View.getDrawingCache()为Null的解决办法

在getDrawingCache()之前调用下面的代码

View.measure(  
                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),  
                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));  
        View.layout(0, 0, View.getMeasuredWidth(),  
        		View.getMeasuredHeight());  
        View.buildDrawingCache();