This test experiment will use the AsyncPlayer class. I found that this class is only useful as is on SDK 2.2 +. But, I thought I would get my feet wet with this simple test. I'm going to play an mp3 audio file that I have in an AWS S3 bucket. I'm not going to add any other controls to this test example. I am going to keep this example very basic. This is just a jumping off point.
AsyncPlayer Example
I started out creating a new Android 2.3 project in Eclipse. In order for this example to work, the internet permission must be set in the manifest file. As always I set debuggable to true. In the main activity class we will only need to add three lines of code to get the mp3 to play when the activity is created. At this point we won't be adding any controls to stop the playback.
First we want to create a string variable to hold the location of the mp3. I used an mp3 that was uploaded to a bucket in my AWS S3 service. I have set the permission policy to allow anyone to download the file.
String url = "http://s3.amazonaws.com/launchcode.album/ThePigotJig.mp3";
The next step is to create a new instance of the AsyncPlayer class. The string "MyTest" is used for debugging purposes. Then play is called with the appropriate variables. The third variable is whether to loop the playback or not.
AsyncPlayer ap = new AsyncPlayer("MyTest");
ap.play(this, Uri.parse(url), false, AudioManager.STREAM_MUSIC);
And that's it. When the app is run on your device, playback of the mp3 stream will begin. Below is the full source for the main Activity. Also available is the source to the AsyncPlayer class. This can be useful in extending the class.
package com.launchcode.music;
import android.app.Activity;
import android.media.AsyncPlayer;
import android.media.AudioManager;
import android.net.Uri;
import android.os.Bundle;
public class TestMusicPlay extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
String url = "http://s3.amazonaws.com/launchcode.album/ThePigotJig.mp3";
AsyncPlayer ap = new AsyncPlayer("MyTest");
ap.play(this, Uri.parse(url), false, AudioManager.STREAM_MUSIC);
}
}
AsyncPlayer class:
/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.media;
import android.content.Context;
import android.net.Uri;
import android.os.PowerManager;
import android.os.SystemClock;
import android.util.Log;
import java.io.IOException;
import java.lang.IllegalStateException;
import java.util.LinkedList;
/**
* Plays a series of audio URIs, but does all the hard work on another thread
* so that any slowness with preparing or loading doesn't block the calling thread.
*/
public class AsyncPlayer {
private static final int PLAY = 1;
private static final int STOP = 2;
private static final boolean mDebug = false;
private static final class Command {
int code;
Context context;
Uri uri;
boolean looping;
int stream;
long requestTime;
public String toString() {
return "{ code=" + code + " looping=" + looping + " stream=" + stream
+ " uri=" + uri + " }";
}
}
private LinkedList<Command> mCmdQueue = new LinkedList();
private void startSound(Command cmd) {
// Preparing can be slow, so if there is something else
// is playing, let it continue until we're done, so there
// is less of a glitch.
try {
if (mDebug) Log.d(mTag, "Starting playback");
MediaPlayer player = new MediaPlayer();
player.setAudioStreamType(cmd.stream);
player.setDataSource(cmd.context, cmd.uri);
player.setLooping(cmd.looping);
player.prepare();
player.start();
if (mPlayer != null) {
mPlayer.release();
}
mPlayer = player;
long delay = SystemClock.uptimeMillis() - cmd.requestTime;
if (delay > 1000) {
Log.w(mTag, "Notification sound delayed by " + delay + "msecs");
}
}
catch (Exception e) {
Log.w(mTag, "error loading sound for " + cmd.uri, e);
}
}
private final class Thread extends java.lang.Thread {
Thread() {
super("AsyncPlayer-" + mTag);
}
public void run() {
while (true) {
Command cmd = null;
synchronized (mCmdQueue) {
if (mDebug) Log.d(mTag, "RemoveFirst");
cmd = mCmdQueue.removeFirst();
}
switch (cmd.code) {
case PLAY:
if (mDebug) Log.d(mTag, "PLAY");
startSound(cmd);
break;
case STOP:
if (mDebug) Log.d(mTag, "STOP");
if (mPlayer != null) {
long delay = SystemClock.uptimeMillis() - cmd.requestTime;
if (delay > 1000) {
Log.w(mTag, "Notification stop delayed by " + delay + "msecs");
}
mPlayer.stop();
mPlayer.release();
mPlayer = null;
} else {
Log.w(mTag, "STOP command without a player");
}
break;
}
synchronized (mCmdQueue) {
if (mCmdQueue.size() == 0) {
// nothing left to do, quit
// doing this check after we're done prevents the case where they
// added it during the operation from spawning two threads and
// trying to do them in parallel.
mThread = null;
releaseWakeLock();
return;
}
}
}
}
}
private String mTag;
private Thread mThread;
private MediaPlayer mPlayer;
private PowerManager.WakeLock mWakeLock;
// The current state according to the caller. Reality lags behind
// because of the asynchronous nature of this class.
private int mState = STOP;
/**
* Construct an AsyncPlayer object.
*
* @param tag a string to use for debugging
*/
public AsyncPlayer(String tag) {
if (tag != null) {
mTag = tag;
} else {
mTag = "AsyncPlayer";
}
}
/**
* Start playing the sound. It will actually start playing at some
* point in the future. There are no guarantees about latency here.
* Calling this before another audio file is done playing will stop
* that one and start the new one.
*
* @param context Your application's context.
* @param uri The URI to play. (see {@link MediaPlayer#setDataSource(Context, Uri)})
* @param looping Whether the audio should loop forever.
* (see {@link MediaPlayer#setLooping(boolean)})
* @param stream the AudioStream to use.
* (see {@link MediaPlayer#setAudioStreamType(int)})
*/
public void play(Context context, Uri uri, boolean looping, int stream) {
Command cmd = new Command();
cmd.requestTime = SystemClock.uptimeMillis();
cmd.code = PLAY;
cmd.context = context;
cmd.uri = uri;
cmd.looping = looping;
cmd.stream = stream;
synchronized (mCmdQueue) {
enqueueLocked(cmd);
mState = PLAY;
}
}
/**
* Stop a previously played sound. It can't be played again or unpaused
* at this point. Calling this multiple times has no ill effects.
*/
public void stop() {
synchronized (mCmdQueue) {
// This check allows stop to be called multiple times without starting
// a thread that ends up doing nothing.
if (mState != STOP) {
Command cmd = new Command();
cmd.requestTime = SystemClock.uptimeMillis();
cmd.code = STOP;
enqueueLocked(cmd);
mState = STOP;
}
}
}
private void enqueueLocked(Command cmd) {
mCmdQueue.add(cmd);
if (mThread == null) {
acquireWakeLock();
mThread = new Thread();
mThread.start();
}
}
/**
* We want to hold a wake lock while we do the prepare and play. The stop probably is
* optional, but it won't hurt to have it too. The problem is that if you start a sound
* while you're holding a wake lock (e.g. an alarm starting a notification), you want the
* sound to play, but if the CPU turns off before mThread gets to work, it won't. The
* simplest way to deal with this is to make it so there is a wake lock held while the
* thread is starting or running. You're going to need the WAKE_LOCK permission if you're
* going to call this.
*
* This must be called before the first time play is called.
*
* @hide
*/
public void setUsesWakeLock(Context context) {
if (mWakeLock != null || mThread != null) {
// if either of these has happened, we've already played something.
// and our releases will be out of sync.
throw new RuntimeException("assertion failed mWakeLock=" + mWakeLock
+ " mThread=" + mThread);
}
PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, mTag);
}
private void acquireWakeLock() {
if (mWakeLock != null) {
mWakeLock.acquire();
}
}
private void releaseWakeLock() {
if (mWakeLock != null) {
mWakeLock.release();
}
}
}
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