问题补充：

Android群英传 3.2View的测量代码

@Override

protected void onMeasure(int widthMeasureSpec,

int heightMeasureSpec) {

setMeasuredDimension(

measureWidth(widthMeasureSpec),

measureHeight(heightMeasureSpec));

}

private int measureWidth(int measureSpec) {

int result = 0;

int specMode = MeasureSpec.getMode(measureSpec);

int specSize = MeasureSpec.getSize(measureSpec);

if (specMode == MeasureSpec.EXACTLY) {

result = specSize;

} else {

result = 200;

if (specMode == MeasureSpec.AT_MOST) {

result = Math.min(result, specSize);

}

}

return result;

}

请问 if (specMode == MeasureSpec.AT_MOST) {

result = Math.min(result, specSize);

语句有什么作用呢？前面result = 200 不是已经设置自定义View的wrap_content默认值为200px了么？