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Back鍵的監聽

　　對于Back鍵的監聽比較容易,可以在多個系統回調處攔截,比如在activity的下列方法中都可以收到Back鍵按下的事件:

@Override
??? public void onBackPressed() {
??????? // super.onBackPressed();//注釋掉這行,back鍵不退出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鍵的廣播監聽

　　對于Home鍵的監聽不是那么容易,因為Home鍵可以將程序退出放在后臺,所以這個事件是直接分發給系統,系統接收到之后做相應處理,Home鍵的事件不是直接傳遞到應用里面.所以在上述監聽Back鍵的代碼中,相應的回調中是收不到Home鍵的事件的.

　　參考文后的博客鏈接,對Home鍵的監聽主要通過注冊廣播接收器實現,攔截讓窗口關閉的系統動作,然后根據Intent里面的具體參數,分析當前到底是Home鍵, 應用切換鍵,還是其他功能按鍵.

　　接收器實現如下:

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();
??????? Log.i(LOG_TAG, "onReceive: action: " + action);
??????? 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鍵
??????????????? Log.i(LOG_TAG, "homekey");

??????????? }
??????????? else if (SYSTEM_DIALOG_REASON_RECENT_APPS.equals(reason)) {
??????????????? // 長按Home鍵 或者 activity切換鍵
??????????????? Log.i(LOG_TAG, "long press home key or activity switch");

??????????? }
??????????? else if (SYSTEM_DIALOG_REASON_LOCK.equals(reason)) {
??????????????? // 鎖屏
??????????????? Log.i(LOG_TAG, "lock");
??????????? }
??????????? else if (SYSTEM_DIALOG_REASON_ASSIST.equals(reason)) {
??????????????? // samsung 長按Home鍵
??????????????? Log.i(LOG_TAG, "assist");
??????????? }

??????? }
??? }

}

　　注意不同手機的按鍵不同,所以需要對不同理由做區分.

?

Home鍵監聽廣播注冊

　　廣播接收器的注冊有兩種方式,一種是靜態注冊,即寫在manifest里面聲明;另一種是動態注冊,即在Java代碼里面注冊.

　　上面對Home鍵實現監聽的這個receiver,靜態注冊如下:

? ? ?<receiver android:name="com.mengdd.hellohome.HomeWatcherReceiver" >
? ? ? ? ? ?<intent-filter>
? ? ? ? ? ? ? ?<action android:name="android.intent.action.CLOSE_SYSTEM_DIALOGS" />
? ? ? ? ? ?</intent-filter>
? ? ? ?</receiver>

　　但是發現靜態注冊不起作用,即收不到onReceive回調.

?

　　采用動態注冊:

private static HomeWatcherReceiver mHomeKeyReceiver = null;

??? private static void registerHomeKeyReceiver(Context context) {
??????? Log.i(LOG_TAG, "registerHomeKeyReceiver");
??????? mHomeKeyReceiver = new HomeWatcherReceiver();
??????? final IntentFilter homeFilter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);

??????? 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里面分別調用:

@Override
??? protected void onResume() {
??????? super.onResume();

??????? registerHomeKeyReceiver(this);
??? }

??? @Override
??? protected void onPause() {

??????? unregisterHomeKeyReceiver(this);
??????? super.onPause();
??? }

　　當然也可以根據需要在其他合適的時機注冊和注銷.

轉載于:https://my.oschina.net/u/579890/blog/372409

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