Platform: Rockchip
OS: Android 6.0
Kernel: 3.10.92

此文實現以廣播的形式動態顯示和隱藏導航欄，這樣不僅避免了系統通過了自帶只針對Activity顯示和隱藏的不便(比如一個app有N多個Activity)，而且可以在任何地方去動態修改。
改動：

diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
index 7
 
c73b83..7da188d 100755
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
@@ -204,6 +204,10 @@ public class PhoneStatusBar extends BaseStatusBar implements DemoMode,
         DragDownHelper.DragDownCallback
 
, ActivityStarter, OnUnlockMethodChangedListener,
         HeadsUpManager.OnHeadsUpChangedListener {
     static final String TAG = "PhoneStatusBar";
+    /*Kris, 170726, hide/show NavigationBar dynamicly. {*/
+    static final String HIDE_NAVIGATION_BAR = "android.intent.action.HIDE_NAVIGATION_BAR";
+    static
 
 final String SHOW_NAVIGATION_BAR = "android.intent.action.SHOW_NAVIGATION_BAR";
+    /*Kris, 170726, hide/show NavigationBar dynamicly. }*/
     public static final boolean DEBUG = BaseStatusBar.DEBUG;
     public static final boolean SPEW = false;
     public static final boolean DUMPTRUCK = true; // extra dumpsys info
@@ -1069,6 +1073,10 @@ public class PhoneStatusBar extends BaseStatusBar implements DemoMode,
             demoFilter.addAction(ACTION_FAKE_ARTWORK);
         }
         demoFilter.addAction(ACTION_DEMO);
+        /*Kris, 170726, hide/show NavigationBar dynamicly. {*/
+    demoFilter.addAction(HIDE_NAVIGATION_BAR);
+        demoFilter.addAction(SHOW_NAVIGATION_BAR);
+    /*Kris, 170726, hide/show NavigationBar dynamicly. }*/
         context.registerReceiverAsUser(mDemoReceiver, UserHandle.ALL, demoFilter,
                 android.Manifest.permission.DUMP, null);

@@ -1304,9 +1312,48 @@ public class PhoneStatusBar extends BaseStatusBar implements DemoMode,
         mWindowManager.addView(mNavigationBarView, getNavigationBarLayoutParams());
     }

+    /*Kris, 170726, hide/show NavigationBar dynamicly. {*/
+    private void addNavigationBarInnerLocked(){
+        if(mNavigationBarView == null){
+            mNavigationBarView = (NavigationBarView) View.inflate(mContext, R.layout.navigation_bar, null);
+            mNavigationBarView.setDisabledFlags(mDisabled1);
+            mNavigationBarView.setBar(this);
+            mNavigationBarView.setOnTouchListener(new View.OnTouchListener() {
+                @Override
+                public boolean onTouch(View v, MotionEvent event) {
+                    checkUserAutohide(v, event);
+                    return false;
+                }
+            });
+            if (mNavigationBarView == null)
+                return;
+            prepareNavigationBarView();
+            try {
+                mWindowManager.addView(mNavigationBarView, getNavigationBarLayoutParams());
+                    } catch (Exception e) {
+                }
+        }
+    }
+
+    private void removeNavigationBar() {
+        if (mNavigationBarView == null)
+            return;
+        mWindowManager.removeView(mNavigationBarView);
+        mNavigationBarView = null;
+    }
+
+    public void displayNavigation(){
+        addNavigationBarInnerLocked();
+    }
+    public void hideNavigation(){
+        removeNavigationBar();
+    }
+    /*Kris, 170726, hide/show NavigationBar dynamicly. }*/
+
     private void repositionNavigationBar() {
         if (mNavigationBarView == null || !mNavigationBarView.isAttachedToWindow()) return;

+
         prepareNavigationBarView();

         mWindowManager.updateViewLayout(mNavigationBarView, getNavigationBarLayoutParams());
@@ -3117,7 +3164,13 @@ public class PhoneStatusBar extends BaseStatusBar implements DemoMode,
                 if (DEBUG_MEDIA_FAKE_ARTWORK) {
                     updateMediaMetaData(true);
                 }
-            }
+        /*Kris, 170726, hide/show NavigationBar dynamicly. {*/
+            }  else     if(HIDE_NAVIGATION_BAR.equals(action)){
+            hideNavigation();
+        }else if(SHOW_NAVIGATION_BAR.equals(action)){
+            displayNavigation();
+        }
+        /*Kris, 170726, hide/show NavigationBar dynamicly. }*/
         }
     };

測試：
隱藏：
[email protected]:/ # am broadcast -a android.intent.action.HIDE_NAVIGATION_BAR
Broadcasting: Intent { act=android.intent.action.HIDE_NAVIGATION_BAR }
Broadcast completed: result=0

顯示：
[email protected]:/ # am broadcast -a android.intent.action.SHOW_NAVIGATION_BAR
Broadcasting: Intent { act=android.intent.action.SHOW_NAVIGATION_BAR }
Broadcast completed: result=0