嵌套的Recycler视图高度不会包装其内容

时间：2014-10-30 09:34:30

标签： android android-layout android-studio android-recyclerview android-support-library

我有一个应用程序来管理书籍集（如播放列表）。

我希望显示一个带有垂直RecyclerView的集合列表，并在每行内部显示水平RecyclerView中的书籍列表。

当我将内部水平RecyclerView的layout_height设置为300dp时，它会正确显示，但当我将其设置为wrap_content时，它不会显示任何内容。 我需要使用wrap_content，因为我希望能够以编程方式更改布局管理器以在垂直和水平显示之间切换。

enter image description here

你知道我做错了吗？

我的片段布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="@color/white">

    <com.twibit.ui.view.CustomSwipeToRefreshLayout
        android:id="@+id/swipe_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <android.support.v7.widget.RecyclerView
                android:id="@+id/shelf_collection_listview"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:paddingTop="10dp"/>

        </LinearLayout>

    </com.twibit.ui.view.CustomSwipeToRefreshLayout>
</LinearLayout>

收集元素布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:orientation="vertical">

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="#FFF">

        <!-- Simple Header -->

    </RelativeLayout>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="@string/empty_collection"
            android:id="@+id/empty_collection_tv"
            android:visibility="gone"
            android:gravity="center"/>

        <android.support.v7.widget.RecyclerView
            android:id="@+id/collection_book_listview"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/> <!-- android:layout_height="300dp" -->

    </FrameLayout>

</LinearLayout>

图书清单项目：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="180dp"
              android:layout_height="220dp"
              android:layout_gravity="center">

        <ImageView
            android:id="@+id/shelf_item_cover"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:maxWidth="150dp"
            android:maxHeight="200dp"
            android:src="@drawable/placeholder"
            android:contentDescription="@string/cover"
            android:adjustViewBounds="true"
            android:background="@android:drawable/dialog_holo_light_frame"/>

</FrameLayout>

这是我的收藏适配器：

private class CollectionsListAdapter extends RecyclerView.Adapter<CollectionsListAdapter.ViewHolder> {
    private final String TAG = CollectionsListAdapter.class.getSimpleName();
    private Context mContext;

    // Create the ViewHolder class to keep references to your views
    class ViewHolder extends RecyclerView.ViewHolder {

        private final TextView mHeaderTitleTextView;
        private final TextView mHeaderCountTextView;

        private final RecyclerView mHorizontalListView;
        private final TextView mEmptyTextView;

        public ViewHolder(View view) {
            super(view);

            mHeaderTitleTextView = (TextView) view.findViewById(R.id.collection_header_tv);
            mHeaderCountTextView = (TextView) view.findViewById(R.id.collection_header_count_tv);

            mHorizontalListView = (RecyclerView) view.findViewById(R.id.collection_book_listview);
            mEmptyTextView = (TextView) view.findViewById(R.id.empty_collection_tv);
        }
    }


    public CollectionsListAdapter(Context context) {
        mContext = context;
    }


    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int i) {
        Log.d(TAG, "CollectionsListAdapter.onCreateViewHolder(" + parent.getId() + ", " + i + ")");
        // Create a new view by inflating the row item xml.
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.shelf_collection, parent, false);

        // Set the view to the ViewHolder
        ViewHolder holder = new ViewHolder(v);

        holder.mHorizontalListView.setHasFixedSize(false);
        holder.mHorizontalListView.setHorizontalScrollBarEnabled(true);

        // use a linear layout manager
        LinearLayoutManager mLayoutManager = new LinearLayoutManager(mContext);
        mLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        holder.mHorizontalListView.setLayoutManager(mLayoutManager);

        return holder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int i) {
        Log.d(TAG, "CollectionsListAdapter.onBindViewHolder(" + holder.getPosition() + ", " + i + ")");

        Collection collection = mCollectionList.get(i);
        Log.d(TAG, "Collection : " + collection.getLabel());

        holder.mHeaderTitleTextView.setText(collection.getLabel());
        holder.mHeaderCountTextView.setText("" + collection.getBooks().size());

        // Create an adapter if none exists
        if (!mBookListAdapterMap.containsKey(collection.getCollectionId())) {
            mBookListAdapterMap.put(collection.getCollectionId(), new BookListAdapter(getActivity(), collection));
        }

        holder.mHorizontalListView.setAdapter(mBookListAdapterMap.get(collection.getCollectionId()));

    }

    @Override
    public int getItemCount() {
        return mCollectionList.size();
    }
}

最后，书适配器：

private class BookListAdapter extends RecyclerView.Adapter<BookListAdapter.ViewHolder> implements View.OnClickListener {
    private final String TAG = BookListAdapter.class.getSimpleName();

    // Create the ViewHolder class to keep references to your views
    class ViewHolder extends RecyclerView.ViewHolder {
        public ImageView mCoverImageView;

        public ViewHolder(View view) {
            super(view);
            mCoverImageView = (ImageView) view.findViewById(R.id.shelf_item_cover);
        }
    }

    @Override
    public void onClick(View v) {
        BookListAdapter.ViewHolder holder = (BookListAdapter.ViewHolder) v.getTag();
        int position = holder.getPosition();
        final Book book = mCollection.getBooks().get(position);

        // Click on cover image
        if (v.getId() == holder.mCoverImageView.getId()) {
            downloadOrOpenBook(book);
            return;
        }
    }

    private void downloadOrOpenBook(final Book book) {
        // do stuff
    }

    private Context mContext;
    private Collection mCollection;

    public BookListAdapter(Context context, Collection collection) {
        Log.d(TAG, "BookListAdapter(" + context + ", " + collection + ")");
        mCollection = collection;
        mContext = context;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int i) {
        Log.d(TAG, "onCreateViewHolder(" + parent.getId() + ", " + i + ")");
        // Create a new view by inflating the row item xml.
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.shelf_grid_item, parent, false);

        // Set the view to the ViewHolder
        ViewHolder holder = new ViewHolder(v);
        holder.mCoverImageView.setOnClickListener(BookListAdapter.this); // Download or Open

        holder.mCoverImageView.setTag(holder);

        return holder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int i) {
        Log.d(TAG, "onBindViewHolder(" + holder.getPosition() + ", " + i + ")");

        Book book = mCollection.getBooks().get(i);

        ImageView imageView = holder.mCoverImageView;
        ImageLoader.getInstance().displayImage(book.getCoverUrl(), imageView);
    }

    @Override
    public int getItemCount() {
        return mCollection.getBooks().size();
    }
}

15 个答案:

答案 0 :(得分：124)

@ user2302510解决方案的效果不尽如人意。方向和动态数据更改的完整解决方法是：

public class MyLinearLayoutManager extends LinearLayoutManager {

    public MyLinearLayoutManager(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);
        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) {
        View view = recycler.getViewForPosition(position);
        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);
        }
    }
}

答案 1 :(得分：44)

<强>更新

版本23.2.0中与此功能相关的许多问题已在23.2.1中修复，而是更新。

随着支持库版本23.2的发布，RecyclerView现在支持！

将build.gradle更新为：

compile 'com.android.support:recyclerview-v7:23.2.1'

或超出该范围的任何版本。

  

此版本为LayoutManager API带来了令人兴奋的新功能：自动测量！这允许RecyclerView根据其内容的大小调整自身大小。这意味着现在可以使用以前不可用的方案，例如使用WRAP_CONTENT作为RecyclerView的维度。您会发现所有内置的LayoutManagers现在都支持自动测量。

如果需要，可以通过setAutoMeasurementEnabled()禁用此功能。详细检查here。

答案 2 :(得分：39)

当您需要将项目设为“wrap_content”时，上面的代码不能正常工作，因为它使用MeasureSpec.UNSPECIFIED测量项目的高度和宽度。经过一些麻烦我修改了解决方案，所以现在项目可以扩展。唯一的区别是它为父母提供高度或宽度MeasureSpec取决于布局方向。

public class MyLinearLayoutManager extends LinearLayoutManager {

public MyLinearLayoutManager(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);
    int width = 0;
    int height = 0;
    for (int i = 0; i < getItemCount(); i++) {


        if (getOrientation() == HORIZONTAL) {

            measureScrapChild(recycler, i,
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    heightSpec,
                    mMeasuredDimension);

            width = width + mMeasuredDimension[0];
            if (i == 0) {
                height = mMeasuredDimension[1];
            }
        } else {
            measureScrapChild(recycler, i,
                    widthSpec,
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    mMeasuredDimension);
            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) {
    View view = recycler.getViewForPosition(position);
    recycler.bindViewToPosition(view, position);
    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);
    }
}
}

答案 3 :(得分：22)

现有布局管理器尚不支持换行内容。

您可以创建一个新的LayoutManager来扩展现有的LayoutManager并覆盖onMeasure方法以测量换行内容。

答案 4 :(得分：21)

正如@yiğit所提到的，你需要覆盖onMeasure（）。 @ user2302510和@DenisNek都有很好的答案，但是如果你想支持ItemDecoration，你可以使用这个自定义布局管理器。

当有更多项目可以在屏幕上显示时，其他答案无法滚动。当有多个项目而不是屏幕大小时，这个使用onMeasure（）的默认实现。

public class MyLinearLayoutManager extends LinearLayoutManager {

public MyLinearLayoutManager(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);
    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];
            }
        }
    }

    // If child view is more than screen size, there is no need to make it wrap content. We can use original onMeasure() so we can scroll view.
    if (height < heightSize && width < widthSize) {

        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);
    } else {
        super.onMeasure(recycler, state, widthSpec, heightSpec);
    }
}

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                               int heightSpec, int[] measuredDimension) {

   View view = recycler.getViewForPosition(position);

   // For adding Item Decor Insets to view
   super.measureChildWithMargins(view, 0, 0);
    if (view != null) {
        RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
        int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                    getPaddingLeft() + getPaddingRight() + getDecoratedLeft(view) + getDecoratedRight(view), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom() + getPaddingBottom() + getDecoratedBottom(view) , p.height);
            view.measure(childWidthSpec, childHeightSpec);

            // Get decorated measurements
            measuredDimension[0] = getDecoratedMeasuredWidth(view) + p.leftMargin + p.rightMargin;
            measuredDimension[1] = getDecoratedMeasuredHeight(view) + p.bottomMargin + p.topMargin;
            recycler.recycleView(view);
        }
    }
}

如果您想将它与GridLayoutManager一起使用，只需从GridLayoutManager扩展它并更改

for (int i = 0; i < getItemCount(); i++)

到

for (int i = 0; i < getItemCount(); i = i + getSpanCount())

答案 5 :(得分：21)

2016年3月更新

支持库版本的Android Support Library 23.2.1。因此，所有 WRAP_CONTENT 都应正常运行。

请在gradle文件中更新库的版本。

compile 'com.android.support:recyclerview-v7:23.2.1'

这允许RecyclerView根据其内容的大小调整自身大小。这意味着以前不可用的方案，例如现在可以使用WRAP_CONTENT作为RecyclerView的维度。

您需要致电 setAutoMeasureEnabled（true）

修复了与更新中各种测量规范方法相关的错误

检查https://developer.android.com/topic/libraries/support-library/features.html

答案 6 :(得分：14)

这个答案是基于Denis Nek给出的解决方案。它解决了不考虑分隔物等装饰的问题。

public class WrappingRecyclerViewLayoutManager extends LinearLayoutManager {

public WrappingRecyclerViewLayoutManager(Context context)    {
    super(context, VERTICAL, false);
}

public WrappingRecyclerViewLayoutManager(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);
    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) {
    View view = recycler.getViewForPosition(position);
    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);
        Rect outRect = new Rect();
        calculateItemDecorationsForChild(view, outRect);
        measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
        measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin + outRect.bottom + outRect.top;
        recycler.recycleView(view);
    }
}

}

答案 7 :(得分：8)

扩展LayoutManager的替代方法可以手动设置视图的大小。

每行高度的项目数（如果所有项目的高度相同且行中包含分隔符）

LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) mListView.getLayoutParams();
params.height = mAdapter.getItemCount() * getResources().getDimensionPixelSize(R.dimen.row_height);
mListView.setLayoutParams(params);

仍然是一种解决方法，但对于基本情况，它可以正常工作。

答案 8 :(得分：5)

我在这里找到了一个解决方案：https://code.google.com/p/android/issues/detail?id=74772

这绝不是我的解决方案。我刚刚从那里复制了它，但我希望它能帮助某人，因为它在实现水平的RecyclerView和wrap_content高度时帮助了我（也应该适用于垂直高度和wrap_content宽度）

解决方案是扩展LayoutManager并覆盖其@Meigit建议的onMeasure方法。

以下是链接死亡时的代码：

public static class MyLinearLayoutManager extends LinearLayoutManager {

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

    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);

        measureScrapChild(recycler, 0,
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                mMeasuredDimension);

        int width = mMeasuredDimension[0];
        int height = mMeasuredDimension[1];

        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
            case View.MeasureSpec.AT_MOST:
                width = widthSize;
                break;
            case View.MeasureSpec.UNSPECIFIED:
        }

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

        setMeasuredDimension(width, height);
    }

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                                   int heightSpec, int[] measuredDimension) {
        View view = recycler.getViewForPosition(position);
        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();
            measuredDimension[1] = view.getMeasuredHeight();
            recycler.recycleView(view);
        }
    }
}

答案 9 :(得分：5)

来自@ sinan-kozak的解决方案，除了修复了一些错误。具体来说，我们不应该在调用View.MeasureSpec.UNSPECIFIED时使用measureScrapChild 两者的宽度和高度，因为它不能正确解释孩子的包装文字。相反，我们将从父级传递宽度和高度模式，这将允许事物适用于水平和垂直布局。

public class MyLinearLayoutManager extends LinearLayoutManager {

public MyLinearLayoutManager(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);
    int width = 0;
    int height = 0;
    for (int i = 0; i < getItemCount(); i++) {    
        if (getOrientation() == HORIZONTAL) {
            measureScrapChild(recycler, i,
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(heightSize, heightMode),
                mMeasuredDimension);

            width = width + mMeasuredDimension[0];
            if (i == 0) {
                height = mMeasuredDimension[1];
            }
        } else {
            measureScrapChild(recycler, i,
                View.MeasureSpec.makeMeasureSpec(widthSize, widthMode),
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                mMeasuredDimension);

            height = height + mMeasuredDimension[1];
            if (i == 0) {
                width = mMeasuredDimension[0];
            }
        }
    }

    // If child view is more than screen size, there is no need to make it wrap content. We can use original onMeasure() so we can scroll view.
    if (height < heightSize && width < widthSize) {

        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);
    } else {
        super.onMeasure(recycler, state, widthSpec, heightSpec);
    }
}

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                               int heightSpec, int[] measuredDimension) {

   View view = recycler.getViewForPosition(position);

   // For adding Item Decor Insets to view
   super.measureChildWithMargins(view, 0, 0);
    if (view != null) {
        RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
        int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                    getPaddingLeft() + getPaddingRight() + getDecoratedLeft(view) + getDecoratedRight(view), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom() + getDecoratedTop(view) + getDecoratedBottom(view) , p.height);
            view.measure(childWidthSpec, childHeightSpec);

            // Get decorated measurements
            measuredDimension[0] = getDecoratedMeasuredWidth(view) + p.leftMargin + p.rightMargin;
            measuredDimension[1] = getDecoratedMeasuredHeight(view) + p.bottomMargin + p.topMargin;
            recycler.recycleView(view);
        }
    }
}

`

答案 10 :(得分：3)

是的，所有答案中显示的解决方法都是正确的，即我们需要自定义线性布局管理器，以便在运行时动态计算其子项的高度。但是所有的答案都没有达到预期的效果。请为自定义布局管理器提供以下答案，并提供所有方向支持。

public class MyLinearLayoutManager extends android.support.v7.widget.LinearLayoutManager {

private static boolean canMakeInsetsDirty = true;
private static Field insetsDirtyField = null;

private static final int CHILD_WIDTH = 0;
private static final int CHILD_HEIGHT = 1;
private static final int DEFAULT_CHILD_SIZE = 100;

private final int[] childDimensions = new int[2];
private final RecyclerView view;

private int childSize = DEFAULT_CHILD_SIZE;
private boolean hasChildSize;
private int overScrollMode = ViewCompat.OVER_SCROLL_ALWAYS;
private final Rect tmpRect = new Rect();

@SuppressWarnings("UnusedDeclaration")
public MyLinearLayoutManager(Context context) {
    super(context);
    this.view = null;
}

@SuppressWarnings("UnusedDeclaration")
public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
    super(context, orientation, reverseLayout);
    this.view = null;
}

@SuppressWarnings("UnusedDeclaration")
public MyLinearLayoutManager(RecyclerView view) {
    super(view.getContext());
    this.view = view;
    this.overScrollMode = ViewCompat.getOverScrollMode(view);
}

@SuppressWarnings("UnusedDeclaration")
public MyLinearLayoutManager(RecyclerView view, int orientation, boolean reverseLayout) {
    super(view.getContext(), orientation, reverseLayout);
    this.view = view;
    this.overScrollMode = ViewCompat.getOverScrollMode(view);
}

public void setOverScrollMode(int overScrollMode) {
    if (overScrollMode < ViewCompat.OVER_SCROLL_ALWAYS || overScrollMode > ViewCompat.OVER_SCROLL_NEVER)
        throw new IllegalArgumentException("Unknown overscroll mode: " + overScrollMode);
    if (this.view == null) throw new IllegalStateException("view == null");
    this.overScrollMode = overScrollMode;
    ViewCompat.setOverScrollMode(view, overScrollMode);
}

public static int makeUnspecifiedSpec() {
    return View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
}

@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);

    final boolean hasWidthSize = widthMode != View.MeasureSpec.UNSPECIFIED;
    final boolean hasHeightSize = heightMode != View.MeasureSpec.UNSPECIFIED;

    final boolean exactWidth = widthMode == View.MeasureSpec.EXACTLY;
    final boolean exactHeight = heightMode == View.MeasureSpec.EXACTLY;

    final int unspecified = makeUnspecifiedSpec();

    if (exactWidth && exactHeight) {
        // in case of exact calculations for both dimensions let's use default "onMeasure" implementation
        super.onMeasure(recycler, state, widthSpec, heightSpec);
        return;
    }

    final boolean vertical = getOrientation() == VERTICAL;

    initChildDimensions(widthSize, heightSize, vertical);

    int width = 0;
    int height = 0;

    // it's possible to get scrap views in recycler which are bound to old (invalid) adapter entities. This
    // happens because their invalidation happens after "onMeasure" method. As a workaround let's clear the
    // recycler now (it should not cause any performance issues while scrolling as "onMeasure" is never
    // called whiles scrolling)
    recycler.clear();

    final int stateItemCount = state.getItemCount();
    final int adapterItemCount = getItemCount();
    // adapter always contains actual data while state might contain old data (f.e. data before the animation is
    // done). As we want to measure the view with actual data we must use data from the adapter and not from  the
    // state
    for (int i = 0; i < adapterItemCount; i++) {
        if (vertical) {
            if (!hasChildSize) {
                if (i < stateItemCount) {
                    // we should not exceed state count, otherwise we'll get IndexOutOfBoundsException. For such items
                    // we will use previously calculated dimensions
                    measureChild(recycler, i, widthSize, unspecified, childDimensions);
                } else {
                    logMeasureWarning(i);
                }
            }
            height += childDimensions[CHILD_HEIGHT];
            if (i == 0) {
                width = childDimensions[CHILD_WIDTH];
            }
            if (hasHeightSize && height >= heightSize) {
                break;
            }
        } else {
            if (!hasChildSize) {
                if (i < stateItemCount) {
                    // we should not exceed state count, otherwise we'll get IndexOutOfBoundsException. For such items
                    // we will use previously calculated dimensions
                    measureChild(recycler, i, unspecified, heightSize, childDimensions);
                } else {
                    logMeasureWarning(i);
                }
            }
            width += childDimensions[CHILD_WIDTH];
            if (i == 0) {
                height = childDimensions[CHILD_HEIGHT];
            }
            if (hasWidthSize && width >= widthSize) {
                break;
            }
        }
    }

    if (exactWidth) {
        width = widthSize;
    } else {
        width += getPaddingLeft() + getPaddingRight();
        if (hasWidthSize) {
            width = Math.min(width, widthSize);
        }
    }

    if (exactHeight) {
        height = heightSize;
    } else {
        height += getPaddingTop() + getPaddingBottom();
        if (hasHeightSize) {
            height = Math.min(height, heightSize);
        }
    }

    setMeasuredDimension(width, height);

    if (view != null && overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS) {
        final boolean fit = (vertical && (!hasHeightSize || height < heightSize))
                || (!vertical && (!hasWidthSize || width < widthSize));

        ViewCompat.setOverScrollMode(view, fit ? ViewCompat.OVER_SCROLL_NEVER : ViewCompat.OVER_SCROLL_ALWAYS);
    }
}

private void logMeasureWarning(int child) {
    if (BuildConfig.DEBUG) {
        Log.w("MyLinearLayoutManager", "Can't measure child #" + child + ", previously used dimensions will be reused." +
                "To remove this message either use #setChildSize() method or don't run RecyclerView animations");
    }
}

private void initChildDimensions(int width, int height, boolean vertical) {
    if (childDimensions[CHILD_WIDTH] != 0 || childDimensions[CHILD_HEIGHT] != 0) {
        // already initialized, skipping
        return;
    }
    if (vertical) {
        childDimensions[CHILD_WIDTH] = width;
        childDimensions[CHILD_HEIGHT] = childSize;
    } else {
        childDimensions[CHILD_WIDTH] = childSize;
        childDimensions[CHILD_HEIGHT] = height;
    }
}

@Override
public void setOrientation(int orientation) {
    // might be called before the constructor of this class is called
    //noinspection ConstantConditions
    if (childDimensions != null) {
        if (getOrientation() != orientation) {
            childDimensions[CHILD_WIDTH] = 0;
            childDimensions[CHILD_HEIGHT] = 0;
        }
    }
    super.setOrientation(orientation);
}

public void clearChildSize() {
    hasChildSize = false;
    setChildSize(DEFAULT_CHILD_SIZE);
}

public void setChildSize(int childSize) {
    hasChildSize = true;
    if (this.childSize != childSize) {
        this.childSize = childSize;
        requestLayout();
    }
}

private void measureChild(RecyclerView.Recycler recycler, int position, int widthSize, int heightSize, int[] dimensions) {
    final View child;
    try {
        child = recycler.getViewForPosition(position);
    } catch (IndexOutOfBoundsException e) {
        if (BuildConfig.DEBUG) {
            Log.w("MyLinearLayoutManager", "MyLinearLayoutManager doesn't work well with animations. Consider switching them off", e);
        }
        return;
    }

    final RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) child.getLayoutParams();

    final int hPadding = getPaddingLeft() + getPaddingRight();
    final int vPadding = getPaddingTop() + getPaddingBottom();

    final int hMargin = p.leftMargin + p.rightMargin;
    final int vMargin = p.topMargin + p.bottomMargin;

    // we must make insets dirty in order calculateItemDecorationsForChild to work
    makeInsetsDirty(p);
    // this method should be called before any getXxxDecorationXxx() methods
    calculateItemDecorationsForChild(child, tmpRect);

    final int hDecoration = getRightDecorationWidth(child) + getLeftDecorationWidth(child);
    final int vDecoration = getTopDecorationHeight(child) + getBottomDecorationHeight(child);

    final int childWidthSpec = getChildMeasureSpec(widthSize, hPadding + hMargin + hDecoration, p.width, canScrollHorizontally());
    final int childHeightSpec = getChildMeasureSpec(heightSize, vPadding + vMargin + vDecoration, p.height, canScrollVertically());

    child.measure(childWidthSpec, childHeightSpec);

    dimensions[CHILD_WIDTH] = getDecoratedMeasuredWidth(child) + p.leftMargin + p.rightMargin;
    dimensions[CHILD_HEIGHT] = getDecoratedMeasuredHeight(child) + p.bottomMargin + p.topMargin;

    // as view is recycled let's not keep old measured values
    makeInsetsDirty(p);
    recycler.recycleView(child);
}

private static void makeInsetsDirty(RecyclerView.LayoutParams p) {
    if (!canMakeInsetsDirty) {
        return;
    }
    try {
        if (insetsDirtyField == null) {
            insetsDirtyField = RecyclerView.LayoutParams.class.getDeclaredField("mInsetsDirty");
            insetsDirtyField.setAccessible(true);
        }
        insetsDirtyField.set(p, true);
    } catch (NoSuchFieldException e) {
        onMakeInsertDirtyFailed();
    } catch (IllegalAccessException e) {
        onMakeInsertDirtyFailed();
    }
}

private static void onMakeInsertDirtyFailed() {
    canMakeInsetsDirty = false;
    if (BuildConfig.DEBUG) {
        Log.w("MyLinearLayoutManager", "Can't make LayoutParams insets dirty, decorations measurements might be incorrect");
    }
}
}

答案 11 :(得分：3)

Android支持库现在也处理WRAP_CONTENT属性。只需在你的gradle中导入它。

compile 'com.android.support:recyclerview-v7:23.2.0'

完成了！

答案 12 :(得分：2)

根据Denis Nek的工作， 如果项目宽度的总和小于容器的大小，则效果很好。除此之外，它将使recyclerview不可滚动，只显示数据的子集。

为了解决这个问题，我修改了解决方案，以便选择提供的大小和计算大小的min。见下文：

package com.linkdev.gafi.adapters;

import android.content.Context;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;

import com.linkdev.gafi.R;

public class MyLinearLayoutManager extends LinearLayoutManager {

    public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout)    {
        super(context, orientation, reverseLayout);
        this.c = context;
    }


    private Context c;
    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);



        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:
        }

        int widthDesired = Math.min(widthSize,width);
        setMeasuredDimension(widthDesired, height);
    }

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                                   int heightSpec, int[] measuredDimension) {
        View view = recycler.getViewForPosition(position);
        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);
        }
    }}

答案 13 :(得分：1)

我尝试了所有解决方案，它们非常有用 但这对我来说效果很好

public class  LinearLayoutManager extends android.support.v7.widget.LinearLayoutManager {

    public LinearLayoutManager(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);
        int width = 0;
        int height = 0;
        for (int i = 0; i < getItemCount(); i++) {


            if (getOrientation() == HORIZONTAL) {

                measureScrapChild(recycler, i,
                        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                        heightSpec,
                        mMeasuredDimension);

                width = width + mMeasuredDimension[0];
                if (i == 0) {
                    height = mMeasuredDimension[1];
                }
            } else {
                measureScrapChild(recycler, i,
                        widthSpec,
                        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                        mMeasuredDimension);
                height = height + mMeasuredDimension[1];
                if (i == 0) {
                    width = mMeasuredDimension[0];
                }
            }
        }

        if (height < heightSize || width < widthSize) {

            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);
        } else {
            super.onMeasure(recycler, state, widthSpec, heightSpec);
        }
    }

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                                   int heightSpec, int[] measuredDimension) {
        View view = recycler.getViewForPosition(position);
        recycler.bindViewToPosition(view, position);
        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);
        }
    }
}

答案 14 :(得分：0)

使用带有网格布局的RecyclerView简单包装内容

图片： Recycler as GridView layout

只需像这样使用GridLayoutManager：

RecyclerView.LayoutManager mRecyclerGrid=new GridLayoutManager(this,3,LinearLayoutManager.VERTICAL,false);
mRecyclerView.setLayoutManager(mRecyclerGrid);

您可以设置一行中应该显示多少个项目（替换3）。

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