Android开发---MediaPlayer简单音乐播放器
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Android开发—MediaPlayer简单音乐播放器
功能介绍
实现一个简单的播放器,类似网易云音乐形式,功能包括:
- 播放、暂停,停止,退出功能;
- 后台播放功能;
- 进度条显示播放进度、拖动进度条改变进度功能;
- 播放时图片旋转,显示当前播放时间功能;
界面样式
功能实现
1. MediaPlayer的实现
- MediaPlayer常用方法介绍
-
MediaPlayer的实现包括初始化MediaPlayer,MediaPlayer的功能实现,包括播放、暂停、停止、离开等,具体细节如下:
MediaPlayer的初始化包括读取一个MP3格式的音乐文件并设置其为循环播放:
public void initMediaPlayer() { try { //String file_path = "/storage/0123-4567/K.Will-Melt.mp3"; String file_path = Environment.getExternalStorageDirectory().getAbsolutePath()+"/K.Will-Melt.mp3"; //String file_path = "/data/K.Will-Melt.mp3"; mediaPlayer.setDataSource(file_path); mediaPlayer.prepare(); mediaPlayer.setLooping(true); // 设置循环播放 } catch (Exception e) { e.printStackTrace(); } }
播放/暂停功能的实现放在Play/Pause按钮中,所以需要二选一判断MediaPlayer的状态来设置音乐的播放与暂停:
public void playOrPause() { flag++; if (flag >= 1000) flag = 2; which = "pause"; if(mediaPlayer.isPlaying()){ mediaPlayer.pause(); animator.pause(); } else { mediaPlayer.start();
类似的,停止功能的实现放在Stop按钮中,用于停止音乐并将其置于初始态即“00:00”:
public void stop() { which = "stop"; animator.pause(); if(mediaPlayer != null) { mediaPlayer.pause(); mediaPlayer.stop(); try { mediaPlayer.prepare(); mediaPlayer.seekTo(0); } catch (Exception e) { e.printStackTrace(); } } }
说明:由于调用stop()后,有时音乐并没有马上停止,所以我额外加了一个pause()来确保音乐停止播放。
同样,离开功能实现放在了Quit按钮中,主要实现整个应用的退出,具体应包括解绑Service,结束Activity等等:
private void quit() { musicService.animator.end(); handler.removeCallbacks(runnable); unbindService(sc); try { finish(); System.exit(0); } catch (Exception e) { e.printStackTrace(); } }
2. Service的应用
- Service即“服务” ,它与Activity属于同一等级的应用程序组件,都代表可执行的程序。不同的是Activity拥有前台运行的用户界面,而Service不能自己运行,需要通过某个Activity或者其他Context对象来调用。Service在后台运行,它不能与用户直接进行交互。在默认情况下,Service运行在应用程序进程的主线程之中。可以通过Context.startService()和Context.bindService()两种方式来启动Service。
- 通过Service可以使程序在退出之后仍然能够对事件或用户操作做出反应,或者在后台继续运行某些程序功能。
- Android赋予Services比处于不活动(inactivity)的Activities更高的优先级,所以它们的进程不会轻易被系统杀掉。
- Activity与Service的交互示意图为:
有了以上知识的积累,基本可以实现Service的必要部分,如下:
1.新建一个继承于Service的MusicService类
public class MusicService extends Service { public final IBinder binder = new MyBinder(); public class MyBinder extends Binder { MusicService getService() { return MusicService.this; } }
/** * onBind 是 Service 的虚方法,因此我们不得不实现它。 * 返回 null,表示客服端不能建立到此服务的连接。 */ @Override public IBinder onBind(Intent intent) { return binder; }
2.并在Activity中绑定MusicService:
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); getOverflowMenu(); setContentView(R.layout.activity_main); bindServiceConnection(); musicService = new MusicService();
private ServiceConnection sc = new ServiceConnection() { @Override public void onServiceConnected(ComponentName componentName, IBinder iBinder) { musicService = ((MusicService.MyBinder) iBinder).getService(); } @Override public void onServiceDisconnected(ComponentName componentName) { musicService = null; } }; private void bindServiceConnection() { Intent intent = new Intent(this, MusicService.class); startService(intent); bindService(intent, sc, this.BIND_AUTO_CREATE); }
3. Handler更新UI界面
通过Handler来管理UI,最要需要用到post和postDelayed两个函数:
1. post(Runnable r)
将r加入到消息队列中(其实就是利用UI主线程执行一段代码,这样可以随时在其他线程中调整控件)
2. postDelayed(Runnabled r,long delayMillis)
将r加入到消息队列中,并在指定时间之后触发(单位为毫秒)
所以,为了实现音乐的播放显示等功能,需要重写Runnable的run函数,具体实现如下:
public Handler handler = new Handler(); public Runnable runnable = new Runnable() { @Override public void run() { isPlay.setOnClickListener(new myOnClickListener()); stop.setOnClickListener(new myOnClickListener()); quit.setOnClickListener(new myOnClickListener()); if(musicService.mediaPlayer.isPlaying()) { stateText.setText("Playing"); } else { if (musicService.which.equals("stop")) { stateText.setText("Stop"); } else if (musicService.which.equals("pause")){ stateText.setText("Pause"); } } playingTime.setText(time.format(musicService.mediaPlayer.getCurrentPosition())); totalTime.setText(time.format(musicService.mediaPlayer.getDuration())); seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition()); seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { if (fromUser) { musicService.mediaPlayer.seekTo(seekBar.getProgress()); } } @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onStopTrackingTouch(SeekBar seekBar) { } }); handler.postDelayed(runnable, 100); } };
4. 实现图片的旋转
图片的动画效果实现需要用到ObjectAnimator类,ObjectAnimator类可用于图片的平移、旋转、缩放等动画,此处我们只需要用到其旋转功能,具体实现如下:
public void AnimatorAction() { if (mediaPlayer.isPlaying()) { animator.setDuration(5000); animator.setInterpolator(new LinearInterpolator()); // 均速旋转 animator.setRepeatCount(ValueAnimator.INFINITE); // 无限循环 animator.setRepeatMode(ValueAnimator.INFINITE); animator.start(); } }
说明:animator是ObjectAnimator的一个实例对象,setDuration为5000表示旋转一周需要的时间为5000,所以可用来设置旋转的速度;同时设置为无线循环模式,并且添加一个插值器达到匀速旋转的目的,最后调用pause()等函数动态控制动画状态,如下:
5. 进度条SeekBar功能实现
SeekBar的功能包括显示歌曲播放进度以及拖动SeekBar至任意位置来改变播放进度,由于android已经封装好了这些函数,所以直接调用就好了,也比较好理解,具体实现如下:
seekBar = (SeekBar) findViewById(R.id.seekBar); seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition()); seekBar.setMax(musicService.mediaPlayer.getDuration());
seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition()); seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { if (fromUser) { musicService.mediaPlayer.seekTo(seekBar.getProgress()); } } @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onStopTrackingTouch(SeekBar seekBar) { } });
6. 动态权限申请
参见Android动态权限申请
7. 判断程序是否处于后台
由于音乐需要支持后台播放,再次由后台进入前台会对前台的事件功能等产生影响,所以可以添加一个后台判断函数,并添加一个标志来记录应用是否进入后台。
private boolean isApplicationBroughtToBackground() { ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE); List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(1); if (!tasks.isEmpty()) { ComponentName topActivity = tasks.get(0).topActivity; if (!topActivity.getPackageName().equals(getPackageName())) { return true; } } return false; }
附上MainActivity和Service部分的完整代码
- MainActivity.java
package com.example.kx.temp;import android.Manifest;import android.animation.ObjectAnimator;import android.animation.ValueAnimator;import android.app.Activity;import android.app.ActivityManager;import android.content.ComponentName;import android.content.Context;import android.content.Intent;import android.content.ServiceConnection;import android.content.pm.PackageManager;import android.media.MediaPlayer;import android.net.Uri;import android.os.Environment;import android.os.Handler;import android.os.IBinder;import android.support.v4.app.ActivityCompat;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.View;import android.view.ViewConfiguration;import android.view.animation.LinearInterpolator;import android.widget.Button;import android.widget.ImageView;import android.widget.SeekBar;import android.widget.TextView;import com.google.android.gms.appindexing.Action;import com.google.android.gms.appindexing.AppIndex;import com.google.android.gms.common.api.GoogleApiClient;import java.lang.reflect.Field;import java.text.SimpleDateFormat;import java.util.List;public class MainActivity extends AppCompatActivity { private Button isPlay; private Button stop; private Button quit; private ImageView coverImage; // private ObjectAnimator animator; private int flag = 0; private TextView totalTime; private TextView playingTime; private TextView stateText; private SeekBar seekBar; private TextView pathText; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); getOverflowMenu(); setContentView(R.layout.activity_main); bindServiceConnection(); musicService = new MusicService(); coverImage = (ImageView) findViewById(R.id.coverImage); musicService.animator = ObjectAnimator.ofFloat(coverImage, "rotation", 0, 359); isPlay = (Button) findViewById(R.id.isPlayButton); isPlay.setOnClickListener(new myOnClickListener()); stop = (Button) findViewById(R.id.stopButton); stop.setOnClickListener(new myOnClickListener()); quit = (Button) findViewById(R.id.quitButton); quit.setOnClickListener(new myOnClickListener()); seekBar = (SeekBar) findViewById(R.id.seekBar); seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition()); seekBar.setMax(musicService.mediaPlayer.getDuration()); totalTime = (TextView) findViewById(R.id.totalTime); playingTime = (TextView) findViewById(R.id.playingTime); stateText = (TextView) findViewById(R.id.stateText); pathText = (TextView) findViewById(R.id.pathText); String sdcard = "音乐文件的路径为:" + Environment.getExternalStorageDirectory().getAbsolutePath().toString()+"/K.Will-Melt.mp3"; pathText.setText(sdcard); } private MusicService musicService; private SimpleDateFormat time = new SimpleDateFormat("mm:ss"); private ServiceConnection sc = new ServiceConnection() { @Override public void onServiceConnected(ComponentName componentName, IBinder iBinder) { musicService = ((MusicService.MyBinder) iBinder).getService(); } @Override public void onServiceDisconnected(ComponentName componentName) { musicService = null; } }; private void bindServiceConnection() { Intent intent = new Intent(this, MusicService.class); startService(intent); bindService(intent, sc, this.BIND_AUTO_CREATE); } public Handler handler = new Handler(); public Runnable runnable = new Runnable() { @Override public void run() { isPlay.setOnClickListener(new myOnClickListener()); stop.setOnClickListener(new myOnClickListener()); quit.setOnClickListener(new myOnClickListener()); if(musicService.mediaPlayer.isPlaying()) { stateText.setText("Playing"); } else { if (musicService.which.equals("stop")) { stateText.setText("Stop"); } else if (musicService.which.equals("pause")){ stateText.setText("Pause"); } } playingTime.setText(time.format(musicService.mediaPlayer.getCurrentPosition())); totalTime.setText(time.format(musicService.mediaPlayer.getDuration())); seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition()); seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { if (fromUser) { musicService.mediaPlayer.seekTo(seekBar.getProgress()); } } @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onStopTrackingTouch(SeekBar seekBar) { } }); handler.postDelayed(runnable, 100); } }; @Override public void onPause(){ super.onPause(); if(isApplicationBroughtToBackground()) { musicService.isReturnTo = 1; Log.e("b","后台中"); } } @Override public void onRestart() { super.onRestart(); musicService.isReturnTo = 1; } @Override protected void onResume() { musicService.AnimatorAction(); verifyStoragePermissions(this); if(musicService.mediaPlayer.isPlaying()) { stateText.setText("Playing"); } else { if (musicService.which.equals("stop")) { stateText.setText("Stop"); } else if (musicService.which.equals("pause")){ stateText.setText("Pause"); } } seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition()); seekBar.setMax(musicService.mediaPlayer.getDuration()); handler.post(runnable); super.onResume(); Log.d("hint", "handler post runnable"); } private class myOnClickListener implements View.OnClickListener { @Override public void onClick(View view) { switch (view.getId()) { case R.id.isPlayButton: changePlay(); musicService.playOrPause(); break; case R.id.stopButton: musicService.stop(); changeStop(); break; case R.id.quitButton: quit(); break; default: break; } } } private void changePlay() { if(musicService.mediaPlayer.isPlaying()){ stateText.setText("Pause"); isPlay.setText("PLAY"); //animator.pause(); } else { stateText.setText("Playing"); isPlay.setText("PAUSE"); } } private void changeStop() { stateText.setText("Stop"); seekBar.setProgress(0); //animator.pause(); } private void quit() { musicService.animator.end(); handler.removeCallbacks(runnable); unbindService(sc); try { finish(); System.exit(0); } catch (Exception e) { e.printStackTrace(); } } @Override public void onStop() { super.onStop(); } @Override public void onDestroy() { unbindService(sc); super.onDestroy(); } //这里是在登录界面label上右上角添加三个点,里面可添加其他功能 @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.settings, menu); return true; } private void getOverflowMenu() { try { ViewConfiguration config = ViewConfiguration.get(this); Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey"); if (menuKeyField != null) { menuKeyField.setAccessible(true); menuKeyField.setBoolean(config, false); } } catch (Exception e) { e.printStackTrace(); } } private boolean isApplicationBroughtToBackground() { ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE); List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(1); if (!tasks.isEmpty()) { ComponentName topActivity = tasks.get(0).topActivity; if (!topActivity.getPackageName().equals(getPackageName())) { return true; } } return false; } // Storage Permissions private static final int REQUEST_EXTERNAL_STORAGE = 1; private static String[] PERMISSIONS_STORAGE = { Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE }; /** * Checks if the app has permission to write to device storage * * If the app does not has permission then the user will be prompted to grant permissions * * @param activity */ public static void verifyStoragePermissions(Activity activity) { // Check if we have write permission int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE); if (permission != PackageManager.PERMISSION_GRANTED) { // We don't have permission so prompt the user ActivityCompat.requestPermissions( activity, PERMISSIONS_STORAGE, REQUEST_EXTERNAL_STORAGE ); } }}
- Service
package com.example.kx.temp;import android.Manifest;import android.animation.ObjectAnimator;import android.animation.ValueAnimator;import android.app.Activity;import android.app.ActivityManager;import android.app.Service;import android.content.ComponentName;import android.content.Context;import android.content.Intent;import android.content.pm.PackageManager;import android.media.MediaPlayer;import android.os.Binder;import android.os.Environment;import android.os.IBinder;import android.support.v4.app.ActivityCompat;import android.util.Log;import android.view.animation.LinearInterpolator;import java.io.File;import java.util.List;/** * Created by kx on 2016/11/3. */public class MusicService extends Service { public final IBinder binder = new MyBinder(); public class MyBinder extends Binder { MusicService getService() { return MusicService.this; } } public static int isReturnTo = 0; public static MediaPlayer mediaPlayer = new MediaPlayer(); public static ObjectAnimator animator; public MusicService() { initMediaPlayer(); } public void initMediaPlayer() { try { //String file_path = "/storage/0123-4567/K.Will-Melt.mp3"; String file_path = Environment.getExternalStorageDirectory().getAbsolutePath()+"/K.Will-Melt.mp3"; //String file_path = "/data/K.Will-Melt.mp3"; mediaPlayer.setDataSource(file_path); mediaPlayer.prepare(); mediaPlayer.setLooping(true); // 设置循环播放 } catch (Exception e) { e.printStackTrace(); } } public void AnimatorAction() { if (mediaPlayer.isPlaying()) { animator.setDuration(5000); animator.setInterpolator(new LinearInterpolator()); // 均速旋转 animator.setRepeatCount(ValueAnimator.INFINITE); // 无限循环 animator.setRepeatMode(ValueAnimator.INFINITE); animator.start(); } } private int flag = 0; public static String which = ""; public void playOrPause() { flag++; if (flag >= 1000) flag = 2; which = "pause"; if(mediaPlayer.isPlaying()){ mediaPlayer.pause(); animator.pause(); } else { mediaPlayer.start(); if ((flag == 1) || (isReturnTo == 1)) { animator.setDuration(5000); animator.setInterpolator(new LinearInterpolator()); // 均速旋转 animator.setRepeatCount(ValueAnimator.INFINITE); // 无限循环 animator.setRepeatMode(ValueAnimator.INFINITE); animator.start(); } else { animator.resume(); } } } public void stop() { which = "stop"; animator.pause(); if(mediaPlayer != null) { mediaPlayer.pause(); mediaPlayer.stop(); try { mediaPlayer.prepare(); mediaPlayer.seekTo(0); } catch (Exception e) { e.printStackTrace(); } } } @Override public void onDestroy() { mediaPlayer.stop(); mediaPlayer.release(); super.onDestroy(); } /** * onBind 是 Service 的虚方法,因此我们不得不实现它。 * 返回 null,表示客服端不能建立到此服务的连接。 */ @Override public IBinder onBind(Intent intent) { return binder; }}
至此,基于MediaPlayer的简单音乐播放器基本可以实现,如有错误或疑问,烦请指出。如需要完整项目代码,可留下邮箱。
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