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();
}
