好了，下面貼一下整個Activity的實現代碼，主要是播放的各種狀態的實現，因為這個音樂播放器并沒有完全開發完，所以朋友們需要弄清楚這一點。如果對代碼的實現有不清楚的，可以給小巫留言，小巫有空一定給大家解答。

PlayerActivity.java代碼：

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package com.wwj.sb.activity;import java.util.List;import android.app.Activity; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.SeekBar; import android.widget.SeekBar.OnSeekBarChangeListener; import android.widget.TextView; import android.widget.Toast;import com.wwj.sb.domain.AppConstant; import com.wwj.sb.domain.Mp3Info; import com.wwj.sb.utils.MediaUtil;/*** 播放音樂界面* @author wwj* 從主界面傳遞過來歌曲的Id、歌曲名、歌手、歌曲路徑、播放狀態*/ public class PlayerActivity extends Activity{private TextView musicTitle = null;private TextView musicArtist = null;private Button previousBtn; // 上一首private Button repeatBtn; // 重復（單曲循環、全部循環）private Button playBtn; // 播放（播放、暫停）private Button shuffleBtn; // 隨機播放private Button nextBtn; // 下一首private Button searchBtn; //查找歌曲private Button queueBtn; //歌曲列表private SeekBar music_progressBar; //歌曲進度private TextView currentProgress; //當前進度消耗的時間private TextView finalProgress; //歌曲時間private String title; //歌曲標題private String artist; //歌曲藝術家private String url; //歌曲路徑private int listPosition; //播放歌曲在mp3Infos的位置private int currentTime; //當前歌曲播放時間private int duration; //歌曲長度private int flag; //播放標識private int repeatState;private final int isCurrentRepeat = 1; // 單曲循環private final int isAllRepeat = 2; // 全部循環private final int isNoneRepeat = 3; // 無重復播放private boolean isPlaying; // 正在播放private boolean isPause; // 暫停private boolean isNoneShuffle; // 順序播放private boolean isShuffle; // 隨機播放private List<Mp3Info> mp3Infos;private PlayerReceiver playerReceiver; public static final String UPDATE_ACTION = "com.wwj.action.UPDATE_ACTION"; //更新動作public static final String CTL_ACTION = "com.wwj.action.CTL_ACTION"; //控制動作public static final String MUSIC_CURRENT = "com.wwj.action.MUSIC_CURRENT"; //音樂當前時間改變動作public static final String MUSIC_DURATION = "com.wwj.action.MUSIC_DURATION";//音樂播放長度改變動作public static final String MUSIC_PLAYING = "com.wwj.action.MUSIC_PLAYING"; //音樂正在播放動作public static final String REPEAT_ACTION = "com.wwj.action.REPEAT_ACTION"; //音樂重復播放動作public static final String SHUFFLE_ACTION = "com.wwj.action.SHUFFLE_ACTION";//音樂隨機播放動作@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.play_activity_layout);musicTitle = (TextView) findViewById(R.id.musicTitle);musicArtist = (TextView) findViewById(R.id.musicArtist);findViewById();setViewOnclickListener();mp3Infos = MediaUtil.getMp3Infos(PlayerActivity.this);playerReceiver = new PlayerReceiver();IntentFilter filter = new IntentFilter();filter.addAction(UPDATE_ACTION);filter.addAction(MUSIC_CURRENT);filter.addAction(MUSIC_DURATION);registerReceiver(playerReceiver, filter);}/*** 從界面上根據id獲取按鈕*/private void findViewById() {previousBtn = (Button) findViewById(R.id.previous_music);repeatBtn = (Button) findViewById(R.id.repeat_music);playBtn = (Button) findViewById(R.id.play_music);shuffleBtn = (Button) findViewById(R.id.shuffle_music);nextBtn = (Button) findViewById(R.id.next_music);searchBtn = (Button) findViewById(R.id.search_music);queueBtn = (Button) findViewById(R.id.play_queue);music_progressBar = (SeekBar) findViewById(R.id.audioTrack);currentProgress = (TextView) findViewById(R.id.current_progress);finalProgress = (TextView) findViewById(R.id.final_progress);}/*** 給每一個按鈕設置監聽器*/private void setViewOnclickListener() {ViewOnclickListener ViewOnClickListener = new ViewOnclickListener();previousBtn.setOnClickListener(ViewOnClickListener);repeatBtn.setOnClickListener(ViewOnClickListener);playBtn.setOnClickListener(ViewOnClickListener);shuffleBtn.setOnClickListener(ViewOnClickListener);nextBtn.setOnClickListener(ViewOnClickListener);searchBtn.setOnClickListener(ViewOnClickListener);queueBtn.setOnClickListener(ViewOnClickListener);music_progressBar.setOnSeekBarChangeListener(new SeekBarChangeListener());}/*** 在OnResume中初始化和接收Activity數據*/@Overrideprotected void onResume() {super.onResume();Intent intent = getIntent();Bundle bundle = intent.getExtras();title = bundle.getString("title");artist = bundle.getString("artist");url = bundle.getString("url");listPosition = bundle.getInt("listPosition");repeatState = bundle.getInt("repeatState");isShuffle = bundle.getBoolean("shuffleState");flag = bundle.getInt("MSG");currentTime = bundle.getInt("currentTime");duration = bundle.getInt("duration");initView();}/*** 初始化界面*/public void initView() {musicTitle.setText(title);musicArtist.setText(artist);music_progressBar.setProgress(currentTime);music_progressBar.setMax(duration);switch (repeatState) {case isCurrentRepeat: // 單曲循環shuffleBtn.setClickable(false);repeatBtn.setBackgroundResource(R.drawable.repeat_current_selector);break;case isAllRepeat: // 全部循環shuffleBtn.setClickable(false);repeatBtn.setBackgroundResource(R.drawable.repeat_all_selector);break;case isNoneRepeat: // 無重復shuffleBtn.setClickable(true);repeatBtn.setBackgroundResource(R.drawable.repeat_none_selector);break;}if(isShuffle) {isNoneShuffle = false;shuffleBtn.setBackgroundResource(R.drawable.shuffle_selector);repeatBtn.setClickable(false);} else {isNoneShuffle = true;shuffleBtn.setBackgroundResource(R.drawable.shuffle_none_selector);repeatBtn.setClickable(true);}if(flag == AppConstant.PlayerMsg.PLAYING_MSG) { //如果播放信息是正在播放Toast.makeText(PlayerActivity.this, "正在播放--" + title, 1).show();}else if(flag == AppConstant.PlayerMsg.PLAY_MSG) { //如果是點擊列表播放歌曲的話play();}playBtn.setBackgroundResource(R.drawable.play_selector);isPlaying = true;isPause = false;}/*** 反注冊廣播*/@Overrideprotected void onStop() {super.onStop();unregisterReceiver(playerReceiver);}@Overrideprotected void onDestroy() {super.onDestroy();}/*** 控件點擊事件* @author wwj**/private class ViewOnclickListener implements OnClickListener {Intent intent = new Intent();@Overridepublic void onClick(View v) {switch(v.getId()) {case R.id.play_music:if (isPlaying) {playBtn.setBackgroundResource(R.drawable.pause_selector);intent.setAction("com.wwj.media.MUSIC_SERVICE");intent.putExtra("MSG", AppConstant.PlayerMsg.PAUSE_MSG);startService(intent);isPlaying = false;isPause = true;} else if (isPause) {playBtn.setBackgroundResource(R.drawable.play_selector);intent.setAction("com.wwj.media.MUSIC_SERVICE");intent.putExtra("MSG", AppConstant.PlayerMsg.CONTINUE_MSG);startService(intent);isPause = false;isPlaying = true;}break;case R.id.previous_music: //上一首歌曲previous_music();break;case R.id.next_music: //下一首歌曲next_music();break;case R.id.repeat_music: //重復播放音樂if (repeatState == isNoneRepeat) {repeat_one();shuffleBtn.setClickable(false); //是隨機播放變為不可點擊狀態repeatState = isCurrentRepeat; } else if (repeatState == isCurrentRepeat) {repeat_all();shuffleBtn.setClickable(false);repeatState = isAllRepeat;} else if (repeatState == isAllRepeat) {repeat_none();shuffleBtn.setClickable(true);repeatState = isNoneRepeat;}Intent intent = new Intent(REPEAT_ACTION);switch (repeatState) {case isCurrentRepeat: // 單曲循環repeatBtn.setBackgroundResource(R.drawable.repeat_current_selector);Toast.makeText(PlayerActivity.this, R.string.repeat_current,Toast.LENGTH_SHORT).show();intent.putExtra("repeatState", isCurrentRepeat);sendBroadcast(intent);break;case isAllRepeat: // 全部循環repeatBtn.setBackgroundResource(R.drawable.repeat_all_selector);Toast.makeText(PlayerActivity.this, R.string.repeat_all,Toast.LENGTH_SHORT).show();intent.putExtra("repeatState", isAllRepeat);sendBroadcast(intent);break;case isNoneRepeat: // 無重復repeatBtn.setBackgroundResource(R.drawable.repeat_none_selector);Toast.makeText(PlayerActivity.this, R.string.repeat_none,Toast.LENGTH_SHORT).show();intent.putExtra("repeatState", isNoneRepeat);break;}break;case R.id.shuffle_music: //隨機播放狀態Intent shuffleIntent = new Intent(SHUFFLE_ACTION);if (isNoneShuffle) { //如果當前狀態為非隨機播放，點擊按鈕之后改變狀態為隨機播放shuffleBtn.setBackgroundResource(R.drawable.shuffle_selector);Toast.makeText(PlayerActivity.this, R.string.shuffle,Toast.LENGTH_SHORT).show();isNoneShuffle = false;isShuffle = true;shuffleMusic();repeatBtn.setClickable(false);shuffleIntent.putExtra("shuffleState", true);sendBroadcast(shuffleIntent);} else if (isShuffle) {shuffleBtn.setBackgroundResource(R.drawable.shuffle_none_selector);Toast.makeText(PlayerActivity.this, R.string.shuffle_none,Toast.LENGTH_SHORT).show();isShuffle = false;isNoneShuffle = true;repeatBtn.setClickable(true);shuffleIntent.putExtra("shuffleState", false);sendBroadcast(shuffleIntent);}break;}}}/*** 實現監聽Seekbar的類* @author wwj**/private class SeekBarChangeListener implements OnSeekBarChangeListener {@Overridepublic void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {if(fromUser) {audioTrackChange(progress); //用戶控制進度的改變}}@Overridepublic void onStartTrackingTouch(SeekBar seekBar) {}@Overridepublic void onStopTrackingTouch(SeekBar seekBar) {}}/*** 播放音樂*/public void play() {//開始播放的時候為順序播放repeat_none();Intent intent = new Intent();intent.setAction("com.wwj.media.MUSIC_SERVICE");intent.putExtra("url", url);intent.putExtra("listPosition", listPosition);intent.putExtra("MSG", flag);startService(intent);}/*** 隨機播放*/public void shuffleMusic() {Intent intent = new Intent(CTL_ACTION);intent.putExtra("control", 4);sendBroadcast(intent);}public void audioTrackChange(int progress) {Intent intent = new Intent();intent.setAction("com.wwj.media.MUSIC_SERVICE");intent.putExtra("url", url);intent.putExtra("listPosition", listPosition);if(isPause) {intent.putExtra("MSG", AppConstant.PlayerMsg.PAUSE_MSG);}else {intent.putExtra("MSG", AppConstant.PlayerMsg.PROGRESS_CHANGE);}intent.putExtra("progress", progress);startService(intent);}/*** 單曲循環*/public void repeat_one() {Intent intent = new Intent(CTL_ACTION);intent.putExtra("control", 1);sendBroadcast(intent);}/*** 全部循環*/public void repeat_all() {Intent intent = new Intent(CTL_ACTION);intent.putExtra("control", 2);sendBroadcast(intent);}/*** 順序播放*/public void repeat_none() {Intent intent = new Intent(CTL_ACTION);intent.putExtra("control", 3);sendBroadcast(intent);}/*** 上一首*/public void previous_music() {playBtn.setBackgroundResource(R.drawable.play_selector);listPosition = listPosition - 1;if(listPosition >= 0) {Mp3Info mp3Info = mp3Infos.get(listPosition); //上一首MP3musicTitle.setText(mp3Info.getTitle());musicArtist.setText(mp3Info.getArtist());url = mp3Info.getUrl();Intent intent = new Intent();intent.setAction("com.wwj.media.MUSIC_SERVICE");intent.putExtra("url", mp3Info.getUrl());intent.putExtra("listPosition", listPosition);intent.putExtra("MSG", AppConstant.PlayerMsg.PRIVIOUS_MSG);startService(intent);}else {Toast.makeText(PlayerActivity.this, "沒有上一首了", Toast.LENGTH_SHORT).show();}}/*** 下一首*/public void next_music() {playBtn.setBackgroundResource(R.drawable.play_selector);listPosition = listPosition + 1;if(listPosition <= mp3Infos.size() - 1) {Mp3Info mp3Info = mp3Infos.get(listPosition);url = mp3Info.getUrl();musicTitle.setText(mp3Info.getTitle());musicArtist.setText(mp3Info.getArtist());Intent intent = new Intent();intent.setAction("com.wwj.media.MUSIC_SERVICE");intent.putExtra("url", mp3Info.getUrl());intent.putExtra("listPosition", listPosition);intent.putExtra("MSG", AppConstant.PlayerMsg.NEXT_MSG);startService(intent);} else {Toast.makeText(PlayerActivity.this, "沒有下一首了", Toast.LENGTH_SHORT).show();}}/*** 用來接收從service傳回來的廣播的內部類* @author wwj**/public class PlayerReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {String action = intent.getAction();if(action.equals(MUSIC_CURRENT)) {currentTime = intent.getIntExtra("currentTime", -1);currentProgress.setText(MediaUtil.formatTime(currentTime));music_progressBar.setProgress(currentTime);} else if(action.equals(MUSIC_DURATION)) {int duration = intent.getIntExtra("duration", -1);music_progressBar.setMax(duration);finalProgress.setText(MediaUtil.formatTime(duration));} else if(action.equals(UPDATE_ACTION)) {//獲取Intent中的current消息，current代表當前正在播放的歌曲listPosition = intent.getIntExtra("current", -1);url = mp3Infos.get(listPosition).getUrl();if(listPosition >= 0) {musicTitle.setText(mp3Infos.get(listPosition).getTitle());musicArtist.setText(mp3Infos.get(listPosition).getArtist());}if(listPosition == 0) {finalProgress.setText(MediaUtil.formatTime(mp3Infos.get(listPosition).getDuration()));playBtn.setBackgroundResource(R.drawable.pause_selector);isPause = true;}}}}}

以上代碼主要有以下幾點實現：

1. 播放狀態（上一首、下一首、暫停音樂、播放音樂、重復播放、隨機播放）

2. 進度更新（自定義Seekbar，Seekbar觸發時間控制音樂播放的位置）

3. 接收來自Service的廣播，對播放時間，歌曲信息的UI更新。

要注意的地方：

1. 在onResume里接收來自HomeActivity里通過Intent傳過來的數據，它是保存在bundle當中的，所以可以通過Bundle來取數據。

2. 通過startSercice來啟動服務，在啟動之前我們往服務傳的數據

/*** 播放音樂*/public void play() {//開始播放的時候為順序播放repeat_none();Intent intent = new Intent();intent.setAction("com.wwj.media.MUSIC_SERVICE");intent.putExtra("url", url);intent.putExtra("listPosition", listPosition);intent.putExtra("MSG", flag);startService(intent);}

可以看到只有url（音樂播放路徑）、listPosition(列表的點擊位置，也就是mp3Infos的位置）、MSG(代表播放信息）。這幾個是來控制播放的，在Service會很清楚看到這幾個參數的作用。這會在下一篇博客中介紹。

總結

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