Android Input事件处理

Input UML 图表

Input UML 图表

系统启动SystemServer时创建其他服务，初始话Input管理服务，创建InputManager、InputReader对象
对于InputReader在初始化成功之后，start启动时，创建InputTread loop工作线程
framework/native/services/inputflinger/reader/InputReader.cpp

InputReader.h
private:std::unique_ptr<InputThread> mThread;InputReader.cpp
status_t InputReader::start() {if (mThread) {return ALREADY_EXISTS;}mThread = std::make_unique<InputThread>("InputReader", [this]() { loopOnce(); }, [this]() { mEventHub->wake(); });return OK;
}

如下图是系统启动input服务时序图：

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如图可知，inputThread这个线程的工作就是通过EventHub的getEvents监听读取Input事件。
获取到事件Input事件之后，通知InputDispatcher派发InputEvent事件
在InputReader中loopOnce方法最后一句是flush

    // Flush queued events out to the listener.// This must happen outside of the lock because the listener could potentially call// back into the InputReader's methods, such as getScanCodeState, or become blocked// on another thread similarly waiting to acquire the InputReader lock thereby// resulting in a deadlock.  This situation is actually quite plausible because the// listener is actually the input dispatcher, which calls into the window manager,// which occasionally calls into the input reader.mQueuedListener->flush();

如下图是flush动作的时序图

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