关于Scrollview嵌套RecyclerView高度显示不全

前言

转载请注明出处：http://blog.csdn.net/dreamsever/article/details/58117072

做 Android开发我们经常会遇到这种ScrollView嵌套Listview或者 嵌套RecyclerView的需求，当我们搜索解决方案时经常会遇到这句话

you should never put a scrollable view inside another scrollable view

虽然很多人不推荐这种方法，但是总有一些人（比如我）面对产品设计的一些奇葩界面不得不采用这种方案，今天我就把我找到的Scrollview嵌套Recyclerview高度显示不全解决办法总结一下。（ScrollView嵌套Listview的情况也是老生常谈的话题，网上太多就不再赘述）

首先

网上已经有前人给我们写出了一个自定义的LinearLayoutManager，我相信你也可以搜索到，下面我先粘贴出来，感兴趣建议好好看看这个类的源码，不要只做搬运工，知其然也要知其所以然，但是使用中会遇到一些小问题，下面讲解

/**
* 工具类 用于Scrollview嵌套recyclerview
* 2017 2 17加入
*/
public class FullyLinearLayoutManager extends LinearLayoutManager {

private static final String TAG = FullyLinearLayoutManager.class.getSimpleName();

public FullyLinearLayoutManager(Context context) {
super(context);
}

public FullyLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}

private int[] mMeasuredDimension = new int[2];

@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
int widthSpec, int heightSpec) {

final int widthMode = View.MeasureSpec.getMode(widthSpec);
final int heightMode = View.MeasureSpec.getMode(heightSpec);
final int widthSize = View.MeasureSpec.getSize(widthSpec);
final int heightSize = View.MeasureSpec.getSize(heightSpec);

Log.i(TAG, "onMeasure called. \nwidthMode " + widthMode
+ " \nheightMode " + heightSpec
+ " \nwidthSize " + widthSize
+ " \nheightSize " + heightSize
+ " \ngetItemCount() " + getItemCount());

int width = 0;
int height = 0;
for (int i = 0; i < getItemCount(); i++) {
measureScrapChild(recycler, i,
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
mMeasuredDimension);

if (getOrientation() == HORIZONTAL) {
width = width + mMeasuredDimension[0];
if (i == 0) {
height = mMeasuredDimension[1];
}
} else {
height = height + mMeasuredDimension[1];
if (i == 0) {
width = mMeasuredDimension[0];
}
}
}
switch (widthMode) {
case View.MeasureSpec.EXACTLY:
width = widthSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}

switch (heightMode) {
case View.MeasureSpec.EXACTLY:
height = heightSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}

setMeasuredDimension(width, height);
}

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
int heightSpec, int[] measuredDimension) {
try {
View view = recycler.getViewForPosition(0);//fix 动态添加时报IndexOutOfBoundsException

if (view != null) {
RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();

int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
getPaddingLeft() + getPaddingRight(), p.width);

int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
getPaddingTop() + getPaddingBottom(), p.height);

view.measure(childWidthSpec, childHeightSpec);
measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
recycler.recycleView(view);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
}
}
}

小问题，值得注意的地方

1，

给scrollview加入一个属性

android:fillViewport="true"

2,

处理滑动冲突情况，如下设置

recyclerView.setNestedScrollingEnabled(false);

3,

我开始用的scrollview，测试设备：小米note黑 adnroid6.0,由于我的里面有两个RecyclerView我发现下面的超出屏幕的部分就不显示了，其他的机型是可以的。网上搜索建议将Scrollview换成android.support.v4.widget.NestedScrollView，我试了一下确实正常工作了

总结

you should never put a scrollable view inside another scrollable view

如果这个界面确实要求不高，这样写确实省了不少功夫，那就这样干吧！