Android音乐播放器——甩动切歌

Android音乐播放器——甩动切歌

前言: 使用MediaPlayer实现Android的音乐播放器，能够播放、暂停、停止歌曲，控制播放上一首，下一首歌曲；同时可以使用感应器来感应甩动动作，然后完成切换歌曲的操作。

1. 第一步

布局文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_margin="20dp"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageButton
            android:id="@+id/previous_ib"
            android:src="@mipmap/previous_track"
            android:background="@null"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <ImageButton
            android:id="@+id/play_ib"
            android:src="@mipmap/bofang"
            android:background="@null"
            android:layout_marginLeft="10dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <ImageButton
            android:id="@+id/pause_ib"
            android:src="@mipmap/pause"
            android:background="@null"
            android:layout_marginLeft="10dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <ImageButton
            android:id="@+id/stop_ib"
            android:src="@mipmap/stop"
            android:background="@null"
            android:layout_marginLeft="10dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <ImageButton
            android:id="@+id/next_ib"
            android:src="@mipmap/next_track"
            android:background="@null"
            android:layout_marginLeft="10dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

    </LinearLayout>

    <LinearLayout
        android:gravity="bottom|right"
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageButton
            android:id="@+id/volume_plus_ib"
            android:src="@mipmap/volume_increase"
            android:background="@null"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <ImageButton
            android:id="@+id/volume_decrease_ib"
            android:src="@mipmap/volume_decrease"
            android:background="@null"
            android:layout_marginTop="20dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

    </LinearLayout>

</RelativeLayout>

布局文件里添加了一写控制音乐的组件，包括播放、暂停、停止、上一首、下一首、音量加、音量减的按钮。

2. 第二步

编写甩动手机时的监听器，ShakeListener.java

public class ShakeListener implements SensorEventListener {

    //速度阈值，当摇晃速度达到这值后产生作用
    private static final int SPEED_SHRESHOLD = 4000;
    //两次检测的时间间隔
    private static final int UPTATE_INTERVAL_TIME = 70;

    //传感器管理器
    private SensorManager sensorManager;
    //传感器
    private Sensor sensor;
    //重力感应监听器
    private OnShakeListener onShakeListener;
    //上下文
    private Context context;
    //手机上一个位置时重力感应坐标
    private float lastX;
    private float lastY;
    private float lastZ;

    //上次检测时间
    private long lastUpdateTime;
    //构造器
    public ShakeListener(Context c) {
        //获得监听对象
        context = c;
        start();
    }

    //开始
    public void start() {
        //获得传感器管理器
        sensorManager = (SensorManager)context.getSystemService(Context.SENSOR_SERVICE);
        if(sensorManager != null) {
            //获得重力传感器
            sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        }
        //注册
        if(sensor != null) {
            sensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_GAME);
        }

    }

    //停止检测
    public void stop() {
        sensorManager.unregisterListener(this);
    }

    //设置重力感应监听器
    public void setOnShakeListener(OnShakeListener listener) {
        onShakeListener = listener;
    }

    @Override
    public void onSensorChanged(SensorEvent sensorEvent) {
        //现在检测时间
        long currentUpdateTime = System.currentTimeMillis();
        //两次检测的时间间隔
        long timeInterval = currentUpdateTime - lastUpdateTime;
        //判断是否达到了检测时间间隔
        if(timeInterval < UPTATE_INTERVAL_TIME)
            return;
        //现在的时间变成last时间
        lastUpdateTime = currentUpdateTime;

        //获得x,y,z坐标
        float x = sensorEvent.values[0];
        float y = sensorEvent.values[1];
        float z = sensorEvent.values[2];

        //获得x,y,z的变化值
        float deltaX = x - lastX;
        float deltaY = y - lastY;
        float deltaZ = z - lastZ;

        //将现在的坐标变成last坐标
        lastX = x;
        lastY = y;
        lastZ = z;

        double speed = Math.sqrt(deltaX*deltaX + deltaY*deltaY + deltaZ*deltaZ)/timeInterval * 10000;
        //达到速度阀值，发出提示
        if(speed >= SPEED_SHRESHOLD)
            onShakeListener.onShake();
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int i) {

    }

    //摇晃监听接口
    public interface OnShakeListener {
        public void onShake();
    }

3. 编写Activity——Music2Activity.java

public class Music2Activity extends AppCompatActivity implements View.OnClickListener, MediaPlayer.OnCompletionListener {

    private ImageButton play,pause,stop,volume_plus,volume_decrease,next,previous;

    private MediaPlayer mediaPlayer = new MediaPlayer();

    private AudioManager audioManager;

    int maxVolume,currentVolume;

    String[] musicList = new String[]{"/sdcard/music1.mp3",
            "/sdcard/music2.mp3","/sdcard/music3.mp3","/sdcard/music4.mp3"};
    int currentMusic = 0;

    private ShakeListener shakeListener;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_music2);

        audioManager = (AudioManager) getSystemService(Service.AUDIO_SERVICE);

        initView();

        play.setOnClickListener(Music2Activity.this);
        pause.setOnClickListener(Music2Activity.this);
        stop.setOnClickListener(Music2Activity.this);
        volume_plus.setOnClickListener(Music2Activity.this);
        volume_decrease.setOnClickListener(Music2Activity.this);
        next.setOnClickListener(Music2Activity.this);
        previous.setOnClickListener(Music2Activity.this);

        //监听器，自动播放下一首歌曲
        mediaPlayer.setOnCompletionListener(Music2Activity.this);

        if (ContextCompat.checkSelfPermission(Music2Activity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)!=
                PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(Music2Activity.this,
                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},1);
        }else {
            initMediaPlayer();//初始化mediaplayer
        }

        shakeListener = new ShakeListener(Music2Activity.this);
        shakeListener.setOnShakeListener(new ShakeListener.OnShakeListener() {
            @Override
            public void onShake() {
                //对手机摇晃后的处理（如换歌曲，换图片……）
                currentMusic++;
                if (currentMusic == musicList.length){
                    currentMusic = 0;
                }
                changeMusic();
            }
        });
    }

    private void initView() {
        play = (ImageButton) findViewById(R.id.play_ib);
        pause = (ImageButton) findViewById(R.id.pause_ib);
        stop = (ImageButton) findViewById(R.id.stop_ib);
        volume_plus = (ImageButton) findViewById(R.id.volume_plus_ib);
        volume_decrease = (ImageButton) findViewById(R.id.volume_decrease_ib);
        next = (ImageButton) findViewById(R.id.next_ib);
        previous = (ImageButton) findViewById(R.id.previous_ib);

    }

    private void initMediaPlayer() {
        try {
            mediaPlayer.setDataSource(musicList[0]);//指定音频文件的路径
            mediaPlayer.prepare();//让mediaplayer进入准备状态
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case 1:
                if (grantResults.length > 0 &&
                        grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    initMediaPlayer();
                } else {
                    Toast.makeText(Music2Activity.this,"denied access",Toast.LENGTH_SHORT).show();
                    finish();
                }
                break;
            default:
        }
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.play_ib:
                if (!mediaPlayer.isPlaying()) {
                    mediaPlayer.start();//开始播放
                }
                break;
            case R.id.pause_ib:
                if (mediaPlayer.isPlaying()) {
                    mediaPlayer.pause();//暂停播放
                }
                break;
            case R.id.stop_ib:
                Toast.makeText(Music2Activity.this,"停止播放",Toast.LENGTH_SHORT).show();
                if (mediaPlayer.isPlaying()) {
                    mediaPlayer.reset();//停止播放
                    initMediaPlayer();
                }
                break;
            //音量加
            case R.id.volume_plus_ib:
                maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
                audioManager.adjustStreamVolume(AudioManager.STREAM_MUSIC,AudioManager.ADJUST_RAISE,AudioManager.FLAG_SHOW_UI);
                currentVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
                Toast.makeText(Music2Activity.this,"音量增加,最大音量是：" + maxVolume + "，当前音量" + currentVolume,
                        Toast.LENGTH_SHORT).show();
                break;
            //音量减
            case R.id.volume_decrease_ib:
                maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
                audioManager.adjustStreamVolume(AudioManager.STREAM_MUSIC,AudioManager.ADJUST_LOWER,AudioManager.FLAG_SHOW_UI);
                currentVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
                Toast.makeText(Music2Activity.this,"音量减小,最大音量是：" + maxVolume + "，当前音量" + currentVolume,
                        Toast.LENGTH_SHORT).show();
                break;
            //下一首
            case R.id.next_ib:
                currentMusic++;
                if (currentMusic == musicList.length){
                    currentMusic = 0;
                }
                changeMusic();
                Toast.makeText(Music2Activity.this,"下一首:"+musicList[currentMusic],Toast.LENGTH_SHORT).show();
                break;
            //上一首
            case R.id.previous_ib:
                currentMusic--;
                if (currentMusic == -1) {
                    currentMusic = musicList.length-1;
                }
                changeMusic();
                Toast.makeText(Music2Activity.this,"上一首:"+musicList[currentMusic],Toast.LENGTH_SHORT).show();
                break;
            default:
                break;
        }
    }

    private void changeMusic() {
        //重置
        mediaPlayer.reset();

        try {
            //设置音乐文件来源
            mediaPlayer.setDataSource(musicList[currentMusic]);
            //准备（缓冲文件）
            mediaPlayer.prepare();
            //播放开始
            mediaPlayer.start();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


    @Override
    public void onCompletion(MediaPlayer mediaPlayer) {
        currentMusic++;
        if (currentMusic == musicList.length){
            currentMusic = 0;
        }
        changeMusic();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mediaPlayer != null) {
            mediaPlayer.stop();
            mediaPlayer.release();
        }
    }
}

前言: 这样我们就可以通过甩动手机来完成切换歌曲的任务了。

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原文链接：Android音乐播放器——甩动切歌，转载请注明来源！