RecycleView的萬能適配器

轉載自http://www.cnblogs.com/liushilin/p/5720926.html

由於RecyclerView的Adapter必須繼承自RecyclerView.Adapter，並且指定我們寫的ViewHolder為泛型，為了達到萬能的效果，我們把需要傳入的Java Bean屬性直接用一個泛型T指代。

下面這些值得你注意：

1）RecyclerView沒有提供Item的點擊事件，所以我們需要自己自定義，建議實現在Adapter中，因為adapter里面會用到ViewHolder，這樣有助用我們寫每一項的點擊事件。

2）RecyclerView不僅支持全局刷新，而且支持局部刷新，所以我們建議把添加和刪除的方法直接寫在Adapter中。

3）我們為了達到萬能的效果，所以我們把設置holder的方法作為一個抽象方法，方面我們通過viewId傳值到相應的控件中，把整個Adapter變成一個抽象方法，這樣在子類中就可以去通過強制實現的方式把我們的數據填充進去。

還是直接看源碼吧。

package com.example.nanchen.commonadaperrecyclerdemo;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.util.List;

/**
 * 萬能的RecyclerView適配器
 * Created by 南塵 on 16-7-30.
 */
public abstract class BaseRecyclerAdapter<T> extends RecyclerView.Adapter<BaseRecyclerHolder> {

    private Context context;//上下文
    private List<T> list;//數據源
    private LayoutInflater inflater;//布局器
    private int itemLayoutId;//布局id
    private boolean isScrolling;//是否在滾動
    private OnItemClickListener listener;//點擊事件監聽器
    private OnItemLongClickListener longClickListener;//長按監聽器
    private RecyclerView recyclerView;

    //在RecyclerView提供數據的時候調用
    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        this.recyclerView = recyclerView;
    }

    @Override
    public void onDetachedFromRecyclerView(RecyclerView recyclerView) {
        super.onDetachedFromRecyclerView(recyclerView);
        this.recyclerView = null;
    }

    /**
     * 定義一個點擊事件接口回調
     */
    public interface OnItemClickListener {
        void onItemClick(RecyclerView parent, View view, int position);
    }

    public interface OnItemLongClickListener {
        boolean onItemLongClick(RecyclerView parent, View view, int position);
    }

    /**
     * 插入一項
     *
     * @param item
     * @param position
     */
    public void insert(T item, int position) {
        list.add(position, item);
        notifyItemInserted(position);
    }

    /**
     * 刪除一項
     *
     * @param position 刪除位置
     */
    public void delete(int position) {
        list.remove(position);
        notifyItemRemoved(position);
    }

    public BaseRecyclerAdapter(Context context, List<T> list, int itemLayoutId) {
        this.context = context;
        this.list = list;
        this.itemLayoutId = itemLayoutId;
        inflater = LayoutInflater.from(context);

        //        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        //            @Override
        //            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        //                super.onScrollStateChanged(recyclerView, newState);
        //                isScrolling = !(newState == RecyclerView.SCROLL_STATE_IDLE);
        //                if (!isScrolling) {
        //                    notifyDataSetChanged();
        //                }
        //            }
        //        });
    }

    @Override
    public BaseRecyclerHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(itemLayoutId, parent, false);
        return BaseRecyclerHolder.getRecyclerHolder(context, view);
    }

    @Override
    public void onBindViewHolder(final BaseRecyclerHolder holder, int position) {

        if (listener != null){
            holder.itemView.setBackgroundResource(R.drawable.recycler_bg);//設置背景
        }
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (listener != null && view != null && recyclerView != null) {
                    int position = recyclerView.getChildAdapterPosition(view);
                    listener.onItemClick(recyclerView, view, position);
                }
            }
        });


        holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                if (longClickListener != null && view != null && recyclerView != null) {
                    int position = recyclerView.getChildAdapterPosition(view);
                    longClickListener.onItemLongClick(recyclerView, view, position);
                    return true;
                }
                return false;
            }
        });

        convert(holder, list.get(position), position, isScrolling);

    }

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

    public void setOnItemClickListener(OnItemClickListener listener) {
        this.listener = listener;
    }

    public void setOnItemLongClickListener(OnItemLongClickListener longClickListener) {
        this.longClickListener = longClickListener;
    }

    /**
     * 填充RecyclerView適配器的方法，子類需要重寫
     *
     * @param holder      ViewHolder
     * @param item        子項
     * @param position    位置
     * @param isScrolling 是否在滑動
     */
    public abstract void convert(BaseRecyclerHolder holder, T item, int position, boolean isScrolling);
}

其他的代碼就很簡單了，java bean類Data和布局和昨天一樣的，大家可以自己去隨便怎么布局。

這里只上一個MainActivity的代碼

package com.example.nanchen.commonadaperrecyclerdemo;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    private List<Data> list;
    private RecyclerView recyclerView;
    private BaseRecyclerAdapter<Data> adapter;
    private EditText text;

    @SuppressWarnings("unchecked")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        list = new ArrayList<>();

        initList();

        adapter = new BaseRecyclerAdapter<Data>(this,list,R.layout.list_item) {
            @Override
            public void convert(BaseRecyclerHolder holder, Data item, int position, boolean isScrolling) {
                holder.setText(R.id.item_text,item.getText());
                if (item.getImageUrl() != null){
                    holder.setImageByUrl(R.id.item_image,item.getImageUrl());
                }else {
                    holder.setImageResource(R.id.item_image,item.getImageId());
                }
            }

        };

        adapter.setOnItemClickListener(new BaseRecyclerAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(RecyclerView parent, final View view, int position) {
                Toast.makeText(MainActivity.this, String.format(Locale.CHINA,"你點擊了第%d項,長按會刪除！",position),Toast.LENGTH_SHORT).show();
            }
        });

        adapter.setOnItemLongClickListener(new BaseRecyclerAdapter.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(RecyclerView parent, View view, int position) {
                adapter.delete(position);
                return true;
            }
        });

        text = (EditText) findViewById(R.id.main_text);
        recyclerView = (RecyclerView) findViewById(R.id.main_recycler);
        recyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));
        recyclerView.setAdapter(adapter);



    }

    public void initList(){
        for (int i = 0; i < 5; i++) {
            list.add(new Data("本地 "+i,R.mipmap.ic_launcher));
        }
        for (int i = 0; i < 5; i++) {
            list.add(new Data("網絡 "+i,"http://pic.cnblogs.com/face/845964/20160301162812.png"));
        }
    }

    public void btnClick(View view) {
        String string = text.getText().toString().trim();
        Data data = new Data(string,R.mipmap.ic_launcher);
//        list.add(list.size()/2,data);
        adapter.insert(data,list.size()/2);

        Toast.makeText(MainActivity.this,list.size()+"",Toast.LENGTH_SHORT).show();
    }
}