获取Android控件的宽和高

在oncreate()方法中获取控件的宽高，只会获得0，缘由是oncreate()方法执行完成后控件才会被度量(measure)，因此咱们在onCreate方法里面经过view.getHeight()获取控件的高度或者宽度确定是0,由于它本身尚未被度量,也就是说他本身都不知道本身有多高,而你这时候去获取它的尺寸,确定是不行的. 解决方法：

//------------------------------------------------方法一

<!-- lang: java -->

int w = View.MeasureSpec.makeMeasureSpec(0,View.MeasureSpec.UNSPECIFIED);  
int h = View.MeasureSpec.makeMeasureSpec(0,View.MeasureSpec.UNSPECIFIED);  
imageView.measure(w, h);  
int height =imageView.getMeasuredHeight();  
int width =imageView.getMeasuredWidth();  
textView.append("\n"+height+","+width);

//-----------------------------------------------方法二

<!-- lang: java -->

ViewTreeObserver vto = imageView.getViewTreeObserver();  
vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {  
    public boolean onPreDraw() {  
        int height = imageView.getMeasuredHeight();  
        int width = imageView.getMeasuredWidth();  
        textView.append("\n"+height+","+width);  
        return true;  
    }  
});

//-----------------------------------------------方法三

<!-- lang: java -->

ViewTreeObserver vto2 = imageView.getViewTreeObserver();    
vto2.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {  
    @Override    
    public void onGlobalLayout() {  
        imageView.getViewTreeObserver().removeGlobalOnLayoutListener(this);    
        textView.append("\n\n"+imageView.getHeight()+","+imageView.getWidth());  
    }    
});

方法一: 比其余的两个方法多了一次计算,也就是多调用了一次onMeasure()方法,该方法虽然看上去简单,可是若是要目标控件计算耗时比较大的话(如listView等),不建议使用. 方法二,在绘制前执行回调方法，它的回调方法会调用不少次,而且滑动TextView的时候任然会调用,因此不建议使用. 方法三,当layout或控件的visibility被调用时，执行此回调

方法四：

<!-- lang: java -->
    private void measureItem(View child) {  
         ViewGroup.LayoutParams p = child.getLayoutParams();  
         if (p == null) {  
             p = new ViewGroup.LayoutParams(  
                     ViewGroup.LayoutParams.MATCH_PARENT,  
                     ViewGroup.LayoutParams.WRAP_CONTENT);  
         }  
   
         int childWidthSpec = ViewGroup.getChildMeasureSpec(mWidthMeasureSpec,  
                 mListPadding.left + mListPadding.right, p.width);  
         int lpHeight = p.height;  
         int childHeightSpec;  
         if (lpHeight > 0) {  
             childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY);  
         } else {  
             childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);  
         }  
         child.measure(childWidthSpec, childHeightSpec);  
     }