Question

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。

这看起来有点傻，而且我是一个完美主义者，就像任何优秀的开发人员和设计师一样，不想在我的项目中出现错误。我正在学习，希望能与你学到很多东西

我见过媒体播放器应用程序允许用户快速反复按下播放/停止按钮而不会杀死应用程序，并且这仍然正常运行，所以我读到了Services，{{1} }和AsyncTask。不仅要在后台播放声音，还要在UI错误中不杀死我的应用程序。我还有很多问题。

我想知道我是否在使用以下资源（found online）的良好路径上，但我已经尝试过，当我按下播放/停止按钮几次或有时根本不播放时，应用程序就会死机曲。

Thread

我想知道我是否应该随时取消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; } } }进程，或者我是否应该添加/修改我的应用程序不会死的内容。我应该怎么做？有人可以指导我吗？

我通常在我的logcast中得到错误（如果出现），如下所示：

AsyncTask

播放/停止按钮：

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

修改

logcat的：

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;
            }
        }

    }

NEW 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)

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

我想我已经有了它，直到我收到错误（就在我服务结束时）:(

已编辑的PlayerService类

 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()

logcat的：

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;
    }

}

Answer 1

在文档中，如果内部播放器引擎尚未初始化或已被释放，您可以读到MediaPlayer.isPlaying()抛出IllegalStateException。

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mediaPlayer之前设置为null应用程序在已发布的isPlaying()上调用mediaPlayer {1}}）。您需要添加一些同步才能使其正常工作（或使用MediaPlayer的异步方法。）

Answer 2

好吧，我想我终于得到了我想要的东西。我不知道我是否应该将@KamilW响应标记为正确，因为它确实是正确的但我会用正确的代码回答我的问题（或者至少认为是正确的）它对其他人有用。

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
}


}

我还希望由专家检查，告诉我在代码中需要改进的内容（如果不是太多要问的话）。 Thak You。

使用Service，AsyncTask和Thread

2 个答案: