Android开发---MediaPlayer简单音乐播放器

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：

播放、暂停，停止，退出功能；

后台播放功能；

进度条显示播放进度、拖动进度条改变进度功能；

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～