Android输入法框架系统(上)

输入法，就是用来输入字符（包括英文，俄文，中文）的工具。输入法你可以看成是一种字符发生器，它将输入数据触摸事件或者按键事件转化为其他更丰富的字符。在PC时代，输入法的原始输入来自实体键盘，鼠标，然后输入法将这些事件对应的ASCII码转换为俄文，中文，当然如果是英文是不需要转换，直接发送即可。而在Android系统里，由于输入法dialog永远没法成为焦点window,所以输入法永远没法获取到按键事件，也就是说输入法的输入数据只能来自触摸事件，输入法显示出键盘(大家称之为软键盘)，用户点击键盘UI, 然后输入法将触摸事件所在位置的字符当做原始字符输入，最后组装成更为丰富的字符（多个字符组成拼音，然后转化为中文），然后就是发送到对应的程序。

        Android系统中，输入法可以是可以安装的，也就是说系统可以有多个输入法（(sougou输入法，百度输入法），但是只有一个是激活的，当然用户可以切换输入法。同时，输入法是以service的方式运行的，输入法同一时间只能服务一个程序，只有最顶层的可见的程序才能接收到输入法的输入数据。

       输入法系统的整个框架如下：

       

       InputMethodManagerService（下文也称IMMS）负责管理系统的所有输入法，包括输入法service(InputMethodService简称IMS)加载及切换。程序获得焦点时，就会通过InputMethodManager向InputMethodManagerService通知自己获得焦点并请求绑定自己到当前输入法上。同时，当程序的某个需要输入法的view比如EditorView获得焦点时就会通过InputMethodManager向InputMethodManagerService请求显示输入法，而这时InputMethodManagerService收到请求后，会将请求的EditText的数据通信接口发送给当前输入法，并请求显输入法。输入法收到请求后，就显示自己的UI dialog,同时保存目标view的数据结构，当用户实现输入后，直接通过view的数据通信接口将字符传递到对应的View。接下来就来分析这些过程。

InputMethodManager创建

        每个程序有一个InputMethodManager实例，这个是程序和InputMethodManagerService通信的接口，该实例在ViewRootImpl初始化的时候创建。

 

public ViewRootImpl(Context context, Display display) {
    mContext = context;
    mWindowSession = WindowManagerGlobal.getWindowSession();
}

public static IWindowSession getWindowSession() {
    synchronized (WindowManagerGlobal.class) {
        if (sWindowSession == null) {
            try {
                //这个进程的InputMethodManager实例就生成了
                InputMethodManager imm = InputMethodManager.getInstance();
                IWindowManager windowManager = getWindowManagerService();
            } catch (RemoteException e) {
                Log.e(TAG, "Failed to open window session", e);
            }
        }
        return sWindowSession;
    }
}

public static InputMethodManager getInstance() {
    synchronized (InputMethodManager.class) {
        if (sInstance == null) {
            // InputMethodManager其实就是一个Binder service的proxy
            IBinder b = ServiceManager.getService(Context.INPUT_METHOD_SERVICE);
            IInputMethodManager service = IInputMethodManager.Stub.asInterface(b);
            sInstance = new InputMethodManager(service, Looper.getMainLooper());
        }
        return sInstance;
    }
}

程序的Window获得焦点

           程序的window获得焦点的时序图如下

 

系统WindowManagerService更新焦点window

         哪个程序获得焦点是由系统决定的，是由WindowManagerService决定的，当系统的window状态发生变化时(比如window新增，删除）就会调用函数updateFocusedWindowLocked来更新焦点window。

private boolean updateFocusedWindowLocked(int mode, boolean updateInputWindows) {
    //计算焦点window
    WindowState newFocus = computeFocusedWindowLocked();
    if (mCurrentFocus != newFocus) {
        //焦点window发生变化，post一个message来通知程序焦点发生变化了
        mH.removeMessages(H.REPORT_FOCUS_CHANGE);
        mH.sendEmptyMessage(H.REPORT_FOCUS_CHANGE);
        return true;
    }
    return false;
}

private WindowState computeFocusedWindowLocked() {
    if (mAnimator.mUniverseBackground != null
            && mAnimator.mUniverseBackground.mWin.canReceiveKeys()) {
        return mAnimator.mUniverseBackground.mWin;
    }

    final int displayCount = mDisplayContents.size();
    for (int i = 0; i < displayCount; i++) {
        final DisplayContent displayContent = mDisplayContents.valueAt(i);
        WindowState win = findFocusedWindowLocked(displayContent);
        if (win != null) {
            return win;
        }
    }
    return null;
}

//该函数就是找出最top的可以接收按键事件的window，这个window就获得焦点
private WindowState findFocusedWindowLocked(DisplayContent displayContent) {
    final WindowList windows = displayContent.getWindowList();
    for (int i = windows.size() - 1; i >= 0; i--) {
        final WindowState win = windows.get(i);
        //是否为activity的window
        AppWindowToken wtoken = win.mAppToken;
        //重要函数，window是否可以获取焦点
        if (!win.canReceiveKeys()) {
            continue;
        }
        // mFocusedApp是最top的activity ，下面逻辑是为了确保焦点window的app
        //必须是焦点程序之上，所以这个逻辑其实并没有多大作用，只是为了检测出
        //错误
        if (wtoken != null && win.mAttrs.type != TYPE_APPLICATION_STARTING &&
                mFocusedApp != null) {
            ArrayList<Task> tasks = displayContent.getTasks();
            for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
                AppTokenList tokens = tasks.get(taskNdx).mAppTokens;
                int tokenNdx = tokens.size() - 1;
                for ( ; tokenNdx >= 0; --tokenNdx) {
                    final AppWindowToken token = tokens.get(tokenNdx);
                    if (wtoken == token) {
                        break;
                    }
                    if (mFocusedApp == token) {
                        return null;
                    }
                }
            }
        }
        return win;
    }
    return null;
}

public final boolean canReceiveKeys() {
    return isVisibleOrAdding()
            && (mViewVisibility == View.VISIBLE)
            && ((mAttrs.flags & WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE) == 0);
}
//由于输入法的window带有FLAG_NOT_FOCUSABLE, 从上可见其不可能是焦点window
//接下来系统开始通知程序端哪个window获得了焦点。

final class H extends Handler {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
            case REPORT_FOCUS_CHANGE: {
                WindowState lastFocus;
                WindowState newFocus;

                synchronized(mWindowMap) {
                    lastFocus = mLastFocus;
                    newFocus = mCurrentFocus;
                    if (lastFocus == newFocus) {
                        // Focus is not changing, so nothing to do.
                        return;
                    }
                    mLastFocus = newFocus;
                }
                if (newFocus != null) {
                    //通知新的焦点程序其获得了焦点
                    newFocus.reportFocusChangedSerialized(true, mInTouchMode);
                    notifyFocusChanged();
                }

                if (lastFocus != null) {
                    //通知老的焦点程序其获得了焦点
                    lastFocus.reportFocusChangedSerialized(false, mInTouchMode);
                }
            } break;
 }

 public void reportFocusChangedSerialized(boolean focused, boolean inTouchMode) {
    try {
        //这个就是通过Binder告知client其获得或失去了焦点
        mClient.windowFocusChanged(focused, inTouchMode);
    } catch (RemoteException e) {
    }
}

        上面的mClient.windowFocusChanged会调回到ViewRootImpl中的W实例：

程序获得焦点改变事件

           

//ViewRootImpl.java
static class W extends IWindow.Stub {
    @Override
    public void windowFocusChanged(boolean hasFocus, boolean inTouchMode) {
        final ViewRootImpl viewAncestor = mViewAncestor.get();
        if (viewAncestor != null) {
            viewAncestor.windowFocusChanged(hasFocus, inTouchMode);
        }
    }


public void windowFocusChanged(boolean hasFocus, boolean inTouchMode) {
    Message msg = Message.obtain();
    msg.what = MSG_WINDOW_FOCUS_CHANGED;
    msg.arg1 = hasFocus ? 1 : 0;
    msg.arg2 = inTouchMode ? 1 : 0;
    mHandler.sendMessage(msg);
}

//程序获得焦点会通过调用mView.dispatchWindowFocusChanged和
//imm.onWindowFocus来通知IMMS焦点信息发生改变，需要更新输入法了
final class ViewRootHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
        case MSG_WINDOW_FOCUS_CHANGED: {
            if (mAdded) {
                boolean hasWindowFocus = msg.arg1 != 0;
                mAttachInfo.mHasWindowFocus = hasWindowFocus;
                mLastWasImTarget = WindowManager.LayoutParams
                        .mayUseInputMethod(mWindowAttributes.flags);
                InputMethodManager imm = InputMethodManager.peekInstance();
                if (mView != null) {
                    //调用根view的dispatchWindowFocusChanged函数通知view
                    //程序获得焦点
                    mView.dispatchWindowFocusChanged(hasWindowFocus);
                    mAttachInfo.mTreeObserver.dispatchOnWindowFocusChange(
indowFocus);
                }
                if (hasWindowFocus) {
                    if (imm != null && mLastWasImTarget && !isInLocalFocusMode()) {
                        //通知imm该window获得焦点
                        imm.onWindowFocus(mView, mView.findFocus(),
                                mWindowAttributes.softInputMode,
                                !mHasHadWindowFocus, mWindowAttributes.flags);
                    }
                }
            }

        } break;
}

//上面的根view就是DecorView，它只是调用父类ViewGroup
//的dispatchWindowFocusChanged
//ViewGroup.java
@Override
public void dispatchWindowFocusChanged(boolean hasFocus) {
    super.dispatchWindowFocusChanged(hasFocus);
    final int count = mChildrenCount;
    final View[] children = mChildren;
    //让每个子view处理window焦点改变时间
    //但是只有获得焦点的view才会处理这个时间
    for (int i = 0; i < count; i++) {
        children[i].dispatchWindowFocusChanged(hasFocus);
    }
}

//View.java
public void onWindowFocusChanged(boolean hasWindowFocus) {
    InputMethodManager imm = InputMethodManager.peekInstance();
    if (!hasWindowFocus) {
    } else if (imm != null && (mPrivateFlags & PFLAG_FOCUSED) != 0) {
        //获得焦点的view通过 InputMethodManager向service通知自己获得焦点
        imm.focusIn(this);
    }
}

焦点View向IMMS请求绑定输入法

         焦点view请求绑定输入法是通过调用InputMethodManager. focusIn实现的

       

public void focusIn(View view) {
    synchronized (mH) {
        focusInLocked(view);
    }
}

void focusInLocked(View view) {
    //保存焦点view变量
    mNextServedView = view;
    scheduleCheckFocusLocked(view);
}

static void scheduleCheckFocusLocked(View view) {
    ViewRootImpl viewRootImpl = view.getViewRootImpl();
    if (viewRootImpl != null) {
        viewRootImpl.dispatchCheckFocus();
    }
}

public void dispatchCheckFocus() {
    if (!mHandler.hasMessages(MSG_CHECK_FOCUS)) {
        // This will result in a call to checkFocus() below.
        mHandler.sendEmptyMessage(MSG_CHECK_FOCUS);
    }
}
        case MSG_CHECK_FOCUS: {
            InputMethodManager imm = InputMethodManager.peekInstance();
            if (imm != null) {
                imm.checkFocus();
            }
        } break;

public void checkFocus() {
    if (checkFocusNoStartInput(false, true)) {
        startInputInner(null, 0, 0, 0);
    }
}


boolean startInputInner(IBinder windowGainingFocus, int controlFlags, int softInputMode,
        int windowFlags) {
    final View view;
    synchronized (mH) {
        //获得上面的焦点view
        view = mServedView;
    }

    EditorInfo tba = new EditorInfo();
    tba.packageName = view.getContext().getPackageName();
    tba.fieldId = view.getId();
    //创建数据通信连接接口，这个会传送到InputMethodService
    //InputMethodService后面就通过这个connection将输入法的字符传递给该view
    InputConnection ic = view.onCreateInputConnection(tba);

    synchronized (mH) {
        mServedInputConnection = ic;
        ControlledInputConnectionWrapper servedContext;
        if (ic != null) {
            mCursorSelStart = tba.initialSelStart;
            mCursorSelEnd = tba.initialSelEnd;
            mCursorCandStart = -1;
            mCursorCandEnd = -1;
            mCursorRect.setEmpty();
            //将InputConnection封装为binder对象，这个是真正可以实现跨进程通
              //信的封装类
              servedContext = new ControlledInputConnectionWrapper(vh.getLooper(), ic, this);
        }
        mServedInputConnectionWrapper = servedContext;

        try {
            InputBindResult res;
            if (windowGainingFocus != null) {
                //focusIn这个不会走到这条分支
                res = mService.windowGainedFocus(mClient, windowGainingFocus,
                        controlFlags, softInputMode, windowFlags,
                        tba, servedContext);
            } else {
                //通知InputMethodManagerService,该程序的view获得焦点，IMMS
                //就会将这个view和输入法绑定
                res = mService.startInput(mClient,
                        servedContext, tba, controlFlags);
            }
            if (res != null) {
                if (res.id != null) {
                    setInputChannelLocked(res.channel);
                    mBindSequence = res.sequence;
                    //获得了输入法的通信接口
                    mCurMethod = res.method;
                    mCurId = res.id;
                }
            }
        }
    }

    return true;
}

 

IMMS处理view绑定输入法事件

         为了讲解整个绑定过程，我们假设此时输入法service还没启动，这个情况下的输入法绑定是最长的，整个过程经历过如下过程：

1)       启动输入法service

2)       绑定输入法window的token

3)       请求输入法为焦点程序创建一个连接会话-

4)       将输入法的接口传递回程序client端

5)       绑定输入法和焦点view

          1-4是和程序相关的，而5是和view相关的。所以你可以说1~4是用来绑定程序window和输入法，而5是用来绑定程序view和输入法。

          输入法还没启动时，弹出输入法会经过1~5，输入法已经启动，但是焦点window发生变化时会经历3~5，焦点window没有变化，只是改变了焦点view,则只会经历5。整个流程如下：

 

启动输入法service

@Override
public InputBindResult startInput(IInputMethodClient client,
        IInputContext inputContext, EditorInfo attribute, int controlFlags) {
    synchronized (mMethodMap) {
        final long ident = Binder.clearCallingIdentity();
        try {
            return startInputLocked(client, inputContext, attribute, controlFlags);
        }
    }
}
InputBindResult startInputLocked(IInputMethodClient client,
        IInputContext inputContext, EditorInfo attribute, int controlFlags) {
    //程序在service端对应的数据结构
    ClientState cs = mClients.get(client.asBinder());
    return startInputUncheckedLocked(cs, inputContext, attribute, controlFlags);
}

InputBindResult startInputUncheckedLocked(ClientState cs,
        IInputContext inputContext, EditorInfo attribute, int controlFlags) {
    //如果新程序和当前活动的程序不同
    if (mCurClient != cs) {
        //取消当前活动程序和输入法的绑定
        unbindCurrentClientLocked();
    }

    //将新程序设置为当前活动的程序
    mCurClient = cs;
    mCurInputContext = inputContext;
    mCurAttribute = attribute;

    if (mCurId != null && mCurId.equals(mCurMethodId)) {
        if (cs.curSession != null) {
            //连接已经建立，直接开始绑定
            return attachNewInputLocked(
                    (controlFlags&InputMethodManager.CONTROL_START_INITIAL) != 0);
        }
        if (mHaveConnection) {
            //输入法的连接是否已经创建，如果已经创建，直接传递给程序client端
            if (mCurMethod != null) {
                requestClientSessionLocked(cs);
                return new InputBindResult(null, null, mCurId, mCurSeq);
            }
        }
    }
    //否则需要启动输入法，并建立连接
    return startInputInnerLocked();
}

InputBindResult startInputInnerLocked() {
    InputMethodInfo info = mMethodMap.get(mCurMethodId);

    unbindCurrentMethodLocked(false, true);

    //启动输入法service
    mCurIntent = new Intent(InputMethod.SERVICE_INTERFACE);
    mCurIntent.setComponent(info.getComponent());
    mCurIntent.putExtra(Intent.EXTRA_CLIENT_LABEL,
            com.android.internal.R.string.input_method_binding_label);
    mCurIntent.putExtra(Intent.EXTRA_CLIENT_INTENT, PendingIntent.getActivity(
            mContext, 0, new Intent(Settings.ACTION_INPUT_METHOD_SETTINGS), 0));
    if (bindCurrentInputMethodService(mCurIntent, this, Context.BIND_AUTO_CREATE
            | Context.BIND_NOT_VISIBLE | Context.BIND_SHOWING_UI)) {
        mHaveConnection = true;
        mCurId = info.getId();
        //这个token是给输入法service用来绑定输入法的window的，通过这个token
        //InputMethodManagerService可以很方便的直接管理输入法的window
        mCurToken = new Binder();
        try {
            mIWindowManager.addWindowToken(mCurToken,
                    WindowManager.LayoutParams.TYPE_INPUT_METHOD);
        } catch (RemoteException e) {
        }
        return new InputBindResult(null, null, mCurId, mCurSeq);
    }
    return null;
}

private boolean bindCurrentInputMethodService(
        Intent service, ServiceConnection conn, int flags) {
    if (service == null || conn == null) {
        Slog.e(TAG, "--- bind failed: service = " + service + ", conn = " + conn);
        return false;
    }
    return mContext.bindServiceAsUser(service, conn, flags,
            new UserHandle(mSettings.getCurrentUserId()));
}

//输入法启动完成后就在函数onBind 传回一个binder接口
@Override
final public IBinder onBind(Intent intent) {
    if (mInputMethod == null) {
        mInputMethod = onCreateInputMethodInterface();
    }
    // IInputMethodWrapper只是一个wrapper，它负责将IMMS的调用转化为message
    //然后在message线程再调用mInputMethod对应的接口
      //这样输入法的处理就是异步的了，因此你说它就是mInputMethod
    return new IInputMethodWrapper(this, mInputMethod);
}

@Override
public AbstractInputMethodImpl onCreateInputMethodInterface() {
    return new InputMethodImpl();
}

//由于IMMS是以bindService的方式启动输入法service，所以当输入法service启动完
//成后它就会回调IMMS的onServiceConnected

@Override
public void onServiceConnected(ComponentName name, IBinder service) {
    synchronized (mMethodMap) {
        if (mCurIntent != null && name.equals(mCurIntent.getComponent())) {
            //保存输入法service传递过来的通信接口IInputMethod
            mCurMethod = IInputMethod.Stub.asInterface(service);
            //将刚刚创建的window token传递给输入法service,然后输入用这个token
            //创建window,这样IMMS可以用根据这个token找到输入法在IMMS里
              //的数据及输入法window在WMS里的数据
              executeOrSendMessage(mCurMethod, mCaller.obtainMessageOO(
                    MSG_ATTACH_TOKEN, mCurMethod, mCurToken));
            if (mCurClient != null) {
            //请求为程序和输入法建立一个连接会话，这样client就可以直接和
               //输入法通信了
                requestClientSessionLocked(mCurClient);
            }
        }
    }
}

 

输入法Window token的绑定及使用分析

      输入法Window token绑定

        IMMS在输入法启动完成并回调onServiceConnected时会将一个Window token传递给输入法。

 

@Override
public void onServiceConnected(ComponentName name, IBinder service) {
    synchronized (mMethodMap) {
        if (mCurIntent != null && name.equals(mCurIntent.getComponent())) {
            mCurMethod = IInputMethod.Stub.asInterface(service);
            executeOrSendMessage(mCurMethod, mCaller.obtainMessageOO(
                    MSG_ATTACH_TOKEN, mCurMethod, mCurToken));
            if (mCurClient != null) {
                clearClientSessionLocked(mCurClient);
                requestClientSessionLocked(mCurClient);
            }
        }
    }
}
        case MSG_ATTACH_TOKEN:
            args = (SomeArgs)msg.obj;
            try {
                //和输入法通信
                ((IInputMethod)args.arg1).attachToken((IBinder)args.arg2);
            } catch (RemoteException e) {
            }
            args.recycle();

public class InputMethodService extends AbstractInputMethodService {
public class InputMethodImpl extends AbstractInputMethodImpl {
    public void attachToken(IBinder token) {
        if (mToken == null) {
            //保存token
            mToken = token;
            //这样输入法的window就绑定这个window token
            mWindow.setToken(token);
        }
    }
}

      输入法Window token使用

       由于系统存在多个输入法，所以输入法要和IMMS通信，必须要个机制来标示自己是哪个输入法，这个就是通过上面的输入法Window token来实现的,比如输入法自己关闭自己：

 

//InputMethodService.java输入法接口
public void requestHideSelf(int flags) {
    //mToken就是上面提到的过程----IMMS传递给输入法的
    mImm.hideSoftInputFromInputMethod(mToken, flags);
}
//InputMethodManager.java
public void hideSoftInputFromInputMethod(IBinder token, int flags) {
    try {
        mService.hideMySoftInput(token, flags);
    } catch (RemoteException e) {
        throw new RuntimeException(e);
    }
}

//IMMS
@Override
public void hideMySoftInput(IBinder token, int flags) {
    if (!calledFromValidUser()) {
        return;
    }
    synchronized (mMethodMap) {
        if (token == null || mCurToken != token) {
            if (DEBUG) Slog.w(TAG, "Ignoring hideInputMethod of uid "
                    + Binder.getCallingUid() + " token: " + token);
            return;
        }
        long ident = Binder.clearCallingIdentity();
        try {
            hideCurrentInputLocked(flags, null);
        } finally {
            Binder.restoreCallingIdentity(ident);
        }
    }
}

输入法连接会话创建

       到此程序和输入法的session就建立了

@Override
public void onServiceConnected(ComponentName name, IBinder service) {
    synchronized (mMethodMap) {
        if (mCurIntent != null && name.equals(mCurIntent.getComponent())) {
            if (mCurClient != null) {
                clearClientSessionLocked(mCurClient);
                requestClientSessionLocked(mCurClient);
            }
        }
    }
}

void requestClientSessionLocked(ClientState cs) {
    if (!cs.sessionRequested) {
        //这里又出现了InputChannel对，很面熟吧，在前面几篇文章已经详细分析过
          //了，可见它已经成为一种通用的跨平台的数据通信接口了
        InputChannel[] channels = InputChannel.openInputChannelPair(cs.toString());
        cs.sessionRequested = true;
        executeOrSendMessage(mCurMethod, mCaller.obtainMessageOOO(
                MSG_CREATE_SESSION, mCurMethod, channels[1],
                new MethodCallback(this, mCurMethod, channels[0])));
    }
 }
        case MSG_CREATE_SESSION: {
            args = (SomeArgs)msg.obj;
            IInputMethod method = (IInputMethod)args.arg1;
            InputChannel channel = (InputChannel)args.arg2;
            try {
                method.createSession(channel, (IInputSessionCallback)args.arg3);
            } catch (RemoteException e) {
            }
//上面是IMMS端，下面就看IMS输入法端的处理
 public abstract class AbstractInputMethodService extends Service
    implements KeyEvent.Callback {
 public abstract class AbstractInputMethodImpl implements InputMethod {
    public void createSession(SessionCallback callback) {
        callback.sessionCreated(onCreateInputMethodSessionInterface());
    }
pre class="java" name="code">     }

}

} @Override public AbstractInputMethodSessionImpl onCreateInputMethodSessionInterface() { //sesion的真正实现 return new InputMethodSessionImpl(); } //然后回到了IMMS void onSessionCreated(IInputMethod method, IInputMethodSession session, InputChannel channel) { synchronized (mMethodMap) { if (mCurMethod != null && method != null && mCurMethod.asBinder() == method.asBinder()) { if (mCurClient != null) { //将session相关的数据封装到SessionState对象里 mCurClient.curSession = new SessionState(mCurClient, method, session, channel); //这个会开始真正的绑定 InputBindResult res = attachNewInputLocked(true); return; } } } }

传递输入法接口给程序

void onSessionCreated(IInputMethod method, IInputMethodSession session,
        InputChannel channel) {
    synchronized (mMethodMap) {
        if (mCurMethod != null && method != null
                && mCurMethod.asBinder() == method.asBinder()) {
            if (mCurClient != null) {
                InputBindResult res = attachNewInputLocked(true);
                if (res.method != null) {
                    executeOrSendMessage(mCurClient.client, mCaller.obtainMessageOO(
                            MSG_BIND_METHOD, mCurClient.client, res));
                }
                return;
            }
        }
    }
    channel.dispose();
}
        case MSG_BIND_METHOD: {
            args = (SomeArgs)msg.obj;
            IInputMethodClient client = (IInputMethodClient)args.arg1;
            InputBindResult res = (InputBindResult)args.arg2;
            try {
                //会调回到程序端
                client.onBindMethod(res);
            }
            args.recycle();
            return true;
        }

 

输入法和view绑定

//IMMS
InputBindResult attachNewInputLocked(boolean initial) {
     if (!mBoundToMethod) {
         executeOrSendMessage(mCurMethod, mCaller.obtainMessageOO(
                 MSG_BIND_INPUT, mCurMethod, mCurClient.binding));
         mBoundToMethod = true;
     }
     final SessionState session = mCurClient.curSession;
     if (initial) {
         executeOrSendMessage(session.method, mCaller.obtainMessageOOO(
                 MSG_START_INPUT, session, mCurInputContext, mCurAttribute));
     } else {
         executeOrSendMessage(session.method, mCaller.obtainMessageOOO(
                 MSG_RESTART_INPUT, session, mCurInputContext, mCurAttribute));
     }
     return new InputBindResult(session.session,
             session.channel != null ? session.channel.dup() : null, mCurId, mCurSeq);
 }
         case MSG_BIND_INPUT:
             args = (SomeArgs)msg.obj;
             try {
                 ((IInputMethod)args.arg1).bindInput((InputBinding)args.arg2);
             } catch (RemoteException e) {
             }
             args.recycle();
             return true;

         case MSG_START_INPUT:
             args = (SomeArgs)msg.obj;
             try {
                 SessionState session = (SessionState)args.arg1;
                 session.method.startInput((IInputContext)args.arg2,
                         (EditorInfo)args.arg3);
             } catch (RemoteException e) {
             }
             args.recycle();
             return true;
 //IMS
 @Override
 public void startInput(IInputContext inputContext, EditorInfo attribute) {
     mCaller.executeOrSendMessage(mCaller.obtainMessageOO(DO_START_INPUT,
             inputContext, attribute));
 }
         case DO_START_INPUT: {
             SomeArgs args = (SomeArgs)msg.obj;
             // IInputContext就是输入法和文本输入view的通信接口
             //通过这个接口，输入法能够获取view的信息，也能够直接将文本传
             //送给view
             IInputContext inputContext = (IInputContext)args.arg1;
             InputConnection ic = inputContext != null
                     ? new InputConnectionWrapper(inputContext) : null;
             EditorInfo info = (EditorInfo)args.arg2;
             inputMethod.startInput(ic, info);
             args.recycle();
             return;
         }
 public class InputMethodImpl extends AbstractInputMethodImpl {
     public void startInput(InputConnection ic, EditorInfo attribute) {
         doStartInput(ic, attribute, false);
     }
 }

 void doStartInput(InputConnection ic, EditorInfo attribute, boolean restarting) {
     if (!restarting) {
         doFinishInput();
     }
     mInputStarted = true;
     mStartedInputConnection = ic;
     mInputEditorInfo = attribute;
     initialize();
     onStartInput(attribute, restarting);
     if (mWindowVisible) {
         if (mShowInputRequested) {
             mInputViewStarted = true;
             //真正的输入法需要在这个接口里实现输入法的内容
             onStartInputView(mInputEditorInfo, restarting);
             startExtractingText(true);
         } else if (mCandidatesVisibility == View.VISIBLE) {
             mCandidatesViewStarted = true;
             onStartCandidatesView(mInputEditorInfo, restarting);
         }
     }
 }

 

        到此焦点view已经通过调用IMMS的startInput和输入法绑定了，但是此时输入法还没有显示。但是系统紧接着会调用windowGainFocus来显示输入法。

程序焦点获取事件导致输入法显示

       请查看输入法框架下篇

输入法响应显示请求

       请查看输入法框架下篇

用户单击输入框View导致输入法显示

       请查看输入法框架下篇

输入法传递输入文本信息给view

       请查看输入法框架下篇