Android实现播放器功能

package com.example.yzj.android_7_27;

import android.content.ContentResolver;
import android.content.DialogInterface;
import android.database.Cursor;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Handler;
import android.os.Message;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;

import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class MusicActivity extends AppCompatActivity implements MediaPlayer.OnBufferingUpdateListener, MediaPlayer.OnPreparedListener {
    private SeekBar sb;
    private Button btn_play;
    private Button btn_pause;
    private Button btn_stop;
    private Button btn_last;
    private Button btn_next;
    private MediaPlayer mediaPlayer;
    private BtnListener btnlistener;
    private MyHandler myHandler;
    private Timer timer;
    private Thread thread;
    private boolean pause;
    private ContentResolver resolver;
    private List<MusicInfo> data;
    private int currentMusic;
    private int currentPosition;
    private boolean stop;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_music);
        init();
        setListener();
        setMediaPlayer();
    }

    private void setListener() {
        btn_play.setOnClickListener(btnlistener);
        btn_pause.setOnClickListener(btnlistener);
        btn_stop.setOnClickListener(btnlistener);
        btn_last.setOnClickListener(btnlistener);
        btn_next.setOnClickListener(btnlistener);
    }

    public void setMediaPlayer() {
        mediaPlayer = new MediaPlayer();
        try {
            mediaPlayer.setDataSource(data.get(currentMusic).getStrMusicPath());
            mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
            mediaPlayer.setOnBufferingUpdateListener(this);
            mediaPlayer.setOnPreparedListener(this);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void start()  {
        if (pause) {
            float i=(float)sb.getProgress()/(float)sb.getMax();
            float j=mediaPlayer.getDuration();
            float n=i*j;
            int m=(int)n;
            mediaPlayer.seekTo(m);
            mediaPlayer.start();
        } else if (!mediaPlayer.isPlaying()) {
                mediaPlayer.prepareAsync();
            if(stop){
                mediaPlayer.seekTo(0);
            }
        }
        pause = false;
        stop=false;
        if (!thread.isAlive()) {
           try{
               thread.start();
           }
           catch (Exception e) {
               thread=new Thread(timer);
               thread.start();
           }
        }
    }

    public void pause() {
        if (mediaPlayer != null) {
            mediaPlayer.pause();
        }
        pause = true;
    }

    public void stop() {
        mediaPlayer.stop();
        stop=true;
    }

    private void init() {
        sb = (SeekBar) findViewById(R.id.sb);
        sb.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                currentPosition=sb.getProgress();
            }
        });
        btn_play = (Button) findViewById(R.id.btn_play);
        btn_pause = (Button) findViewById(R.id.btn_pause);
        btn_stop = (Button) findViewById(R.id.btn_stop);
        btn_last = (Button) findViewById(R.id.btn_last);
        btn_next = (Button) findViewById(R.id.btn_next);
        data=new ArrayList<>();
        getMusicInfo();
        btnlistener = new BtnListener();
        myHandler = new MyHandler();
        timer = new Timer();
        thread = new Thread(timer);
    }

    @Override
    public void onBufferingUpdate(MediaPlayer mp, int percent) {

    }

    @Override
    public void onPrepared(MediaPlayer mp) {
        float i=(float)currentPosition/(float)sb.getMax();
        float j=mediaPlayer.getDuration();
        float n=i*j;
        int m=(int)n;
        mediaPlayer.seekTo(m);
        mediaPlayer.start();
    }

    private class BtnListener implements View.OnClickListener {

        @Override
        public void onClick(View v) {
            switch (v.getId()) {
                case R.id.btn_play:
                    start();
                    break;
                case R.id.btn_pause:
                    pause();
                    break;
                case R.id.btn_stop:
                    stop();
                    break;
                case R.id.btn_last:
                    currentMusic--;
                    if (currentMusic==-1) {
                        currentMusic=data.size()-1;
                    }
                    if (pause) {
                        pause = false;
                    }
                   try{

　　　　　　　　　　　　　　thread.start();

　　　　　　　　　　　　　　}
　　　　　　　　　　　　catch(Exception e){
　　　　　　　　　　　　　　　　Log.v("msg","线程已经启动");
　　　　　　　　　　　　　　}

                    mediaPlayer.reset();
                    try {
                        mediaPlayer.setDataSource(data.get(currentMusic).getStrMusicPath());
                        mediaPlayer.prepareAsync();

                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    thread.interrupt();
                    break;
                case R.id.btn_next:
                    currentMusic++;
                    if (pause) {
                        pause = false;
                    }

　　　　　　　　　　　　 try{

　　　　　　　　　　　　　　thread.start();

　　　　　　　　　　　　　　}
　　　　　　　　　　　　catch(Exception e){
　　　　　　　　　　　　　　　　Log.v("msg","线程已经启动");
　　　　　　　　　　　　　　}

                    mediaPlayer.reset();
                    if(currentMusic>data.size()-1){
                        currentMusic=0;
                    }
                    try {
                        mediaPlayer.setDataSource(data.get(currentMusic).getStrMusicPath());
                        mediaPlayer.prepareAsync();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    thread.interrupt();
                    break;
            }
        }
    }

    private class MyHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if (msg.what == 0x123) {
                int position = mediaPlayer.getCurrentPosition();
                int duration = mediaPlayer.getDuration();
                if (duration > 0) {
                    long pos = sb.getMax() * position / duration;
                    sb.setProgress((int) pos);
                }
            }
        }
    }

    private class Timer implements Runnable {
        @Override
        public void run() {
            while (!pause&&!stop) {
                try {
                    Message msg = myHandler.obtainMessage();
                    msg.what = 0x123;
                    msg.sendToTarget();
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private void getMusicInfo() {
        resolver = getContentResolver();
        Cursor musicCursor = resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null,
                MediaStore.Audio.Media.DEFAULT_SORT_ORDER);
        //获取歌曲时间
        while (musicCursor.moveToNext()) {
            MusicInfo musicInfo = new MusicInfo();
            int duration = musicCursor.getInt(musicCursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DURATION));
            String strMusicName = musicCursor.getString(musicCursor.getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE));
            String strMusicPath = musicCursor.getString(musicCursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DATA));
            musicInfo.setnMusicTime(duration);
            musicInfo.setStrMusicName(strMusicName);
            musicInfo.setStrMusicPath(strMusicPath);
            data.add(musicInfo);
        }
    }
}

package com.example.yzj.android_7_27;

import java.io.Serializable;

/**
 * Created by YZJ on 2016/7/27.
 */
public class MusicInfo implements Serializable {
    private String strMusicName;
    private int nMusicTime;
    private String strMusicPath;

    public String getStrMusicName() {
        return strMusicName;
    }

    public void setStrMusicName(String strMusicName) {
        this.strMusicName = strMusicName;
    }

    public int getnMusicTime() {
        return nMusicTime;
    }

    public void setnMusicTime(int nMusicTime) {
        this.nMusicTime = nMusicTime;
    }

    public String getStrMusicPath() {
        return strMusicPath;
    }

    public void setStrMusicPath(String strMusicPath) {
        this.strMusicPath = strMusicPath;
    }
}