Android PhoneWindowManager監聽屏幕右側向左滑動實現返回功能

        由於項目沒有設計返回鍵，一旦進入別的應用，就無法回到桌面。只能通過串口輸入input keyevent 4（返回鍵）來返回桌面，爲了方便調試，在Framework 中監聽手勢，實現返回功能。

       在frameworks\base\services\core\java\com\android\server\policy\PhoneWindowManager中有這麼一段代碼

mSystemGestures = new SystemGesturesPointerEventListener(context,
                new SystemGesturesPointerEventListener.Callbacks() {
                    @Override
                    public void onSwipeFromTop() {
						Log.i("gyx","onSwipeFromTop");
                        if (mStatusBar != null) {
                            requestTransientBars(mStatusBar);
                        }
                    }
                    @Override
                    public void onSwipeFromBottom() {
						Log.i("gyx","onSwipeFromBottom");
                        if (mNavigationBar != null && mNavigationBarPosition == NAV_BAR_BOTTOM) {
                            requestTransientBars(mNavigationBar);
                        }
                    }
                    @Override
                    public void onSwipeFromRight() {
						Log.i("gyx","onSwipeFromRight");
						sendKeyCode(4);
						Log.i("gyx","sendKeyCode 4");

                        if (mNavigationBar != null && mNavigationBarPosition == NAV_BAR_RIGHT) {
                            requestTransientBars(mNavigationBar);
                        }
                    }
                    @Override
                    public void onSwipeFromLeft() {
						Log.i("gyx","onSwipeFromLeft");
                        if (mNavigationBar != null && mNavigationBarPosition == NAV_BAR_LEFT) {
                            requestTransientBars(mNavigationBar);
                        }
                    }
                    @Override
                    public void onFling(int duration) {
                        if (mPowerManagerInternal != null) {
                            mPowerManagerInternal.powerHint(
                                    PowerHint.INTERACTION, duration);
                        }
                    }
                    @Override
                    public void onDebug() {
                        // no-op
                    }
                    @Override
                    public void onDown() {
                        mOrientationListener.onTouchStart();
                    }
                    @Override
                    public void onUpOrCancel() {
                        mOrientationListener.onTouchEnd();
                    }
                    @Override
                    public void onMouseHoverAtTop() {
                        mHandler.removeMessages(MSG_REQUEST_TRANSIENT_BARS);
                        Message msg = mHandler.obtainMessage(MSG_REQUEST_TRANSIENT_BARS);
                        msg.arg1 = MSG_REQUEST_TRANSIENT_BARS_ARG_STATUS;
                        mHandler.sendMessageDelayed(msg, 500);
                    }
                    @Override
                    public void onMouseHoverAtBottom() {
                        mHandler.removeMessages(MSG_REQUEST_TRANSIENT_BARS);
                        Message msg = mHandler.obtainMessage(MSG_REQUEST_TRANSIENT_BARS);
                        msg.arg1 = MSG_REQUEST_TRANSIENT_BARS_ARG_NAVIGATION;
                        mHandler.sendMessageDelayed(msg, 500);
                    }
                    @Override
                    public void onMouseLeaveFromEdge() {
                        mHandler.removeMessages(MSG_REQUEST_TRANSIENT_BARS);
                    }
                });

代碼中監聽了手勢操作，其中onSwipeFromRight()就是當從屏幕的右側向左滑動時會觸發，只要在這裏加入返回的功能即可；
實現返回按鍵的功能代碼如下

private void sendKeyCode(final int keyCode) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    // 創建一個Instrumentation對象
                    Instrumentation inst = new Instrumentation();
                    // 調用inst對象的按鍵模擬方法
                    inst.sendKeyDownUpSync(keyCode);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }