一个基于RecycleView的通用Adapter

Demo地址：https://github.com/Pedestrian0209/Adapter
RecycleView的好用不言而喻，但也不宜粗制滥造，反而加重了代码的重量。本文从RecyclerView.Adapter着手，寥寥数行代码，设计一款通用的Adapter，为大家提供一种思路。
RecyclerView.Adapter需要从两个方面入手，一个是RecyclerView.ViewHolder，一个是数据。一个Adapter可以适配不同的RecycleView列表，列表也会包含不同的类目item，就需要将RecyclerView.ViewHolder统一，以及拿到数据的共性即数据模型。

代码结构：

核心的类就是adapter目录下的三个类，bean目录下是我做测试用的数据类型，仅作参考。

数据模型

先看一下RecyclerView.Adapter默认需要实现的方法：

    //根据每个item的类型返回不同的ViewHolder
    @NonNull
    @Override
    public RecycleView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
        return null;
    }
    //给ViewHolder绑定数据
    @Override
    public void onBindViewHolder(@NonNull RecycleView.ViewHolder viewHolder, int position) {
    }
    //获取列表item的数量
    @Override
    public int getItemCount() {
        return 0;
    }
    //如果列表有多个item类目，则需要实现该方法，返回每个item的类型
    @Override
    public int getItemViewType(int position) {
        return super.getItemViewType(position);
    }

假设每个item的类型是相同的，getItemViewType默认返回0即可，如果有多个类型，则需要为不同类型的item设置惟一的返回值。正常情况下不同类型的item，数据和布局都不相同，那将布局的id作为getItemViewType的返回值是最好的选择了，布局的id可以设计成从数据类型里面获取，使每种数据类型管理自己的布局id，即所有的数据类型都需要实现接口IRecycleViewData：

public interface IRecycleViewData {
    //获取当前item的布局id
    int getItemViewId();
}

对应的RecyclerView.Adapter实现如下：

public abstract class RecycleViewAdapter extends RecyclerView.Adapter<RecycleViewHolder> {
    private List<IRecycleViewData> iRecycleViewData;

    @NonNull
    @Override
    public RecycleViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
        if (viewType <= 0) {
            Log.e("RecycleViewAdapter", "Please make your data implement IRecycleViewData");
            return null;
        }
        return new RecycleViewHolder(LayoutInflater.from(viewGroup.getContext()).inflate(viewType, viewGroup, false));
    }

    @Override
    public void onBindViewHolder(@NonNull RecycleViewHolder viewHolder, int position) {
        bindData(viewHolder, iRecycleViewData.get(position), position);
    }

    @Override
    public void onBindViewHolder(@NonNull RecycleViewHolder holder, int position, @NonNull List<Object> payloads) {
        if (payloads.isEmpty()) {
            onBindViewHolder(holder, position);
        } else {
            bindData(holder, iRecycleViewData.get(position), position, payloads);
        }
    }

    protected abstract void bindData(@NonNull RecycleViewHolder viewHolder, IRecycleViewData data, int position);

    protected void bindData(@NonNull RecycleViewHolder viewHolder, IRecycleViewData data, int position, @NonNull List<Object> payloads) {

    }

    @Override
    public int getItemCount() {
        return iRecycleViewData == null ? 0 : iRecycleViewData.size();
    }

    @Override
    public int getItemViewType(int position) {
        if (iRecycleViewData != null && !iRecycleViewData.isEmpty()) {
            //这里利用item的布局id作为type返回
            return iRecycleViewData.get(position).getItemViewId();
        }
        return super.getItemViewType(position);
    }


    /**
     * 添加单个数据
     *
     * @param data
     */
    public void addData(IRecycleViewData data) {
        if (iRecycleViewData == null) {
            iRecycleViewData = new ArrayList<>();
        }
        iRecycleViewData.add(data);
        notifyDataSetChanged();
    }

    /**
     * 添加一组数据
     *
     * @param data
     */
    public void addData(Collection<? extends IRecycleViewData> data) {
        if (iRecycleViewData == null) {
            iRecycleViewData = new ArrayList<>();
        }
        iRecycleViewData.addAll(data);
        notifyDataSetChanged();
    }

    /**
     * 添加数据到制定位置
     *
     * @param index
     * @param data
     */
    public void addData(int index, IRecycleViewData data) {
        if (iRecycleViewData == null || iRecycleViewData.isEmpty() || index >= iRecycleViewData.size()) {
            addData(data);
        } else {
            iRecycleViewData.add(index, data);
        }
        notifyDataSetChanged();
    }

    /**
     * 修改指定位置的数据
     *
     * @param index
     * @param data
     */
    public void setData(int index, IRecycleViewData data) {
        if (iRecycleViewData == null || iRecycleViewData.isEmpty() || index >= iRecycleViewData.size()) {
            return;
        } else {
            iRecycleViewData.set(index, data);
        }
        notifyDataSetChanged();
    }

    /**
     * 修改指定的数据
     *
     * @param oldData
     * @param newData
     */
    public void setData(IRecycleViewData oldData, IRecycleViewData newData) {
        if (iRecycleViewData == null || iRecycleViewData.isEmpty()) {
            return;
        } else {
            int index = iRecycleViewData.indexOf(oldData);
            if (index < -1) {
                return;
            } else {
                iRecycleViewData.set(index, newData);
            }
        }
        notifyDataSetChanged();
    }

    /**
     * 删除指定位置的数据
     *
     * @param index
     */
    public void removeData(int index) {
        if (iRecycleViewData == null || iRecycleViewData.isEmpty() || index >= iRecycleViewData.size()) {
            return;
        } else {
            iRecycleViewData.remove(index);
        }
        notifyDataSetChanged();
    }

    /**
     * 删除数据
     *
     * @param data
     */
    public void removeData(IRecycleViewData data) {
        if (iRecycleViewData == null || iRecycleViewData.isEmpty()) {
            return;
        } else {
            int index = iRecycleViewData.indexOf(data);
            if (index < -1) {
                return;
            } else {
                iRecycleViewData.remove(data);
            }
        }
        notifyDataSetChanged();
    }

    /**
     * 删除一组数据
     *
     * @param data
     */
    public void removeData(Collection<? extends IRecycleViewData> data) {
        if (iRecycleViewData == null || iRecycleViewData.isEmpty()) {
            return;
        } else {
            iRecycleViewData.removeAll(data);
        }
        notifyDataSetChanged();
    }

    /**
     * 替换所有数据
     *
     * @param data
     */
    public void replaceAllData(Collection<? extends IRecycleViewData> data) {
        if (iRecycleViewData == null) {
            iRecycleViewData = new ArrayList<>();
        }
        iRecycleViewData.clear();
        iRecycleViewData.addAll(data);
        notifyDataSetChanged();
    }

    /**
     * 清除数据
     */
    public void clear() {
        if (iRecycleViewData != null) {
            iRecycleViewData.clear();
            iRecycleViewData = null;
        }
        notifyDataSetChanged();
    }
}

这里封装了一些基本的操作，可自行扩展。

RecyclerView.ViewHolder

公共ViewHolder的代码实现如下：

public class RecycleViewHolder extends RecyclerView.ViewHolder {
    private SparseArray<View> viewSparseArray;

    public RecycleViewHolder(@NonNull View itemView) {
        super(itemView);
        viewSparseArray = new SparseArray<>();
    }

    public View getView(int id) {
        View view = viewSparseArray.get(id);
        if (view == null) {
            view = itemView.findViewById(id);
            viewSparseArray.put(id, view);
        }
        return view;
    }

    public RecycleViewHolder setText(int id, String text) {
        ((TextView) getView(id)).setText(text);
        return this;
    }

    public RecycleViewHolder setTextColor(int id, int textColor) {
        ((TextView) getView(id)).setTextColor(textColor);
        return this;
    }

    public RecycleViewHolder setTextSize(int id, int textSize) {
        ((TextView) getView(id)).setTextSize(textSize);
        return this;
    }
}

这里只给了几个基本的对view操作的方法，可自行完善。

例子

定义三个数据类型：

//左边的对话
public class LeftMessage implements IRecycleViewData {
    private String message;
    public LeftMessage(String message) {
        this.message = message;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    @Override
    public int getItemViewId() {
        return R.layout.view_left_message;
    }
}
//右边的对话
public class RightMessage extends LeftMessage {
    public RightMessage(String message) {
        super(message);
    }

    @Override
    public int getItemViewId() {
        return R.layout.view_right_message;
    }
}
//时间戳
public class TimeMessage implements IRecycleViewData {
    private String time;

    public TimeMessage(String time) {
        this.time = time;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }

    @Override
    public int getItemViewId() {
        return R.layout.view_time_message;
    }
}

Adapter的使用

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private RecyclerView recyclerView;
    private RecycleViewAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.add).setOnClickListener(this);
        findViewById(R.id.delete).setOnClickListener(this);
        recyclerView = findViewById(R.id.recycle_view);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        recyclerView.setLayoutManager(linearLayoutManager);
        initAdapter();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        recyclerView.setAdapter(null);
        if (adapter != null) {
            adapter.clear();
            adapter = null;
        }
    }

    private void initAdapter() {
        adapter = new RecycleViewAdapter() {
            @Override
            protected void bindData(@NonNull RecycleViewHolder viewHolder, IRecycleViewData data, int position) {
                if (data instanceof TimeMessage) {
                    viewHolder.setText(R.id.time, ((TimeMessage) data).getTime());
                } else if (data instanceof LeftMessage) {
                    viewHolder.setText(R.id.message, ((LeftMessage) data).getMessage());
                } else if (data instanceof RightMessage) {
                    viewHolder.setText(R.id.message, ((RightMessage) data).getMessage());
                }
            }
        };
        recyclerView.setAdapter(adapter);
        addData();
    }

    private void addData() {
        List<IRecycleViewData> data = new ArrayList<>();
        data.add(new TimeMessage(new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date())));
        data.add(new LeftMessage("你好呀"));
        data.add(new RightMessage("很高兴认识你"));
        adapter.addData(data);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.add:
                addData();
                break;
            case R.id.delete:
                adapter.removeData(0);
                break;
        }
    }
}