如何在 MediaPlayer 上播放 Android InputStream？

Question

因此，我的资产文件夹中有一个小音频文件，我想打开一个 InputStream 来写入缓冲区，然后写入一个临时文件，然后打开 MediaPlayer 来播放该临时文件。问题是，当媒体播放器点击 mp.Prepare() 时，它不会播放并且永远不会到达 toast。以前有人这样做过吗？

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    InputStream str;

    try {

        str = this.getAssets().open("onestop.mid");
        Toast.makeText(this, "Successful Input Stream Opened.", Toast.LENGTH_SHORT).show();
        takeInputStream(str);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}//end on create

public void takeInputStream(InputStream stream) throws IOException
{
    //fileBeingBuffered = (FileInputStream) stream;
    //Toast.makeText(this, "sucessful stream conversion.", Toast.LENGTH_SHORT).show();
    try
    {
        convertedFile = File.createTempFile("convertedFile", ".dat", getDir("filez", 0));
        Toast.makeText(this, "Successful file and folder creation.", Toast.LENGTH_SHORT).show();

        out = new FileOutputStream(convertedFile);
        Toast.makeText(this, "Success out set as output stream.", Toast.LENGTH_SHORT).show();

        //RIGHT AROUND HERE -----------

        byte buffer[] = new byte[16384];
        int length = 0;
        while ( (length = stream.read(buffer)) != -1 ) 
        {
          out.write(buffer,0, length);
        }

        //stream.read(buffer);
        Toast.makeText(this, "Success buffer is filled.", Toast.LENGTH_SHORT).show();
        out.close();

        playFile();
    }catch(Exception e)
    {
        Log.e(TAG, e.toString());
        e.printStackTrace();
    }//end catch
}//end grabBuffer

public void playFile()
{
    try {
        String path = convertedFile.getAbsolutePath();
        mp = new MediaPlayer();
        mp.setDataSource(path);
        Toast.makeText(this, "Success, Path has been set", Toast.LENGTH_SHORT).show();

        mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
        mp.prepare();
        Toast.makeText(this, "Media Player prepared", Toast.LENGTH_SHORT).show();

        mp.start();
        Toast.makeText(this, "Media Player playing", Toast.LENGTH_SHORT).show();
    } catch (IllegalArgumentException e) {
        Log.e(TAG, e.toString());
        e.printStackTrace();
    } catch (IllegalStateException e) {
        Log.e(TAG, e.toString());
        e.printStackTrace();
    } catch (IOException e) {
        Log.e(TAG, e.toString());
        e.printStackTrace();
    }

}//end playFile

Answer 1

修好了。事实证明，在将缓冲区写入“File”创建的临时文件中后，您可以使用 FileInputStream 打开该文件，然后继续播放它，如下所示。感谢你们所有的帮助。

mp = new MediaPlayer();

FileInputStream fis = new FileInputStream(convertedFile);
mp.setDataSource(fis.getFD());

Toast.makeText(this, "Success, Path has been set", Toast.LENGTH_SHORT).show();

mp.prepare();
mp.start();

Answer 2

这是对我有用的代码，

//preserved to stop previous actions 
MediaPlayer lastmp;

public void playSound(String file) {
    try {
        if (lastmp!=null) lastmp.stop();
        MediaPlayer mp = new MediaPlayer();
        lastmp = mp;
        AssetFileDescriptor descriptor;

        AssetManager assetManager = act.getAssets();

        descriptor =  assetManager.openFd(fileName);
        mp.setDataSource(descriptor.getFileDescriptor(), descriptor.getStartOffset(), descriptor.getLength());
        descriptor.close();
        mp.prepare();
        mp.start();

    } catch (Exception e) {
        e.printStackTrace();
    }
}

文件应该位于资产文件夹中

Answer 3

如果您想播放InputStream而不将其保存在任何地方（出于安全原因）。

这对您有用：

import android.media.MediaDataSource;
import java.io.IOException;
import java.io.InputStream;

public class InputStreamMediaDataSource extends MediaDataSource {
    private InputStream inputStream;
    private long size;

    public InputStreamMediaDataSource(InputStream inputStream, long size) {
        this.inputStream = inputStream;
        this.size = size;
    }

    @Override
    public int readAt(long position, byte[] buffer, int offset, int size) throws IOException {
        if (position >= this.size) {
            return -1;  // End of data
        }
        if (position + size > this.size) {
            size = (int) (this.size - position);
        }

        inputStream.reset();
        inputStream.skip(position);

        return inputStream.read(buffer, offset, size);
    }

    @Override
    public long getSize() throws IOException {
        return size;
    }

    @Override
    public void close() throws IOException {
        inputStream.close();
    }
}

然后我将其用作：

mMediaPlayer.setDataSource(new InputStreamMediaDataSource(mInputStream, mSize));

警告： Min-SDK =23