System.UnauthorizedAccessException：对路径“/Download”的访问被拒绝。在 xamarin 安卓中答案

【问题标题】：System.UnauthorizedAccessException: Access to the path "/Download" is denied. in xamarin androidSystem.UnauthorizedAccessException：对路径“/Download”的访问被拒绝。在 xamarin 安卓中
【发布时间】：2017-01-08 21:00:37
【问题描述】：

我正在尝试从字节数组生成 PDF。但它给出了“访问路径被拒绝”的问题。我已经在清单文件中给予了许可。我正在发送我的代码块，请检查一下并提供一些建议和反馈，以便我完成它。

 private void ObjbtnViewSlip_Click(object sender, EventArgs e)
    {
        var result = objPaySlipViewModel.GetPaySlipByte(GlobalApplicationSession.EmployeeCode, GlobalApplicationSession.CompanyId, selectedPeriod);
        if (File.Exists(Android.OS.Environment.DirectoryDownloads + "/RSI/PaySlip/temp.pdf") == false)
        {
            Directory.CreateDirectory(Android.OS.Environment.DirectoryDownloads + "/RSI/PaySlip/");
            File.Create(Android.OS.Environment.DirectoryDownloads + "/RSI/PaySlip/temp.pdf");
            System.IO.File.WriteAllBytes(Android.OS.Environment.DirectoryDownloads + "/RSI/PaySlip/", result);
        }
    }

【问题讨论】：

请将图片改为内联代码。人们可以将代码复制粘贴到 IDE 中，帮助您更快地修复它。
@matthewrdev 请检查。我需要你的建议来解决这个问题

标签： android c#-4.0 xamarin xamarin.android xamarin.forms

【解决方案1】：

首先，您提供的路径不正确。 Android.OS.Environment.DirectoryDownloads 只会返回“下载”

修改您的代码以获取下载文件夹的完整路径，例如：

//The following will return the downloads folder path.
string directory = Path.Combine(Android.OS.Environment.ExternalStorageDirectory.AbsolutePath, Android.OS.Environment.DirectoryDownloads);
string file = Path.Combine(directory, "/RSI/PaySlip/temp.pdf");

还要检查 AndroidManifest.xml 文件中是否提到了以下内容以授予应用程序权限。

uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"
uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"

【讨论】：

【解决方案2】：

  string localStoragePath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
            string localFilename = Path.GetFileName(serverFileName);
            string localFilePath = Path.Combine(localStoragePath, localFilename);

            if (!System.IO.File.Exists(localFilePath))
            {
                WebClient webClient = new WebClient();
                webClient.DownloadFile(serverFileName, localFilePath);          
            }

            OpenFile(localFilePath);


            });

public void OpenFile(字符串文件路径) {

        var bytes = File.ReadAllBytes(filePath);

        //Copy the private file's data to the EXTERNAL PUBLIC location
        string externalStorageState = global::Android.OS.Environment.ExternalStorageState;
        string application = "";

        string extension = System.IO.Path.GetExtension(filePath);

        switch (extension.ToLower())
        {
            case ".doc":
            case ".docx":
                application = "application/msword";
                break;
            case ".pdf":
                application = "application/pdf";
                break;
            case ".xls":
            case ".xlsx":
                application = "application/vnd.ms-excel";
                break;
            case ".jpg":
            case ".jpeg":
            case ".png":
                application = "image/jpeg";
                break;
            default:
                application = "*/*";
                break;
        }
        var externalPath = global::Android.OS.Environment.ExternalStorageDirectory.Path + "/report" + extension;
        File.WriteAllBytes(externalPath, bytes);

        Java.IO.File file = new Java.IO.File(externalPath);
        file.SetReadable(true);
        //Android.Net.Uri uri = Android.Net.Uri.Parse("file://" + filePath);
        var uri = global::Android.Net.Uri.FromFile(file);
        Intent intent = new Intent(Intent.ActionView);
        intent.SetDataAndType(uri, application);
        intent.SetFlags(ActivityFlags.ClearWhenTaskReset | ActivityFlags.NewTask);

        try
        {
            Application.Context.StartActivity(intent);
        }
        catch (Exception)
        {
            Toast.MakeText(Application.Context, "No Application Available to View PDF", ToastLength.Short).Show();
        }
    }

【讨论】：