Android开发中使用Studio实现一个音乐播放器

package com.example.dell.musicbox3; import android.app.Activity; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.media.AudioManager; import android.os.Bundle; import android.view.View; import android.view.Window; import android.widget.ImageButton; import android.widget.SeekBar; import android.widget.TextView; public class MainActivity extends Activity implements View.OnClickListener { // 获取界面中显示歌曲标题、作者文本框 TextView title, author; // 播放/暂停、停止按钮 ImageButton play, next, last; // 声明音量管理器 public AudioManager mAudioManager = null; // 定义进度条 public static SeekBar audioSeekBar = null; // 定义音量大小 public SeekBar audioVolume = null; ActivityReceiver activityReceiver; public static final String CTL_ACTION = "org.crazyit.action.CTL_ACTION"; public static final String UPDATE_ACTION = "org.crazyit.action.UPDATE_ACTION"; // 定义音乐的播放状态，0x11代表没有播放；0x12代表正在播放；0x13代表暂停 int status = 0x11; String[] titleStrs = new String[] { "龙卷风", "可爱女人", "星晴" }; String[] authorStrs = new String[] { "JayChou", "JayChou", "JayChou" }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.layout); // 获取程序界面界面中的两个按钮 play = (ImageButton) this.findViewById(R.id.play); last = (ImageButton) this.findViewById(R.id.last); next = (ImageButton) this.findViewById(R.id.next); audioVolume = (SeekBar) findViewById(R.id.seekBar2); audioSeekBar = (SeekBar) findViewById(R.id.seekBar1); title = (TextView) findViewById(R.id.title); author = (TextView) findViewById(R.id.author); // 为两个按钮的单击事件添加监听器 play.setOnClickListener(this); last.setOnClickListener(this); next.setOnClickListener(this); // 播放进度监听 audioSeekBar.setOnSeekBarChangeListener(new SeekBarChangeEvent()); // 退出后再次进去程序时，进度条保持持续更新 if (MusicService.mPlayer != null) { // 设置进度条的最大值 MainActivity.audioSeekBar.setMax(MusicService.mPlayer.getDuration()); audioSeekBar.setProgress(MusicService.mPlayer.getCurrentPosition()); } // 得到当前音量对象 mAudioManager = (AudioManager) getSystemService(AUDIO_SERVICE); // 把当前音量值赋给进度条 audioVolume.setProgress(mAudioManager .getStreamVolume(AudioManager.STREAM_MUSIC)); // 监听音量 audioVolume.setOnSeekBarChangeListener(new AudioVolumeChangeEvent()); activityReceiver = new ActivityReceiver(); // 创建IntentFilter IntentFilter filter = new IntentFilter(); // 指定BroadcastReceiver监听的Action filter.addAction(UPDATE_ACTION); // 注册BroadcastReceiver registerReceiver(activityReceiver, filter); Intent intent = new Intent(this, MusicService.class); // 启动后台Service startService(intent); } // 音量监听 class AudioVolumeChangeEvent implements SeekBar.OnSeekBarChangeListener { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0); } @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onStopTrackingTouch(SeekBar seekBar) { } } // 播放进度监听，别忘了Service里面还有个进度条刷新 class SeekBarChangeEvent implements SeekBar.OnSeekBarChangeListener { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { // 假设改变源于用户拖动 if (fromUser) { MusicService.mPlayer.seekTo(progress); // 当进度条的值改变时，音乐播放器从新的位置开始播放 } } @Override public void onStartTrackingTouch(SeekBar seekBar) { MusicService.mPlayer.pause(); } @Override public void onStopTrackingTouch(SeekBar seekBar) { MusicService.mPlayer.start(); } } // 自定义的BroadcastReceiver，负责监听从Service传回来的广播 public class ActivityReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { // 获取Intent中的update消息，update代表播放状态 int update = intent.getIntExtra("update", -1); // 获取Intent中的current消息，current代表当前正在播放的歌曲 int current = intent.getIntExtra("current", -1); if (current >= 0) { title.setText(titleStrs[current]); author.setText(authorStrs[current]); } switch (update) { case 0x11: play.setImageResource(R.drawable.play); status = 0x11; break; // 控制系统进入播放状态 case 0x12: // 播放状态下设置使用暂停图标 play.setImageResource(R.drawable.pause); // 设置当前状态 status = 0x12; break; // 控制系统进入暂停状态 case 0x13: // 暂停状态下设置使用播放图标 play.setImageResource(R.drawable.play); // 设置当前状态 status = 0x13; break; } } } @Override public void onClick(View source) { // 创建Intent Intent intent = new Intent("org.crazyit.action.CTL_ACTION"); switch (source.getId()) { // 按下播放/暂停按钮 case R.id.play: intent.putExtra("control", 1); break; case R.id.last: intent.putExtra("control", 2); break; //按下上一首按钮 case R.id.next: intent.putExtra("control", 3); break; } // 发送广播，将被Service组件中的BroadcastReceiver接收到 sendBroadcast(intent); } }

package com.example.dell.musicbox3; import java.io.IOException; import android.app.Service; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.content.res.AssetFileDescriptor; import android.content.res.AssetManager; import android.media.MediaPlayer; import android.media.MediaPlayer.OnCompletionListener; import android.os.IBinder; public class MusicService extends Service implements Runnable { MyReceiver serviceReceiver; //asset文件管理对象 AssetManager am; String[] musics = new String[] { "周杰倫 - 龙卷风.mp3", "周杰倫 - 星晴.mp3", "周杰倫 - 可爱女人.mp3" }; public static MediaPlayer mPlayer; // 当前的状态，0x11代表没有播放；0x12代表正在播放；0x13代表暂停 int status = 0x11; // 记录当前正在播放的音乐 int current = 0; @Override //非绑定式服务 public IBinder onBind(Intent intent) { return null; } @Override //定义初始化函数 public void onCreate() { super.onCreate(); //获取asset文件夹里的所有歌曲 am = getAssets(); // 创建具有筛选功能的服务端接收器 serviceReceiver = new MyReceiver(); // 创建IntentFilter过滤器 IntentFilter filter = new IntentFilter(); //使音乐服务端的接收器只能接收客户端发来的CTL_ACTION消息 filter.addAction(MainActivity.CTL_ACTION); //注册带有此筛选器且名字叫做serviceReceiver的接收器 registerReceiver(serviceReceiver, filter); // 创建MediaPlayer mPlayer = new MediaPlayer(); // 为MediaPlayer播放完成事件绑定监听器 mPlayer.setOnCompletionListener(new OnCompletionListener() // ① { @Override public void onCompletion(MediaPlayer mp) { current++; if (current >= 3) { current = 0; } //发送广播通知Activity更改文本框 Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION); sendIntent.putExtra("current", current); // 发送广播，将被Activity组件中的BroadcastReceiver接收到 sendBroadcast(sendIntent); // 准备并播放音乐 prepareAndPlay(musics[current]); } }); } public class MyReceiver extends BroadcastReceiver { @Override public void onReceive(final Context context, Intent intent) { int control = intent.getIntExtra("control", -1); switch (control) { // 播放或暂停 case 1: // 原来处于没有播放状态 if (status == 0x11) { // 准备并播放音乐 prepareAndPlay(musics[current]); status = 0x12; } // 原来处于播放状态 else if (status == 0x12) { // 暂停 mPlayer.pause(); // 改变为暂停状态 status = 0x13; } // 原来处于暂停状态 else if (status == 0x13) { // 播放 mPlayer.start(); // 改变状态 status = 0x12; } break; // 停止声音 case 2: //上一首切换 if (current <= 0) { //停止播放 mPlayer.stop(); //修改current current = musics.length-1; //播放 prepareAndPlay(musics[current]); status = 0x12; } else{ mPlayer.stop(); current--; prepareAndPlay(musics[current]); status = 0x12; } break; //下一首切换 case 3: if (current >= 2) { mPlayer.stop(); current = 0; prepareAndPlay(musics[current]); status = 0x12; } else{ mPlayer.stop(); current++; prepareAndPlay(musics[current]); status = 0x12; } break; } // 广播通知Activity更改图标、文本框 Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION); sendIntent.putExtra("update", status); sendIntent.putExtra("current", current); // 发送广播，将被Activity组件中的BroadcastReceiver接收到 sendBroadcast(sendIntent); } } private void prepareAndPlay(String music) { try { // 打开指定音乐文件 AssetFileDescriptor afd = am.openFd(music); mPlayer.reset(); // 使用MediaPlayer加载指定的声音文件。 mPlayer.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength()); // 准备声音 mPlayer.prepare(); // 播放 mPlayer.start(); // 设置进度条最大值 MainActivity.audioSeekBar.setMax(MusicService.mPlayer.getDuration()); new Thread(this).start(); } catch (IOException e) { e.printStackTrace(); } } // 刷新进度条 public void run() { int CurrentPosition = 0; int total = mPlayer.getDuration(); while (mPlayer != null && CurrentPosition < total) { try { Thread.sleep(1000); if (mPlayer != null) { CurrentPosition = mPlayer.getCurrentPosition(); } } catch (InterruptedException e) { e.printStackTrace(); } MainActivity.audioSeekBar.setProgress(CurrentPosition); } } }

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