Android上如何让应用截获系统按键
本文章主要讲述Android智能机上，应用捕获按键的处理。遥控器上按键分为两种，普通按键和热键。普通按键就是我们常用的数字键，上下左右功能键，设置，返回，确认等按键。而在android上，对于遥控器的映射中，规定某些按键应用是无法拦截到的，我们称此为热键，如静音键，电源键,HOME键，直播键等等。
1. 应用拦截普通按键的处理：
// 拦截系统热键 @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); } 在按键的处理过程中，若应用重写了dispatchKeyEvent,并且对响应的按键进行了处理完后，直接return true,则系统将不再处理此按键的响应。如果不写return true,super.dispatchKeyEvent(event)将会将按键再次交给系统进行处理。
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2.应用拦截热键的处理：
[1]在Activity中重写onAttachedToWindow方法，设置一个0x80000000的flags下去。//仅一个标志而已
@Override public void onAttachedToWindow() { System.out.println("onAttachedToWindow ............"); this.getWindow().addFlags(0x80000000);// super.onAttachedToWindow(); }[2]修改phoneWindownManager.java.在相应按键的事件派发前进行如下处理：【以home键为例】
在进行事件处理前，先获取当前WindowManager.LayoutParams，通过flags可以判断应用是否可以处理该按键消息，若可以，直接return 0,不再进行按键处理，交留给应用去处理。如果flags判断应用无法获取该按键消息，将还会进行系统原有的按键处理流程。
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; } } /** * 特殊处理，让应用程序能拦截HOME按键 */ 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]热键在应用中的处理：
参照普通按键的处理流程。重写dispatchKeyEvent。
来自：http://my.oschina.net/hiliusl/blog/137541