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Android MediaPlayer full path to file

由 被刻印的时光 ゝ 提交于 2019-12-04 08:45:59

问题


I need to get the full path to a file somewhere on the phone (any location) and play it with MediaPlayer.

ive heard of using a file chooser for Android (by launching an intent).

In the test code, I just copied a resource to a another file, got the path and passed it to AudioVideoEntry (as i show later, a very simple and thin wrapper around MediaPlayer)

Here's the test code I've written:

private String ave_path;
    private String ave_file_name = "my_media_content";
    private InputStream ave_fis;
    private OutputStream ave_fos;
    public void testAudioVideoEntry()
    {
        //get the Activity
        Module_JournalEntry journalentryactivity = getActivity();
        //open an InputStream to a resource file (in this case strokes.mp3)
        ave_fis = journalentryactivity.getResources().openRawResource(module.jakway.JournalEntry.R.raw.strokes);

        //open an OutputStream to a new file
        try {
            ave_fos = journalentryactivity.openFileOutput(ave_file_name, 
                                                Context.MODE_PRIVATE);
        } catch (FileNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
            assertTrue(false);
        }
        catch(Exception e)
        {
            assertTrue(false);
        }

        //copy the data from the resource into
        //the OutputStream
        int data;
        try {
        while((data = ave_fis.read()) != -1)
        {
            ave_fos.write(data);
        }
            assertTrue(true);
        }
        catch(Exception e)
        {
            assertTrue(false);
        }

        //get the full path of the file we wrote to
        ave_path = journalentryactivity.getFileStreamPath(ave_file_name).toString();

        //and construct a new object of AudioVideoEntry with that path
        AudioVideoEntry ave = new AudioVideoEntry(ave_path);

        //register an error listener via MediaPlayer's setOnErrorListener
        ave.setOnErrorListener(new OnErrorListener()
                                {
                                    @Override
                                    public boolean onError(MediaPlayer mp,
                                            int what, int extra) {
                                        Log.e("MEDIAPLAYER ERRORS",
                                        "what: " + what + "  extra: "   + extra);
                                        assertTrue(false);
                                        // TODO Auto-generated method stub
                                        return false;
                                    }
                                });
        ave.prepareMedia();
        ave.playMedia();
        try {
        ave_fis.close();
        ave_fos.close();
        }
        catch(Exception e)
        {
            assertTrue(false);
            e.printStackTrace();
        }

AudioVideoEntry is basically a thin wrapper around MediaPlayer that can hold its own path:

public class AudioVideoEntry
{
    private String path_to_audio_file;
    private MediaPlayer mediaplayer;

    /**
     * Initialize the internal MediaPlayer
     * from the String parameter
     * @param set_path_to_audio_file
     */
    public AudioVideoEntry(String set_path_to_audio_file)
    {
        path_to_audio_file = set_path_to_audio_file;
        mediaplayer = new MediaPlayer();
        try {
            mediaplayer.setDataSource(path_to_audio_file);
            mediaplayer.prepare();
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public AudioVideoEntry(FileDescriptor fd)
    {

        mediaplayer = new MediaPlayer();
        try {
            mediaplayer.setDataSource(fd);
            mediaplayer.prepare();
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }



    /**
     * Begin playing media
     */
    public void prepareMedia()
    {
        try {
            mediaplayer.prepare();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * play media
     * don't forget to prepare() if necessary
     */
    public void playMedia()
    {
        mediaplayer.start();
    }

    /**
     * pause the media
     * can be played later
     */
    public void pauseMedia()
    {
        mediaplayer.pause();
    }

    /**
     * stop media
     */
    public void stopMedia()
    {
        mediaplayer.stop();
    }

    public void setOnErrorListener(OnErrorListener listener)
    {
        mediaplayer.setOnErrorListener(listener);
    }
}

here's the logcat output from the JUnit test (the tests were successful, the actual results - as the logat shows - were not)

02-07 09:40:23.129: ERROR/MediaPlayer(1209): error (1, -2147483648)
02-07 09:40:23.139: WARN/System.err(1209): java.io.IOException: Prepare failed.: status=0x1
02-07 09:40:23.149: WARN/System.err(1209):     at android.media.MediaPlayer.prepare(Native Method)
02-07 09:40:23.149: WARN/System.err(1209):     at module.jakway.JournalEntry.AudioVideoEntry.<init>(AudioVideoEntry.java:39)
02-07 09:40:23.149: WARN/System.err(1209):     at module.jakway.JournalEntry.test.Module_JournalEntryTest.testAudioVideoEntry(Module_JournalEntryTest.java:182)
02-07 09:40:23.149: WARN/System.err(1209):     at java.lang.reflect.Method.invokeNative(Native Method)
02-07 09:40:23.149: WARN/System.err(1209):     at java.lang.reflect.Method.invoke(Method.java:507)
02-07 09:40:23.159: WARN/System.err(1209):     at android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:204)
02-07 09:40:23.159: WARN/System.err(1209):     at android.test.InstrumentationTestCase.runTest(InstrumentationTestCase.java:194)
02-07 09:40:23.159: WARN/System.err(1209):     at android.test.ActivityInstrumentationTestCase2.runTest(ActivityInstrumentationTestCase2.java:186)
02-07 09:40:23.159: WARN/System.err(1209):     at junit.framework.TestCase.runBare(TestCase.java:127)
02-07 09:40:23.169: WARN/System.err(1209):     at junit.framework.TestResult$1.protect(TestResult.java:106)
02-07 09:40:23.169: WARN/System.err(1209):     at junit.framework.TestResult.runProtected(TestResult.java:124)
02-07 09:40:23.169: WARN/System.err(1209):     at junit.framework.TestResult.run(TestResult.java:109)
02-07 09:40:23.179: WARN/System.err(1209):     at junit.framework.TestCase.run(TestCase.java:118)
02-07 09:40:23.179: WARN/System.err(1209):     at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:169)
02-07 09:40:23.179: WARN/System.err(1209):     at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:154)
02-07 09:40:23.179: WARN/System.err(1209):     at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:529)
02-07 09:40:23.189: WARN/System.err(1209):     at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1447)
02-07 09:40:23.189: ERROR/MediaPlayer(1209): prepareAsync called in state 0
02-07 09:40:23.189: WARN/System.err(1209): java.lang.IllegalStateException
02-07 09:40:23.189: WARN/System.err(1209):     at android.media.MediaPlayer.prepare(Native Method)
02-07 09:40:23.189: WARN/System.err(1209):     at module.jakway.JournalEntry.AudioVideoEntry.prepareMedia(AudioVideoEntry.java:79)
02-07 09:40:23.199: WARN/System.err(1209):     at module.jakway.JournalEntry.test.Module_JournalEntryTest.testAudioVideoEntry(Module_JournalEntryTest.java:197)
02-07 09:40:23.199: WARN/System.err(1209):     at java.lang.reflect.Method.invokeNative(Native Method)
02-07 09:40:23.199: WARN/System.err(1209):     at java.lang.reflect.Method.invoke(Method.java:507)
02-07 09:40:23.199: WARN/System.err(1209):     at android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:204)
02-07 09:40:23.199: WARN/System.err(1209):     at android.test.InstrumentationTestCase.runTest(InstrumentationTestCase.java:194)
02-07 09:40:23.199: WARN/System.err(1209):     at android.test.ActivityInstrumentationTestCase2.runTest(ActivityInstrumentationTestCase2.java:186)
02-07 09:40:23.199: WARN/System.err(1209):     at junit.framework.TestCase.runBare(TestCase.java:127)
02-07 09:40:23.199: WARN/System.err(1209):     at junit.framework.TestResult$1.protect(TestResult.java:106)
02-07 09:40:23.199: WARN/System.err(1209):     at junit.framework.TestResult.runProtected(TestResult.java:124)
02-07 09:40:23.199: WARN/System.err(1209):     at junit.framework.TestResult.run(TestResult.java:109)
02-07 09:40:23.199: WARN/System.err(1209):     at junit.framework.TestCase.run(TestCase.java:118)
02-07 09:40:23.199: WARN/System.err(1209):     at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:169)
02-07 09:40:23.199: WARN/System.err(1209):     at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:154)
02-07 09:40:23.199: WARN/System.err(1209):     at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:529)
02-07 09:40:23.199: WARN/System.err(1209):     at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1447)
02-07 09:40:23.199: ERROR/MediaPlayer(1209): start called in state 0
02-07 09:40:23.199: ERROR/MediaPlayer(1209): error (-38, 0)

Edit: why is MediaPlayer failing?

thanks! dragonwrenn


回答1:


The second call to MediaPlayer.prepare() (already called once in the AudioVideoEntry ctor) in the AudioVideoEntry.prepareMedia() method was easy to spot as other people have noticed.

The harder error to find was the first error.

I used an Ogg file for testing.

First clue was from davidsparks reply (last one) in android-platform - Ogg on G1

As long as the files have a .ogg extension, they should play with the built-in music player. We rely on the file extensions because there is no centralized file recognizer for the media scanner.

Second clue was from [android-developers] Re: File permission about MediaPlayer

Due to the Android security model, MediaPlayer does not have root access rights. It can access the sdcard, but it can't access private app directories.

Your app can explicitly grant MediaPlayer temporary access to secure files by opening the file and passing the file descriptor to MediaPlayer using the setDataSource(FileDescriptor fd) method.

If you look at the absolute path of the output stream, you see it's in the /data/data directory under the app's package name's directory.

Excuse the timestamps - I worked backwards to get data to show on a OS2.1update1 (API7) emulator.

Your code had:

String ave_file_name = "my_media_content";

ave_fos = activity.openFileOutput(ave_file_name, Context.MODE_PRIVATE);

DDMS showed:

02-10 05:10:28.253: WARN/MediaPlayer(1992): info/warning (1, 26)
02-10 05:10:28.253: ERROR/PlayerDriver(31): Command PLAYER_SET_DATA_SOURCE completed with an error or info PVMFErrNotSupported
02-10 05:10:28.253: ERROR/MediaPlayer(1992): error (1, -4)
02-10 05:10:28.274: WARN/PlayerDriver(31): PVMFInfoErrorHandlingComplete

If we change JUST the file to MODE_WORLD_READABLE:

String ave_file_name = "my_media_content";

ave_fos = activity.openFileOutput(ave_file_name, Context.MODE_WORLD_READABLE);

DDMS shows no improvement:

02-10 05:08:28.543: WARN/MediaPlayer(1900): info/warning (1, 26)
02-10 05:08:28.553: ERROR/PlayerDriver(31): Command PLAYER_SET_DATA_SOURCE completed with an error or info PVMFErrNotSupported
02-10 05:08:28.553: ERROR/MediaPlayer(1900): error (1, -4)
02-10 05:08:28.563: WARN/PlayerDriver(31): PVMFInfoErrorHandlingComplete

If we change JUST the file extension to ogg:

String ave_file_name = "my_media_content.ogg";

ave_fos = activity.openFileOutput(ave_file_name, Context.MODE_PRIVATE);

We get a change in DDMS output:

02-10 04:59:30.153: ERROR/MediaPlayerService(31):   error: -2
02-10 04:59:30.163: ERROR/MediaPlayer(1603): Unable to to create media player

But when we combine the two:

String ave_file_name = "my_media_content.ogg";

ave_fos = activity.openFileOutput(ave_file_name, Context.MODE_WORLD_READABLE);

DDMS shows no errors.




回答2:


Some points:

  1. Do not call prepare() twice (once in the constructor and the other explicitly). That could be one of the reasons that the IllegalStateException is thrown.

  2. Also, is the file that you are trying to play inside the application? If so, why are you trying to create a stream? If the file is already within the application (and within /res/raw, you could try and save yourself the hassle of using prepare() by creating the mediaplayer object like so:

    mediaplayer = new MediaPlayer.create(this, R.raw.resource-name here);

The create function calls prepare() within.
3. You can also try and use the reset() function if any one of the stages in the MediaPlayer fails resulting in the MediaPlayer object entering the error state. Using reset() would bring it back to Idle state.
4. The last time I had that error status=0x1 message, it turned out that I had not had the correct permissions set for the files (external storage etc. in Manifest) and some files placed in incorrect folders. You may also want to take a look at that.

Let me know in case that does not work,
We can try something else.
Sriram.




回答3:


It seems you are calling prepare() twice, first in the constructor of AudioVideoEntry, and second in the method prepareMedia(), that's why it's giving an IllegalStateException.

If you read carefully the documentation you can understand the State Diagram and why gives such exceptions.



来源：https://stackoverflow.com/questions/4924600/android-mediaplayer-full-path-to-file

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