关于三级菜单的实现方式

近日产品提出一个要一个三级菜单列表的功能，网上也一些资源，但是并不能满足需求。有4种实现思路：

（1）最常见的是两个expandlistview相互嵌套，亲身检测，比较繁琐，代码也不够简洁，而且会有三级惨淡测绘高度失效的情况.

（2）使用一个recycleview，自己来维护数据集合，亲测，这种方式两层的数据格式时，还是可以接受的，但是三层的时候，维护数据的复杂度就不是一个量级，比较复杂。

（3）使用3个recycleview嵌套，数据维持就相对简单，只要处理recycleview的测绘高度冲突即可，网上有很多，这里不多说。

（4）这是我实现的方式，自认为这种实现方式是比较简单且清晰的，两个控件嵌套，expandlistview和recycleview嵌套，童谣要处理好recycleview子类item项的高度测绘问题（这也是我的实现方式）

代码如下：

activity中的代码------------

public class MainActivity extends AppCompatActivity {


    private List<BeanData> mBeanDataList = new ArrayList<>();

    Context mContext;
    ExpandableListView mExpandableListView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = this;
        initData();

        mExpandableListView = findViewById(R.id.expandableListView);
        mExpandableListView.setAdapter(new Myadapter(mContext, mBeanDataList));

    }

    /**
     * 初始化数据集合
     */
    private void initData() {
        for (int i = 0; i < 5; i++) {
            BeanData beanData = new BeanData();
            beanData.setContent("parent" + i);
            List<BeanData> beanDataList = new ArrayList<>();
            for (int j = 0; j < 5; j++) {
                BeanData beanData1 = new BeanData();
                beanData1.setContent("child" + j);
                List<BeanData> beanDataList1 = new ArrayList<>();
                for (int k = 0; k < 5; k++) {
                    BeanData beanData2 = new BeanData();
                    beanData2.setContent("secondChild" + k);
                    beanData2.setBeanData(new ArrayList<BeanData>());
                    beanDataList1.add(beanData2);
                }
                beanData1.setBeanData(beanDataList1);
                beanDataList.add(beanData1);
            }
            beanData.setBeanData(beanDataList);
            mBeanDataList.add(beanData);
        }
    }
}

布局的话就是一个expandlistview控件，就不贴了

一个实体类如下：

public class BeanData {

    private List<BeanData> mBeanData;
    private String content;

    public List<BeanData> getBeanData() {
        return mBeanData;
    }

    public void setBeanData(List<BeanData> beanData) {
        mBeanData = beanData;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }
}

两个adapter  代码如下：

public class Myadapter extends BaseExpandableListAdapter {
    Context mContext;
    List<BeanData> list;

    public Myadapter(Context context, List<BeanData> list) {
        mContext = context;
        this.list = list;
    }

    @Override
    public int getGroupCount() {
        return list.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return list.get(groupPosition).getBeanData().size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        return list.get(groupPosition);
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return list.get(groupPosition).getBeanData().get(childPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    @Override
    public boolean hasStableIds() {
        return false;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        parentViewHolder holder;
        if (convertView == null) {
            convertView = LayoutInflater.from(mContext).inflate(R.layout.parent_item_layout, parent, false);
            holder = new parentViewHolder();
            holder.parent_tv = convertView.findViewById(R.id.partent);
            convertView.setTag(holder);
        } else {
            holder = (parentViewHolder) convertView.getTag();
        }

        holder.parent_tv.setText(list.get(groupPosition).getContent());

        return convertView;
    }

    class parentViewHolder {
        TextView parent_tv;
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        final childViewHolder holder;
        if (convertView == null) {
            convertView = LayoutInflater.from(mContext).inflate(R.layout.child_item_layout, parent, false);
            holder = new childViewHolder();
            holder.child_tv = convertView.findViewById(R.id.partent1);
            holder.child_tv.setTag(false);
            holder.mAllHeightRecyclerView = convertView.findViewById(R.id.recyclerView);
            holder.mAllHeightRecyclerView.setLayoutManager(new LinearLayoutManager(parent.getContext()));
            convertView.setTag(holder);
        } else {
            holder = (childViewHolder) convertView.getTag();
        }

        recyclerAdapter recyclerAdapter = new recyclerAdapter(list.get(groupPosition).getBeanData().get(childPosition).getBeanData());

        holder.mAllHeightRecyclerView.setAdapter(recyclerAdapter);

        holder.child_tv.setText(list.get(groupPosition).getBeanData().get(childPosition).getContent());

        holder.child_tv.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                boolean isShow = (boolean) v.getTag();
                holder.mAllHeightRecyclerView.setVisibility(!isShow ? View.VISIBLE : View.GONE);
                v.setTag(!isShow);
            }
        });
        return convertView;
    }

    class childViewHolder {
        TextView child_tv;
        AllHeightRecyclerView mAllHeightRecyclerView;
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return false;
    }
}

    

public class recyclerAdapter extends RecyclerView.Adapter<recyclerAdapter.RecyViewHolder> {

    private List<BeanData> mBeanDataList;

    private OnItemClickListener mOnItemClickListener;

    /**
     * Created by joker on 2018/1/10.
     */

    public interface OnItemClickListener {
        void onClick(int position, ShowData showData);
    }

    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
        mOnItemClickListener = onItemClickListener;
    }

    public recyclerAdapter(List<BeanData> beanDataList) {
        mBeanDataList = beanDataList;
    }

    @Override
    public recyclerAdapter.RecyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        TextView textView = new TextView(parent.getContext());

        return new RecyViewHolder(textView);
    }

    @Override
    public void onBindViewHolder(recyclerAdapter.RecyViewHolder holder, int position) {
        holder.mTextView.setText(mBeanDataList.get(position).getContent());
    }

    @Override
    public int getItemCount() {
        return mBeanDataList.size();
    }

    class RecyViewHolder extends RecyclerView.ViewHolder {

        private TextView mTextView;
        RecyViewHolder(TextView itemView) {
            super(itemView);
            mTextView = itemView;
        }

    }
}

这里是一个强行测绘的recycleview：

/**
 * Created by jp on 2017/9/11.
 * 重新测量recyclerview高度，强制绘制全部高度
 */


public class AllHeightRecyclerView extends RecyclerView {

    public AllHeightRecyclerView(Context context) {
        super(context);
    }

    public AllHeightRecyclerView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public AllHeightRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

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

三个列表布局中，需要注意的就是二级列表的布局了，代码如下：

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:id="@+id/partent1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <com.joker.threelevelslist.AllHeightRecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:visibility="gone"/>

</LinearLayout>

这个样完美完成三级列表的功能了