當耳機的媒體按鍵被單擊后，Android系統會發出一個廣播，該廣播的攜帶者一個Action名為MEDIA_BUTTON的Intent。監聽該廣播便可以獲取手機的耳機媒體按鍵的單擊事件。
在Android中有個AudioManager類，該類會維護MEDIA_BUTTON廣播的分發，所以要實現耳機按鍵監聽需要向AudioManager注冊一個用于接收耳機按鍵單擊事件的接收器：
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| 1 2 3 4 5 | AudioManager audioManager = (AudioManager)context??????.getSystemService(Context.AUDIO_SERVICE);ComponentName name = newComponentName(context.getPackageName(),??????MediaButtonReceiver.class.getName());audioManager.registerMediaButtonEventReceiver(name); |
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該方法的原型為：
publicvoid registerMediaButtonEventReceiver (PendingIntent eventReceiver)
Added in API level 18
Registera component to be the sole receiver of MEDIA_BUTTON intents. This is like registerMediaButtonEventReceiver(android.content.ComponentName), but allows the buttons to go to any PendingIntent. Note that you shouldonly use this form if you know you will continue running for the full timeuntil unregistering the PendingIntent.
Parameters
| eventReceiver | target that will receive media button intents. The PendingIntent will be sent an ACTION_MEDIA_BUTTON event when a media button action occurs, with EXTRA_KEY_EVENT added and holding the key code of the media button that was pressed. |
從API注釋中可知：
1、 在AudioManager對象注冊一個MediaoButtonRecevie，使它成為MEDIA_BUTTON的唯一接收器，也就是說只有我能收到，其他的都收不到這個廣播了，否則的話大家都收到會照成一定的混亂；
2、該廣播必須在AndroidManifest.xml文件中進行聲明，否則就監聽不到該MEDIA_BUTTON廣播了。
注，因為當我們注冊了AudioManager媒體按鍵的接收器，并且該接收器是媒體按鍵的唯一接收器，所以要在不使用按鍵監聽的時候取消該注冊：
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| 1 2 3 | AudioManager audioManager = (AudioManager)context??? .getSystemService(Context.AUDIO_SERVICE);ComponentName name = newComponentName(context.getPackageName(),??? MediaButtonReceiver.class.getName());audioManager.unregisterMediaButtonEventReceiver(name); |
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當耳機媒體鍵發生單擊事件的時候Android系統會發出兩次廣播，第一次是按鍵按下去的時候，第二次是松開按鍵的時候，為了能夠準確的獲知用戶單擊了幾次媒體鍵，我們只需要在按鍵松開的時候處理單擊事件即可：
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| 1 2 3 4 | KeyEvent keyEvent = (KeyEvent)intent.getParcelableExtra(Intent.EXTRA_KEY_EVENT); //獲得KeyEvent對象if(keyEvent.getAction()== KeyEvent.ACTION_UP){//在這里處理單擊事件} |
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下面就分別講解一下為了實現線控效果所用到的幾個類：
1. 耳機線控管理工具類HeadSetUtil：
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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 | package com.jph.lc;import android.content.ComponentName;import android.content.Context;import android.media.AudioManager;import android.util.Log;/**?* 耳機線控管理工具類 單例?* @author JPH?* @date 2015-6-9 下午4:03:45?*/public class HeadSetUtil {????private static HeadSetUtil headSetUtil;????private OnHeadSetListener headSetListener = null;????public static HeadSetUtil getInstance() {????????if (headSetUtil == null) {????????????headSetUtil = new HeadSetUtil();????????}????????return headSetUtil;????}????/**?????* 設置耳機單擊雙擊監聽接口 必須在open前設置此接口，否則設置無效?????* @param headSetListener?????*/????public void setOnHeadSetListener(OnHeadSetListener headSetListener) {????????this.headSetListener = headSetListener;????}????/**?????* 為MEDIA_BUTTON 意圖注冊接收器（注冊開啟耳機線控監聽, 請務必在設置接口監聽之后再調用此方法，否則接口無效）?????* @param context?????*/????public void open(Context context) {????????if(headSetListener==null){????????????throw new IllegalStateException(please set headSetListener);????????}????????AudioManager audioManager = (AudioManager) context????????????????.getSystemService(Context.AUDIO_SERVICE);????????ComponentName name = new ComponentName(context.getPackageName(),????????????????MediaButtonReceiver.class.getName());????????audioManager.registerMediaButtonEventReceiver(name);????????Log.i(ksdinf, open);????}????/**?????* 關閉耳機線控監聽 ?????* @param context?????*/????public void close(Context context) {????????AudioManager audioManager = (AudioManager) context????????????????.getSystemService(Context.AUDIO_SERVICE);????????ComponentName name = new ComponentName(context.getPackageName(),????????????????MediaButtonReceiver.class.getName());????????audioManager.unregisterMediaButtonEventReceiver(name);????}????/**?????* 刪除耳機單機雙擊監聽接口?????*/????public void delHeadSetListener() {????????this.headSetListener = null;????}????/**?????* 獲取耳機單擊雙擊接口?????* ?????* @return?????*/????protected OnHeadSetListener getOnHeadSetListener() {????????return headSetListener;????}????/**?????* 耳機按鈕單雙擊監聽?????*/????public interface OnHeadSetListener {????????/**?????????* 單擊觸發,主線程。 此接口真正觸發是在單擊操作1秒后 因為需要判斷1秒內是否仍監聽到點擊，有的話那就是雙擊了?????????*/????????public void onClick();????????/**?????????* 雙擊觸發，此接口在主線程，可以放心使用?????????*/????????public void onDoubleClick();????????/**?????????* 三連擊?????????*/????????public void onThreeClick();????}} |
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2.耳機媒體按鍵廣播接收器MediaButtonReceiver：
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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 | package com.jph.lc;import java.util.Timer;import java.util.TimerTask;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.os.Handler;import android.os.Message;import android.util.Log;import android.view.KeyEvent;import com.jph.lc.HeadSetUtil.OnHeadSetListener;/**?* MEDIA_BUTTON耳機媒體按鍵廣播接收器?* @author JPH?* @Date2015-6-9 下午8:35:40?*/public class MediaButtonReceiver extends BroadcastReceiver{????private Timer timer = null;????private OnHeadSetListener headSetListener = null;????private static MTask myTimer = null;????/**單擊次數**/????private static int clickCount;????public MediaButtonReceiver(){????????timer = new Timer(true);????????this.headSetListener = HeadSetUtil.getInstance().getOnHeadSetListener();????}????@Override????public void onReceive(Context context, Intent intent) {????????Log.i(ksdinf, onReceive);?????????String intentAction = intent.getAction() ;????????????if(Intent.ACTION_MEDIA_BUTTON.equals(intentAction)){????????????????KeyEvent keyEvent = (KeyEvent)intent.getParcelableExtra(Intent.EXTRA_KEY_EVENT); //獲得KeyEvent對象? ????????????????if(headSetListener != null){????????????????????try {????????????????????????if(keyEvent.getAction() == KeyEvent.ACTION_UP){????????????????????????????if (clickCount==0) {//單擊????????????????????????????????clickCount++;????????????????????????????????myTimer = new MTask();????????????????????????????????timer.schedule(myTimer,1000);????????????????????????????}else if (clickCount==1) {//雙擊????????????????????????????????clickCount++;????????????????????????????}else if (clickCount==2) {//三連擊????????????????????????????????clickCount=0;????????????????????????????????myTimer.cancel();????????????????????????????????headSetListener.onThreeClick();????????????????????????????}????????????????????????}????????????????????} catch (Exception e) {????????????????????}????????????????}?? ????????????}????????????abortBroadcast();//終止廣播(不讓別的程序收到此廣播，免受干擾)? ????}????/**?????* 定時器，用于延遲1秒，判斷是否會發生雙擊和三連擊?????*/????class MTask extends TimerTask{????????????@Override????????????public void run() {????????????????try {????????????????????if (clickCount==1) {????????????????????????mhHandler.sendEmptyMessage(1);????????????????????}else if (clickCount==2) {????????????????????????mhHandler.sendEmptyMessage(2);????????????????????}????????????????????clickCount=0;????????????????} catch (Exception e) {????????????????????// TODO: handle exception????????????????}????????????}????};????/**?????* 此handle的目的主要是為了將接口在主線程中觸發?????* ，為了安全起見把接口放到主線程觸發?????*/????Handler mhHandler = new Handler(){????????@Override????????public void handleMessage(Message msg) {????????????super.handleMessage(msg);????????????if(msg.what==1){//單擊????????????????headSetListener.onClick();????????????}else if (msg.what==2) {//雙擊????????????????headSetListener.onDoubleClick();????????????}else if (msg.what==3) {//三連擊????????????????headSetListener.onThreeClick();????????????}????????}????};?????????} |
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該類中有個名為Mtask的內部類，該內部類是一個定時任務，該任務會在指定的時間里分析是否會發生雙擊和三連擊。
另外，該類中還有一個myHandler對象，該對象是為了將回調監聽發生在UI線程中，以方便UI的更新。
3.監聽器的使用類MainActivity：
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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | package com.jph.lc;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.widget.TextView;import com.jph.lc.HeadSetUtil.OnHeadSetListener;/**?* 耳機線控實例，藍牙耳機按鈕監聽（仿酷狗線控效果）?* @author JPH?* @Date2015-6-10 上午9:49:02?*/public class MainActivity extends Activity {????TextView txt = null;????@Override????protected void onCreate(Bundle savedInstanceState) {????????super.onCreate(savedInstanceState);????????setContentView(R.layout.activity_main);????????txt = (TextView) findViewById(R.id.text);????????HeadSetUtil.getInstance().setOnHeadSetListener(headSetListener);????????HeadSetUtil.getInstance().open(this);????}????@Override????protected void onDestroy() {????????super.onDestroy();????????HeadSetUtil.getInstance().close(this);????}????OnHeadSetListener headSetListener = new OnHeadSetListener() {????????@Override????????public void onDoubleClick() {????????????txt.setText(雙擊);????????????Log.i(ksdinf, 雙擊);????????}????????@Override????????public void onClick() {????????????txt.setText(單擊);????????????Log.i(ksdinf, 單擊);????????}????????@Override????????public void onThreeClick() {????????????txt.setText(三連擊);????????????Log.i(ksdinf, 三連擊);????????}????};} |
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該類中舉要介紹了媒體按鍵監聽的使用。
