scrollview 嵌套 recyclerview 所有问题简单处理

问题一 recyclerview 只显示一行 item(每个item高度固定)

第一步 scrollview 换成 NestedScrollView
第二步 recyclerview 的 高度设置为 wrap_content
不要固定高度 不要match_parent

问题二 scrollview 的滑动变得卡顿

只需要一步 重写LinearLayoutManager,把canScrollVertically方法的返回值改为false

@Override
public boolean canScrollVertically() {
    return false;//   不再卡顿
}

问题三 recyclerview 的高度问题 item显示不全(每个item高度不固定,类似淘宝评论,有的带图片有的不带图片)

第一步 重写LinearLayoutManager

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 {
    }
}
}

第二步 XML布局中 recyclerview 高度设置为wrap_content

问题四 页面初始化时scrollview 自动滑动,不在顶部(Recyclerview抢夺焦点)

这个问题一般情况是recyclerview抢占了焦点,通过仔细观察我们不难发现,scrollview 滚动的位置是recyclerview的位置。手欠的我经常遇到这个问题。在这里写下笔记
Scrollview嵌套recyclerview时,scrollview中只允许有一个子控件,我们一般用Linearlayout或者RelativeLayout。所有的布局都会写在Linearlayout或者RelativeLayout中

解决方法一:Linearlayout或者RelativeLayout中添加
android:descendantFocusability=”blocksDescendants”
方法二:在recyclerview 控件中添加
android:descendantFocusability=”afterDescendants”

你可能感兴趣的:(学习笔记)