Android PhoneWindowManager监听屏幕右侧向左滑动实现返回功能移动开发weixin35649059的博客-

        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frameworksbaseservicescorejavacomandroidserverpolicyPhoneWindowManager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();     }