一、案例——音乐播放器
在生活中经常会用到服务，为了让大家更好的理解服务通信，接下来通过一个音乐播放器的案例来演示如何使用服务进行通信。
布局文件：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
android:orientation="vertical" >
<EditText
android:id="@+id/et_inputpath"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="a.mp3"/>
<SeekBar
android:id="@+id/seekBar1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:layout_marginTop="20dp" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_gravity="center_horizontal"
android:gravity="center">
<TextView
android:id="@+id/bt_play"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="播放"
android:gravity="center"
android:drawableTop="@android:drawable/ic_media_play"
android:drawablePadding="3dp"/>
<TextView
android:id="@+id/bt_pause"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:drawableTop="@android:drawable/ic_media_pause"
android:drawablePadding="3dp"
android:gravity="center"
android:text="暂停" />
<TextView
android:id="@+id/bt_replay"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:drawableTop="@android:drawable/ic_media_play"
android:drawablePadding="3dp"
android:gravity="center"
android:text="重播" />
<TextView
android:id="@+id/bt_stop"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:drawablePadding="3dp"
android:drawableTop="@android:drawable/ic_media_pause"
android:gravity="center"
android:text="停止" />
</LinearLayout>
</LinearLayout>
MusicService.java
public class MusicService extends Service {
private static final String TAG = "MusicService";
public MediaPlayer mediaPlayer;
class MyBinder extends Binder {
// 播放音乐
public void plays(String path) {
play(path);
}
// 暂停播放
public void pauses() {
pause();
}
// 重新播放
public void replays(String path) {
replay(path);
}
// 停止播放
public void stops() {
stop();
}
// 获取当前播放进度
public int getCurrentPosition() {
return getCurrentProgress();
}
// 获取音乐文件的长度
public int getMusicWidth() {
return getMusicLength();
}
}
public void onCreate() {
super.onCreate();
}
// 播放音乐
@SuppressLint("NewApi")
public void play(String path) {
try {
if (mediaPlayer == null) {
Log.i(TAG, "开始播放音乐");
// 创建一个MediaPlayer播放器
mediaPlayer = new MediaPlayer();
// 指定参数为音频文件
mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
// 指定播放的路径
mediaPlayer.setDataSource(path);
// 准备播放
mediaPlayer.prepare();
mediaPlayer.setOnPreparedListener(new OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mp) {
// TODO Auto-generated method stub
// 开始播放
mediaPlayer.start();
}
});
} else {
int position = getCurrentProgress();
mediaPlayer.seekTo(position);
try {
mediaPlayer.prepare();
} catch (Exception e) {
e.printStackTrace();
}
mediaPlayer.start();
}
} catch (Exception e) {
e.printStackTrace();
}
}
// 暂停音乐
public void pause() {
if (mediaPlayer != null && mediaPlayer.isPlaying()) {
Log.i(TAG, "播放暂停");
mediaPlayer.pause(); // 暂停播放
} else if (mediaPlayer != null && (!mediaPlayer.isPlaying())) {
mediaPlayer.start();
}
}
// 重新播放音乐
public void replay(String path) {
if (mediaPlayer != null) {
Log.i(TAG, "重新开始播放");
mediaPlayer.seekTo(0);
try {
mediaPlayer.prepare();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
mediaPlayer.start();
}
}
// 停止音乐
public void stop() {
if (mediaPlayer != null) {
Log.i(TAG, "停止播放");
mediaPlayer.stop();
mediaPlayer.release();
mediaPlayer = null;
} else {
Toast.makeText(getApplicationContext(), "已停止", 0).show();
}
}
// 获取资源文件的长度
public int getMusicLength() {
if (mediaPlayer != null) {
return mediaPlayer.getDuration();
}
return 0;
}
// 获取当前进度
public int getCurrentProgress() {
if (mediaPlayer != null & mediaPlayer.isPlaying()) {
Log.i(TAG, "获取当前进度");
return mediaPlayer.getCurrentPosition();
} else if (mediaPlayer != null & (!mediaPlayer.isPlaying())) {
return mediaPlayer.getCurrentPosition();
}
return 0;
}
public void onDestroy() {
if (mediaPlayer != null) {
mediaPlayer.stop();
mediaPlayer.release();
mediaPlayer = null;
}
super.onDestroy();
}
public IBinder onBind(Intent intent) {
// 第一步执行onBind方法
return new MyBinder();
}
}
MainActivity.java
public class MainActivity extends Activity implements OnClickListener {
private EditText path;
private Intent intent;
private myConn conn;
MyBinder binder;
private SeekBar mSeekBar;
private Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case 100:
int currentPosition = (Integer) msg.obj;
mSeekBar.setProgress(currentPosition);
break;
default:
break;
}
};
};
private Thread mThread;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
path = (EditText) findViewById(R.id.et_inputpath);
findViewById(R.id.bt_play).setOnClickListener(this);
findViewById(R.id.bt_pause).setOnClickListener(this);
findViewById(R.id.bt_replay).setOnClickListener(this);
findViewById(R.id.bt_stop).setOnClickListener(this);
mSeekBar = (SeekBar) findViewById(R.id.seekBar1);
conn = new myConn();
intent = new Intent(this, MusicService.class);
bindService(intent, conn, BIND_AUTO_CREATE);
}
// 初始化进度条的长度,获取音乐文件的长度
private void initSeekBar() {
// TODO Auto-generated method stub
int musicWidth = binder.getMusicWidth();
mSeekBar.setMax(musicWidth);
}
// 更新音乐播放的进度
private void UpdateProgress() {
mThread = new Thread() {
public void run() {
while (!interrupted()) {
// 调用服务中的获取当前播放进度
int currentPosition = binder.getCurrentPosition();
Message message = Message.obtain();
message.obj = currentPosition;
message.what = 100;
handler.sendMessage(message);
}
};
};
mThread.start();
}
private class myConn implements ServiceConnection {
public void onServiceConnected(ComponentName name, IBinder service) {
binder = (MyBinder) service;
}
public void onServiceDisconnected(ComponentName name) {
}
}
public void onClick(View v) {
String pathway = path.getText().toString().trim();
File SDpath = Environment.getExternalStorageDirectory();
File file = new File(SDpath, pathway);
String path = file.getAbsolutePath();
switch (v.getId()) {
case R.id.bt_play:
if (file.exists() && file.length() > 0) {
binder.plays(path);
initSeekBar();
UpdateProgress();
}else{
Toast.makeText(this, "找不到音乐文件", 0).show();
}
break;
case R.id.bt_pause:
binder.pauses();
break;
case R.id.bt_replay:
binder.replays(pathway);
break;
case R.id.bt_stop:
// 停止音乐之前首先要退出子线程
mThread.interrupt();
if (mThread.isInterrupted()) {
binder.stops();
}
break;
default:
break;
}
}
protected void onDestroy() {
// 如果线程没有退出,则退出
if (mThread != null & !mThread.isInterrupted()) {
mThread.interrupt();
}
unbindService(conn);
super.onDestroy();
}
}
