Android小玩意儿-- 从头开发一个正经的MusicPlayer（三）

提示：扫一扫查出行
【扫一扫了解最新限行尾号】
复制提示

MusicService已经能够接收广播，通过广播接收的内容来做出相应的MediaPlayer对象的处理，包括播放，暂停，停止等，并当MediaPlayer对象的生命周期发生变化的时候，同样通过发送广播，让UI层产生变换。现在后台处理已经写好。下面就来实现前台的Activity。

1·构建UI布局框架##

1.先构建一个RelativeLayout布局，指定一个背景。

2.我的构想是把整个平面分为三部分，第一部分用来调节音量，因为音量调节常用。第二部分是音乐列表。第三部分是音乐控制按钮和音乐进度条。

3.这三部分一步一步的做出来。先做第一部分调节音量的视图。

这一部分先这样布局，以后如果体验不好再重新修改。

第二部分是歌曲列表的布局

<ListView android:id="@+id/main_listview" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_above="@+id/linearLayout1" android:layout_below="@id/main_volumeLayout" android:fastScrollEnabled="true" android:layout_marginLeft="10dip" android:layout_marginRight="10dip" android:background="@drawable/widget_bg" android:cacheColorHint="#00000000"></ListView>

第三部分是音乐控制的布局。

这样整个UI的布局就完成了。

2在之前的MainActivity的基础上继续开发##

先实现最基础的功能，让音乐播放器能够播放，暂停，下一首，上一首，停止。要实现这个功能就要思考，怎么样才能让MusicService能够按照我们UI的状态变化来操纵MediaPlayer对象呢？最直观的一点就是，最起码要让我们的按钮都有响应了，所以要为我们的音乐控制按钮都加上事件监听器，比如，播放按钮，如果触发了播放按钮，就应该让监听器监听到播放按钮被按下，然后我们需要做的就是在用户按下按钮之后，在监听器下做出相应的相应。MusicService里的MediaPlayer对象有绑定了广播接收器。我们可以让按钮按下之后分发相应的广播。通过广播来通知Service。所以，要给各个按钮增加事件监听器，并分发广播。

MainActivity.java

package com.zharma.greatlovemusic;

import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Timer; import com.zharma.data.Music; import com.zharma.data.MusicList; import android.support.v7.app.ActionBarActivity; import android.database.Cursor; import android.os.Bundle; import android.os.Handler; import android.provider.MediaStore; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.widget.AdapterView; import android.widget.ImageButton; import android.widget.ImageView; import android.widget.ListView; import android.widget.RelativeLayout; import android.widget.SeekBar; import android.widget.SeekBar.OnSeekBarChangeListener; import android.widget.SimpleAdapter; import android.widget.TextView; import android.widget.AdapterView.OnItemClickListener;public class MainActivity extends ActionBarActivity {// 显示组件 private TextView tv_current_time; private TextView tv_total_time; private ImageButton imgBtn_Previous; private ImageButton imgBtn_PlayOrPause; private ImageButton imgBtn_Stop; private ImageButton imgBtn_Next; private SeekBar seekBar; private ListView listView; private RelativeLayout root_Layout;// 当前歌曲的持续时间和当前位置，作用于进度条 private int total_time; private int curent_time;//当前歌曲的序号，下标从零开始 private int number;// 播放状态标志位 private int status;//歌曲列表对象 private ArrayList<Music> musicArrayList;//音量控制 private TextView tv_vol; private SeekBar seekbar_vol;// 进度条控制常量 private static final int PROGRESS_INCREASE = 0; private static final int PROGRESS_PAUSE = 1; private static final int PROGRESS_RESET = 2;// 更新进度条的Handler private Handler seekBarHandler;//睡眠模式相关组件，标识常量 private ImageView iv_sleep; private Timer timer_sleep ; private static final boolean NOTSLEEP = false; private static final boolean ISSLEEP = true;@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);findViews(); initMusicList(); initListView(); registerListeners(); checkMusicfile(); startService(new Intent(this, MusicService.class)); // 绑定广播接收器，可以接收广播 bindStatusChangedReceiver(); sendBroadcastOnCommand(MusicService.COMMAND_CHECK_IS_PLAYING); //初始化进度条的Handler initSeekBarHandler(); status = MusicService.COMMAND_STOP; }void findViews() { listView = (ListView) findViewById(R.id.main_listview); tv_current_time = (TextView) findViewById(R.id.main_tv_curtime); tv_total_time = (TextView) findViewById(R.id.main_tv_totaltime); imgBtn_Previous = (ImageButton) findViewById(R.id.main_ibtn_pre); imgBtn_PlayOrPause = (ImageButton) findViewById(R.id.main_ibtn_play); imgBtn_Previous = (ImageButton) findViewById(R.id.main_ibtn_pre); imgBtn_Next = (ImageButton) findViewById(R.id.main_ibtn_next); imgBtn_Stop = (ImageButton) findViewById(R.id.main_ibtn_stop); seekBar = (SeekBar) findViewById(R.id.main_seekBar); root_Layout = (RelativeLayout) findViewById(R.id.relativeLayout1);tv_vol = (TextView)findViewById(R.id.main_tv_volumeText); seekbar_vol = (SeekBar)findViewById(R.id.main_sb_volumebar); iv_sleep = (ImageView)findViewById(R.id.main_iv_sleep); }/**初始化音乐列表对象*/ private void initMusicList() { musicArrayList = MusicList.getMusicList(); //避免重复添加音乐 if(musicArrayList.isEmpty()) { Cursor mMusicCursor = this.getContentResolver().query( MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null, MediaStore.Audio.AudioColumns.TITLE); int indexTitle = mMusicCursor.getColumnIndex(MediaStore.Audio.AudioColumns.TITLE); int indexArtist = mMusicCursor.getColumnIndex(MediaStore.Audio.AudioColumns.ARTIST); int indexTotalTime = mMusicCursor.getColumnIndex(MediaStore.Audio.AudioColumns.DURATION); int indexPath = mMusicCursor.getColumnIndex(MediaStore.Audio.AudioColumns.DATA);/**通过mMusicCursor游标遍历数据库，并将Music类对象加载带ArrayList中*/ for (mMusicCursor.moveToFirst(); !mMusicCursor.isAfterLast(); mMusicCursor .moveToNext()) { String strTitle = mMusicCursor.getString(indexTitle); String strArtist = mMusicCursor.getString(indexArtist); String strTotoalTime = mMusicCursor.getString(indexTotalTime); String strPath = mMusicCursor.getString(indexPath);if (strArtist.equals("<unknown>")) strArtist = "无艺术家"; Music music = new Music(strTitle, strArtist, strPath, strTotoalTime); musicArrayList.add(music); } } } /**设置适配器并初始化listView*/ private void initListView() { List<Map<String, String>> list_map = new ArrayList<Map<String, String>>(); HashMap<String, String> map; SimpleAdapter simpleAdapter; for (Music music : musicArrayList) { map = new HashMap<String, String>(); map.put("musicName", music.getMusicName()); map.put("musicArtist", music.getMusicArtist()); list_map.add(map); } String[] from = new String[] { "musicName", "musicArtist" }; int[] to = { R.id.listview_tv_title_item, R.id.listview_tv_artist_item };simpleAdapter = new SimpleAdapter(this, list_map, R.layout.listview,from, to); listView.setAdapter(simpleAdapter); }private void registerListeners() { imgBtn_Previous.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { sendBroadcastOnCommand(MusicService.COMMAND_PREVIOUS); } });imgBtn_PlayOrPause.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { switch (status) { case MusicService.STATUS_PLAYING: sendBroadcastOnCommand(MusicService.COMMAND_PAUSE); break; case MusicService.STATUS_PAUSED: sendBroadcastOnCommand(MusicService.COMMAND_RESUME); break; case MusicService.COMMAND_STOP: sendBroadcastOnCommand(MusicService.COMMAND_PLAY); break; default: break; } } });imgBtn_Stop.setOnClickListener(new OnClickListener() { public void onClick(View view) { sendBroadcastOnCommand(MusicService.COMMAND_STOP); } });imgBtn_Next.setOnClickListener(new OnClickListener() { public void onClick(View view) { sendBroadcastOnCommand(MusicService.COMMAND_NEXT); } });listView.setOnItemClickListener(new OnItemClickListener() {@Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { number = position; sendBroadcastOnCommand(MusicService.COMMAND_PLAY); } });seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {@Override public void onStopTrackingTouch(SeekBar seekBar) { if (status == MusicService.STATUS_PLAYING) { // 发送广播给MusicService，执行跳转 sendBroadcastOnCommand(MusicService.COMMAND_SEEK_TO); // 进度条恢复移动 seekBarHandler.sendEmptyMessageDelayed(PROGRESS_INCREASE, 1000); } }@Override public void onStartTrackingTouch(SeekBar seekBar) { // 进度条暂停移动 seekBarHandler.sendEmptyMessage(PROGRESS_PAUSE); }@Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { if (status != MusicService.STATUS_STOPPED) { curent_time = progress; // 更新文本 tv_current_time.setText(formatTime(curent_time)); } } });} }

现在主体已经写好，后面就是具体的各个实现方法。把发送广播的方法与格式化时间的方法实现如下：

/** 发送命令，控制音乐播放。参数定义在MusicService类中 */ private void sendBroadcastOnCommand(int command) { Intent intent = new Intent(MusicService.BROADCAST_MUSICSERVICE_CONTROL); intent.putExtra("command", command); // 根据不同命令，封装不同的数据 switch (command) { case MusicService.COMMAND_PLAY: intent.putExtra("number", number); break; case MusicService.COMMAND_SEEK_TO: intent.putExtra("time", curent_time); break; case MusicService.COMMAND_PREVIOUS: case MusicService.COMMAND_NEXT: case MusicService.COMMAND_PAUSE: case MusicService.COMMAND_STOP: case MusicService.COMMAND_RESUME: default: break; } sendBroadcast(intent); } /**如果列表没有歌曲，则播放按钮不可用，并提醒用户*/ private void checkMusicfile() { if (musicArrayList.isEmpty()) { imgBtn_Next.setEnabled(false); imgBtn_PlayOrPause.setEnabled(false); imgBtn_Previous.setEnabled(false); imgBtn_Stop.setEnabled(false); Toast.makeText(getApplicationContext(), "当前没有歌曲文件",Toast.LENGTH_SHORT).show(); } else { imgBtn_Next.setEnabled(true); imgBtn_PlayOrPause.setEnabled(true); imgBtn_Previous.setEnabled(true); imgBtn_Stop.setEnabled(true); } } /** 绑定广播接收器 */ private void bindStatusChangedReceiver() { receiver = new StatusChangedReceiver(); IntentFilter filter = new IntentFilter( MusicService.BROADCAST_MUSICSERVICE_UPDATE_STATUS); registerReceiver(receiver, filter); } /** 内部类，用于播放器状态更新的接收广播 */ class StatusChangedReceiver extends BroadcastReceiver { public void onReceive(Context context, Intent intent) { // 获取播放器状态 status = intent.getIntExtra("status", -1); switch (status) { case MusicService.STATUS_PLAYING: String musicName = intent.getStringExtra("musicName"); String musicArtist = intent.getStringExtra("musicArtist"); seekBarHandler.removeMessages(PROGRESS_INCREASE); curent_time = intent.getIntExtra("time", 0); total_time = intent.getIntExtra("duration", 0); number = intent.getIntExtra("number", number); listView.setSelection(number);seekBar.setProgress(curent_time); seekBar.setMax(total_time); seekBarHandler.sendEmptyMessageDelayed(PROGRESS_INCREASE, 1000);tv_total_time.setText(formatTime(total_time)); imgBtn_PlayOrPause.setBackgroundResource(R.drawable.pause);// 设置Activity的标题栏文字，提示正在播放的歌曲 MainActivity.this.setTitle("正在播放:" + musicName + " "+ musicArtist); break; case MusicService.STATUS_PAUSED: seekBarHandler.sendEmptyMessage(PROGRESS_PAUSE); String string = MainActivity.this.getTitle().toString().replace("正在播放:", "已暂停:"); MainActivity.this.setTitle(string); imgBtn_PlayOrPause.setBackgroundResource(R.drawable.play); break; case MusicService.STATUS_STOPPED: curent_time = 0; total_time = 0; tv_current_time.setText(formatTime(curent_time)); tv_total_time.setText(formatTime(total_time)); seekBarHandler.sendEmptyMessage(PROGRESS_RESET); MainActivity.this.setTitle("GracePlayer"); imgBtn_PlayOrPause.setBackgroundResource(R.drawable.play); break; case MusicService.STATUS_COMPLETED: number = intent.getIntExtra("number", 0); //顺序模式：到达列表末端时发送停止命令，否则播放下一首 if(playmode == MainActivity.MODE_LIST_SEQUENCE) { if(number == MusicList.getMusicList().size()-1) sendBroadcastOnCommand(MusicService.STATUS_STOPPED); else sendBroadcastOnCommand(MusicService.COMMAND_NEXT); } //单曲循环 else if(playmode == MainActivity.MODE_SINGLE_CYCLE) sendBroadcastOnCommand(MusicService.COMMAND_PLAY); //列表循环：到达列表末端时，把要播放的音乐设置为第一首 else if(playmode == MainActivity.MODE_LIST_CYCLE) { //然后发送播放命令。 if(number == musicArrayList.size()-1) { number = 0; sendBroadcastOnCommand(MusicService.COMMAND_PLAY); } else sendBroadcastOnCommand(MusicService.COMMAND_NEXT); } //随机播放 else if (playmode == MainActivity.MODE_LIST_RANDOM) { Random random = new Random(); int randomnum = random.nextInt(listView.getCount()); number = randomnum; sendBroadcastOnCommand(MusicService.COMMAND_PLAY); } seekBarHandler.sendEmptyMessage(PROGRESS_RESET); MainActivity.this.setTitle("GracePlayer"); imgBtn_PlayOrPause.setBackgroundResource(R.drawable.play); break; default: break; } } } private void initSeekBarHandler() { seekBarHandler = new Handler() { public void handleMessage(Message msg) { super.handleMessage(msg);switch (msg.what) { case PROGRESS_INCREASE: if (seekBar.getProgress() < total_time) { // 进度条前进1秒 seekBar.incrementProgressBy(1000); seekBarHandler.sendEmptyMessageDelayed( PROGRESS_INCREASE, 1000); // 修改显示当前进度的文本 tv_current_time.setText(formatTime(curent_time)); curent_time += 1000; } break; case PROGRESS_PAUSE: seekBarHandler.removeMessages(PROGRESS_INCREASE); break; case PROGRESS_RESET: // 重置进度条界面 seekBarHandler.removeMessages(PROGRESS_INCREASE); seekBar.setProgress(0); tv_current_time.setText("00:00"); break; } } }; }

3·AndroidManifest.xml文件配置##

最后还要把我们的Service加到配置文件里。

<service android:name="com.zharma.greatlovemusic.MusicService" android:exported="true" > <intent-filter> <action android:name="VideoService.START_Video_SERVICE" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> </service>

到目前为止，这个播放器已经实现了基本的音乐播放功能，后面有时间就会再加一些网络歌词获取，放到一个Activity里。搞个华丽的侧滑界面。弄个睡眠模式，播放模式之类的东西，让这个播放器看起来更正儿八经。