RecycleView的万能适配器

转载自http://www.cnblogs.com/liushilin/p/5720926.html

由于RecyclerView的Adapter必须继承自RecyclerView.Adapter，并且指定我们写的ViewHolder为泛型，为了达到万能的效果，我们把需要传入的Java Bean属性直接用一个泛型T指代。

下面这些值得你注意：

1）RecyclerView没有提供Item的点击事件，所以我们需要自己自定义，建议实现在Adapter中，因为adapter里面会用到ViewHolder，这样有助用我们写每一项的点击事件。

2）RecyclerView不仅支持全局刷新，而且支持局部刷新，所以我们建议把添加和删除的方法直接写在Adapter中。

3）我们为了达到万能的效果，所以我们把设置holder的方法作为一个抽象方法，方面我们通过viewId传值到相应的控件中，把整个Adapter变成一个抽象方法，这样在子类中就可以去通过强制实现的方式把我们的数据填充进去。

还是直接看源码吧。

 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;

 /**
  * 万能的RecyclerView适配器
  * Created by 南尘 on 16-7-30.
  */
 public abstract class BaseRecyclerAdapter<T> extends RecyclerView.Adapter<BaseRecyclerHolder> {

     private Context context;//上下文
     private List<T> list;//数据源
     private LayoutInflater inflater;//布局器
     private int itemLayoutId;//布局id
     private boolean isScrolling;//是否在滚动
     private OnItemClickListener listener;//点击事件监听器
     private OnItemLongClickListener longClickListener;//长按监听器
     private RecyclerView recyclerView;

     //在RecyclerView提供数据的时候调用
     @Override
     public void onAttachedToRecyclerView(RecyclerView recyclerView) {
         super.onAttachedToRecyclerView(recyclerView);
         this.recyclerView = recyclerView;
     }

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

     /**
      * 定义一个点击事件接口回调
      */
     public interface OnItemClickListener {
         void onItemClick(RecyclerView parent, View view, int position);
     }

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

     /**
      * 插入一项
      *
      * @param item
      * @param position
      */
     public void insert(T item, int position) {
         list.add(position, item);
         notifyItemInserted(position);
     }

     /**
      * 删除一项
      *
      * @param position 删除位置
      */
     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);//设置背景
         }
         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适配器的方法，子类需要重写
      *
      * @param holder      ViewHolder
      * @param item        子项
      * @param position    位置
      * @param isScrolling 是否在滑动
      */
     public abstract void convert(BaseRecyclerHolder holder, T item, int position, boolean isScrolling);
 }

其他的代码就很简单了，java bean类Data和布局和昨天一样的，大家可以自己去随便怎么布局。

这里只上一个MainActivity的代码

 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,"你点击了第%d项,长按会删除！",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("网络 "+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();
     }
 }