解决android 显示内容被底部导航栏遮挡的问题

public class AndroidBug5497Workaround {
 
 // For more information, see https://code.google.com/p/android/issues/detail?id=5497
 // To use this class, simply invoke assistActivity() on an Activity that already has its content 
 
view set.
 
 public static void assistActivity (Activity activity) {
 new AndroidBug5497Workaround(activity);
 }
 private Activity activity;
 private View mChildOfContent;
 private int usableHeightPrevious;
 private FrameLayout.LayoutParams frameLayoutParams;
 
 private AndroidBug5497Workaround(Activity activity) {
 this.activity = activity;
 FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
 mChildOfContent = content.getChildAt(0);
 mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(new 
 
ViewTreeObserver.OnGlobalLayoutListener() {
  public void onGlobalLayout() {
  possiblyResizeChildOfContent();
  }
 });
 frameLayoutParams = (FrameLayout.LayoutParams) mChildOfContent.getLayoutParams();
 }
 
 private void possiblyResizeChildOfContent() {
 int usableHeightNow = computeUsableHeight();
 LogUtils.e("possiblyResizeChildOfContent","usableHeightNow:"+usableHeightNow);
 LogUtils.e("possiblyResizeChildOfContent","usableHeightPrevious:"+usableHeightPrevious);
 if (usableHeightNow != usableHeightPrevious) {
  int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
 
  //这个判断是为了解决19之前的版本不支持沉浸式状态栏导致布局显示不完全的问题
  if(Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT){
  Rect frame = new Rect();
  activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
  int statusBarHeight = frame.top;
  usableHeightSansKeyboard -= statusBarHeight;
  }
  int heightDifference = usableHeightSansKeyboard - usableHeightNow;
  if (heightDifference > (usableHeightSansKeyboard/4)) {
  // keyboard probably just became visible
  frameLayoutParams.height = usableHeightSansKeyboard - heightDifference;
  } else {
  // keyboard probably just became hidden
  frameLayoutParams.height = usableHeightSansKeyboard;
  }
  mChildOfContent.requestLayout();
  usableHeightPrevious = usableHeightNow;
 }
 }
 
 private int computeUsableHeight() {
 Rect frame = new Rect();
 activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
 int statusBarHeight = frame.top;
 
 Rect r = new Rect();
 mChildOfContent.getWindowVisibleDisplayFrame(r);
 
 //这个判断是为了解决19之后的版本在弹出软键盘时，键盘和推上去的布局（adjustResize）之间有黑色区域
 
的问题
 if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT){
  return (r.bottom - r.top)+statusBarHeight;
 }
 
 return (r.bottom - r.top);
 }
 
}