问题描述
编辑后可以解决问题
在Android中,我需要将pdf文件下载到文档"文件夹,然后使用默认程序将其打开.我下载了文档并将其存储在Byte数组中.然后我调用此方法:
In Android, I need to download a pdf file to "Documents" folder and open it with the default program.I downloaded the document and stored it in a Byte array.Then I call this method:
/// <summary>
/// Save data bytes on "My documents" folder and open
/// </summary>
/// <param name="fileName">Filename, for example: "Test.pdf"</param>
/// <param name="data">Array of bytes to save</param>
/// <returns>True if success or false if error</returns>
public bool SaveAndOpen(string fileName, byte[] data)
{
try
{
// Get my documents path
string filePath = Path.Combine(Android.OS.Environment.ExternalStorageDirectory.AbsolutePath, Android.OS.Environment.DirectoryDownloads);
// Combine with filename
string fullName = Path.Combine(filePath, fileName);
// If the file exist on device delete it
if (File.Exists(fullName))
{
// Note: In the second run of this method, the file exists
File.Delete(fullName);
}
// Write bytes on "My documents"
File.WriteAllBytes(fullName, data);
// Launch file as process
Process.Start(fullName);
return true;
}
catch (Exception ex)
{
Console.WriteLine("ERROR: " + ex.Message + ex.StackTrace);
return false;
}
}
问题是使用默认的pdf阅读器打开pdf文档.
The problem is to open the pdf document with the default pdf reader.
"Process.Start(fullName);"行引发异常
The line "Process.Start(fullName);" throws an exception
感谢您的时间!
推荐答案
我找到了一种保存和打开文件的方法:
I found a way to save and open the file:
/// <summary>
/// Save data bytes on "My documents" folder and open
/// </summary>
/// <param name="fileName">Filename, for example: "Test.pdf"</param>
/// <param name="data">Array of bytes to save</param>
/// <returns>True if success or false if error</returns>
public bool SaveAndOpen(string fileName, byte[] data)
{
try
{
// Get my downloads path
string filePath = Path.Combine(Android.OS.Environment.ExternalStorageDirectory.AbsolutePath, Android.OS.Environment.DirectoryDownloads);
// Combine with filename
string fullName = Path.Combine(filePath, fileName);
// If the file exist on device delete it
if (File.Exists(fullName))
{
// Note: In the second run of this method, the file exists
File.Delete(fullName);
}
// Write bytes on "My documents"
File.WriteAllBytes(fullName, data);
// Get the uri for the saved file
Android.Net.Uri file = Android.Support.V4.Content.FileProvider.GetUriForFile(
this,
this.PackageName + ".fileprovider",
new Java.IO.File(fileName));
Intent intent = new Intent(Intent.ActionView);
intent.SetDataAndType(file, "application/pdf");
intent.SetFlags(ActivityFlags.ClearWhenTaskReset | ActivityFlags.NewTask | ActivityFlags.GrantReadUriPermission | ActivityFlags.NewTask);
this.ApplicationContext.StartActivity(intent);
return true;
}
catch (Exception ex)
{
Console.WriteLine("ERROR: " + ex.Message + ex.StackTrace);
return false;
}
}
需要在运行时请求权限.我使用了Nuget上的Plugin.Permisions:
It's needed to request the permissions at runtime. I used Plugin.Permisions available on Nuget:
Plugin.Permissions.PermissionsImplementation.Current.RequestPermissionsAsync(
new Plugin.Permissions.Abstractions.Permission[]
{
Plugin.Permissions.Abstractions.Permission.Storage,
Plugin.Permissions.Abstractions.Permission.MediaLibrary
});
还要在AndroidManifest.xml文件中添加一个提供程序:
Also add a provider in the AndroidManifest.xml file:
<application android:label="My app" android:icon="@mipmap/icon">
<provider android:name="android.support.v4.content.FileProvider" android:authorities="${applicationId}.fileprovider" android:exported="false" android:grantUriPermissions="true">
<meta-data android:name="android.support.FILE_PROVIDER_PATHS" android:resource="@xml/file_paths"></meta-data>
</provider>
</application>
在同一AndroidManifest中添加以下项的权限:
In the same AndroidManifest add permisions for:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MANAGE_DOCUMENTS" />
并在Resources/xml/file_paths.xml中添加外部路径
And add an external path in Resources/xml/file_paths.xml
<external-path name="external_files" path="."/>
不知道我是否不需要权限,但是可以用这种方式工作.
Don't know if I have not needed permissions, but with this way works.
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