath)) return;

        var bf = new BinaryFormatter();
        using (var fs = new FileStream(filePath, FileMode.Create))
            bf.Serialize(fs, this);
    }

    public static Users Load(string filePath)
    {
        if (!File.Exists(filePath)) return null;

        var bf = new BinaryFormatter();
        using (var sr = new FileStream(filePath, FileMode.Open))
            return bf.Deserialize(sr) as Users;
    }

    public bool ContainsUserName(string userName) => 
        Accounts.Any(x => x.UserName == userName);

    public bool ContainsAccount(string userName, string pass) =>
        Accounts.Any(x => x.UserName == userName && x.Password == pass);

    public User Get(string userName, string pass) =>
        Accounts.FirstOrDefault(x => x.UserName == userName && x.Password == pass);

    public bool Add(string userName, string pass)
    {
        if (ContainsUserName(userName)) return false;

        Accounts.Add(new User(userName, pass));
        return true;
    }
}

在您的实现中，要创建、加载和保存您的数据：

//Load...
users = Users.Load(dataFilePath);

//Or create new object...
if (users is null)
    users = new Users();

//and when it comes to save...
users.Save(dataFilePath);

使用该ContainsUserName方法找出给定的用户名是否已经存在，以避免重复。该Add方法将执行相同的操作，并将有效的新条目添加到列表中。该Get方法在列表中搜索给定的用户名和密码，User如果有null，则返回一个对象，ContainsAccount如果您不需要返回一个User对象，该方法将执行相同的操作。

var user = users.Get("user", "pass");
if (user is null)
    Console.WriteLine("Incorrect username and/or password...");

//or
if (!users.ContainsAccount("user", "pass"))
    Console.WriteLine("Incorrect username and/or password...");

将其应用于您的main：

public static void Main(string[] args)
{
    Console.WriteLine("To Login Type 1, To Create a new account Type 2");
    int LogInOrSignUp;
    do
    {
        int.TryParse(Console.ReadLine(), out LogInOrSignUp);
    } while (LogInOrSignUp != 1 && LogInOrSignUp != 2);

    var filePath = Path.Combine(AppContext.BaseDirectory, "SignUp.dat");
    var userName = "";
    var password = "";
    var successfull = false;
    var userDetails = Users.Load(filePath);

    if (userDetails is null)
        userDetails = new Users();

    while (!successfull)
    {
        if (LogInOrSignUp == 1)
        {
            Console.WriteLine("Write your username:");
            userName = Console.ReadLine();
            Console.WriteLine("Enter your password:");
            password = Console.ReadLine();
            if (userDetails.ContainsAccount(userName, password))
            {
                Console.WriteLine("You have logged in successfully!");
                successfull = true;
                break;
            }
            else
                Console.WriteLine("Your username or password is incorect, try again!");
        }

        else //if (LogInOrSignUp == 2)
        {
            Console.WriteLine("Enter a username:");
            userName = Console.ReadLine();

            if (userDetails.ContainsUserName(userName))
                Console.WriteLine("The username is taken. Try another one.");
            else
            {
                Console.WriteLine("Enter a password:");
                password = Console.ReadLine();

                successfull = true;
                userDetails.Add(userName, password);
                userDetails.Save(filePath);
                Console.WriteLine($"A new account for {userName} has been created.");
            }
        }
    }
    Console.ReadLine();
}

^{? 注意：最好使用switch语句来选择LogInOrSignUp而不是if语句}