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前言

本次作业使用as开发简易音乐播放器能实现音乐的播放和暂停以及切换上一首和下一首播放并显示歌曲基本信息
编写音乐盒代码，参考文件：老师的源码Musicbox，添加音乐播放的 上一首 和 下一首 控制。

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一、效果展示

二、部分核心代码

布局展示

代码展示：

MainActivity.java

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.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageButton;
import android.widget.TextView;public class MainActivity extends Activity implements 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，上一首，下一首按钮ImageButton play, stop, before,after;ActivityReceiver activityReceiver;public static final String CTL_ACTION ="org.xr.action.CTL_ACTION";public static final String UPDATE_ACTION ="org.xr.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[] { " 打上花火 ", " BRE@TH／／LESS ", " カワキヲアメク "," 病名は愛だった" ," Starfall"};String[] authorStrs = new String[] { " 米津玄师 ", " 小林未郁 ", " 美波 "," 鏡音レン"," 袁娅维" };@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);// 获取程序界面界面中的三个按钮play = (ImageButton) this.findViewById(R.id.play);before=(ImageButton)this.findViewById(R.id.before);after=(ImageButton)this.findViewById(R.id.after);title = (TextView) findViewById(R.id.title);author = (TextView) findViewById(R.id.author);before.setImageResource(R.drawable.before);after.setImageResource(R.drawable.after);// 为三个按钮的单击事件添加监听器play.setOnClickListener(this);before.setOnClickListener(this);after.setOnClickListener(this);activityReceiver = new ActivityReceiver();// 创建IntentFilterIntentFilter filter = new IntentFilter();// 指定BroadcastReceiver监听的Actionfilter.addAction(UPDATE_ACTION);// 注册BroadcastReceiverregisterReceiver(activityReceiver, filter);Intent intent = new Intent(this, MusicService.class);// 启动后台ServicestartService(intent);}// 自定义的BroadcastReceiver，负责监听从Service传回来的广播public class ActivityReceiver extends BroadcastReceiver
{@Overridepublic 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;}}
}@Overridepublic void onClick(View source){// 创建IntentIntent intent = new Intent("org.xr.action.CTL_ACTION");switch (source.getId()){// 按下播放/暂停按钮case R.id.play:intent.putExtra("control", 1);break;//按下上一首case R.id.before:intent.putExtra("control",2);break;//按下下一首case R.id.after:intent.putExtra("control",3);break;}// 发送广播，将被Service组件中的BroadcastReceiver接收到sendBroadcast(intent);}
}

MusicService.java

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
{MyReceiver serviceReceiver;AssetManager am;String[] musics = new String[] { "打上花火.mp3", "小林未郁 - BRE@TH／／LESS.mp3","美波 - カワキヲアメク.mp3","Neru,鏡音リン,鏡音レン - 病名は愛だった.mp3","袁娅维 - Starfall.mp3"};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;@Overridepublic IBinder onBind(Intent intent){return null;}@Overridepublic void onCreate(){super.onCreate();am = getAssets();// 创建BroadcastReceiverserviceReceiver = new MyReceiver();// 创建IntentFilterIntentFilter filter = new IntentFilter();filter.addAction(MainActivity.CTL_ACTION);registerReceiver(serviceReceiver, filter);// 创建MediaPlayermPlayer = new MediaPlayer();// 为MediaPlayer播放完成事件绑定监听器mPlayer.setOnCompletionListener(new OnCompletionListener() // ①{@Overridepublic void onCompletion(MediaPlayer mp){current++;if (current >= 5){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
{@Overridepublic 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;//上一首case 2://原来处于播放状态if (status==0x12){current=(current-1+5)%5;//五首歌循环prepareAndPlay(musics[current]);}// 原来处于暂停状态else if (status == 0x13){// 播放current=(current-1+5)%5;prepareAndPlay(musics[current]);mPlayer.start();// 改变状态status = 0x12;}break;//下一首case 3://原来处于播放状态if (status==0x12){   current=(current+1+5)%5;prepareAndPlay(musics[current]);}// 原来处于暂停状态else if (status == 0x13){// 播放current=(current+1+5)%5;prepareAndPlay(musics[current]);mPlayer.start();// 改变状态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();}catch (IOException e){e.printStackTrace();}}
}

完整代码

完整代码见gitee:https://gitee.com/nekopalaa/ht_-music-box