我正在尝试使用 MediaController.MediaPlayerControl 在我的自定义 View 底部显示一个 MediaController 但我无法让它工作。每当我尝试加载此 View 时，它都会在 ctrl.show(); 处崩溃并出现以下异常:

E/AndroidRuntime( 3007): Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running?

这是我的代码。

public class MediaPlayerView extends ImageView implements MediaPlayerControl {

    private MediaPlayer mp;
    private MediaController ctrl;
    private Uri data;
    private Context mContext;

    public MediaPlayerView(Context context, Uri data) {
        super(context);
        this.mContext = context;
        this.data = data;
        init();
    }

    public void init() {
        mp = new MediaPlayer();
        try {
            mp.setDataSource(mContext, data);
            mp.prepare();
        } catch(IOException e) {
            e.printStackTrace();
        }
        ctrl = new MediaController(mContext);
        ctrl.setMediaPlayer(this);
        ctrl.setAnchorView(this);
        ctrl.setEnabled(true);
        ctrl.show();
    }

    public boolean canPause() {
        return true;
    }

    public boolean canSeekBackward() {
        return false;
    }

    public boolean canSeekForward() {
        return false;
    }

    public int getBufferPercentage() {
        return (mp.getCurrentPosition()*100)/mp.getDuration();
    }

    public int getCurrentPosition() {
        return mp.getCurrentPosition();
    }

    public int getDuration() {
        return mp.getDuration();
    }

    public boolean isPlaying() {
        return mp.isPlaying();
    }

    public void pause() {
        mp.pause();
    }

    public void seekTo(int pos) {
        mp.seekTo(pos);
    }

    public void start() {
        mp.start();
    }
}

非常感谢任何帮助!

最佳答案

灵感来自VideoView的实现

package org.myvideo;

import android.app.AlertDialog;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnPreparedListener;
import android.media.MediaPlayer.OnCompletionListener;
import android.media.MediaPlayer.OnErrorListener;
import android.view.MotionEvent;
import android.net.Uri;
import android.util.Log;
import android.view.View;
import android.view.KeyEvent;
import android.widget.ImageView;
import android.widget.MediaController;
import android.widget.MediaController.MediaPlayerControl;
import android.util.AttributeSet;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;

import java.io.IOException;

public class MyAudioView extends ImageView implements MediaPlayerControl {
    // settable by the client
    private Uri         mUri;

    // All the stuff we need for playing and showing a video
    private MediaPlayer mMediaPlayer = null;
    private MediaController mMediaController;
    private int mCurrentBufferPercentage;
    private boolean     mStartWhenPrepared;
    private int         mSeekWhenPrepared;
    private Context mContext;
    private boolean     mIsPrepared;
    private MediaPlayer.OnPreparedListener mOnPreparedListener;
    private OnErrorListener mOnErrorListener;
    private OnCompletionListener mOnCompletionListener;

    public MyAudioView(Context context) {
        super(context);
        mContext = context;
    }

    public MyAudioView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
        mContext = context;
    }

    public MyAudioView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mContext = context;
    }

    public void setVideoPath(String path) {
        setAudioURI(Uri.parse(path));
    }

    public void setAudioURI(Uri uri) {
        mUri = uri;
        mStartWhenPrepared = false;
        mSeekWhenPrepared = 0;
        openVideo();
        requestLayout();
        invalidate();
    }

    public void stopPlayback() {
        if (mMediaPlayer != null) {
            mMediaPlayer.stop();
            mMediaPlayer.release();
            mMediaPlayer = null;
        }
    }

    private void openVideo() {
        if (mUri == null) {
            // not ready for playback just yet, will try again later
            return;
        }
        // Tell the music playback service to pause 
        // TODO: these constants need to be published somewhere in the framework.
        Intent i = new Intent("com.android.music.musicservicecommand");
        i.putExtra("command", "pause");
        mContext.sendBroadcast(i);

        if (mMediaPlayer != null) {
            mMediaPlayer.reset();
            mMediaPlayer.release();
            mMediaPlayer = null;
        }
        try {
            mMediaPlayer = new MediaPlayer();
            mMediaPlayer.setOnPreparedListener(mPreparedListener);
            mIsPrepared = false;
            mMediaPlayer.setOnCompletionListener(mCompletionListener);
            mMediaPlayer.setOnErrorListener(mErrorListener);
            mMediaPlayer.setOnBufferingUpdateListener(mBufferingUpdateListener);
            mCurrentBufferPercentage = 0;
            mMediaPlayer.setDataSource(mContext, mUri);
            mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
            mMediaPlayer.setScreenOnWhilePlaying(true);
            mMediaPlayer.prepareAsync();
            attachMediaController();
        } catch (IOException ex) {
            Log.w("MyAudioView", "Unable to open content: " + mUri, ex);
            return;
        } catch (IllegalArgumentException ex) {
            Log.w("MyAudioView", "Unable to open content: " + mUri, ex);
            return;
        }
    }

    public void setMediaController(MediaController controller) {
        if (mMediaController != null) {
            mMediaController.hide();
        }
        mMediaController = controller;
        attachMediaController();
    }

    private void attachMediaController() {
        if (mMediaPlayer != null && mMediaController != null) {
            mMediaController.setMediaPlayer(this);
            View anchorView = this.getParent() instanceof View ?
                    (View)this.getParent() : this;
            mMediaController.setAnchorView(anchorView);
            mMediaController.setEnabled(mIsPrepared);
        }
    }

    MediaPlayer.OnPreparedListener mPreparedListener = new MediaPlayer.OnPreparedListener() {
        public void onPrepared(MediaPlayer mp) {
            // briefly show the mediacontroller
            mIsPrepared = true;
            if (mOnPreparedListener != null) {
                mOnPreparedListener.onPrepared(mMediaPlayer);
            }
            if (mMediaController != null) {
                mMediaController.setEnabled(true);
            }
            if (mStartWhenPrepared) {
                mMediaPlayer.start();
            }
        }
    };

    private MediaPlayer.OnCompletionListener mCompletionListener =
        new MediaPlayer.OnCompletionListener() {
        public void onCompletion(MediaPlayer mp) {
            if (mMediaController != null) {
                mMediaController.hide();
            }
            if (mOnCompletionListener != null) {
                mOnCompletionListener.onCompletion(mMediaPlayer);
            }
        }
    };

    private MediaPlayer.OnErrorListener mErrorListener =
        new MediaPlayer.OnErrorListener() {
        public boolean onError(MediaPlayer mp, int a, int b) {
            Log.d("MyAudioView", "Error: " + a + "," + b);
            if (mMediaController != null) {
                mMediaController.hide();
            }

            /* If an error handler has been supplied, use it and finish. */
            if (mOnErrorListener != null) {
                if (mOnErrorListener.onError(mMediaPlayer, a, b)) {
                    return true;
                }
            }

            /* Otherwise, pop up an error dialog so the user knows that
             * something bad has happened. Only try and pop up the dialog
             * if we're attached to a window. When we're going away and no
             * longer have a window, don't bother showing the user an error.
             */
            if (getWindowToken() != null) {
                new AlertDialog.Builder(mContext)
                        .setTitle("Error")
                        .setMessage("This track could not be played")
                        .setPositiveButton("OK",
                                new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int whichButton) {
                                        /* If we get here, there is no onError listener, so
                                         * at least inform them that the video is over.
                                         */
                                        if (mOnCompletionListener != null) {
                                            mOnCompletionListener.onCompletion(mMediaPlayer);
                                        }
                                    }
                                })
                        .setCancelable(false)
                        .show();
            }
            return true;
        }
    };

    private MediaPlayer.OnBufferingUpdateListener mBufferingUpdateListener =
        new MediaPlayer.OnBufferingUpdateListener() {
        public void onBufferingUpdate(MediaPlayer mp, int percent) {
            mCurrentBufferPercentage = percent;
        }
    };

    /**
     * Register a callback to be invoked when the media file
     * is loaded and ready to go.
     *
     * @param l The callback that will be run
     */
    public void setOnPreparedListener(MediaPlayer.OnPreparedListener l)
    {
        mOnPreparedListener = l;
    }

    /**
     * Register a callback to be invoked when the end of a media file
     * has been reached during playback.
     *
     * @param l The callback that will be run
     */
    public void setOnCompletionListener(OnCompletionListener l)
    {
        mOnCompletionListener = l;
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if (mIsPrepared && mMediaPlayer != null && mMediaController != null) {
            toggleMediaControlsVisiblity();
        }
        return false;
    }

    @Override
    public boolean onTrackballEvent(MotionEvent ev) {
        if (mIsPrepared && mMediaPlayer != null && mMediaController != null) {
            toggleMediaControlsVisiblity();
        }
        return false;
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event)
    {
        if (mIsPrepared &&
                keyCode != KeyEvent.KEYCODE_BACK &&
                keyCode != KeyEvent.KEYCODE_VOLUME_UP &&
                keyCode != KeyEvent.KEYCODE_VOLUME_DOWN &&
                keyCode != KeyEvent.KEYCODE_MENU &&
                keyCode != KeyEvent.KEYCODE_CALL &&
                keyCode != KeyEvent.KEYCODE_ENDCALL &&
                mMediaPlayer != null &&
                mMediaController != null) {
            if (keyCode == KeyEvent.KEYCODE_HEADSETHOOK) {
                if (mMediaPlayer.isPlaying()) {
                    pause();
                    mMediaController.show();
                } else {
                    start();
                    mMediaController.hide();
                }
                return true;
            } else {
                toggleMediaControlsVisiblity();
            }
        }

        return super.onKeyDown(keyCode, event);
    }

    private void toggleMediaControlsVisiblity() {
        if (mMediaController.isShowing()) { 
            mMediaController.hide();
        } else {
            mMediaController.show();
        }
    }

    public void start() {
        if (mMediaPlayer != null && mIsPrepared) {
                mMediaPlayer.start();
                mStartWhenPrepared = false;
        } else {
            mStartWhenPrepared = true;
        }
    }

    public void pause() {
        if (mMediaPlayer != null && mIsPrepared) {
            if (mMediaPlayer.isPlaying()) {
                mMediaPlayer.pause();
            }
        }
        mStartWhenPrepared = false;
    }

    public int getDuration() {
        if (mMediaPlayer != null && mIsPrepared) {
            return mMediaPlayer.getDuration();
        }
        return -1;
    }

    public int getCurrentPosition() {
        if (mMediaPlayer != null && mIsPrepared) {
            return mMediaPlayer.getCurrentPosition();
        }
        return 0;
    }

    public void seekTo(int msec) {
        if (mMediaPlayer != null && mIsPrepared) {
            mMediaPlayer.seekTo(msec);
        } else {
            mSeekWhenPrepared = msec;
        }
    }    

    public boolean isPlaying() {
        if (mMediaPlayer != null && mIsPrepared) {
            return mMediaPlayer.isPlaying();
        }
        return false;
    }

    public int getBufferPercentage() {
        if (mMediaPlayer != null) {
            return mCurrentBufferPercentage;
        }
        return 0;
    }

    public boolean canSeekForward() {
      return true;
    }

    public boolean canSeekBackward() {
      return true;
    }

    public boolean canPause() {
      return true;
    }
}

package org.myvideo;

import android.app.Activity;
import android.os.Bundle;
import android.widget.MediaController;
import android.net.Uri;

public class MyVideo extends Activity
{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        MyAudioView video = new MyAudioView(this);
        video.setMediaController(new MediaController(this));
        super.onCreate(savedInstanceState);
        video.setAudioURI(Uri.parse("http://url_to_media"));
        video.setImageResource(R.drawable.icon);
        setContentView(video);
    }
}

关于android - 如何使用MediaController.MediaPlayerControl？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/3535949/