Android PhoneWindowManager监听屏幕右侧向左滑动实现返回功能

由于项目没有设计返回键，一旦进入别的应用，就无法回到桌面。只能通过串口输入input keyevent 4（返回键）来返回桌面，为了方便调试，在Framework 中监听手势，实现返回功能。

       在frameworks\base\services\core\java\com\android\server\policy\PhoneWindowManager中有这么一段代码

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);
          }
        });

代码中监听了手势操作，其中onSwipeFromRight()就是当从屏幕的右侧向左滑动时会触发，只要在这里加入返回的功能即可；

实现返回按键的功能代码如下

private void sendKeyCode(final int keyCode) {
    new Thread(new Runnable() {
      @Override
      public void run() {
        try {
          // 创建一个Instrumentation对象
          Instrumentation inst = new Instrumentation();
          // 调用inst对象的按键模拟方法
          inst.sendKeyDownUpSync(keyCode);
        } catch (Exception e) {
          e.printStackTrace();
        }
      }
    }).start();
  }