普通的做法是设置一个高度,然后里面能显示出来几行就是几行，如果里面的内容高度变了，就需要重新调整高度来适配。
观察了一下它的onMeasure
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { ..... if (heightMode == MeasureSpec.AT_MOST) {
int ourSize = mListPadding.top + mListPadding.bottom;
final int numColumns = mNumColumns;
for (int i = ; i < count; i += numColumns) {
ourSize += childHeight;
if (i + numColumns < count) {
ourSize += mVerticalSpacing;
}
if (ourSize >= heightSize) {
ourSize = heightSize;
break;
}
}
heightSize = ourSize;
}
... }
发现，如果是它设置wrap_content，可以通过改变它的adapter来确定行数，具体方法如下是：
MyAdapter
@Override
public int getCount() {
if (mIsOnMeasure && super.getCount() >MAX_COUNT) {
return MAX_COUNT;
}
return super.getCount();
} public void setOnMeasureStatus(boolean isOnMeasure) {
mIsOnMeasure = isOnMeasure;
} Gridview- > @Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode == MeasureSpec.AT_MOST) {
((MyAdapter) getAdapter()).setOnMeasureStatus(true);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int height = getMeasuredHeight();
((FolderAdapter) getAdapter()).setOnMeasureStatus(false);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidthAndState(),
MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
} else {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
在onMeasure的时候，先让adapter假装有行数×列数的内容，调用 super.onMeasure先算出一个高，这个就是期望高度。
然后在调用一次 super.onMeasure(widthMeasureSpec, heightMeasureSpec)，把整个view绘制出来
最后通过setMeasuredDimension就可以做到了。