基于Android的模拟点击探索

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前言

压力测试中，一般会用到自动化测试。准备写一个APP，可以记录屏幕上的点击事件，然后通过shell命令来模拟自动执行。shell指令，比较容易实现。那么，关键的一步是获取点击的坐标。对于Android来说，为便于开发者调试，Android系统中的"开发者选项"中，有一个"指针位置"的选项。打开这个选项，点击屏幕，就会显示当前点击的位置坐标。接下来，来看一下打开选项的过程。

开发者选项页面

"开发者选项"的源码位于packages/apps/settings/src/com/android/settings/DevelopmentSettings.java文件中。

private SwitchPreference mPointerLocation;

在onCreate()方法中初始化:

mPointerLocation = findAndInitSwitchPref(POINTER_LOCATION_KEY);

findAndInitSwitchPref()方法:

private SwitchPreference findAndInitSwitchPref(String key) {
    SwitchPreference pref = (SwitchPreference) findPreference(key);
    if (pref == null) {
        throw new IllegalArgumentException("Cannot find preference with key = " + key);
    }
    mAllPrefs.add(pref);
    mResetSwitchPrefs.add(pref);
    return pref;
}

当点击选项开关切换后，会把当前的开关状态存入Settings数据库。

private void writePointerLocationOptions() {
    Settings.System.putInt(getActivity().getContentResolver(),
            Settings.System.POINTER_LOCATION, mPointerLocation.isChecked() ? 1 : 0);
}

PhoneWindowManager

PhoneWindowManager的源码位于framework/base/services/core/java/com/android/server/policy/PhoneWindowManager.java文件中。

PhoneWindowManager会监听Settings.System.POINTER_LOCATION字段的变化。

class SettingsObserver extends ContentObserver {
    SettingsObserver(Handler handler) {
        super(handler);
    }

    void observe() {
        // Observe all users' changes
        ContentResolver resolver = mContext.getContentResolver();
        ...
        resolver.registerContentObserver(Settings.System.getUriFor(
                Settings.System.POINTER_LOCATION), false, this,
                UserHandle.USER_ALL);
        ...
        updateSettings();
    }

    @Override public void onChange(boolean selfChange) {
        updateSettings();
        updateRotation(false);
    }
}

当这个值发生变化时，在updateSettings()方法中调用：

public void updateSettings() {
    ContentResolver resolver = mContext.getContentResolver();
    boolean updateRotation = false;
    synchronized (mLock) {
        ...

        if (mSystemReady) {
            int pointerLocation = Settings.System.getIntForUser(resolver,
                    Settings.System.POINTER_LOCATION, 0, UserHandle.USER_CURRENT);
            if (mPointerLocationMode != pointerLocation) {
                mPointerLocationMode = pointerLocation;
                mHandler.sendEmptyMessage(pointerLocation != 0 ?
                        MSG_ENABLE_POINTER_LOCATION : MSG_DISABLE_POINTER_LOCATION);
            }
        }
        ...
    }
    synchronized (mWindowManagerFuncs.getWindowManagerLock()) {
        PolicyControl.reloadFromSetting(mContext);
    }
    if (updateRotation) {
        updateRotation(true);
    }
}

在这个方法中，会通过Handler能送一个Message去处理。

private class PolicyHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
            case MSG_ENABLE_POINTER_LOCATION:
                enablePointerLocation();
                break;
            case MSG_DISABLE_POINTER_LOCATION:
                disablePointerLocation();
                break;
			...
        }
    }
}

如果打开了"指针位置"的选项开关，那么会调用enablePointerLocation()方法

private void enablePointerLocation() {
    if (mPointerLocationView == null) {
        mPointerLocationView = new PointerLocationView(mContext);
        mPointerLocationView.setPrintCoords(false);
        WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.MATCH_PARENT,
                WindowManager.LayoutParams.MATCH_PARENT);
        lp.type = WindowManager.LayoutParams.TYPE_SECURE_SYSTEM_OVERLAY;
        lp.flags = WindowManager.LayoutParams.FLAG_FULLSCREEN
                | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
                | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
        if (ActivityManager.isHighEndGfx()) {
            lp.flags |= WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;
            lp.privateFlags |=
                    WindowManager.LayoutParams.PRIVATE_FLAG_FORCE_HARDWARE_ACCELERATED;
        }
        lp.format = PixelFormat.TRANSLUCENT;
        lp.setTitle("PointerLocation");
        WindowManager wm = (WindowManager) mContext.getSystemService(WINDOW_SERVICE);
        lp.inputFeatures |= WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL;
        wm.addView(mPointerLocationView, lp);
        mWindowManagerFuncs.registerPointerEventListener(mPointerLocationView);
    }
}

在这个方法中，首先初始化一个PointerLocationView对象，然后设置WindowManager.LayoutParams，然后将PointerLocationView实例添加到window中。再通过WindowManagerFuncs注册监听。

当屏幕上有点击时，会回调PointerLocationView的onPointerEvent()方法：

@Override
public void onPointerEvent(MotionEvent event) {
    ...
}

通过反射可以获取到PointerLocationView的实例，但是无法获取到WindowManagerFuncs实例。WindowManagerFuncs是在PhoneWindowManager的init()方法中初始化的。

@Override
public void init(Context context, IWindowManager windowManager,
        WindowManagerFuncs windowManagerFuncs) {
    mContext = context;
    mWindowManager = windowManager;
    mWindowManagerFuncs = windowManagerFuncs;
    ...

对于WindowManager的流程不了解。这种方法看来是行不通了。。。

在网上查了相关的资料，还有种方法是通过adb的getevent命令来获取/dev/input/路径下的event事件数据，然后解析相关数据。不过对于这块也不熟悉，就没有再深入研究。

总的来说，开发基于Android的模拟点击的应用是以失败告终。后面有时间再研究下是否有其它方法可以实现。