Android 应用程序建立与WMS服务之间的通信过程

public static IWindowSession getWindowSession() {
	synchronized (WindowManagerGlobal.class) {
		if (sWindowSession == null) {
			try {
				InputMethodManager imm = InputMethodManager.getInstance();
				//得到WindowManagerService服务的代理对象
				IWindowManager windowManager = getWindowManagerService();
				//通过WindowManagerService服务代理对象请求在WMS中创建Session本地对象
				sWindowSession = windowManager.openSession(imm.getClient(), imm.getInputContext());
				float animatorScale = windowManager.getAnimationScale(2);
				ValueAnimator.setDurationScale(animatorScale);
			} catch (RemoteException e) {
				Log.e(TAG, "Failed to open window session", e);
			}
		}
		return sWindowSession;
	}
}

public static IWindowManager getWindowManagerService() {
	synchronized (WindowManagerGlobal.class) {
		if (sWindowManagerService == null) {
			sWindowManagerService = IWindowManager.Stub.asInterface(
					ServiceManager.getService("window"));
		}
		return sWindowManagerService;
	}
}

public IWindowSession openSession(IInputMethodClient client,
		IInputContext inputContext) {
	if (client == null) throw new IllegalArgumentException("null client");
	if (inputContext == null) throw new IllegalArgumentException("null inputContext");
	Session session = new Session(this, client, inputContext);
	return session;
}

2.建立WMS服务到应用程序进程之间的连接

public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
	synchronized (this) {
		if (mView == null) {
			mView = view;
			...
			//mWindow为W本地对象
			res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
					getHostVisibility(), mDisplay.getDisplayId(),
					mAttachInfo.mContentInsets, mInputChannel);
			...
			if (mInputChannel != null) {
				if (mInputQueueCallback != null) {
					mInputQueue = new InputQueue();
					mInputQueueCallback.onInputQueueCreated(mInputQueue);
				}
				mInputEventReceiver = new WindowInputEventReceiver(mInputChannel,
						Looper.myLooper());
			}
			...
		}
	}
}

public int addToDisplay(IWindow window, int seq, WindowManager.LayoutParams attrs,
		int viewVisibility, int displayId, Rect outContentInsets,
		InputChannel outInputChannel) {
	return mService.addWindow(this, window, seq, attrs, viewVisibility, displayId,
			outContentInsets, outInputChannel);
}

public int addWindow(Session session, IWindow client, int seq,
		WindowManager.LayoutParams attrs, int viewVisibility, int displayId,
		Rect outContentInsets, InputChannel outInputChannel) {
		...
		WindowToken token = mTokenMap.get(attrs.token);
		if (token == null) {
			...
			token = new WindowToken(this, attrs.token, -1, false);
			addToken = true;
		//应用程序窗口
		} else if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {
			AppWindowToken atoken = token.appWindowToken;
			...
		//输入法窗口
		} else if (type == TYPE_INPUT_METHOD) {
			...
		//墙纸窗口
		} else if (type == TYPE_WALLPAPER) {
			...
		} else if (type == TYPE_DREAM) {
			...
		}
		//在WMS服务中为窗口创建WindowState对象
		win = new WindowState(this, session, client, token,
				attachedWindow, appOp[0], seq, attrs, viewVisibility, displayContent);
		...
		win.setShowToOwnerOnlyLocked(mPolicy.checkShowToOwnerOnly(attrs));
		res = mPolicy.prepareAddWindowLw(win, attrs);
		...
		if (outInputChannel != null && (attrs.inputFeatures
				& WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL) == 0) {
			String name = win.makeInputChannelName();
			InputChannel[] inputChannels = InputChannel.openInputChannelPair(name);
			win.setInputChannel(inputChannels[0]);
			inputChannels[1].transferTo(outInputChannel);
			mInputManager.registerInputChannel(win.mInputChannel, win.mInputWindowHandle);
		}
		...
		if (addToken) {
			//mTokenMap哈希表保存了所有的WindowToken对象
			mTokenMap.put(attrs.token, token);
		}
		win.attach();
		//mWindowMap哈希表以键值对的方式保存了所有的WindowState对象及W代理对象：<IWindow.Proxy，WindowState>
		mWindowMap.put(client.asBinder(), win);
		if (win.mAppOp != AppOpsManager.OP_NONE) {
			if (mAppOps.startOpNoThrow(win.mAppOp, win.getOwningUid(), win.getOwningPackage())
					!= AppOpsManager.MODE_ALLOWED) {
				win.setAppOpVisibilityLw(false);
			}
		}
		...
	}
	...
}

WindowState(WindowManagerService service, Session s, IWindow c, WindowToken token,
	   WindowState attachedWindow, int appOp, int seq, WindowManager.LayoutParams a,
	   int viewVisibility, final DisplayContent displayContent) {
	mService = service;//标识WMS服务
	mSession = s;//标识接收应用程序进程的Session本地对象
	mClient = c;//标识应用程序进程中窗口的W代理对象
	mAppOp = appOp;
	mToken = token;//标识应用程序进程中的窗口布局参数的Token
	mOwnerUid = s.mUid;
	mWindowId = new IWindowId.Stub() {
		@Override
		public void registerFocusObserver(IWindowFocusObserver observer) {
			WindowState.this.registerFocusObserver(observer);
		}
		@Override
		public void unregisterFocusObserver(IWindowFocusObserver observer) {
			WindowState.this.unregisterFocusObserver(observer);
		}
		@Override
		public boolean isFocused() {
			return WindowState.this.isFocused();
		}
	};
	...
}

void attach() {
	if (WindowManagerService.localLOGV) Slog.v(
		TAG, "Attaching " + this + " token=" + mToken
		+ ", list=" + mToken.windows);
	mSession.windowAddedLocked();
}

void windowAddedLocked() {
	if (mSurfaceSession == null) {
		mSurfaceSession = new SurfaceSession();
		mService.mSessions.add(this);
	}
	mNumWindow++;
}

3. IWindowId代理对象获取过程

public WindowId getWindowId() {
	if (mAttachInfo == null) {
		return null;
	}
	if (mAttachInfo.mWindowId == null) {
		try {
			/**获取WMS服务端的IWindowId代理对象，mAttachInfo在前面创建ViewRootImpl对象时创建
			 * mWindow = new W(this);
			 * mAttachInfo = new View.AttachInfo(mWindowSession, mWindow, display, this, mHandler, this);
			 * 在AttachInfo的构造函数中：
			 * mWindow = window;
                         * mWindowToken = window.asBinder();
			 * 因此AttachInfo的成员变量mWindow和mWindowToken引用了同一对象，该对象就是类型为W的本地binder对象
			 * 下面通过W本地binder对象，来获取AMS服务端的IWindowId的代理对象
			 */
			mAttachInfo.mIWindowId = mAttachInfo.mSession.getWindowId(mAttachInfo.mWindowToken);
			WindowId类的定义主要是为了方便在进程间传输IWindowId Binder对象
			mAttachInfo.mWindowId = new WindowId(mAttachInfo.mIWindowId);
		} catch (RemoteException e) {
		}
	}
	return mAttachInfo.mWindowId;
}

public IWindowId getWindowId(IBinder window) {
	return mService.getWindowId(window);
}

public IWindowId getWindowId(IBinder token) {
	synchronized (mWindowMap) {
		//通过W的binder代理对象从mWindowMap哈希表中查找对应的WindowState对象。
		WindowState window = mWindowMap.get(token);
		return window != null ? window.mWindowId : null;
	}
}