1. Android可以通过adb shell input xxx命令注入输入事件，调用IMS.injectInputEvent，最终走到通过JNI调用InputDispatcher注入事件，没有经过InputReader

public class Input extends BaseCommand {// ... ... ... ...Input() {COMMANDS.put("text", new InputText());COMMANDS.put("keyevent", new InputKeyEvent());COMMANDS.put("tap", new InputTap());COMMANDS.put("swipe", new InputSwipe());COMMANDS.put("draganddrop", new InputDragAndDrop());COMMANDS.put("press", new InputPress());COMMANDS.put("roll", new InputRoll());COMMANDS.put("motionevent", new InputMotionEvent());}@Overridepublic void onRun() throws Exception {String arg = nextArgRequired();int inputSource = InputDevice.SOURCE_UNKNOWN;// Get source (optional).if (SOURCES.containsKey(arg)) {inputSource = SOURCES.get(arg);arg = nextArgRequired();}// Get displayId (optional).int displayId = INVALID_DISPLAY;if ("-d".equals(arg)) {displayId = getDisplayId();arg = nextArgRequired();}// Get command and run.InputCmd cmd = COMMANDS.get(arg);if (cmd != null) {try {cmd.run(inputSource, displayId);return;} catch (NumberFormatException ex) {throw new IllegalArgumentException(INVALID_ARGUMENTS + arg);}}throw new IllegalArgumentException("Error: Unknown command: " + arg);}// ... ... ... ...class InputKeyEvent implements InputCmd {@Overridepublic void run(int inputSource, int displayId) {String arg = nextArgRequired();final boolean longpress = "--longpress".equals(arg);if (longpress) {arg = nextArgRequired();}do {final int keycode = KeyEvent.keyCodeFromString(arg);sendKeyEvent(inputSource, keycode, longpress, displayId);} while ((arg = nextArg()) != null);}private void sendKeyEvent(int inputSource, int keyCode, boolean longpress, int displayId) {final long now = SystemClock.uptimeMillis();int repeatCount = 0;KeyEvent event = new KeyEvent(now, now, KeyEvent.ACTION_DOWN, keyCode, repeatCount,0 /*metaState*/, KeyCharacterMap.VIRTUAL_KEYBOARD, 0 /*scancode*/, 0 /*flags*/,inputSource);event.setDisplayId(displayId);injectKeyEvent(event);if (longpress) {repeatCount++;injectKeyEvent(KeyEvent.changeTimeRepeat(event, now, repeatCount,KeyEvent.FLAG_LONG_PRESS));}injectKeyEvent(KeyEvent.changeAction(event, KeyEvent.ACTION_UP));}}

2. 通过InputManager提供的接口注入

invokeSetDisplayId(mMotionSetDisplayId, ev, displayId); Class clm = MotionEvent.class;m.invoke(ev, displayId);   // mMotionSetDisplayId = clm.getMethod("setDisplayId", int.class);            InjectionUtil.getInstance().injectInputEvent(ev, INJECT_INPUT_EVENT_MODE_WAIT_FOR_FINISH);invokeInjectInputEvent(event, mode);Class cl = InputManager.class;Method method = cl.getMethod("getInstance");            mInjectInputEvent = cl.getMethod("injectInputEvent", InputEvent.class, int.class);mInjectInputEvent.invoke(inputManager, event, mode);  //InputManager::injectInputEvent
@frameworks/base/core/java/android/hardware/input/InputManager.javareturn mIm.injectInputEvent(event, mode);......
@frameworks/native/services/inputflinger/dispatcher/InputDispatcher.cpp                 InputDispatcher::injectInputEvent
@frameworks/native/include/input/Input.h          event->getDisplayId()needWake |= enqueueInboundEventLocked(std::move(injectedEntries.front()));mInboundQueue.push_back(std::move(newEntry));  //向InputDispatcher中的mInboundQueue队列注入事件