音乐播放器之简单播放（MediaPlayer、Service、BroadcastRecevier的结合用法）

(小白一个，代码仅供参考)

做一个音乐播放器，就要考虑到实现后台音乐的播放，进度条的实现，播放时间和音频时间的实现。 在Android中，BroadcastRecevier Service 和 MediaPlayer就可以实现下面的操作。

先看Activity

package com.example.bear.test;

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.widget.Button;
import android.widget.ImageButton;
import android.widget.SeekBar;
import android.widget.TextView;

public class MainActivity extends Activity implements View.OnClickListener{
    //为日志工具设置标签
    private static String TAG = "MusicService";
    protected boolean isplay = false;
    private static final int PLAY = 1;
    private static final int PAUSE = 2;
    private static final int STOP = 3;// 停止
    private static final int PROGRESS_CHANGE = 4;
    private static final int STATE_PLAY = 1;// 播放状态设为1
    private static final int STATE_PAUSE = 2;// 播放状态设为2
    private SeekBar mSeekBar;
    private ImageButton btnStart;
    private Button btnStop;
    private int flag;// 标记
    private TextView startTime, stopTime;
    private MyBroadcastReceiver myBroadcastReceiver = new MyBroadcastReceiver();

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initlizeViews();
    }

    @Override
    protected void onResume() {
        super.onResume();
        //注册广播接收器
        IntentFilter filter = new IntentFilter();
        //设置接收广播的类型，这里要和Service里设置的类型匹配，还可以在AndroidManifest.xml文件中注册
        filter.addAction("com.bear.app");
        this.registerReceiver(myBroadcastReceiver, filter);
        mSeekBar.setProgress(0);
        play();

    }

    @Override
    protected void onStop() {
        super.onStop();
        this.unregisterReceiver(myBroadcastReceiver);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        stop();
        this.unregisterReceiver(myBroadcastReceiver);
        finish();
    }

    private void initlizeViews() {
        btnStart = (ImageButton) findViewById(R.id.startMusic);
        btnStop = (Button) findViewById(R.id.stopMusic);
        mSeekBar = (SeekBar) findViewById(R.id.seekbar1);
        startTime = (TextView) findViewById(R.id.startTime);
        stopTime = (TextView) findViewById(R.id.stopTime);

        //绑定点击监听
        btnStart.setOnClickListener(this);
        btnStop.setOnClickListener(this);

        ShowSeekBar();
    }

    @Override
    public void onClick(View v) {
        //显示指定  intent所指的对象是个   service
        if(v.getId() == R.id.startMusic){
            switch (flag) {
                case STATE_PLAY:
                    //开始服务
                    pause();
                    break;
                case STATE_PAUSE:
                    //停止服务
                    play();
                    break;
            }
        }else {
            stop();
        }

    }

    private void stop() {
        Intent intent = new Intent();
        intent.setAction("com.app.media.MUSIC_SERVICE");
        intent.setPackage(getPackageName());
        stopService(intent);
    }

    private void ShowSeekBar() {
        mSeekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                if (fromUser) {
                    Intent intent = new Intent();
                    intent.setAction("com.app.media.MUSIC_SERVICE");
                    intent.setPackage(getPackageName());
                    intent.putExtra("op", PROGRESS_CHANGE);
                    intent.putExtra("progress", progress);
                    startService(intent);
                }
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });
    }

    /**
     * 播放时间转换
     */
    public String toTime(int time) {

        time /= 1000;
        int minute = time / 60;
        int second = time % 60;
        minute %= 60;
        return String.format("%02d:%02d", minute, second);
    }

    /**
     * 在播放布局里先把播放按钮先删除并用background设置为透明。然后在代码添加按钮
     */
    public void play() {
        flag = PLAY;
        btnStart.setImageResource(R.drawable.player_btn_player_pause);
        Intent intent = new Intent();
        intent.setAction("com.app.media.MUSIC_SERVICE");
        intent.setPackage(getPackageName());
        intent.putExtra("op", PLAY);// 向服务传递数据
        startService(intent);

    }
    /**
     * 暂停
     */
    public void pause() {
        flag = PAUSE;
        btnStart.setImageResource(R.drawable.player_btn_player_play);
        Intent intent = new Intent();
        intent.setAction("com.app.media.MUSIC_SERVICE");
        intent.setPackage(getPackageName());
        intent.putExtra("op", PAUSE);
        startService(intent);

    }

    class MyBroadcastReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            int duration = intent.getIntExtra("duration",-1);
            int progress = intent.getIntExtra("seekBarProgress",-1);
            if(duration != -1){
                mSeekBar.setMax(duration);
                stopTime.setText(toTime(duration));
            }
            if(progress != -1){
                mSeekBar.setProgress(progress);
                startTime.setText(toTime(progress));
            }

        }
    }
}

在MainActivity中，我把play、pause、和改变进度条的事件传到service中，然后在service中实现；而且在service中把音频的总长度和当前播放长度传到主线程中，从而实现了以上功能

看Service

package com.example.bear.test;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.util.Log;

/**
 * Created by Bear on 2015/8/7.
 */
public class MusicService extends Service{

    //为日志工具设置标签
    private static String TAG = "MusicService";
    //定义音乐播放器变量
    private MediaPlayer mPlayer;
    private final int mSeekBarLen = 2000;
    private SeekBarThread seekBarThread;
    private static final int MUSIC_PLAY = 1;
    private static final int MUSIC_PAUSE = 2;
    private static final int MUSIC_STOP = 3;
    private static final int PROGRESS_CHANGE = 4;

    //该服务不存在需要被创建时被调用，不管startService()还是bindService()都会启动时调用该方法
    @Override
    public void onCreate() {
        mPlayer = MediaPlayer.create(getApplicationContext(), R.raw.music);
        //设置可以重复播放
        mPlayer.setLooping(true);

        super.onCreate();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        startBarThread();
        int op = intent.getIntExtra("op",-1);
        if(op != -1) {
            switch (op) {
                case MUSIC_PLAY:
                    if (!mPlayer.isPlaying()) {
                        mPlayer.start();
                    }
                    break;
                case MUSIC_PAUSE:
                    if (mPlayer.isPlaying()) {
                        mPlayer.pause();
                    }
                    break;
                case PROGRESS_CHANGE:
                    int currentTime = intent.getExtras().getInt("progress");
                    mPlayer.seekTo(currentTime);
                    break;
            }
        }
        return super.onStartCommand(intent, flags, startId);
    }


    @Override
    public void onDestroy() {
        mPlayer.stop();
        if (seekBarThread != null) {
            seekBarThread.off();
        }
        super.onDestroy();
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    private void startBarThread() {
        if (seekBarThread != null) {
            seekBarThread.off();
        }
        seekBarThread = new SeekBarThread();
        seekBarThread.start();
    }

    class SeekBarThread extends Thread {
        boolean flag = true;
        int duration = 1;
        int seekBarProgress = 0;
        int position = 0;
        public SeekBarThread() {};

        public void off() {
            flag = false;
        }
        public void run() {
            flag = true;
            if(mPlayer!=null) {
                duration = mPlayer.getDuration();
            }

            seekBarProgress = 0;
            position = 0;
            while (flag) {
                if(mPlayer!=null) {
                    position = mPlayer.getCurrentPosition();
                }
                seekBarProgress =position;
//                Log.e("TEST",position+"");
//                Log.e("TEST",seekBarProgress+"");
//                Log.e("TEST",duration+"");
                Intent intent = new Intent();
                intent.putExtra("seekBarProgress",seekBarProgress);
                intent.putExtra("duration",duration);
                //设置广播的类型
                intent.setAction("com.bear.app");
                sendBroadcast(intent);


                try {
                    sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }// while
    }

}

在service中，实现一个新的线程来实现音频时间的处理，从而减少主线程的时间。我们都知道，主线程时间不能够长，长时间的操作应该放到其他线程中。

注意：感觉说了这么多，还是没什么用，看代码才是重点。

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