多类型的RecyclerView

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1.由于recyclerView没有提供像Listview一样的addheadView的方法，就需要我们自己设置head。
这里写图片描述
布局很简单上下两个头和脚布局。内容写了一些假数据。贴一下adapter中的代码：

public class HeadFootAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {    /**     * ITEM的类型     */    private static final int HEAD_TYPE = 0;    private static final int FOOT_TYPE = 1;    private static final int CONTENT_TYPE = 2;    private Context context;    private List<String> list;    /**     * 头布局的数量     */    private int HEAD_COUNT = 1;    /**     * 脚布局的数量     */    private int FOOT_COUNT = 1;    public HeadFootAdapter(Context context, List<String> list) {        this.context = context;        this.list = list;    }    //判断当前item是否是HeadView    public boolean isHeaderView(int position) {        return HEAD_COUNT != 0 && position < HEAD_COUNT;    }    //判断当前item是否是FooterView    public boolean isBottomView(int position) {        return FOOT_COUNT != 0 && position >= (HEAD_COUNT + list.size());    }    @Override    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        if (viewType == HEAD_TYPE) {            return new HeadViewHolder(View.inflate(context, R.layout.item_head, null));        } else if (viewType == FOOT_TYPE) {            return new FootViewHolder(View.inflate(context, R.layout.item_foot, null));        } else {            return new ContentViewHolder(View.inflate(context, R.layout.item_head_foot, null));        }    }    @Override    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {        if (holder instanceof HeadViewHolder) {//头布局        } else if (holder instanceof FootViewHolder) {//            脚布局        } else {            ((ContentViewHolder) holder).txtContent.setText(list.get(position-1));        }    }    @Override    public int getItemCount() {        return HEAD_COUNT + list.size() + FOOT_COUNT;    }    @Override    public int getItemViewType(int position) {        int dataCount = list.size();        if (HEAD_COUNT != 0 && position < HEAD_COUNT) {            return HEAD_TYPE;        } else if (FOOT_COUNT != 0 && position >= (HEAD_COUNT + dataCount)) {            return FOOT_TYPE;        } else {            return CONTENT_TYPE;        }    }/** * 内容的VIEWHOLDER */public static class ContentViewHolder extends RecyclerView.ViewHolder {    public TextView txtContent;    public ContentViewHolder(View itemView) {        super(itemView);        txtContent = get(itemView, R.id.txt_content);    }    private static <T extends View> T get(View view, int id) {        SparseArray<View> viewholder = (SparseArray<View>) view.getTag();        if (viewholder == null) {            viewholder = new SparseArray<View>();            view.setTag(viewholder);        }        View chicldView = viewholder.get(id);        if (chicldView == null) {            chicldView = view.findViewById(id);            viewholder.put(id, chicldView);        }        return (T) chicldView;    }}/** * 头布局的VIEWHOLDER */public static class HeadViewHolder extends RecyclerView.ViewHolder {    public HeadViewHolder(View itemView) {        super(itemView);    }    private static <T extends View> T get(View view, int id) {        SparseArray<View> viewholder = (SparseArray<View>) view.getTag();        if (viewholder == null) {            viewholder = new SparseArray<View>();            view.setTag(viewholder);        }        View chicldView = viewholder.get(id);        if (chicldView == null) {            chicldView = view.findViewById(id);            viewholder.put(id, chicldView);        }        return (T) chicldView;    }}/** * 脚布局的VIEWHOLDER */public static class FootViewHolder extends RecyclerView.ViewHolder {    public FootViewHolder(View itemView) {        super(itemView);    }    private static <T extends View> T get(View view, int id) {        SparseArray<View> viewholder = (SparseArray<View>) view.getTag();        if (viewholder == null) {            viewholder = new SparseArray<View>();            view.setTag(viewholder);        }        View chicldView = viewholder.get(id);        if (chicldView == null) {            chicldView = view.findViewById(id);            viewholder.put(id, chicldView);        }        return (T) chicldView;    }}}

首先通过getViewType设置item的类型：

@Override    public int getItemViewType(int position) {        int dataCount = list.size();        if (HEAD_COUNT != 0 && position < HEAD_COUNT) {            return HEAD_TYPE;        } else if (FOOT_COUNT != 0 && position >= (HEAD_COUNT + dataCount)) {            return FOOT_TYPE;        } else {            return CONTENT_TYPE;        }    }

在onCreateViewHolder中通过类型判断设置item的布局：

 @Override    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        if (viewType == HEAD_TYPE) {            return new HeadViewHolder(View.inflate(context, R.layout.item_head, null));        } else if (viewType == FOOT_TYPE) {            return new FootViewHolder(View.inflate(context, R.layout.item_foot, null));        } else {            return new ContentViewHolder(View.inflate(context, R.layout.item_head_foot, null));        }    }

最后在Activity中设置Adapter：

 @Override    protected void onCreate(@Nullable Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.head_foot_activity);        headFootRecyclerView = (RecyclerView) findViewById(R.id.headFootRecyclerView);        initData();        final GridLayoutManager grid = new GridLayoutManager(this, 4);        headFootRecyclerView.setLayoutManager(grid);        final HeadFootAdapter adapter = new HeadFootAdapter(this, list);        headFootRecyclerView.setAdapter(adapter);        grid.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {            @Override            public int getSpanSize(int position) {                return (adapter.isHeaderView(position)||adapter.isBottomView(position))?grid.getSpanCount():1;            }        });    }

在设置头布局的时候为头布局设置spansize设置了占据4格的单元格：

 grid.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {            @Override            public int getSpanSize(int position) {                return (adapter.isHeaderView(position)||adapter.isBottomView(position))?grid.getSpanCount():1;            }        });

通过判断当前位置是否是头布局或脚布局，如果是的话就让头布局占据4格。

(adapter.isHeaderView(position)||adapter.isBottomView(position))?grid.getSpanCount():1;

布局比较简单就不贴了，源码链接：git源码

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