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
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 = Environment.getExternalStorageDirectory().getAbsolutePath()+
"/K.Will-Melt.mp3";
mediaPlayer.setDataSource(file_path);
mediaPlayer.prepare();
mediaPlayer.setLooping(
true);
}
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());
animator.setRepeatCount(ValueAnimator.INFINITE);
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 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");
}
else {
stateText.setText(
"Playing");
isPlay.setText(
"PAUSE");
}
}
private void changeStop() {
stateText.setText(
"Stop");
seekBar.setProgress(
0);
}
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();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
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;
}
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) {
int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);
if (permission != PackageManager.PERMISSION_GRANTED) {
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 = Environment.getExternalStorageDirectory().getAbsolutePath()+
"/K.Will-Melt.mp3";
mediaPlayer.setDataSource(file_path);
mediaPlayer.prepare();
mediaPlayer.setLooping(
true);
}
catch (Exception e) {
e.printStackTrace();
}
}
public void AnimatorAction() {
if (mediaPlayer.isPlaying()) {
animator.setDuration(
5000);
animator.setInterpolator(
new LinearInterpolator());
animator.setRepeatCount(ValueAnimator.INFINITE);
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());
animator.setRepeatCount(ValueAnimator.INFINITE);
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;
}
}
完整项目参见github，如君心情好，别忘了加心哦。。。 祝君好心情～
