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'

您好，新手在 xamarin c# 中制作了一个非常基本的登录/注册系统，该系统使用 Systsem.IO 中的 StreamReader 来读取存储了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。 我尝试输入完整路径但没有成功，并以管理员身份运行，以防万一它与权限有关。 有什么问题吗？

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

如果您将Logins.txt 文件更改为嵌入式资源，则可以在运行时从程序集中加载该资源，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 指的是在您构建项目时将生成的程序集 (dll) 的名称。如果您不知道这是什么，或者没有更改它，它很可能与项目同名。

Xamarin 文档有一个很好的例子来说明如何做到这一点：File Handling in Xamarin.Forms

编辑：

在构造函数中执行此操作的更完整示例，并处理内容，以便您可以进行身份​​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;}
}

添加一个属性来保存这个类：

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容易多了。以前我们首先检查用户名/密码是否都存在于我们的已知数据集中，然后检查它们是否在两个列表中的相同索引处。

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");
    }
}