Android上如何讓應用截獲系統按鍵
本文章主要講述Android智能機上，應用捕獲按鍵的處理。遙控器上按鍵分為兩種，普通按鍵和熱鍵。普通按鍵就是我們常用的數字鍵，上下左右功能鍵，設置，返回，確認等按鍵。而在android上，對于遙控器的映射中，規定某些按鍵應用是無法攔截到的，我們稱此為熱鍵，如靜音鍵，電源鍵,HOME鍵，直播鍵等等。
1. 應用攔截普通按鍵的處理：
// 攔截系統熱鍵
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
int key = event.getKeyCode();
Log.i(TAG, "[test] dispatchKeyEvent event = " + event);
if (key == KeyEvent.KEYCODE_VOLUME_DOWN
|| key == KeyEvent.KEYCODE_VOLUME_UP) {
Log.i(TAG, "[test] catch event!! return true! ");
return true;
}
return super.dispatchKeyEvent(event);
} 在按鍵的處理過程中，若應用重寫了dispatchKeyEvent,并且對響應的按鍵進行了處理完后，直接return true,則系統將不再處理此按鍵的響應。如果不寫return true,super.dispatchKeyEvent(event)將會將按鍵再次交給系統進行處理。
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2.應用攔截熱鍵的處理：
[1]在Activity中重寫onAttachedToWindow方法，設置一個0x80000000的flags下去。//僅一個標志而已
@Override
public void onAttachedToWindow() {
System.out.println("onAttachedToWindow ............");
this.getWindow().addFlags(0x80000000);//
super.onAttachedToWindow();
}[2]修改phoneWindownManager.java.在相應按鍵的事件派發前進行如下處理：【以home鍵為例】
在進行事件處理前，先獲取當前WindowManager.LayoutParams，通過flags可以判斷應用是否可以處理該按鍵消息，若可以，直接return 0,不再進行按鍵處理，交留給應用去處理。如果flags判斷應用無法獲取該按鍵消息，將還會進行系統原有的按鍵處理流程。
if (keyCode == KeyEvent.KEYCODE_HOME){
// If we have released the home key, and didn't do anything else
// while it was pressed, then it is time to go home!
if (mHomePressed && !down) {
mHomePressed = false;
if (!canceled) {
// If an incoming call is ringing, HOME is totally disabled.
// (The user is already on the InCallScreen at this point,
// and his ONLY options are to answer or reject the call.)
boolean incomingRinging = false;
try {
ITelephony telephonyService = getTelephonyService();
if (telephonyService != null) {
incomingRinging = telephonyService.isRinging();
}
} catch (RemoteException ex) {
Log.w(TAG, "RemoteException from getPhoneInterface()", ex);
}
if (incomingRinging) {
Log.i(TAG, "Ignoring HOME; there's a ringing incoming call.");
}else if(mHoldHomePressed == true){
mHoldHomePressed = false;
}else{
mHoldHomePressed = false;
launchHomeFromHotKey();
}
} else {
Log.i(TAG, "Ignoring HOME; event canceled.");
}
return -1;
}
// If a system window has focus, then it doesn't make sense
// right now to interact with applications.
WindowManager.LayoutParams attrs = win != null ? win.getAttrs() : null;
if (attrs != null) {
final int type = attrs.type;
if (type == WindowManager.LayoutParams.TYPE_KEYGUARD
|| type == WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG) {
// the "app" is keyguard, so give it the key
return 0;
}
final int typeCount = WINDOW_TYPES_WHERE_HOME_DOESNT_WORK.length;
for (int i=0; i<typeCount; i++) {
if (type == WINDOW_TYPES_WHERE_HOME_DOESNT_WORK[i]) {
// don't do anything, but also don't pass it to the app
return -1;
}
}
/**
* 特殊處理，讓應用程序能攔截HOME按鍵
*/
final int attrFlags = attrs.flags;
if((attrFlags & 0x80000000) != 0) {
return 0;
}
}
if (down) {
if (repeatCount == 0) {
mHomePressed = true;
} else if ((event.getFlags() & KeyEvent.FLAG_LONG_PRESS) != 0) {
if (!keyguardOn) {
//handleLongPressOnHome();
mHoldHomePressed = true;
Intent intentShowRecent = new Intent("hi_action_show_recent");
mContext.sendBroadcast(intentShowRecent);
}
}
}
return -1;
} [3]熱鍵在應用中的處理：
參照普通按鍵的處理流程。重寫dispatchKeyEvent。
來自：http://my.oschina.net/hiliusl/blog/137541