如果有人想为spaceBetween, paddingLeft, paddingTop, paddingRight和paddingBottom设置不同的值。

class ItemPaddingDecoration(
    private val spaceBetween: Int,
    private val paddingLeft: Int = spaceBetween,
    private val paddingTop: Int = spaceBetween,
    private val paddingRight: Int = spaceBetween,
    private val paddingBottom: Int = spaceBetween
) : RecyclerView.ItemDecoration() {

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        val position = parent.getChildAdapterPosition(view)
        val orientation = when (val layoutManager = parent.layoutManager) {
            is LinearLayoutManager -> {
                layoutManager.orientation
            }
            is GridLayoutManager -> {
                layoutManager.orientation
            }
            else -> {
                RecyclerView.HORIZONTAL
            }
        }
        if (orientation == RecyclerView.HORIZONTAL) {
            when {
                position == 0 -> {
                    outRect.set(paddingLeft, paddingTop, spaceBetween, paddingBottom)
                }
                position < parent.adapter!!.itemCount - 1 -> {
                    outRect.set(0, paddingTop, spaceBetween, paddingBottom)
                }
                else -> {
                    outRect.set(0, paddingTop, paddingRight, paddingBottom)
                }
            }
        } else {
            when {
                position == 0 -> {
                    outRect.set(paddingLeft, paddingTop, paddingRight, paddingBottom)
                }
                position < parent.adapter!!.itemCount - 1 -> {
                    outRect.set(paddingLeft, 0, paddingRight, spaceBetween)
                }
                else -> {
                    outRect.set(paddingLeft, 0, paddingRight, paddingBottom)
                }
            }
        }
    }
}

为了在RecylerView中实现项目之间的间隔，我们可以使用ItemDecorators:

addItemDecoration(object : RecyclerView.ItemDecoration() {

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State,
    ) {
        super.getItemOffsets(outRect, view, parent, state)
        if (parent.getChildAdapterPosition(view) > 0) {
            outRect.top = 8.dp // Change this value with anything you want. Remember that you need to convert integers to pixels if you are working with dps :)
        }
    }
})

对于我粘贴的代码，有几件事需要考虑:

You don't really need to call super.getItemOffsets but I chose to, because I want to extend the behavior defined by the base class. If the library got an update doing more logic behind the scenes, we would miss it. As an alternative to adding top spacing to the Rect, you could also add bottom spacing, but the logic related to getting the last item of the adapter is more complex, so this might be slightly better. I used an extension property to convert a simple integer to dps: 8.dp. Something like this might work:

val Int.dp: Int
    get() = (this * Resources.getSystem().displayMetrics.density + 0.5f).toInt()

// Extension function works too, but invoking it would become something like 8.dp()

请注意一下Alex Fu在GitHub上的这个文件: 链接

它是“直接从支持演示中提取”的diveritemdecoration .java示例文件。

在我的项目中导入这个文件后，我能够很好地获得分隔线，并将其作为项目装饰添加到回收器视图。

下面是我的onCreateView在我的片段中包含Recyclerview的样子:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_recycler_view, container, false);

    mRecyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
    mRecyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL));

    mRecyclerView.setHasFixedSize(true);
    mLayoutManager = new LinearLayoutManager(getActivity());
    mRecyclerView.setLayoutManager(mLayoutManager);
    mRecyclerView.setItemAnimator(new DefaultItemAnimator());

    return rootView;
}

我确信可以做额外的造型，但这只是一个起点。：）

RecyclerView没有为绘制列表分隔符提供一个简单的接口。但实际上它为我们提供了更灵活的 划分隔线的方法。

我们使用RecyclerView。用分隔线或任何你想要的东西来装饰RecyclerView的瓷砖。这也是为什么它被称为ItemDecoration。

如《材料设计指南》所述:

分隔符位于贴图的基线内。

所以如果你想遵循材料设计指南，你不需要额外的空间来画分隔线。把它们画在瓷砖上。然而，你有权利做任何你想做的事。所以我实现了一个让你能够设置嵌入以及在瓷砖上/下面绘制的功能。

public class InsetDivider extends RecyclerView.ItemDecoration {

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

    private Paint mPaint;
    // in pixel
    private int mDividerHeight;
    // left inset for vertical list, top inset for horizontal list
    private int mFirstInset;
    // right inset for vertical list, bottom inset for horizontal list
    private int mSecondInset;
    private int mColor;
    private int mOrientation;
    // set it to true to draw divider on the tile, or false to draw beside the tile.
    // if you set it to false and have inset at the same time, you may see the background of
    // the parent of RecyclerView.
    private boolean mOverlay;

    private InsetDivider() {
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setStyle(Paint.Style.FILL);
    }

    public int getDividerHeight() {
        return mDividerHeight;
    }

    public void setDividerHeight(int dividerHeight) {
        this.mDividerHeight = dividerHeight;
    }

    public int getFirstInset() {
        return mFirstInset;
    }

    public void setFirstInset(int firstInset) {
        this.mFirstInset = firstInset;
    }

    public int getSecondInset() {
        return mSecondInset;
    }

    public void setSecondInset(int secondInset) {
        this.mSecondInset = secondInset;
    }

    public int getColor() {
        return mColor;
    }

    public void setColor(int color) {
        this.mColor = color;
        mPaint.setColor(color);
    }

    public int getOrientation() {
        return mOrientation;
    }

    public void setOrientation(int orientation) {
        this.mOrientation = orientation;
    }

    public boolean getOverlay() {
        return mOverlay;
    }

    public void setOverlay(boolean overlay) {
        this.mOverlay = overlay;
    }

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }
    }

    protected void drawVertical(Canvas c, RecyclerView parent) {
        final int left = parent.getPaddingLeft() + mFirstInset;
        final int right = parent.getWidth() - parent.getPaddingRight() - mSecondInset;
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            if (parent.getChildAdapterPosition(child) == (parent.getAdapter().getItemCount() - 1)) {
                continue;
            }
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int bottom;
            final int top;
            if (mOverlay) {
                bottom = child.getBottom() + params.bottomMargin + Math.round(ViewCompat.getTranslationY(child));
                top = bottom - mDividerHeight;
            } else {
                top = child.getBottom() + params.bottomMargin + Math.round(ViewCompat.getTranslationY(child));
                bottom = top + mDividerHeight;
            }
            c.drawRect(left, top, right, bottom, mPaint);
        }
    }

    protected void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop() + mFirstInset;
        final int bottom = parent.getHeight() - parent.getPaddingBottom() - mSecondInset;
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            if (parent.getChildAdapterPosition(child) == (parent.getAdapter().getItemCount() - 1)) {
                continue;
            }
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                .getLayoutParams();
            final int right;
            final int left;
            if (mOverlay) {
                right = child.getRight() + params.rightMargin + Math.round(ViewCompat.getTranslationX(child));
                left = right - mDividerHeight;
            } else {
                left = child.getRight() + params.rightMargin + Math.round(ViewCompat.getTranslationX(child));
                right = left + mDividerHeight;
            }
            c.drawRect(left, top, right, bottom, mPaint);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (mOverlay) {
            super.getItemOffsets(outRect, view, parent, state);
            return;
        }

        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDividerHeight);
        } else {
            outRect.set(0, 0, mDividerHeight, 0);
        }
    }

    /**
     * Handy builder for creating {@link InsetDivider} instance.
     */
    public static class Builder {

        private Context mContext;
        private int mDividerHeight;
        private int mFirstInset;
        private int mSecondInset;
        private int mColor;
        private int mOrientation;
        private boolean mOverlay = true; // set default to true to follow Material Design Guidelines

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

        public Builder dividerHeight(int dividerHeight) {
            mDividerHeight = dividerHeight;
            return this;
        }

        public Builder insets(int firstInset, int secondInset) {
            mFirstInset = firstInset;
            mSecondInset = secondInset;
            return this;
        }

        public Builder color(@ColorInt int color) {
            mColor = color;
            return this;
        }

        public Builder orientation(int orientation) {
            mOrientation = orientation;
            return this;
        }

        public Builder overlay(boolean overlay) {
            mOverlay = overlay;
            return this;
        }

        public InsetDivider build() {
            InsetDivider insetDivider = new InsetDivider();

            if (mDividerHeight == 0) {
                // Set default divider height to 1dp.
                 insetDivider.setDividerHeight(mContext.getResources().getDimensionPixelSize(R.dimen.divider_height));
            } else if (mDividerHeight > 0) {
                insetDivider.setDividerHeight(mDividerHeight);
            } else {
                throw new IllegalArgumentException("Divider's height can't be negative.");
            }

            insetDivider.setFirstInset(mFirstInset < 0 ? 0 : mFirstInset);
            insetDivider.setSecondInset(mSecondInset < 0 ? 0 : mSecondInset);

            if (mColor == 0) {
                throw new IllegalArgumentException("Don't forget to set color");
            } else {
                insetDivider.setColor(mColor);
            }

            if (mOrientation != InsetDivider.HORIZONTAL_LIST && mOrientation != InsetDivider.VERTICAL_LIST) {
                throw new IllegalArgumentException("Invalid orientation");
            } else {
                insetDivider.setOrientation(mOrientation);
            }

            insetDivider.setOverlay(mOverlay);

            return insetDivider;
        }
    }
}

你可以这样使用它:

ItemDecoration divider = new InsetDivider.Builder(this)
                            .orientation(InsetDivider.VERTICAL_LIST)
                            .dividerHeight(getResources().getDimensionPixelSize(R.dimen.divider_height))
                            .color(getResources().getColor(R.color.colorAccent))
                            .insets(getResources().getDimensionPixelSize(R.dimen.divider_inset), 0)
                            .overlay(true)
                            .build();

RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.addItemDecoration(divider);

我还写了一个关于如何实现ItemDecoration以及如何使用它们的演示应用程序。你可以查看我的GitHub存储库Dividers-For-RecyclerView。它有三个实现:

下隔板 叠加分隔器 插入分隔器

对于GridLayoutManager，我使用这个:

public class GridSpacesItemDecoration : RecyclerView.ItemDecoration
{
    private int space;

    public GridSpacesItemDecoration(int space) {
        this.space = space;
    }

    public override void GetItemOffsets(Android.Graphics.Rect outRect, View view, RecyclerView parent, RecyclerView.State state)
    {
        var position = parent.GetChildLayoutPosition(view);

        /// Only for GridLayoutManager Layouts
        var manager = parent.GetLayoutManager() as GridLayoutManager;

        if (parent.GetChildLayoutPosition(view) < manager.SpanCount)
            outRect.Top = space;

        if (position % 2 != 0) {
            outRect.Right = space;
        }

        outRect.Left = space;
        outRect.Bottom = space;
    }
}

这适用于任何跨度。

只需在回收器视图对象的init之后添加这一行。

在片段:

mRecyclerView.addItemDecoration(new DividerItemDecoration(getActivity(),android.R.drawable.divider_horizontal_bright));

在活动

mRecyclerView.addItemDecoration(new DividerItemDecoration(this,android.R.drawable.divider_horizontal_bright));

项目装饰

public class DividerItemDecoration extends RecyclerView.ItemDecoration {
    public static final int VERTICAL_LIST = 0;

    public DividerItemDecoration(ListActivity listActivity, Object p1) {
    }

    private static final int[] ATTRS = new int[]{android.R.attr.listDivider};

    private Drawable mDivider;

    /**
     * Default divider will be used
     */
    public DividerItemDecoration(Context context) {
        final TypedArray styledAttributes = context.obtainStyledAttributes(ATTRS);
        mDivider = styledAttributes.getDrawable(0);
        styledAttributes.recycle();
    }

    /**
     * Custom divider will be used
     */
    public DividerItemDecoration(Context context, int resId) {
        mDivider = ContextCompat.getDrawable(context, resId);
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();

        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);

            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + mDivider.getIntrinsicHeight();

            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }
}