《Android内核剖析》笔记第13章 View的按键消息处理，跨平台移动开发答案

最新推荐文章于 2023-08-19 00:35:38 发布

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最新推荐文章于 2023-08-19 00:35:38 发布 · 174 阅读

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#面试 #android #移动开发

本文详细介绍了Android中View的按键消息处理流程，从handleMotion和dispatchKey函数开始，深入到deliverKeyEvent的执行，包括输入法拦截、预处理和后处理。文中提及了dispatchKeyEvent在Activity和ViewGroup中的分发机制，以及如何在不同层级处理按键事件。

public void handleMotion(MotionEvent event, InputQueue.FinishedCallback finishedCallback) {
startInputEvent(finishedCallback);
dispatchMotion(event, true);
}
};

dispatchKey()函数内部发送一个DISPATCH_KEY消息，消息的处理函数为deliverKeyEvent():

[java] view plain copy

private void dispatchKey(KeyEvent event, boolean sendDone) {
//noinspection ConstantConditions
if (false && event.getAction() == KeyEvent.ACTION_DOWN) {
if (event.getKeyCode() == KeyEvent.KEYCODE_CAMERA) {
if (DBG) Log.d(“keydisp”, “===================================================”);
if (DBG) Log.d(“keydisp”, “Focused view Hierarchy is:”);
debug();
if (DBG) Log.d(“keydisp”, “===================================================”);
}
}
Message msg = obtainMessage(DISPATCH_KEY);
msg.obj = event;
msg.arg1 = sendDone ? 1 : 0;
if (LOCAL_LOGV) Log.v(
TAG, "sending key " + event + " to " + mView);
enqueueInputEvent(msg, event.getEventTime());
}
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
…
case FINISHED_EVENT:
handleFinishedEvent(msg.arg1, msg.arg2 != 0);
break;
case DISPATCH_KEY:
deliverKeyEvent((KeyEvent)msg.obj, msg.arg1 != 0);
break;
case DISPATCH_POINTER:
deliverPointerEvent((MotionEvent) msg.obj, msg.arg1 != 0);
break;