Android开发---MediaPlayer简单音乐播放器

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/zhaokx3/article/details/53432718

Android开发—MediaPlayer简单音乐播放器

功能介绍

• 实现一个简单的播放器，类似网易云音乐形式，功能包括：

  1. 播放、暂停，停止，退出功能；
  2. 后台播放功能；
  3. 进度条显示播放进度、拖动进度条改变进度功能；
  4. 播放时图片旋转，显示当前播放时间功能；

• 界面样式
  

功能实现

1. MediaPlayer的实现

• MediaPlayer常用方法介绍
• 
  MediaPlayer的实现包括初始化MediaPlayer，MediaPlayer的功能实现，包括播放、暂停、停止、离开等，具体细节如下：
  MediaPlayer的初始化包括读取一个MP3格式的音乐文件并设置其为循环播放：

public void initMediaPlayer() {
        try {
            //String file_path = "/storage/0123-4567/K.Will-Melt.mp3";
            String file_path = Environment.getExternalStorageDirectory().getAbsolutePath()+"/K.Will-Melt.mp3";
            //String file_path = "/data/K.Will-Melt.mp3";
            mediaPlayer.setDataSource(file_path);
            mediaPlayer.prepare();
            mediaPlayer.setLooping(true);  // 设置循环播放
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

播放/暂停功能的实现放在Play/Pause按钮中，所以需要二选一判断MediaPlayer的状态来设置音乐的播放与暂停：

public void playOrPause() {
        flag++;
        if (flag >= 1000) flag = 2;

        which = "pause";

        if(mediaPlayer.isPlaying()){
            mediaPlayer.pause();
            animator.pause();
        } else {
            mediaPlayer.start();

类似的，停止功能的实现放在Stop按钮中，用于停止音乐并将其置于初始态即“00:00”：

public void stop() {
        which = "stop";
        animator.pause();
        if(mediaPlayer != null) {
            mediaPlayer.pause();
            mediaPlayer.stop();
            try {
                mediaPlayer.prepare();
                mediaPlayer.seekTo(0);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

说明：由于调用stop()后，有时音乐并没有马上停止，所以我额外加了一个pause()来确保音乐停止播放。

同样，离开功能实现放在了Quit按钮中，主要实现整个应用的退出，具体应包括解绑Service，结束Activity等等：

private void quit() {
        musicService.animator.end();
        handler.removeCallbacks(runnable);
        unbindService(sc);
        try {
            finish();
            System.exit(0);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

2. Service的应用

• Service即“服务” ，它与Activity属于同一等级的应用程序组件，都代表可执行的程序。不同的是Activity拥有前台运行的用户界面，而Service不能自己运行，需要通过某个Activity或者其他Context对象来调用。Service在后台运行，它不能与用户直接进行交互。在默认情况下，Service运行在应用程序进程的主线程之中。可以通过Context.startService()和Context.bindService()两种方式来启动Service。
• 通过Service可以使程序在退出之后仍然能够对事件或用户操作做出反应，或者在后台继续运行某些程序功能。
• Android赋予Services比处于不活动（inactivity）的Activities更高的优先级，所以它们的进程不会轻易被系统杀掉。
• Activity与Service的交互示意图为：
  
  有了以上知识的积累，基本可以实现Service的必要部分,如下：
  1.新建一个继承于Service的MusicService类

public class MusicService extends Service {
    public final IBinder binder = new MyBinder();
    public class MyBinder extends Binder {
        MusicService getService() {
            return MusicService.this;
        }
    }

/**
     * onBind 是 Service 的虚方法，因此我们不得不实现它。
     * 返回 null，表示客服端不能建立到此服务的连接。
     */
    @Override
    public IBinder onBind(Intent intent) {
        return binder;
    }

2.并在Activity中绑定MusicService：

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getOverflowMenu();
        setContentView(R.layout.activity_main);

        bindServiceConnection();
        musicService = new MusicService();

private ServiceConnection sc = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            musicService = ((MusicService.MyBinder) iBinder).getService();
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            musicService = null;
        }
    };

    private void bindServiceConnection() {
        Intent intent = new Intent(this, MusicService.class);
        startService(intent);
        bindService(intent, sc, this.BIND_AUTO_CREATE);
    }

3. Handler更新UI界面

通过Handler来管理UI，最要需要用到post和postDelayed两个函数：
1. post(Runnable r)
将r加入到消息队列中（其实就是利用UI主线程执行一段代码，这样可以随时在其他线程中调整控件）
2. postDelayed(Runnabled r,long delayMillis)
将r加入到消息队列中，并在指定时间之后触发（单位为毫秒）
所以，为了实现音乐的播放显示等功能，需要重写Runnable的run函数，具体实现如下：

public Handler handler = new Handler();
    public Runnable runnable = new Runnable() {
        @Override
        public void run() {

            isPlay.setOnClickListener(new myOnClickListener());
            stop.setOnClickListener(new myOnClickListener());
            quit.setOnClickListener(new myOnClickListener());

            if(musicService.mediaPlayer.isPlaying()) {
                stateText.setText("Playing");
            } else {
                if (musicService.which.equals("stop"))  {
                    stateText.setText("Stop");
                } else if (musicService.which.equals("pause")){
                    stateText.setText("Pause");
                }
            }
            playingTime.setText(time.format(musicService.mediaPlayer.getCurrentPosition()));
            totalTime.setText(time.format(musicService.mediaPlayer.getDuration()));
            seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition());
            seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
                @Override
                public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                    if (fromUser) {
                        musicService.mediaPlayer.seekTo(seekBar.getProgress());
                    }
                }

                @Override
                public void onStartTrackingTouch(SeekBar seekBar) {

                }

                @Override
                public void onStopTrackingTouch(SeekBar seekBar) {

                }
            });
            handler.postDelayed(runnable, 100);
        }
    };

4. 实现图片的旋转

图片的动画效果实现需要用到ObjectAnimator类，ObjectAnimator类可用于图片的平移、旋转、缩放等动画，此处我们只需要用到其旋转功能，具体实现如下：

public  void AnimatorAction() {
        if (mediaPlayer.isPlaying()) {
            animator.setDuration(5000);
            animator.setInterpolator(new LinearInterpolator()); // 均速旋转
            animator.setRepeatCount(ValueAnimator.INFINITE); // 无限循环
            animator.setRepeatMode(ValueAnimator.INFINITE);
            animator.start();
        }
    }

说明：animator是ObjectAnimator的一个实例对象，setDuration为5000表示旋转一周需要的时间为5000，所以可用来设置旋转的速度；同时设置为无线循环模式，并且添加一个插值器达到匀速旋转的目的，最后调用pause()等函数动态控制动画状态，如下：

5. 进度条SeekBar功能实现

SeekBar的功能包括显示歌曲播放进度以及拖动SeekBar至任意位置来改变播放进度，由于android已经封装好了这些函数，所以直接调用就好了，也比较好理解，具体实现如下：

seekBar = (SeekBar) findViewById(R.id.seekBar);
        seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition());
        seekBar.setMax(musicService.mediaPlayer.getDuration());

seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition());
            seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
                @Override
                public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                    if (fromUser) {
                        musicService.mediaPlayer.seekTo(seekBar.getProgress());
                    }
                }

                @Override
                public void onStartTrackingTouch(SeekBar seekBar) {

                }

                @Override
                public void onStopTrackingTouch(SeekBar seekBar) {

                }
            });

6. 动态权限申请

参见Android动态权限申请

7. 判断程序是否处于后台

由于音乐需要支持后台播放，再次由后台进入前台会对前台的事件功能等产生影响，所以可以添加一个后台判断函数，并添加一个标志来记录应用是否进入后台。

private boolean isApplicationBroughtToBackground() {
        ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(1);
        if (!tasks.isEmpty()) {
            ComponentName topActivity = tasks.get(0).topActivity;
            if (!topActivity.getPackageName().equals(getPackageName())) {
                return true;
            }
        }
        return false;
    }

附上MainActivity和Service部分的完整代码

• MainActivity.java

package com.example.kx.temp;

import android.Manifest;
import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.app.Activity;
import android.app.ActivityManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.content.pm.PackageManager;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Environment;
import android.os.Handler;
import android.os.IBinder;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.animation.LinearInterpolator;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.TextView;

import com.google.android.gms.appindexing.Action;
import com.google.android.gms.appindexing.AppIndex;
import com.google.android.gms.common.api.GoogleApiClient;

import java.lang.reflect.Field;
import java.text.SimpleDateFormat;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private Button isPlay;
    private Button stop;
    private Button quit;

    private ImageView coverImage;
    // private ObjectAnimator animator;
    private int flag = 0;

    private TextView totalTime;
    private TextView playingTime;
    private TextView stateText;

    private SeekBar seekBar;
    private TextView pathText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getOverflowMenu();
        setContentView(R.layout.activity_main);

        bindServiceConnection();
        musicService = new MusicService();

        coverImage = (ImageView) findViewById(R.id.coverImage);
        musicService.animator = ObjectAnimator.ofFloat(coverImage, "rotation", 0, 359);

        isPlay = (Button) findViewById(R.id.isPlayButton);
        isPlay.setOnClickListener(new myOnClickListener());

        stop = (Button) findViewById(R.id.stopButton);
        stop.setOnClickListener(new myOnClickListener());

        quit = (Button) findViewById(R.id.quitButton);
        quit.setOnClickListener(new myOnClickListener());

        seekBar = (SeekBar) findViewById(R.id.seekBar);
        seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition());
        seekBar.setMax(musicService.mediaPlayer.getDuration());

        totalTime = (TextView) findViewById(R.id.totalTime);
        playingTime = (TextView) findViewById(R.id.playingTime);
        stateText = (TextView) findViewById(R.id.stateText);

        pathText = (TextView) findViewById(R.id.pathText);
        String sdcard = "音乐文件的路径为：" + Environment.getExternalStorageDirectory().getAbsolutePath().toString()+"/K.Will-Melt.mp3";
        pathText.setText(sdcard);

    }

    private MusicService musicService;
    private SimpleDateFormat time = new SimpleDateFormat("mm:ss");
    private ServiceConnection sc = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            musicService = ((MusicService.MyBinder) iBinder).getService();
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            musicService = null;
        }
    };

    private void bindServiceConnection() {
        Intent intent = new Intent(this, MusicService.class);
        startService(intent);
        bindService(intent, sc, this.BIND_AUTO_CREATE);
    }

    public Handler handler = new Handler();
    public Runnable runnable = new Runnable() {
        @Override
        public void run() {

            isPlay.setOnClickListener(new myOnClickListener());
            stop.setOnClickListener(new myOnClickListener());
            quit.setOnClickListener(new myOnClickListener());

            if(musicService.mediaPlayer.isPlaying()) {
                stateText.setText("Playing");
            } else {
                if (musicService.which.equals("stop"))  {
                    stateText.setText("Stop");
                } else if (musicService.which.equals("pause")){
                    stateText.setText("Pause");
                }
            }
            playingTime.setText(time.format(musicService.mediaPlayer.getCurrentPosition()));
            totalTime.setText(time.format(musicService.mediaPlayer.getDuration()));
            seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition());
            seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
                @Override
                public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                    if (fromUser) {
                        musicService.mediaPlayer.seekTo(seekBar.getProgress());
                    }
                }

                @Override
                public void onStartTrackingTouch(SeekBar seekBar) {

                }

                @Override
                public void onStopTrackingTouch(SeekBar seekBar) {

                }
            });
            handler.postDelayed(runnable, 100);
        }
    };

    @Override
    public void onPause(){
        super.onPause();
        if(isApplicationBroughtToBackground()) {
            musicService.isReturnTo = 1;
            Log.e("b","后台中");
        }
    }

    @Override
    public void onRestart() {
        super.onRestart();
        musicService.isReturnTo = 1;
    }

    @Override
    protected void onResume() {

        musicService.AnimatorAction();
        verifyStoragePermissions(this);

        if(musicService.mediaPlayer.isPlaying()) {
            stateText.setText("Playing");
        } else {
            if (musicService.which.equals("stop"))  {
                stateText.setText("Stop");
            } else if (musicService.which.equals("pause")){
                stateText.setText("Pause");
            }
        }
        seekBar.setProgress(musicService.mediaPlayer.getCurrentPosition());
        seekBar.setMax(musicService.mediaPlayer.getDuration());
        handler.post(runnable);
        super.onResume();
        Log.d("hint", "handler post runnable");
    }

    private class myOnClickListener implements View.OnClickListener {
        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.isPlayButton:
                    changePlay();
                    musicService.playOrPause();
                    break;
                case R.id.stopButton:
                    musicService.stop();
                    changeStop();
                    break;
                case R.id.quitButton:
                    quit();
                    break;
                default:
                    break;
            }
        }
    }

    private void changePlay() {

        if(musicService.mediaPlayer.isPlaying()){
            stateText.setText("Pause");
            isPlay.setText("PLAY");
            //animator.pause();
        } else {
            stateText.setText("Playing");
            isPlay.setText("PAUSE");

        }
    }

    private void changeStop() {
        stateText.setText("Stop");
        seekBar.setProgress(0);
        //animator.pause();
    }

    private void quit() {
        musicService.animator.end();
        handler.removeCallbacks(runnable);
        unbindService(sc);
        try {
            finish();
            System.exit(0);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onStop() {
        super.onStop();
    }
    @Override
    public void onDestroy() {
        unbindService(sc);
        super.onDestroy();
    }

    //这里是在登录界面label上右上角添加三个点，里面可添加其他功能
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.settings, menu);
        return true;
    }

    private void getOverflowMenu() {
        try {
            ViewConfiguration config = ViewConfiguration.get(this);
            Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");
            if (menuKeyField != null) {
                menuKeyField.setAccessible(true);
                menuKeyField.setBoolean(config, false);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private boolean isApplicationBroughtToBackground() {
        ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(1);
        if (!tasks.isEmpty()) {
            ComponentName topActivity = tasks.get(0).topActivity;
            if (!topActivity.getPackageName().equals(getPackageName())) {
                return true;
            }
        }
        return false;
    }

    // Storage Permissions
    private static final int REQUEST_EXTERNAL_STORAGE = 1;
    private static String[] PERMISSIONS_STORAGE = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };

    /**
     * Checks if the app has permission to write to device storage
     *
     * If the app does not has permission then the user will be prompted to grant permissions
     *
     * @param activity
     */
    public static void verifyStoragePermissions(Activity activity) {
        // Check if we have write permission
        int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);

        if (permission != PackageManager.PERMISSION_GRANTED) {
            // We don't have permission so prompt the user
            ActivityCompat.requestPermissions(
                    activity,
                    PERMISSIONS_STORAGE,
                    REQUEST_EXTERNAL_STORAGE
            );
        }
    }
}

• Service

package com.example.kx.temp;

import android.Manifest;
import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.app.Activity;
import android.app.ActivityManager;
import android.app.Service;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.media.MediaPlayer;
import android.os.Binder;
import android.os.Environment;
import android.os.IBinder;
import android.support.v4.app.ActivityCompat;
import android.util.Log;
import android.view.animation.LinearInterpolator;

import java.io.File;
import java.util.List;

/**
 * Created by kx on 2016/11/3.
 */
public class MusicService extends Service {
    public final IBinder binder = new MyBinder();
    public class MyBinder extends Binder {
        MusicService getService() {
            return MusicService.this;
        }
    }

    public static int isReturnTo = 0;
    public static MediaPlayer mediaPlayer = new MediaPlayer();
    public static ObjectAnimator animator;
    public MusicService() {
        initMediaPlayer();

    }

    public void initMediaPlayer() {
        try {
            //String file_path = "/storage/0123-4567/K.Will-Melt.mp3";
            String file_path = Environment.getExternalStorageDirectory().getAbsolutePath()+"/K.Will-Melt.mp3";
            //String file_path = "/data/K.Will-Melt.mp3";
            mediaPlayer.setDataSource(file_path);
            mediaPlayer.prepare();
            mediaPlayer.setLooping(true);  // 设置循环播放
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public  void AnimatorAction() {
        if (mediaPlayer.isPlaying()) {
            animator.setDuration(5000);
            animator.setInterpolator(new LinearInterpolator()); // 均速旋转
            animator.setRepeatCount(ValueAnimator.INFINITE); // 无限循环
            animator.setRepeatMode(ValueAnimator.INFINITE);
            animator.start();
        }
    }
    private int flag = 0;
    public static String which = "";
    public void playOrPause() {
        flag++;
        if (flag >= 1000) flag = 2;

        which = "pause";

        if(mediaPlayer.isPlaying()){
            mediaPlayer.pause();
            animator.pause();
        } else {
            mediaPlayer.start();

            if ((flag == 1) || (isReturnTo == 1)) {
                animator.setDuration(5000);
                animator.setInterpolator(new LinearInterpolator()); // 均速旋转
                animator.setRepeatCount(ValueAnimator.INFINITE); // 无限循环
                animator.setRepeatMode(ValueAnimator.INFINITE);
                animator.start();
            } else {
                animator.resume();
            }
        }
    }
    public void stop() {
        which = "stop";
        animator.pause();
        if(mediaPlayer != null) {
            mediaPlayer.pause();
            mediaPlayer.stop();
            try {
                mediaPlayer.prepare();
                mediaPlayer.seekTo(0);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }


    @Override
    public void onDestroy() {
        mediaPlayer.stop();
        mediaPlayer.release();
        super.onDestroy();
    }
    /**
     * onBind 是 Service 的虚方法，因此我们不得不实现它。
     * 返回 null，表示客服端不能建立到此服务的连接。
     */
    @Override
    public IBinder onBind(Intent intent) {
        return binder;
    }

}

至此，基于MediaPlayer的简单音乐播放器基本可以实现，如有错误或疑问，烦请指出。

完整项目参见github，如君心情好，别忘了加心哦。。。
祝君好心情～