找不到txt文件StreamReader

Question

'未处理的异常：

System.IO.FileNotFoundException：找不到文件“ /Logins.txt”发生了

嗨，新手在xamarin c＃中建立了一个非常基本的登录/注册系统，该系统使用Systsem.IO中的StreamReader读取带有存储的用户名和密码的文本文件。 txt文件与.cs文件本身位于同一目录中，并且在解决方案资源管理器中可见。 我已经尝试过没有成功的完整路径，并且以管理员身份运行，以防万一这与权限有关。 哪里不对了？

public partial class LoginPage : ContentPage
{
    public LoginPage()
    {
        InitializeComponent();
    }
    List<string> user = new List<string>();
    List<string> pass = new List<string>();

    public void btnLogin_Clicked(object sender, EventArgs e)
    {
        //Read the txt
        StreamReader sr = new StreamReader("Logins.txt");
        string line = "";

        //Read every line until there is nothing in the next line
        while ((line = sr.ReadLine()) != null)
        {
            //Grab items within new lines separated by a space and chuck them into their array
            string[] components = line.Split(" ".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
            user.Add(components[0]);
            pass.Add(components[0]);
        }
        //Check entries are on the same line and match
        if (user.Contains(txtUsername.Text) && pass.Contains(txtPassword.Text) && Array.IndexOf(user.ToArray(), txtUsername.Text) == Array.IndexOf(pass.ToArray(), txtPassword.Text))
        {
            Navigation.PushModalAsync(new HomeScreen());
        }
        else
            DisplayAlert("Error", "The username or password you have entered is incorrect", "Ok");
    }
    private void Cancel_Clicked(object sender, EventArgs e)
    {
        Navigation.PushModalAsync(new MainPage());
    }
}

Answer 1

如果将Logins.txt文件更改为嵌入式资源，则可以在运行时从程序Logins.txt加载该资源，如下所示：

var assembly = IntrospectionExtensions.GetTypeInfo(typeof(LoginPage)).Assembly;
Stream stream = assembly.GetManifestResourceStream("YourAssembly.Logins.txt");
string text = "";
using (var reader = new System.IO.StreamReader (stream)) 
{
    text = reader.ReadToEnd();
}

YouAssembly指的是在生成项目时将生成的程序集（dll）的名称。 如果您不知道这是什么或未更改，则它可能与项目名称相同。

Xamarin文档提供了一个很好的示例说明： Xamarin.Forms中的文件处理

编辑：

在构造函数中执行此操作并处理内容的完整示例，您可以执行身份验证处理。

但首先，让我们定义一个POCO来保存用户名/密码详细信息：

public class UserCredentials
{
    public string Username {get;set;}
    public string Password {get;set;}
}

添加一个属性以将其保存到类中：

List<UserCredentials> CredentialList {get;set;}

现在，在构造函数中：

public LoginPage()
{
    InitializeComponent();

    // Read in the content of the embedded resource, but let's read 
    // each line to make processing a little easier
    var assembly = IntrospectionExtensions.GetTypeInfo(typeof(LoginPage)).Assembly;
    Stream stream = assembly.GetManifestResourceStream("YourAssembly.Logins.txt");
    var textLines = new List<string>();
    string line = null;
    using (var reader = new System.IO.StreamReader (stream)) 
    {
        while ((line = sr.ReadLine()) != null) 
        {
            textLines.Add(line);
        }
    }

    // Init our cred list
    this.CredentialList = new List<UserCredentials>();

    // Read out the contents of the username/password combinations
    foreach (var line in textLines)
    {
        // Grab items within new lines separated by a space and chuck them into their array
        string[] components = line.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);

        // Add the combination to our list
        this.CredentialList.Add(new UserCredential 
        {
            Username = user.Add(components[0]),
            Password = pass.Add(components[0])
        });
    }
}

现在，我们的登录变得更加容易。 以前，我们先检查用户名/密码在我们的已知数据集中是否存在，然后再检查它们在两个列表中是否位于相同的索引中。

public void btnLogin_Clicked(object sender, EventArgs e)
{
    // Now can use linq to validate the user
    // NOTE: this is case sensitive
    if (this.CredentialList.Any(a => a.Username == txtUsername.Text && a.Password == txtPassword.Text))
    {
        // NOTE: you've only validated the user here, but aren't passing
        // or storing any detail of who the currently logged in user is
        Navigation.PushModalAsync(new HomeScreen());
    }
    else
    {
        DisplayAlert("Error", "The username or password you have entered is incorrect", "Ok");
    }
}