<item name="android:windowTranslucentStatus">true</item>

 private void initStatusBar() {
    if (statusBarView == null) {
      //android系统级的资源id得这么拿,不然拿不到
      int identifier = getResources().getIdentifier("statusBarBackground", "id", "android");
      statusBarView = getWindow().findViewById(identifier);
    }
    if (statusBarView != null) {
      statusBarView.setBackgroundResource("你的渐变drawable资源id");
    }
  }

    Looper.myQueue().addIdleHandler(new MessageQueue.IdleHandler() {
      @Override
      public boolean queueIdle() {
        if (isStatusBar()) {
          initStatusBar();
          getWindow().getDecorView().addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
            @Override
            public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
              initStatusBar();
            }
          });
        }
        return false;
      }
    });

  private View statusBarView;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    //延时加载数据.
    Looper.myQueue().addIdleHandler(new MessageQueue.IdleHandler() {
      @Override
      public boolean queueIdle() {
        if (isStatusBar()) {
          initStatusBar();
          getWindow().getDecorView().addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
            @Override
            public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
              initStatusBar();
            }
          });
        }
        //只走一次
        return false;
      }
    });
  }
  private void initStatusBar() {
    if (statusBarView == null) {
      int identifier = getResources().getIdentifier("statusBarBackground", "id", "android");
      statusBarView = getWindow().findViewById(identifier);
    }
    if (statusBarView != null) {
        statusBarView.setBackgroundResource("你的渐变drawable资源id");
    }
  }

   protected boolean isStatusBar() {
    return true;
  }