使用 Service、AsyncTask 和 Thread 制作智能 Android 媒体播放器应用答案

【问题标题】：Making a smart Android Media Player app using Service, AsyncTask and Thread使用 Service、AsyncTask 和 Thread 制作智能 Android 媒体播放器应用
【发布时间】：2015-09-08 06:38:01
【问题描述】：

首先： 对不起，如果我有拼写错误。我来自巴拉圭，我正在使用谷歌翻译。

这可能看起来有点傻，而且我是一个完美主义者，并且像任何优秀的开发人员和设计师一样，不希望我的项目中出现错误。我正在学习中，希望能和你一起学习很多东西

我看到媒体播放器应用程序允许用户快速重复地按下播放/停止按钮而不会终止应用程序，而且它仍然可以正常运行，所以我读到了 Services、AsyncTask 和 @987654324 @。不仅要在后台播放声音，而且不要因为 UI 错误而杀死我的应用程序。我还有很多问题。

我想知道我是否在使用以下资源 (found online) 的道路上走得很好，但我已经尝试过，当我按几次播放/停止按钮或有时根本不播放歌曲时，应用程序就会死机。

package com.myaudioservice.app;

import android.app.Service;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.AsyncTask;
import android.os.Binder;
import android.os.IBinder;

/**
 * Service to serv MediaPlayer in background
 *
 * @author Eugeny Pozharsky
 */
public class PlayerService extends Service {
    private final IBinder mBinder = new LocalBinder();
    private MediaPlayer mediaPlayer;
    private PlayerCallback callback;

    public class LocalBinder extends Binder {
        PlayerService getService() {
            return PlayerService.this;
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }

    /**
     * Kill MediaPlayer to release resources
     */
    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mediaPlayer != null) {
            stop();
            mediaPlayer.release();
        }
    }

    /**
     * Starts playing stream.
     * Note that we just start media player and do not obtain real URL of the stream.
     * So, URL that will be redirected by server will not work. To make such URLs works, adding
     * algorithm to obtain the real URL (f.e., create HttpConnection, connect to the server and
     * get real URL from connection).
     *
     * @param url String with URL of a server to connect
     */
    public void start(String url) {
        if (mediaPlayer == null) {
            mediaPlayer = new MediaPlayer();
        }
        if (isPlaying()) {
            mediaPlayer.stop();
            mediaPlayer.reset();
        }
        new Player().execute(url);
        Log.e("PlayerService", "start()");
    }

    /**
     * Stops playing of the stream.
     */
    public void stop() {
        // stopping MediaPlayer in separate thread because it can take a time
        new Thread(new Runnable() {
            @Override
            public void run() {
                if (mediaPlayer != null) {
                    if (mediaPlayer.isPlaying()) {
                        mediaPlayer.stop();
                    }
                    //mediaPlayer.release();
                    //mediaPlayer = null;
                }
            }
        }).start();
        if (callback != null) {
            callback.onStopped();
        }
        Log.e("PlayerService", "stop()");
    }

    /**
     * Is stream playing?
     *
     * @return true or false
     */
    public Boolean isPlaying() {
        return mediaPlayer != null && mediaPlayer.isPlaying();
    }

    public void setCallback(PlayerCallback callback) {
        this.callback = callback;
    }

    /**
     * Background task to start MediaPlayer. It is used because starting playing of remote stream may
     * take long time and we must not block UI thread.
     * Also, this approach allows to cancel starting process (not implemented in current version)
     */
    private class Player extends AsyncTask<String, Void, Void> {

        /**
         * This function called in UI thread and we callback to activity to update UI elements
         */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            if (callback != null) {
                callback.onPreStart();
            }
        }

        /**
         * This function called in UI thread and we callback to activity to update UI elements
         */
        @Override
        protected void onPostExecute(Void aVoid) {
            super.onPostExecute(aVoid);
            if (mediaPlayer == null || !mediaPlayer.isPlaying()) {
                // Start MediaPlayer fail.
                if (callback != null) {
                    callback.onStartFailed();
                }
            } else {
                if (callback != null) {
                    callback.onStarted();
                }
            }
        }

        /**
         * This function called from separate thread and we do long-time operation in it
         *
         * @param strings params
         * @return null
         */
        @Override
        protected Void doInBackground(String... strings) {
            //mediaPlayer = new MediaPlayer();
            try {
                mediaPlayer.setDataSource(strings[0]);
                mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
                mediaPlayer.prepare();
                mediaPlayer.start();
            } catch (Exception e) {
                if (mediaPlayer != null) {
                    mediaPlayer.release();
                }
                mediaPlayer = null;
            }
            return null;
        }
    }
}

我想知道我是否应该随时取消我的AsyncTask 进程，或者我是否应该添加/修改一些我的应用程序不会死掉的东西。我应该怎么做？有人可以指导我吗？

我通常会在我的日志广播中收到错误（如果出现），如下所示：

java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once)

对于播放/停止按钮：

btn_control.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                control((!ON_PLAY) ? 1 : 0);
            }
        });

private void control(int est) {

        if(est==1){
            if (!hayConexion()) {
                Toast.makeText(Principal.this, getString(R.string.error_conexion_txt), Toast.LENGTH_SHORT).show();
            } else {
                if (mBound) {
                    mService.start();
                    ON_PLAY = true;
                }
            }
        }else if(est==0) {

            if (mBound) {
                mService.stop();
                ON_PLAY = false;
            }
        }

    }

编辑：

Logcat：

09-08 03:13:08.333  32438-32474/com.myaudioservice.app V/MediaPlayer-JNI﹕ native_setup
09-08 03:13:08.333  32438-32474/com.myaudioservice.app V/MediaPlayer﹕ constructor
09-08 03:13:08.343  32438-32474/com.myaudioservice.app V/MediaPlayer﹕ setListener
09-08 03:13:08.343  32438-32474/com.myaudioservice.app I/MediaPlayer﹕ path is null
09-08 03:13:08.343  32438-32474/com.myaudioservice.app D/MediaPlayer﹕ setDataSource IOException happend :
    java.io.FileNotFoundException: No content provider: rtsp://ip/folder/file.stream
            at android.content.ContentResolver.openTypedAssetFileDescriptor(ContentResolver.java:1053)
            at android.content.ContentResolver.openAssetFileDescriptor(ContentResolver.java:907)
            at android.content.ContentResolver.openAssetFileDescriptor(ContentResolver.java:834)
            at android.media.MediaPlayer.setDataSource(MediaPlayer.java:988)
            at android.media.MediaPlayer.setDataSource(MediaPlayer.java:942)
            at com.myaudioservice.app.PlayerService$Player.doInBackground(PlayerService.java:156)
            at com.myaudioservice.app.PlayerService$Player.doInBackground(PlayerService.java:130)
            at android.os.AsyncTask$2.call(AsyncTask.java:288)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)
09-08 03:13:08.343  32438-32474/com.myaudioservice.app D/MediaPlayer﹕ Couldn't open file on client side, trying server side
09-08 03:13:08.353  32438-32474/com.myaudioservice.app V/MediaPlayer-JNI﹕ setAudioStreamType: 3
09-08 03:13:08.353  32438-32474/com.myaudioservice.app V/MediaPlayer﹕ MediaPlayer::setAudioStreamType
09-08 03:13:08.353  32438-32474/com.myaudioservice.app D/com.myaudioservice.app.PlayerService﹕ Preparing: rtsp://ip/folder/file.stream
09-08 03:13:08.353  32438-32474/com.myaudioservice.app V/MediaPlayer﹕ setVideoSurfaceTexture
09-08 03:13:08.353  32438-32474/com.myaudioservice.app V/MediaPlayer﹕ prepare
09-08 03:13:09.384  32438-32438/com.myaudioservice.app E/PlayerService﹕ stop()
09-08 03:13:09.394  32438-32495/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 03:13:09.394  32438-32495/com.myaudioservice.app V/MediaPlayer-JNI﹕ release
09-08 03:13:09.394  32438-32495/com.myaudioservice.app V/MediaPlayer﹕ setListener
09-08 03:13:09.394  32438-32495/com.myaudioservice.app V/MediaPlayer﹕ disconnect
09-08 03:13:09.544  32438-32438/com.myaudioservice.app D/AndroidRuntime﹕ Shutting down VM
09-08 03:13:09.544  32438-32438/com.myaudioservice.app W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x4193eda0)
09-08 03:13:09.544  32438-32438/com.myaudioservice.app E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.myaudioservice.app, PID: 32438
    java.lang.IllegalStateException
            at android.media.MediaPlayer.isPlaying(Native Method)
            at com.myaudioservice.app.PlayerService.reproduciendo(PlayerService.java:118)
            at com.myaudioservice.app.PlayerService.start(PlayerService.java:84)
            at com.myaudioservice.app.MainActivity.control(MainActivity.java:298)
            at com.myaudioservice.app.MainActivity.access$100(MainActivity.java:38)
            at com.myaudioservice.app.MainActivity$1.onClick(MainActivity.java:173)
            at android.view.View.performClick(View.java:4640)
            at android.view.View$PerformClick.run(View.java:19425)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:146)
            at android.app.ActivityThread.main(ActivityThread.java:5593)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
            at dalvik.system.NativeStart.main(Native Method)

新的 LOGCAT：

 09-08 14:49:24.360    9651-9651/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
    09-08 14:49:24.360    9651-9651/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
    09-08 14:49:24.390    9651-9651/com.myaudioservice.app E/PlayerService﹕ start()
    09-08 14:49:24.480   9651-10534/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
    09-08 14:49:24.480   9651-10534/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
    09-08 14:49:24.480   9651-10534/com.myaudioservice.app V/MediaPlayer-JNI﹕ reset
    09-08 14:49:24.480   9651-10534/com.myaudioservice.app V/MediaPlayer﹕ reset
    09-08 14:49:24.490    9651-9651/com.myaudioservice.app E/PlayerService﹕ stop()
    09-08 14:49:24.620    9651-9651/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
    09-08 14:49:24.620    9651-9651/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
    09-08 14:49:24.650    9651-9651/com.myaudioservice.app E/PlayerService﹕ start()
    09-08 14:49:24.770   9651-10535/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
    09-08 14:49:24.770   9651-10535/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
    09-08 14:49:24.770   9651-10535/com.myaudioservice.app V/MediaPlayer-JNI﹕ reset
    09-08 14:49:24.770   9651-10535/com.myaudioservice.app V/MediaPlayer﹕ reset
    09-08 14:49:24.780    9651-9651/com.myaudioservice.app E/PlayerService﹕ stop()
    09-08 14:49:24.890    9651-9651/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
    09-08 14:49:24.890    9651-9651/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
    09-08 14:49:24.910    9651-9651/com.myaudioservice.app E/PlayerService﹕ start()
    09-08 14:49:25.021   9651-10540/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
    09-08 14:49:25.031   9651-10540/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
    09-08 14:49:25.031   9651-10540/com.myaudioservice.app V/MediaPlayer-JNI﹕ reset
    09-08 14:49:25.031   9651-10540/com.myaudioservice.app V/MediaPlayer﹕ reset
    09-08 14:49:25.041    9651-9651/com.myaudioservice.app E/PlayerService﹕ stop()
    09-08 14:49:25.151    9651-9651/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
    09-08 14:49:25.151    9651-9651/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
    09-08 14:49:25.181    9651-9651/com.myaudioservice.app E/PlayerService﹕ start()

编辑 2： -------------------------------------------------- ---------------------

我以为我已经有了它，直到我遇到了一个错误（就在我的服务结束时）:(

编辑 PlayerService 类

package com.myaudioservice.app;

import android.app.Service;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;


public class PlayerService extends Service implements MediaPlayer.OnPreparedListener, MediaPlayer.OnInfoListener, MediaPlayer.OnCompletionListener {

    private static final String LOG_TAG = PlayerService.class.getName();
    private String URL_STREAM = "rtsp://domain/folder/file.stream";

    private MediaPlayer mMediaPlayer = null;
    private PlayerCallback callback;
    private final IBinder mBinder = new LocalBinder();

    public class LocalBinder extends Binder {
        PlayerService getService() {
            return PlayerService.this;
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }


    @Override
    public void onDestroy(){
        if (mMediaPlayer != null) {
            stop();
            mMediaPlayer.release();
            mMediaPlayer = null;
        }
    }

    /**
     * Starts playing stream.
     * Note that we just start media player and do not obtain real URL of the stream.
     * So, URL that will be redirected by server will not work. To make such URLs works, adding
     * algorithm to obtain the real URL (f.e., create HttpConnection, connect to the server and
     * get real URL from connection).
     *
     * //@param url String with URL of a server to connect
     */
    public void start() {
        if (mMediaPlayer == null) mMediaPlayer = new MediaPlayer();
        if (isPlaying()) {
            mMediaPlayer.stop();
            mMediaPlayer.reset();
        }

        try {
            mMediaPlayer.setDataSource(URL_STREAM);
            mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
            if (callback != null) callback.onPreStart();
            Log.e(LOG_TAG, "Preparando: " + URL_STREAM);
            mMediaPlayer.prepareAsync();

        } catch (Exception e) {
            if (mMediaPlayer != null) {
                mMediaPlayer.reset();
            }
            Log.e(LOG_TAG, e.toString());
            //mMediaPlayer = null;
        }

        mMediaPlayer.setOnPreparedListener(this);
        mMediaPlayer.setOnInfoListener(this);
        mMediaPlayer.setOnCompletionListener(this);
    }

    @Override
    public void onPrepared(MediaPlayer mp) {
        mp.start();
        Log.e(LOG_TAG, "start()");
    }


    @Override
    public boolean onInfo(MediaPlayer mp, int what, int extra) {
        switch (what) {
            case MediaPlayer.MEDIA_ERROR_IO:
            case MediaPlayer.MEDIA_ERROR_MALFORMED:
            case MediaPlayer.MEDIA_ERROR_NOT_VALID_FOR_PROGRESSIVE_PLAYBACK:
            case MediaPlayer.MEDIA_ERROR_SERVER_DIED:
            case MediaPlayer.MEDIA_ERROR_TIMED_OUT:
            case MediaPlayer.MEDIA_ERROR_UNSUPPORTED:
                if (mMediaPlayer == null || !mMediaPlayer.isPlaying()) {
                    // Start MediaPlayer fail.
                    if (callback != null) callback.onStartFailed();
                }
                Log.e(LOG_TAG, "Error");
                break;
            case MediaPlayer.MEDIA_INFO_BUFFERING_START:
                if (callback != null) callback.onStarted();
                Log.e(LOG_TAG, "Almacenando en búfer");
                break;
            case MediaPlayer.MEDIA_INFO_BUFFERING_END:
                if (callback != null) callback.onPlaying();
                Log.e(LOG_TAG, "Reproduciendo");
                break;
        }
        return false;
    }

    @Override
    public void onCompletion(MediaPlayer mp) {
        Log.e(LOG_TAG, "Reproducción finalizada");
        stop();
    }

    /**
     * Stops playing of the stream.
     */
    public void stop() {
        // stopping MediaPlayer in separate thread because it can take a time
        new Thread(new Runnable() {
            @Override
            public void run() {
                if (mMediaPlayer != null) {
                    if (mMediaPlayer.isPlaying()) mMediaPlayer.stop(); // I get the error here when I destroy the Service quickly
                    mMediaPlayer.reset();
                }
            }
        }).start();
        if (callback != null) callback.onStopped();
        Log.e(LOG_TAG, "stop()");
    }

    /**
     * Is stream playing?
     *
     * @return true or false
     */
    public Boolean isPlaying() {
        return mMediaPlayer != null && mMediaPlayer.isPlaying();
    }

    public void setCallback(PlayerCallback callback) {
        this.callback = callback;
    }

}

Logcat：

09-08 19:15:39.578  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
09-08 19:15:39.578  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:39.578  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ setAudioStreamType: 3
09-08 19:15:39.578  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ MediaPlayer::setAudioStreamType
09-08 19:15:39.578  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ Preparando: rtsp://domain/folder/file.stream
09-08 19:15:39.578  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ setVideoSurfaceTexture
09-08 19:15:39.578  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ prepareAsync
09-08 19:15:39.678  27582-31945/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:39.678  27582-31945/com.myaudioservice.app V/MediaPlayer-JNI﹕ reset
09-08 19:15:39.678  27582-31945/com.myaudioservice.app V/MediaPlayer﹕ reset
09-08 19:15:39.678  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=1, ext1=0, ext2=0
09-08 19:15:39.688  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(1, 0, 0) callback on disconnected mediaplayer
09-08 19:15:39.688  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=8, ext1=0, ext2=0
09-08 19:15:39.688  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(8, 0, 0) callback on disconnected mediaplayer
09-08 19:15:39.688  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ stop()
09-08 19:15:39.798  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
09-08 19:15:39.798  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:39.808  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ setAudioStreamType: 3
09-08 19:15:39.808  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ MediaPlayer::setAudioStreamType
09-08 19:15:39.808  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ Preparando: rtsp://domain/folder/file.stream
09-08 19:15:39.808  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ setVideoSurfaceTexture
09-08 19:15:39.808  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ prepareAsync
09-08 19:15:39.938  27582-31952/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:39.938  27582-31952/com.myaudioservice.app V/MediaPlayer-JNI﹕ reset
09-08 19:15:39.938  27582-31952/com.myaudioservice.app V/MediaPlayer﹕ reset
09-08 19:15:39.938  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=1, ext1=0, ext2=0
09-08 19:15:39.938  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(1, 0, 0) callback on disconnected mediaplayer
09-08 19:15:39.938  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=8, ext1=0, ext2=0
09-08 19:15:39.938  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(8, 0, 0) callback on disconnected mediaplayer
09-08 19:15:39.948  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ stop()
09-08 19:15:40.069  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
09-08 19:15:40.069  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:40.079  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ setAudioStreamType: 3
09-08 19:15:40.079  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ MediaPlayer::setAudioStreamType
09-08 19:15:40.079  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ Preparando: rtsp://domain/folder/file.stream
09-08 19:15:40.079  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ setVideoSurfaceTexture
09-08 19:15:40.079  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ prepareAsync
09-08 19:15:40.179  27582-31957/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:40.179  27582-31957/com.myaudioservice.app V/MediaPlayer-JNI﹕ reset
09-08 19:15:40.179  27582-31957/com.myaudioservice.app V/MediaPlayer﹕ reset
09-08 19:15:40.179  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=1, ext1=0, ext2=0
09-08 19:15:40.189  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(1, 0, 0) callback on disconnected mediaplayer
09-08 19:15:40.189  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=8, ext1=0, ext2=0
09-08 19:15:40.189  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(8, 0, 0) callback on disconnected mediaplayer
09-08 19:15:40.189  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ stop()
09-08 19:15:40.289  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
09-08 19:15:40.289  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:40.299  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ setAudioStreamType: 3
09-08 19:15:40.299  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ MediaPlayer::setAudioStreamType
09-08 19:15:40.299  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ Preparando: rtsp://domain/folder/file.stream
09-08 19:15:40.299  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ setVideoSurfaceTexture
09-08 19:15:40.299  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ prepareAsync
09-08 19:15:40.429  27582-31966/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:40.429  27582-31966/com.myaudioservice.app V/MediaPlayer-JNI﹕ reset
09-08 19:15:40.429  27582-31966/com.myaudioservice.app V/MediaPlayer﹕ reset
09-08 19:15:40.429  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=1, ext1=0, ext2=0
09-08 19:15:40.429  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(1, 0, 0) callback on disconnected mediaplayer
09-08 19:15:40.429  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ stop()
09-08 19:15:40.429  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=8, ext1=0, ext2=0
09-08 19:15:40.429  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(8, 0, 0) callback on disconnected mediaplayer
09-08 19:15:40.549  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ isPlaying: no active player
09-08 19:15:40.549  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:40.559  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ setAudioStreamType: 3
09-08 19:15:40.559  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ MediaPlayer::setAudioStreamType
09-08 19:15:40.559  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ Preparando: rtsp://domain/folder/file.stream
09-08 19:15:40.559  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ setVideoSurfaceTexture
09-08 19:15:40.559  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ prepareAsync
09-08 19:15:40.659  27582-31972/com.myaudioservice.app V/MediaPlayer-JNI﹕ isPlaying: 0
09-08 19:15:40.659  27582-31972/com.myaudioservice.app V/MediaPlayer-JNI﹕ reset
09-08 19:15:40.659  27582-31972/com.myaudioservice.app V/MediaPlayer﹕ reset
09-08 19:15:40.659  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=1, ext1=0, ext2=0
09-08 19:15:40.659  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(1, 0, 0) callback on disconnected mediaplayer
09-08 19:15:40.659  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ message received msg=8, ext1=0, ext2=0
09-08 19:15:40.659  27582-27596/com.myaudioservice.app V/MediaPlayer﹕ notify(8, 0, 0) callback on disconnected mediaplayer
09-08 19:15:40.669  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ stop()
09-08 19:16:01.281  27582-27582/com.myaudioservice.app D/AbsListView﹕ onDetachedFromWindow
09-08 19:16:01.311  27582-27582/com.myaudioservice.app E/com.myaudioservice.app.PlayerService﹕ stop()
09-08 19:16:01.311  27582-27582/com.myaudioservice.app V/MediaPlayer-JNI﹕ release
09-08 19:16:01.311  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ setListener
09-08 19:16:01.311  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ disconnect
09-08 19:16:01.311  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ destructor
09-08 19:16:01.311  27582-32148/com.myaudioservice.app W/dalvikvm﹕ threadid=14: thread exiting with uncaught exception (group=0x4193eda0)
09-08 19:16:01.311  27582-27582/com.myaudioservice.app V/MediaPlayer﹕ disconnect
09-08 19:16:01.321  27582-32148/com.myaudioservice.app E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-15992
    Process: com.myaudioservice.app, PID: 27582
    java.lang.IllegalStateException
            at android.media.MediaPlayer.isPlaying(Native Method)
            at com.myaudioservice.app.PlayerService$1.run(PlayerService.java:129)
            at java.lang.Thread.run(Thread.java:841)

【问题讨论】：

在 android 中处理视频和图像可能会导致应用程序没有足够内存时出现内存不足错误。分享您的 logcat，以便我们更好地识别。
谢谢@MurtazaKhursheedHussain 我知道这不是内存问题。已添加 Logcat。
如您所见，有两个错误 1. File Not found 和 2. Illegal State。
不不，文件存在。当我使用 setDataSource(context, url) 而不是 setDataSource(url)) 时会出现此信息我刚刚编辑了流 url 以进行共享。

标签： java android android-asynctask

【解决方案1】：

在文档中你可以看到MediaPlayer.isPlaying() 抛出 IllegalStateException 如果内部播放器引擎尚未初始化或已发布。

此代码不是线程安全的，这可能是此异常的原因（线程调用release() 和之前的mediaPlayer 设置为null 应用程序在发布isPlaying() 时调用mediaPlayer）。您需要添加一些同步以使其工作（或使用MediaPlayer 形式的异步方法）。

【讨论】：

我应该如何进行同步？如果在此代码中，简单地用prepareAsync() 替换prepare() 方法不起作用，并且如果我用prepareAsync() 尝试使用AsyncTask，通常，logcat 返回：start called in the state 4 如果我按几次播放/停止按钮 :(。现在，我尝试从 stop() 方法中删除 release()，我可以在不停止的情况下快速与我的应用程序交互。我在方法 play() 和 stop() 上添加了 log 并分享新的logcat。音频播放一次，然后按下几次... :(
向此代码添加同步可能很棘手。我认为最好的解决方案是删除AsyncTask 并在OnPreparedListener 中使用prepareAsync() 和mediaPlayer.start()。
好的，我会按照你说的做。然后让你知道我怎么样。顺便说一句，我应该在哪里打电话给prepareAsync()？
你真的在帮助我吗@KamilW，我谢谢你！我修改了代码以执行您的建议 (EDIT 2)，结果几乎完美。我想我离我的目标更近了，但是在按下按钮几次后快速关闭我的应用程序，它再次使用 isPlaying() 方法失败，这次是在 Thread 中。 ):
如果我之前没有调用release() 方法并且mMediaPlayer 不为空，为什么会发生这种情况？也许我应该在if (mMediaPlayer.isPlaying()) mMediaPlayer.stop(); 之前再次初始化？还是我应该删除那条线，只留下reset()？这是一个好习惯吗？

【解决方案2】：

好吧，我想我终于得到了我想要的。我不知道我是否应该将@KamilW 响应标记为正确，因为它确实完全正确，但我会用正确的代码（或至少认为是正确的）回答我的问题，它可能对其他人有用。

我的最终代码：

package com.myaudioservice.app;

import android.app.Service;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;


public class PlayerService extends Service implements MediaPlayer.OnPreparedListener, MediaPlayer.OnInfoListener, MediaPlayer.OnErrorListener, MediaPlayer.OnCompletionListener {

    private static final String LOG_TAG = PlayerService.class.getName();
    private String URL_STREAM = "rtsp://domain/folder/file.stream";

    private MediaPlayer mMediaPlayer = null;
    private PlayerCallback callback;
    private final IBinder mBinder = new LocalBinder();

    public class LocalBinder extends Binder {
        PlayerService getService() {
            return PlayerService.this;
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }


    @Override
        public void onDestroy(){
            if (mMediaPlayer != null) {
                mMediaPlayer.release();
                mMediaPlayer = null;
            }
        }

    /**
     * Starts playing stream.
     * Note that we just start media player and do not obtain real URL of the stream.
     * So, URL that will be redirected by server will not work. To make such URLs works, adding
     * algorithm to obtain the real URL (f.e., create HttpConnection, connect to the server and
     * get real URL from connection).
     *
     * //@param url String with URL of a server to connect
     */
    public void start() {
        if (mMediaPlayer == null) mMediaPlayer = new MediaPlayer();
        if (isPlaying()) {
            mMediaPlayer.stop();
            mMediaPlayer.reset();
        }

        try {
            mMediaPlayer.setDataSource(URL_STREAM);
            mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
            if (callback != null) callback.onPreStart();
            Log.e(LOG_TAG, "Preparando: " + URL_STREAM);
            mMediaPlayer.prepareAsync();

        } catch (Exception e) {
            if (mMediaPlayer != null) {
                mMediaPlayer.reset();
            }
            if (callback != null) callback.onStartFailed();
            Log.e(LOG_TAG, e.toString());
            //mMediaPlayer = null;
        }

        mMediaPlayer.setOnPreparedListener(this);
        mMediaPlayer.setOnInfoListener(this);
        mMediaPlayer.setOnErrorListener(this);
        mMediaPlayer.setOnCompletionListener(this);
    }

    @Override
    public void onPrepared(MediaPlayer mp) {
        mp.start();
        Log.e(LOG_TAG, "start()");
    }


    @Override
    public boolean onInfo(MediaPlayer mp, int what, int extra) {
        switch (what) {
            case MediaPlayer.MEDIA_INFO_BUFFERING_START:
                if (callback != null) callback.onStarted();
                Log.e(LOG_TAG, "Almacenando en búfer");
                break;
            case MediaPlayer.MEDIA_INFO_BUFFERING_END:
                if (callback != null) callback.onPlaying();
                Log.e(LOG_TAG, "Reproduciendo");
                break;
        }
        return false;
    }

    @Override
    public void onCompletion(MediaPlayer mp) {
        Log.e(LOG_TAG, "Reproducción finalizada");
        stop();
    }

    /**
     * Stops playing of the stream.
     */
    public void stop() {
        // stopping MediaPlayer in separate thread because it can take a time
        new Thread(new Runnable() {
            @Override
            public void run() {
                if (mMediaPlayer != null) {
                    if (mMediaPlayer.isPlaying()) mMediaPlayer.stop();
                    mMediaPlayer.reset();
                }
            }
        }).start();
        if (callback != null) callback.onStopped();
        Log.e(LOG_TAG, "stop()");
    }

    /**
     * Is stream playing?
     *
     * @return true or false
     */
    public Boolean isPlaying() {
        return mMediaPlayer != null && mMediaPlayer.isPlaying();
    }

    public void setCallback(PlayerCallback callback) {
        this.callback = callback;
    }

@Override
public boolean onError(MediaPlayer mp, int what, int extra){

    if(what == MediaPlayer.MEDIA_ERROR_UNKNOWN ||
            what == MediaPlayer.MEDIA_ERROR_SERVER_DIED ||
            extra == MediaPlayer.MEDIA_ERROR_IO ||
            extra == MediaPlayer.MEDIA_ERROR_MALFORMED ||
            extra == MediaPlayer.MEDIA_ERROR_UNSUPPORTED ||
            extra == MediaPlayer.MEDIA_ERROR_TIMED_OUT ||
            extra == MediaPlayer.MEDIA_ERROR_NOT_VALID_FOR_PROGRESSIVE_PLAYBACK){

        stop();
        if (callback != null) callback.onStartFailed();
    }
    return true;// Si hay error, no es necesario llamar a onCompletionListener, por eso: true
}


}

我还想接受专家的检查，告诉我我需要在代码中改进哪些方面（如果要求不高的话）。谢谢。

【讨论】：