解决ViewPager高度无法wrap_content问题

直接上解决方法，需要重写ViewPager中的onMeasure方法。

/**
* ViewPager wrapContent解决方案
*/
public class WrapContentHeightViewPager extends ViewPager {

/**
* Constructor
*
* @param context the context
*/
public WrapContentHeightViewPager(Context context) {
super(context);
}

/**
* Constructor
*
* @param context the context
* @param attrs the attribute set
*/
public WrapContentHeightViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}

// @Override
// protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// super.onMeasure(widthMeasureSpec, heightMeasureSpec);
//
// // find the first child view
// View view = getChildAt(0);
// if (view != null) {
// // measure the first child view with the specified measure spec
// view.measure(widthMeasureSpec, heightMeasureSpec);
// }
//
// setMeasuredDimension(getMeasuredWidth(), measureHeight(heightMeasureSpec, view));
// }
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

int height = 0;
for(int i = 0; i < getChildCount(); i++) {
View child = getChildAt(i);
child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
int h = child.getMeasuredHeight();
if(h > height) height = h;
}

heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);

super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
/**
* Determines the height of this view
*
* @param measureSpec A measureSpec packed into an int
* @param view the base view with already measured height
*
* @return The height of the view, honoring constraints from measureSpec
*/
private int measureHeight(int measureSpec, View view) {
int result = 0;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);

if (specMode == MeasureSpec.EXACTLY) {
result = specSize;
} else {
// set the height from the base view if available
if (view != null) {
result = view.getMeasuredHeight();
}
if (specMode == MeasureSpec.AT_MOST) {
result = Math.min(result, specSize);
}
}
return result;
}

}