监听 HOME键 BACK键 POWER键 + 总结

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Back键的监听

　　对于Back键的监听比较容易,可以在多个系统回调处拦截,比如在activity的下列方法中都可以收到Back键按下的事件:

 @Override    public void onBackPressed() {        // super.onBackPressed();//注释掉这行,back键不退出activity        Log.i(LOG_TAG, "onBackPressed");    }    @Override    public boolean dispatchKeyEvent(KeyEvent event) {        Log.i(LOG_TAG, "dispatchKeyEvent: keyCode -- " + event.getKeyCode());        return super.dispatchKeyEvent(event);    }    @Override    public boolean onKeyDown(int keyCode, KeyEvent event) {        Log.i(LOG_TAG, "onKeyDown: keyCode -- " + keyCode);        switch (keyCode) {        case KeyEvent.KEYCODE_BACK:            Log.i(LOG_TAG, "KeyEvent.KEYCODE_BACK");            break;        case KeyEvent.KEYCODE_MENU:            Log.i(LOG_TAG, "KeyEvent.KEYCODE_MENU");            break;        case KeyEvent.KEYCODE_HOME:            Log.i(LOG_TAG, "KeyEvent.KEYCODE_HOME");            // 收不到            break;        case KeyEvent.KEYCODE_APP_SWITCH:            Log.i(LOG_TAG, "KeyEvent.KEYCODE_APP_SWITCH");            // 收不到            break;        default:            break;        }        return super.onKeyDown(keyCode, event);    }

Home键的广播监听

　　对于Home键的监听不是那么容易,因为Home键可以将程序退出放在后台,所以这个事件是直接分发给系统,系统接收到之后做相应处理,Home键的事件不是直接传递到应用里面.所以在上述监听Back键的代码中,相应的回调中是收不到Home键的事件的.

　　参考文后的博客链接,对Home键的监听主要通过注册广播接收器实现,拦截让窗口关闭的系统动作,然后根据Intent里面的具体参数,分析当前到底是Home键, 应用切换键,还是其他功能按键.

　　接收器实现如下:

 package com.mengdd.hellohome;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.util.Log;public class HomeWatcherReceiver extends BroadcastReceiver {    private static final String LOG_TAG = "HomeReceiver";    private static final String SYSTEM_DIALOG_REASON_KEY = "reason";    private static final String SYSTEM_DIALOG_REASON_RECENT_APPS = "recentapps";    private static final String SYSTEM_DIALOG_REASON_HOME_KEY = "homekey";    private static final String SYSTEM_DIALOG_REASON_LOCK = "lock";    private static final String SYSTEM_DIALOG_REASON_ASSIST = "assist";    @Override    public void onReceive(Context context, Intent intent) {        String action = intent.getAction();                //监听HOME键        if (action.equals(Intent.ACTION_CLOSE_SYSTEM_DIALOGS)) {            // android.intent.action.CLOSE_SYSTEM_DIALOGS            String reason = intent.getStringExtra(SYSTEM_DIALOG_REASON_KEY);            Log.i(LOG_TAG, "reason: " + reason);            if (SYSTEM_DIALOG_REASON_HOME_KEY.equals(reason)) {                // 短按Home键                Log.i(LOG_TAG, "homekey");            }            else if (SYSTEM_DIALOG_REASON_RECENT_APPS.equals(reason)) {                // 长按Home键 或者 activity切换键                Log.i(LOG_TAG, "long press home key or activity switch");            }            else if (SYSTEM_DIALOG_REASON_LOCK.equals(reason)) {                // 锁屏                Log.i(LOG_TAG, "lock");            }            else if (SYSTEM_DIALOG_REASON_ASSIST.equals(reason)) {                // samsung 长按Home键                Log.i(LOG_TAG, "assist");            }        }                //监听POWER键        if(action.equals(Intent.ACTION_SCREEN_OFF))        {           //点击power键导致屏幕熄灭               }<pre name="code" class="java">        if(action.equals(Intent.ACTION_SCREEN_ON))        {           //点击power键导致屏幕亮起             }

}

　　注意不同手机的按键不同,所以需要对不同理由做区分.

POWER键和Home键监听（广播实现）

　　广播接收器的注册有两种方式,一种是静态注册,即写在manifest里面声明;另一种是动态注册,即在Java代码里面注册.

　　上面对Home键实现监听的这个receiver,静态注册如下:

</pre><pre name="code" class="html"> <pre>        <span style="color:#00ff00;"><</span><span style="color:#800000;">receiver </span><span style="color:#ff0000;">android:name</span><span style="color:#00ff00;">="com.mengdd.hellohome.HomeWatcherReceiver"</span> <span style="color:#00ff00;">></span>            <span style="color:#00ff00;"><</span><span style="color:#800000;">intent-filter</span><span style="color:#00ff00;">></span>                <span style="color:#00ff00;"><</span><span style="color:#800000;">action </span><span style="color:#ff0000;">android:name</span><span style="color:#00ff00;">="android.intent.action.CLOSE_SYSTEM_DIALOGS"</span> <span style="color:#00ff00;">/></span>            <span style="color:#00ff00;"></</span><span style="color:#800000;">intent-filter</span><span style="color:#00ff00;">></span>        <span style="color:#00ff00;"></</span><span style="color:#800000;">receiver</span><span style="color:#00ff00;">></span>

但是发现静态注册不起作用,即收不到onReceive回调.

　　采用动态注册:

   private static HomeWatcherReceiver mHomeKeyReceiver = null;    private static void registerHomeKeyReceiver(Context context) {        Log.i(LOG_TAG, "registerHomeKeyReceiver");        mHomeKeyReceiver = new HomeWatcherReceiver();        IntentFilter homeFilter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);                //添加过滤为了能监听POWER的点击        homeFileter.addAction(Intent.ACTION_SCREEN_OFF);        homeFileter.addAction(Intent.ACTION_SCREEN_ON);         context.registerReceiver(mHomeKeyReceiver, homeFilter);    }    private static void unregisterHomeKeyReceiver(Context context) {        Log.i(LOG_TAG, "unregisterHomeKeyReceiver");        if (null != mHomeKeyReceiver) {            context.unregisterReceiver(mHomeKeyReceiver);        }    }

　　在Activity的onResume和onPause里面分别调用:

 @Override    protected void onResume() {        super.onResume();        registerHomeKeyReceiver(this);    }    @Override    protected void onPause() {        unregisterHomeKeyReceiver(this);        super.onPause();    }

　　当然也可以根据需要在其他合适的时机注册和注销.

总结

虽然我们可以监听不同的事件来达到区分用户点击了什么按键，来分别完成不同的任务，但是当：我们的POWER键，BACK键，HOME键都要完成相同的功能，这时候我们怎么处理呢？

答案是：onResume(),onPause()，onStop(),onStart()这几个函数。

因为：POWER键，BACK键，HOME键都会触发这几个函数。

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