详解 Android Views 元素的 layout_weight 属性

所有View(视图)元素中都有一个XML属性android:layout_weight，其值为0，1，2，3...等整数值。使用了之后，其对应界面中的元素比例就会发生变化，变大或者变小。layout_weight属性其实就是一个元素重要度的属性，用于在线性布局中为不同的view元素设置不同的重要度。

　　所有的视图都有一个layout_weight值，其默认值为0，表示视图多大就占据多大的屏幕空间。若赋一个>0的数值，则各视图元素将会把父视图中的可用空间进行分割，分割大小具体取决于每一个视图的layout_weight值以及该值在当前屏幕布局的整体layout_weight值和在其它视图屏幕布局的layout_weight值中所占的比率而定。

　　比如：说我们在水平方向两个文本标签(TextView)，两个文本标签各自并指定layout_weight值为1，则各占一半，一个是1，一个2，则一个占2/3屏幕，一个占1/3。

　　需要注意的是：layout_weight值越小其重要度越高，占用屏幕越大。

layout_weight用于给一个线性布局中的诸多视图的重要度赋值。所有的视图都有一个layout_weight值，默认为零，意思是需要显示多大的视图就占据多大的屏幕空 间。若赋一个高于零的值，则将父视图中的可用空间分割，分割大小具体取决于每一个视图的layout_weight值以及该值在当前屏幕布局的整体layout_weight值和在其它视图屏幕布局的layout_weight值中所占的比率而定。

ayout_weight is used in LinearLayouts to assign "importance" to Views within the layout. All Views have a default layout_weight of zero, meaning they take up only as much room on the screen as they need to be displayed. Assigning a value higher than zero will split up the rest of the available space in the parent View, according to the value of each View's layout_weight and its ratio to the overall layout_weight specified in the current layout for this and other View elements.

To give an example: let's say we have a text label and two text edit elements in a horizontal row. The label has no layout_weight specified, so it takes up the minimum space required to render. If the layout_weight of each of the two text edit elements is set to 1, the remaining width in the parent layout will be split equally between them (because we claim they are equally important). If the first one has a layout_weight of 1 and the second has a layout_weight of 2, then one third of the remaining space will be given to the first, and two thirds to the second (because we claim the second one is more important).