//在onCreate中使用，rlRoot是根布局
rlRoot.getViewTreeObserver().addOnGlobalLayoutListener(
				new ViewTreeObserver.OnGlobalLayoutListener() {

					@Override
					public void onGlobalLayout() {
						if (!hasSetSize) {
							changeScreen();
							hasSetSize = true;
						}

					}
				});

private void changeScreen() {
		DisplayMetrics displayMetrics = new DisplayMetrics();
		getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
		int height = displayMetrics.heightPixels;
		int width = displayMetrics.widthPixels;
		if (getWindow().getDecorView().getWidth() == width) {
			getWindow().setLayout(
					(int) (width * Constants.SCREEN_MAIN_WIDTH
							/ Constants.SCREEN_WIDTH),
					(int) (height * Constants.SCREEN_MAIN_HEIGHT
							/ Constants.SCREEN_HEIGHT));
		} else {
//			getWindow().setLayout(width, height);
		}
	}