Android Java写入文件内部存储器并共享

Question

i cannot understand about sharing internal txt file. (not external !) I noticed that is not possibile by default, but i writed my ContetProvider class

< provider android:name="myProvider" android:authorities="com.mobilemerit.usbhost" android:exported="true" />

public class myProvider extends ContentProvider {
@Override
public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {       
     File cacheDir = getContext().getCacheDir();
     File privateFile = new File(cacheDir, "file.txt");

     return ParcelFileDescriptor.open(privateFile, ParcelFileDescriptor.MODE_READ_WRITE);
}

then

 try {
            InputStream is = c.getAssets().open("file.txt");

            File cacheDir = c.getCacheDir();
            File outFile = new File(cacheDir, "file.txt");

            OutputStream os = new FileOutputStream(outFile.getAbsolutePath());


            String content = "Hello Java Code Geeks";
            byte[] buff = new byte[1024];
            int len;
            while ((len = is.read(buff)) > 0) {
                os.write(buff, 0, len);
            }

            os.flush();
            os.close();
            is.close();

        } catch (IOException e) {
            e.printStackTrace(); // TODO: should close streams properly here
        }


     Uri uri = Uri.parse("content://com.mobilemerit.usbhost/file.txt");
        InputStream is = null;          
        StringBuilder result = new StringBuilder();
        try {
            is = c.getContentResolver().openInputStream(uri);
            BufferedReader r = new BufferedReader(new InputStreamReader(is));
            String line;
            while ((line = r.readLine()) != null) {

                result.append(line);
            }               
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try { if (is != null) is.close(); } catch (IOException e) { }
        }

but the new sharing intent that i'm writing is attaching a file.txt that is not impossible to send. It seem the attachment "it's not valid". What am i wronging? I cannot use external memory

Intent intent = new Intent(android.content.Intent.ACTION_SEND);
             intent.setType("text/plain");
             intent.putExtra(Intent.EXTRA_STREAM, Uri.parse("content://com.mobilemerit.usbhost/file.txt"));
             startActivity(Intent.createChooser(intent, ""));

Answer 1

If the only intention is to share/email an internal file, it isn't necessary to create a content provider. You can use setReadable ( 1 ) method to let every process access the file. Sample below.

//open existing file
File emailFile= new File( getFilesDir(), "sampleFile.txt" ); 
//allow read for others
emailFile.setReadable( true, false ); 
Uri emailFileUri = Uri.fromFile( emailFile );
Intent intentToEmailFile = new Intent( Intent.ACTION_SEND );
intentToEmailFile.setType( "message/rfc822" );
intentToEmailFile.putExtra(android.content.Intent.EXTRA_STREAM, emailFileUri );

Intent chooserIntent = Intent.createChooser( intentToEmailFile, "Send email" );
startActivity( chooserIntent );

That will attach an internal file correctly to the email client of your choice.