Android仿内涵段子详情页评论功能-技术圈

首先看实现效果图：

类似的这种需求在实际的项目中还是挺多的。说说的详情页，顶部显示内容，然后显示一个热门评论，最后显示全部评论。两个评论列表数量都是动态的，并且全部评论还可以下拉刷新。‍

我们来实现这个效果。

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1、布局

最关键的是 NestedScrollView 控件，看这张图

NestedScrollView  // 滚动页 - LinearLayout  // NestedScrollView 只能包含一个 LinearLayout   - LinearLayout // 说说详情   - LinearLayout // 热门评论     - RecyclerView   - LinearLayout // 全部评论     - RecyclerView

2、重写 LinearLayoutManager

初始化 RecyclerView 时需要设置 setLayoutManager(),我们需要重写它来计算列表的高度。

代码如下：

public class WrappingLinearLayoutManager extends LinearLayoutManager{
    public WrappingLinearLayoutManager(Context context) {        super(context);    }
    private int[] mMeasuredDimension = new int[2];
    @Override    public boolean canScrollVertically() {        return false;    }
    @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),                        heightSpec,                        mMeasuredDimension);
                width = width + mMeasuredDimension[0];                if (i == 0) {                    height = mMeasuredDimension[1];                }            } else {                measureScrapChild(recycler, i,                        widthSpec,                        View.MeasureSpec.makeMeasureSpec(0, 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);        if (view.getVisibility() == View.GONE) {            measuredDimension[0] = 0;            measuredDimension[1] = 0;            return;        }        // For adding Item Decor Insets to view        super.measureChildWithMargins(view, 0, 0);        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);    }}

3、初始化 RecyclerView

就是按照正常的流程初始化 RecyclerView，只不过在 setLayoutManager() 时，

使用我们自定的 WrappingLinearLayoutManager。

至于其中的 DetailCommentAdapter 就是正常的 RecyclerView.Adapter。

RecyclerView RecyclerHot;RecyclerView RecyclerAll;
private DetailCommentAdapter mHotCommentAdapter;private DetailCommentAdapter mAllCommentAdapter;
private List mHotCommentsList = new ArrayList<>();private List mAllCommentsList = new ArrayList<>();
private void setView() {    // 设置热门评论列表    WrappingLinearLayoutManager wrappingLinearLayoutManager = new WrappingLinearLayoutManager(mContext);    wrappingLinearLayoutManager.setAutoMeasureEnabled(false);// 如果导入的包是  Android Support Library 23.2.0  以上的，需要加这句    RecyclerHot.setLayoutManager(wrappingLinearLayoutManager);
    mHotCommentAdapter = new DetailCommentAdapter(mContext, mHotCommentsList, DetailCommentAdapter.COMMENT_TYPE_HOT);    RecyclerHot.setAdapter(mHotCommentAdapter);    RecyclerHot.setNestedScrollingEnabled(false);

    // 设置全部评论列表    WrappingLinearLayoutManager wrappingLinearLayoutManager2 = new WrappingLinearLayoutManager(mContext);    wrappingLinearLayoutManager2.setAutoMeasureEnabled(false);// 如果导入的包是  Android Support Library 23.2.0  以上的，需要加这句    RecyclerAll.setLayoutManager(wrappingLinearLayoutManager2);
    mAllCommentAdapter = new DetailCommentAdapter(mContext, mAllCommentsList, DetailCommentAdapter.COMMENT_TYPE_ALL);    RecyclerAll.setAdapter(mAllCommentAdapter);    RecyclerAll.setNestedScrollingEnabled(true);}

注意：

wrappingLinearLayoutManager.setAutoMeasureEnabled(false);
如果导入的包是 Android Support Library 23.2.0 以上的，需要加这句。
RecyclerHot.setNestedScrollingEnabled(false);
在这里setNestedScrollingEnabled（false）禁用滚动为RecyclerView，它不会拦截从NestedScrollView滚动事件。
setHasFixedSize（false）（默认false）
确定适配器内容中的更改可以更改RecyclerView的大小。

至此就可以实现想要达到的效果。

源码地址：

https://github.com/Wing-Li/DoubleList

到这里就结束啦。