利用BaseMultiItemQuickAdapter打造二、三级级菜单

去网上找了下资料，然后自己整理了下二级、三级菜单的实现，直接上代码。

  Recyclerview记得要导包：implementation 'com.android.support:recyclerview-v7:28.0.0'

一、首先在app下的build.gradle中加入：

//适配器
implementation 'com.github.CymChad:BaseRecyclerViewAdapterHelper:2.6.1'

二、在project下的build.gradle中加入：

maven { url 'https://jitpack.io' }
如图：

三、建立三个bean类并实现MultiItemEntity

public class ExpandItem extends AbstractExpandableItem implements MultiItemEntity {

    private String title;

    public ExpandItem(String title) {
        this.title = title;
    }

    @Override
    public int getLevel() {
        return 0;
    }

    @Override
    public int getItemType() {
        return QuickExpandableAdapter.TYPE_LEVEL_0;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

public class Expand1Item extends AbstractExpandableItem implements MultiItemEntity {

    private String title;

    public Expand1Item(String title){
        this.title = title;
    }

    @Override
    public int getLevel() {
        return 1;
    }

    @Override
    public int getItemType() {
        return QuickExpandableAdapter.TYPE_LEVEL_1;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

public class Expand2Item implements MultiItemEntity {

    private String title;

    public Expand2Item(String title) {
        this.title = title;
    }

    @Override
    public int getItemType() {
        return QuickExpandableAdapter.TYPE_LEVEL_2;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

四、建立QuickExpandableAdapter

public class QuickExpandableAdapter extends BaseMultiItemQuickAdapter {

    public static final int TYPE_LEVEL_0 = 0;
    public static final int TYPE_LEVEL_1 = 1;
    public static final int TYPE_LEVEL_2 = 2;

    /**
     *     * Same as QuickAdapter#QuickAdapter(Context,int) but with
     *     * some initialization data.
     *     *
     *     * @param data A new list is created out of this one to avoid mutable list
     *    
     */
    public QuickExpandableAdapter(List data) {
        super(data);
        addItemType(TYPE_LEVEL_0, R.layout.view_expand_0);
        addItemType(TYPE_LEVEL_1, R.layout.view_expand_1);
        addItemType(TYPE_LEVEL_2, R.layout.view_expand_2);
    }

    @Override
    protected void convert(final BaseViewHolder helper, MultiItemEntity item) {
        switch (helper.getItemViewType()) {
            case TYPE_LEVEL_0:
                final ExpandItem item0 = (ExpandItem) item;
                helper.setText(R.id.expand_list_item0_tv, item0.getTitle());
                helper.itemView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        int pos = helper.getAdapterPosition();
                        if (item0.isExpanded()) {
                            collapse(pos);
                            Toast.makeText(mContext, "收起：" + item0.getTitle(), Toast.LENGTH_SHORT).show();
                        } else {
                            expand(pos);
                            Toast.makeText(mContext, "展开：" + item0.getTitle(), Toast.LENGTH_SHORT).show();
                        }
                    }
                });
                break;
            case TYPE_LEVEL_1:
                final Expand1Item item1 = (Expand1Item) item;
                helper.setText(R.id.expand_list_item1_tv, item1.getTitle());
                helper.itemView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        int pos = helper.getAdapterPosition();
                        if (item1.isExpanded()) {
                            collapse(pos, false);
                            Toast.makeText(mContext, "收起：" + item1.getTitle(), Toast.LENGTH_SHORT).show();
                        } else {
                            expand(pos, false);
                            Toast.makeText(mContext, "展开：" + item1.getTitle(), Toast.LENGTH_SHORT).show();
                        }
                    }
                });
                break;
            case TYPE_LEVEL_2:
                final Expand2Item item2 = (Expand2Item) item;
                helper.setText(R.id.expand_list_item2_tv, item2.getTitle());
                helper.itemView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Toast.makeText(mContext, "点击：" + item2.getTitle(), Toast.LENGTH_SHORT).show();
                    }
                });
                break;
        }
    }
}

五、主界面代码

public class ListActivity extends AppCompatActivity {
    private QuickExpandableAdapter expandableAdapter;
    private RecyclerView recyclerView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list);

        recyclerView = findViewById(R.id.recyclerView);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        //设置布局管理器
        recyclerView.setLayoutManager(layoutManager);
        //设置为垂直布局，这也是默认的
        layoutManager.setOrientation(OrientationHelper.VERTICAL);

        //设置增加或删除条目的动画
        recyclerView.setItemAnimator(new DefaultItemAnimator());

        expandableAdapter = new QuickExpandableAdapter(getExpandListData(10));
        expandableAdapter.openLoadAnimation(BaseQuickAdapter.SLIDEIN_RIGHT);
        recyclerView.setAdapter(expandableAdapter);

        expandableAdapter.expandAll(0, true);

    }

    private List getExpandListData(int count) {
        int lvCount = count;
        int lv1Count = 3;
        int lv2Count = 5;

        List data = new ArrayList<>();
        for (int i = 0; i < lvCount; i++) {
            ExpandItem item0 = new ExpandItem("一级列表标题" + i);
            for (int j = 0; j < lv1Count; j++) {
                Expand1Item item1 = new Expand1Item("二级列表标题" + j);
                for (int k = 0; k < lv2Count; k++) {
                    item1.addSubItem(new Expand2Item("三级列表标题" + k));
                }
                item0.addSubItem(item1);
            }
            data.add(item0);
        }

        return data;
    }
}

六、布局文件

好了，到这里代码已经全部写完了，因为很简单，所以就写的粗糙了些，拿上能直接用。

这里有个问题：

         1.是和我做的项目有关联，如果你的recycleView外面嵌套了NestedScrollView的话，数据量一大就会导致你的列表好卡，我表示深受其害，这是因为你嵌套了NestedScrollView后，会把recyclerview所有的条目都加载出来，相当于吧recycleView的复用机制给禁掉。想想多可怕~~~

         2.用ScrollView虽然可以复用，但是又会与recyclerview有滑动冲突，所以最好是不要嵌套，要不然又要解决冲突。

  因为我之前解决NestedScrollView和Recyclerview的冲突就是禁掉了Recyclerview的滑动事件，只用外层NestedScrollView的滑动事件，所以最后坑了自己一把。。。。。。。。