ScrollView中嵌套recycleView 出现的不显示，显示不全，终极解决方案

https://www.cnblogs.com/woaixingxing/p/6098726.html

最近公司项目中用到了ScrollView去嵌套recycleView, 最开始我天真的把recycleView直接放入scrollView中,结果可想而知，什么都不显示，瞬间懵逼，我心想应该是和嵌套ListView差不多吧，看来需要重写recycleView中onMeasure()方法，

像这样：

 @Override
    protected void onMeasure(int widthSpec, int heightSpec) {
        int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2,MeasureSpec.AT_MOST);
        super.onMeasure(widthSpec, expandSpec);
    }

结果：运行还是什么都没有。

 

　　 没办法上网搜索解决方案，一搜看来网友很多跟我有一样的需求，网上也有大神提供的解决方案

例如这样: 

 <RelativeLayout
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:descendantFocusability="blocksDescendants">
       <android.support.v7.widget.RecyclerView
          android:id="@+id/menuRv"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_marginLeft="@dimen/margin_16"
          android:layout_marginRight="@dimen/margin_16"/>
 RelativeLayout>

我的结果: 运行还是原来一样没有任何反应.

注意： 你们可以试试，说是解决在Android6.0显示不全的问题，如果成功了那祝贺你们,如果没有成功的话就跟着我往下看。

 

例如这样: 重写LinearLayoutManager，来计算每个item进行显示

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 {
        }
    }
}

结果：运行成功 好开心，但是发现显示不完全，item越多这个就无法显示完全，不是最后一个被挡了，就是明明已经是最后一个item了，可是滚动条还没有结束，再继续往下滚，下面没有数据而是空了一大片白。没办法这是算失败了。

注意： 你们可以试试，说是可以解决item不显示问题和显示不全问题，结果我是失败了，所以你们如果用这个方法成功了那么恭喜，如果没有请看接下来。

 

　　国内目前大多数都是上面几种解决方案，很不幸我逐一试了都不行，最后一个最有希望结果还是失败了，没办法，只能国外找了终于在国外的找到了解决方法，不知道你们是不是用了这个，反正我是用了这个了，结果成功了，很满意。

接下来进入正题：

      1.废话不多说先上个xml看看

xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#F2F2F2"
    android:orientation="vertical" >

    <include layout="@layout/include_header_view" />

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true"
         >
        <LinearLayout
            android:id="@+id/li_show_recyclerView"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/tvHeaderStormTitle"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_margin="1dp"
                android:background="@color/white"
                android:gravity="center_vertical"
                android:minHeight="40dp"
                android:paddingLeft="15dp"
                android:paddingRight="10dp"
                android:textColor="#808080"
                android:textSize="16sp" />

            <TextView
                android:id="@+id/tvHeaderStormEditContent"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_margin="1dp"
                android:background="@color/white"
                android:padding="5dp"
                android:textColor="#404040"
                android:textSize="17sp" />
            
            <android.support.v7.widget.RecyclerView
                android:id="@+id/id_recyclerview"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginTop="10dp" />
        LinearLayout>
    ScrollView>

LinearLayout>

看完xml后是不是很失望发现和你们的并没有什么不一样 ，但我既然贴了代码就要说明白，这里1.最好为ScrollView加上android:fillViewport="true"这个属性。 2.最好将RecyclerView的高度属性 设成android:layout_height="wrap_content"，这2点是建议，

我不知道这两点会不会影响接下来的事，但最好这样设置吧，我没有试过你们可以试试。

      2.接下来看java代码(这里只是截取了用到recycleView的代码)

FullyLinearLayoutManager mLayoutManager = new FullyLinearLayoutManager(this);

    @Override
    public void initView() {
        mReplyList = new ArrayList();
        mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview);// 设置item动画
        mRecyclerView.setItemAnimator(new DefaultItemAnimator());
        if (null == mRecyclerAdapter) {
　　　　　　　//设置布局样式            
　　　　　　　mRecyclerView.setLayoutManager(mLayoutManager);
    　　　　　//设置分割线
            HeaderStormItemDiratcion diraction = new HeaderStormItemDiratcion(1);
            mRecyclerView.addItemDecoration(diraction);
　　　　　　　　//设置适配器
            mRecyclerAdapter = new AdapterHeaderStorm(ActivityHeaderStormShow.this, mReplyList);
　　　　　　　//设置item点击事件
            mRecyclerAdapter.setOnItemClickLitener(this);
            mRecyclerView.setAdapter(mRecyclerAdapter);

        } else {
　　　　　　//刷新，这里的适配器是我自己单独写的别直接复制这段代码
            mRecyclerAdapter.notifyView(mReplyList);
        }

    }

这里看完是不是发现好像还是没有什么区别,的确是没有区别，但注意里面红色代码标注的地方，没错用了名字和前面重写LinearLayoutManager用的名字一样,但内部是不一样的，接下来就来看看这里面到底改变了什么

　　完全重新重写的FullyLinearLayoutManager如下：

import java.lang.reflect.Field;
import com.loopj.android.http.BuildConfig;
import android.content.Context;
import android.graphics.Rect;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
/**
 * 重写 LinearLayoutManager 为了ScrollView可以显示RecyclerView 垂直布局
 * 
 * @author M.Z
 */
public class FullyLinearLayoutManager extends 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();

    public FullyLinearLayoutManager(Context context) {
        super(context);
        this.view = null;
    }

    public FullyLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
        this.view = null;
    }

    public FullyLinearLayoutManager(RecyclerView view) {
        super(view.getContext());
        this.view = view;
        this.overScrollMode = ViewCompat.getOverScrollMode(view);
    }

    public FullyLinearLayoutManager(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("LinearLayoutManager", "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("LinearLayoutManager", "LinearLayoutManager 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("LinearLayoutManager", "Can't make LayoutParams insets dirty, decorations measurements might be incorrect");
        }
    }
}

忽然一看，我的天是不是改变太大了，对没错，这就是终极的解决方案，最上面的国内的重写代码思路是对的，但还是处理的不够全面，而这个应该是一个外国的大牛写的，写的很详细全面，我拿来试了试，果然很完美的解决了我的问题.

 

我用了评论区2楼的方案写的demo ：DEMO.ZIP

 

总结：自身的技术还是太嫩了，完全不够用，自身解决问题能力不行，作为一个伸手党我们还是别忘了还要真正的去学习别人的思路想法和技术构思，

　　　这里我贴出写这个代码的地址：https://github.com/serso/android-linear-layout-manager/blob/master/lib/src/main/java/org/solovyev/android/views/llm/LinearLayoutManager.java

　　　提问的出处的地址:http://stackoverflow.com/questions/27083091/recyclerview-inside-scrollview-is-not-working