线性布局LayoutManager的RecyclerView高度随Item自适应

LayoutManager布局的RecyclerView高度随Item自适应 的解决办法就是自己去重写布局管理器LayoutManager。

package com.art.artcircle.widget;

import android.content.Context;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
public class SyLinearLayoutManager extends LinearLayoutManager {
    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 int childSize = DEFAULT_CHILD_SIZE;
    private boolean hasChildSize;

    @SuppressWarnings("UnusedDeclaration")
    public SyLinearLayoutManager(Context context) {
        super(context);
    }

    @SuppressWarnings("UnusedDeclaration")
    public SyLinearLayoutManager(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;
        Log.d("state:", state.toString());
        for (int i = 0; i < getItemCount(); i++) {
            try {
                measureScrapChild(recycler, i,
                        widthSpec,
                        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                        mMeasuredDimension);
            } catch (IndexOutOfBoundsException e) {
                e.printStackTrace();
            }
            if (getOrientation() == HORIZONTAL) {
                width = width + mMeasuredDimension[0];
                if (i == 0) {
                    height = mMeasuredDimension[1];
                }
            } else {
                height = height + mMeasuredDimension[1];
                if (i == 0) {
                    width = mMeasuredDimension[0];
                }
            }
        }
//        Logger.d("ll width:"+width+";widthSize:"+widthSize+";widthSpec:"+widthSpec);
//        Logger.d("ll height:"+width+";heightSize:"+heightSize+";heightSpec:"+heightSpec);
//        Logger.d("ll widthMode:"+widthMode+";heightMode:"+heightMode);
        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(widthSpec, height);
    }
    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 childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom(), p.height);
            view.measure(widthSpec, childHeightSpec);
            measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
            measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
            recycler.recycleView(view);
        }
    }
    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
//        Logger.e("SyLinearLayoutManager state:" + state.toString());
        super.onLayoutChildren(recycler, state);
    }
}
在Activity中这样使用：

 SyLinearLayoutManager careerManager = new SyLinearLayoutManager(mContext);
        careerManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        mCareerDirectionView.setLayoutManager(careerManager);

这样就完美实现你想要的RecyclerView高度随Item自适应效果了。