ListView中提前测量View尺寸

/*** ListView中提前测量View尺寸，如headerView*/private void measureView(View view) {    ViewGroup.LayoutParams p = view.getLayoutParams();    if (p == null) {        p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,                ViewGroup.LayoutParams.WRAP_CONTENT);    }

//第一个参数spec =0,mode是UNSPECIFIED(未指定)，父元素不对子元素施加任何束缚,第二个参数，是外边距和内边距    int width = ViewGroup.getChildMeasureSpec(0, 0, p.width);

　　int height; int tempHeight = p.height; 　　if (tempHeight > 0) { 　　height = MeasureSpec.makeMeasureSpec(tempHeight, MeasureSpec.EXACTLY); 　　　　} else { 　　　　height = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 　　　　} 　　view.measure(width, height); }