Android App: 按键识别

Android app监听普通的按键有两种方式:

实现Activity的onKeyDown方法

public class Android_game extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_android_game);    }    public boolean onKeyDown(int keyCode, KeyEvent event) {        if(keyCode == KeyEvent.KEYCODE_BACK){                Intent i = new Intent(this,Android_game_menu.class);                startActivity(i);        }         return false;    }}

实现OnClickListener接口的方式

public class MyActivity extends Activity implementsOnClickListener {    // ...    public void onClick(View v) {        switch (v.getId()) {            case R.id.about_button:                Intent i = new Intent(this, About.class);                startActivity(i);                break;    // More buttons go here (if any) ...        }    }}

Android app Home Key的监听方式:

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.所以在上述监听一般的按键(比如volume key等)的代码中,相应的回调中是收不到Home键的事件的.
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.

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");            }        }    }}

注意不同手机的按键不同,所以需要对不同理由做区分.
Home键监听广播注册:
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的静态注册如下:

        <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();        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.

Android app监听普通的按键有两种方式:

实现Activity的onKeyDown方法

实现OnClickListener接口的方式

Android app Home Key的监听方式:

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