RecyclerViewSelectableAdapterDemo【封装BaseSelectableAdapter用于多选、单选，以及切换选中状态等功能】

前言

记录封装单选、多选、切换选中状态的BaseSelectableAdapter基类，配合Recyclerview使用。

注意：此Demo只是一个简单的使用，那么实际项目中需要灵活处理！

效果图

代码分析

BaseSelectableAdapter：基类；

BaseSelectable：接口；

OnItemCheckListener：单选图片的监听事件

使用步骤

一、项目组织结构图

注意事项：

1、导入类文件后需要change包名以及重新import R文件路径

2、 Values目录下的文件（strings.xml、dimens.xml、colors.xml等），如果项目中存在，则复制里面的内容，不要整个覆盖

二、导入步骤

（1）在build.gradle中引用recyclerview【版本号和appcompat保持一致】

apply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "com.why.project.recyclerviewselectableadapterdemo"
        minSdkVersion 16
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support.constraint:constraint-layout:1.1.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

    //RecyclerView
    compile "com.android.support:recyclerview-v7:27.1.1"
}

（2）在项目中实现Recyclerview基本数据展现

1、创建Bean类

package com.why.project.recyclerviewselectableadapterdemo.bean;

/**
 * Created by HaiyuKing
 * Used 列表项的bean类
 */

public class Photo {
    private String id;
    private String path;

    public Photo(String id, String path) {
        this.id = id;
        this.path = path;
    }

    public Photo() {
    }

    public String getPath() {
        return path;
    }

    public void setPath(String path) {
        this.path = path;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

Photo.java

2、创建Adapter以及item的布局文件【此时的Adapter只是最开始的基本写法，后续继承BaseSelectableAdapter后还需要修改】

package com.why.project.recyclerviewselectableadapterdemo.adapter;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;

import com.why.project.recyclerviewselectableadapterdemo.R;
import com.why.project.recyclerviewselectableadapterdemo.bean.Photo;
import com.why.project.recyclerviewselectableadapterdemo.util.ResDrawableImgUtil;

import java.util.ArrayList;

/**
 * Created by HaiyuKing
 * Used 列表适配器
 */

public class ChannelAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{
    /**上下文*/
    private Context myContext;
    /**频道集合*/
    private ArrayList<Photo> listitemList;

    /**
     * 构造函数
     */
    public ChannelAdapter(Context context, ArrayList<Photo> itemlist) {
        myContext = context;
        listitemList = itemlist;
    }

    /**
     * 获取总的条目数
     */
    @Override
    public int getItemCount() {
        return listitemList.size();
    }

    /**
     * 创建ViewHolder
     */
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(myContext).inflate(R.layout.channel_list_item, parent, false);
        ItemViewHolder itemViewHolder = new ItemViewHolder(view);
        return itemViewHolder;
    }

    /**
     * 声明grid列表项ViewHolder*/
    static class ItemViewHolder extends RecyclerView.ViewHolder
    {
        public ItemViewHolder(View view)
        {
            super(view);

            listItemLayout = view.findViewById(R.id.griditemLayout);
            gridImg =  view.findViewById(R.id.pic_gridimage);
            choseImg = view.findViewById(R.id.pic_chose);
        }

        RelativeLayout listItemLayout;
        ImageView gridImg;
        ImageView choseImg;
    }

    /**
     * 将数据绑定至ViewHolder
     */
    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int index) {

        //判断属于列表项还是上拉加载区域
        if(viewHolder instanceof ItemViewHolder){
            Photo photo = listitemList.get(index);
            final ItemViewHolder itemViewHold = ((ItemViewHolder)viewHolder);

            String imgPath = photo.getPath();
            Log.e("ChannelAdapter","imgPath="+imgPath);
            itemViewHold.gridImg.setImageResource(ResDrawableImgUtil.getResourceIdByIdentifier(myContext,imgPath));

            //如果设置了回调，则设置点击事件
            if (mOnItemClickLitener != null)
            {
                itemViewHold.listItemLayout.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        int position = itemViewHold.getLayoutPosition();//在增加数据或者减少数据时候，position和index就不一样了
                        mOnItemClickLitener.onItemClick(itemViewHold.listItemLayout, position);
                    }
                });
                //长按事件
                itemViewHold.listItemLayout.setOnLongClickListener(new View.OnLongClickListener() {
                    @Override
                    public boolean onLongClick(View view) {
                        int position = itemViewHold.getLayoutPosition();//在增加数据或者减少数据时候，position和index就不一样了
                        mOnItemClickLitener.onItemLongClick(itemViewHold.listItemLayout, position);
                        return false;
                    }
                });
            }

        }
    }

    /**
     * 添加Item--用于动画的展现*/
    public void addItem(int position,Photo listitemBean) {
        listitemList.add(position,listitemBean);
        notifyItemInserted(position);
    }
    /**
     * 删除Item--用于动画的展现*/
    public void removeItem(int position) {
        listitemList.remove(position);
        notifyItemRemoved(position);
    }

    /*=====================添加OnItemClickListener回调================================*/
    public interface OnItemClickLitener
    {
        void onItemClick(View view, int position);
        void onItemLongClick(View view, int position);
    }

    private OnItemClickLitener mOnItemClickLitener;

    public void setOnItemClickLitener(OnItemClickLitener mOnItemClickLitener)
    {
        this.mOnItemClickLitener = mOnItemClickLitener;
    }
}

ChannelAdapter.java

<?xml version="1.0" encoding="utf-8"?>
<!-- 选择图片界面的九宫格item布局 -->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/griditemLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#00C9C9C9"
    android:layout_margin="5dp">

    <!-- 图片使用src和android:scaleType="centerCrop"、android:adjustViewBounds="true"，可以实现宽高等边 -->
    <ImageView
        android:id="@+id/pic_gridimage"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="fitXY"
        android:src="@drawable/item_img2"
        android:adjustViewBounds="true"
        android:layout_centerInParent="true"
        android:contentDescription="显示图片"
        android:layout_margin="2dp"
        />

    <!-- 选中图标区域 -->
    <ImageView
        android:id="@+id/pic_chose"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:padding="10dp"
        android:adjustViewBounds="true"
        android:contentDescription="显示单选框图标"
        android:scaleType="centerCrop"
        android:src="@drawable/radio_img_noselect"
        />

</RelativeLayout>

channel_list_item.xml

3、将单选框图标复制到项目中

4、在Activity布局文件中引用Recyclerview控件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#F4F4F4">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:cacheColorHint="#00000000"
        android:divider="@null"
        android:listSelector="#00000000"
        android:scrollbars="none"
        />

</RelativeLayout>

5、在Activity类中初始化recyclerview数据【此时只是最基本的写法，后续还需要修改】

package com.why.project.recyclerviewselectableadapterdemo;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;

import com.why.project.recyclerviewselectableadapterdemo.adapter.ChannelAdapter;
import com.why.project.recyclerviewselectableadapterdemo.bean.Photo;

import java.util.ArrayList;
import java.util.Random;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private ArrayList<Photo> mPhotoArrayList;
    private ChannelAdapter mChannelAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initViews();
        initDatas();
        initEvents();

    }

    private void initViews() {
        mRecyclerView = findViewById(R.id.recycler_view);
    }

    private void initDatas() {
        //初始化集合
        mPhotoArrayList = new ArrayList<Photo>();
        for(int i=0; i<10;i++){
            Photo photo = new Photo();
            photo.setId("img"+i);
            int imgIndex = 1 + new Random().nextInt(3) % (1 + (3 - 1));
            photo.setPath("item_img" + imgIndex + ".jpg");

            mPhotoArrayList.add(photo);
        }

        //设置布局管理器
        GridLayoutManager gridLayoutManager = new GridLayoutManager(this,3);
        mRecyclerView.setLayoutManager(gridLayoutManager);

        //设置适配器
        if(mChannelAdapter == null){
            //设置适配器
            mChannelAdapter = new ChannelAdapter(this, mPhotoArrayList);
            mRecyclerView.setAdapter(mChannelAdapter);
            //添加分割线
            //设置添加删除动画
            //调用ListView的setSelected(!ListView.isSelected())方法，这样就能及时刷新布局
            mRecyclerView.setSelected(true);
        }else{
            mChannelAdapter.notifyDataSetChanged();
        }
    }

    private void initEvents() {
        //列表适配器的点击监听事件
        mChannelAdapter.setOnItemClickLitener(new ChannelAdapter.OnItemClickLitener() {
            @Override
            public void onItemClick(View view, int position) {

            }

            @Override
            public void onItemLongClick(View view, int position) {

            }
        });
    }
}

MainActivity.java

6、Demo中使用到的图片资源放在res/drawable中，所以demo中使用到了《ResDrawableImgUtil【根据图片名称获取resID值或者Bitmap对象】》

（3）将adapter/base包复制到项目中【根据实际情况更换Bean类】

（4）将ChannelAdapter继承BaseSelectableAdapter<RecyclerView.ViewHolder>并修改

1、继承BaseSelectableAdapter<RecyclerView.ViewHolder>

2、注释或者去掉context、ArrayList<Photo>变量的声明，因为BaseSelectableAdapter中已经声明了；如果ArrayList<Photo>变量的名称不相同的话，需要修改一处（ChannelAdapter或者BaseSelectableAdapter）

3、添加OnItemCheckListener回调，并添加到单选框图标的点击事件监听中

4、初始化单选框图标的选中/未选中状态

package com.why.project.recyclerviewselectableadapterdemo.adapter;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;

import com.why.project.recyclerviewselectableadapterdemo.R;
import com.why.project.recyclerviewselectableadapterdemo.adapter.base.BaseSelectableAdapter;
import com.why.project.recyclerviewselectableadapterdemo.adapter.base.OnItemCheckListener;
import com.why.project.recyclerviewselectableadapterdemo.bean.Photo;
import com.why.project.recyclerviewselectableadapterdemo.util.ResDrawableImgUtil;

import java.util.ArrayList;

/**
 * Created by HaiyuKing
 * Used 列表适配器
 */

public class ChannelAdapter extends BaseSelectableAdapter<RecyclerView.ViewHolder> {

    /**上下文*/
    //private Context myContext;//因为BaseSelectableAdapter中定义了，所以此处需要注释掉
    /**频道集合*/
    //private ArrayList<Photo> listitemList;//因为BaseSelectableAdapter中定义了，所以此处需要注释掉

    /**
     * 构造函数
     */
    public ChannelAdapter(Context context, ArrayList<Photo> itemlist) {
        myContext = context;
        listitemList = itemlist;
    }

    /**
     * 获取总的条目数
     */
    @Override
    public int getItemCount() {
        return listitemList.size();
    }

    /**
     * 创建ViewHolder
     */
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(myContext).inflate(R.layout.channel_list_item, parent, false);
        ItemViewHolder itemViewHolder = new ItemViewHolder(view);
        return itemViewHolder;
    }

    /**
     * 声明grid列表项ViewHolder*/
    static class ItemViewHolder extends RecyclerView.ViewHolder
    {
        public ItemViewHolder(View view)
        {
            super(view);

            listItemLayout = view.findViewById(R.id.griditemLayout);
            gridImg =  view.findViewById(R.id.pic_gridimage);
            choseImg = view.findViewById(R.id.pic_chose);
        }

        RelativeLayout listItemLayout;
        ImageView gridImg;
        ImageView choseImg;
    }

    /**
     * 将数据绑定至ViewHolder
     */
    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int index) {

        //判断属于列表项还是上拉加载区域
        if(viewHolder instanceof ItemViewHolder){
            final Photo photo = listitemList.get(index);
            final ItemViewHolder itemViewHold = ((ItemViewHolder)viewHolder);

            String imgPath = photo.getPath();
            Log.e("ChannelAdapter","imgPath="+imgPath);
            itemViewHold.gridImg.setImageResource(ResDrawableImgUtil.getResourceIdByIdentifier(myContext,imgPath));

            //如果设置了回调，则设置点击事件
            if (mOnItemClickLitener != null)
            {
                itemViewHold.listItemLayout.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        int position = itemViewHold.getLayoutPosition();//在增加数据或者减少数据时候，position和index就不一样了
                        mOnItemClickLitener.onItemClick(itemViewHold.listItemLayout, position);
                    }
                });
                //长按事件
                itemViewHold.listItemLayout.setOnLongClickListener(new View.OnLongClickListener() {
                    @Override
                    public boolean onLongClick(View view) {
                        int position = itemViewHold.getLayoutPosition();//在增加数据或者减少数据时候，position和index就不一样了
                        mOnItemClickLitener.onItemLongClick(itemViewHold.listItemLayout, position);
                        return false;
                    }
                });
            }

            //初始化列表项的是否选中状态
            boolean isChecked = isSelected(photo);
            if(isChecked) {//选中状态
                itemViewHold.choseImg.setImageResource(R.drawable.radio_img_selected);
            }else{//未选中状态
                itemViewHold.choseImg.setImageResource(R.drawable.radio_img_noselect);
            }

            //单选框图标的点击事件
            itemViewHold.choseImg.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    int position = itemViewHold.getLayoutPosition();//在增加数据或者减少数据时候，position和index就不一样了

                    //注意，这里是根据isEnable判断是否可切换选择状态， 如果可以的话，就进行切换（通过toggleSelection方法添加/移除photo实体类），然后展现出来
                    boolean isEnable = true;//默认可选择，而且是可选择任意数目
                    if (mOnItemCheckListener != null) {//对于单选、多选（设置最大个数）的情况，是在onItemCheck中特殊处理的，并返回Boolean结果（超过多选的最大数目，就不能选择了，所以需要返回false）
                        isEnable = mOnItemCheckListener.onItemCheck(position, photo,getSelectedPhotos().size() + (isSelected(photo) ? -1: 1));
                    }
                    if(isEnable){//如果可选择，则可切换选中状态
                        toggleSelection(photo);//添加/移除到选择的集合中
                        notifyItemChanged(position);
                    }
                }
            });

        }
    }

    /**
     * 添加Item--用于动画的展现*/
    public void addItem(int position,Photo listitemBean) {
        listitemList.add(position,listitemBean);
        notifyItemInserted(position);
    }
    /**
     * 删除Item--用于动画的展现*/
    public void removeItem(int position) {
        listitemList.remove(position);
        notifyItemRemoved(position);
    }

    /*=====================添加OnItemClickListener回调================================*/
    public interface OnItemClickLitener
    {
        void onItemClick(View view, int position);
        void onItemLongClick(View view, int position);
    }

    private OnItemClickLitener mOnItemClickLitener;

    public void setOnItemClickLitener(OnItemClickLitener mOnItemClickLitener)
    {
        this.mOnItemClickLitener = mOnItemClickLitener;
    }

    /*=====================添加OnItemCheckListener回调================================*/
    private OnItemCheckListener mOnItemCheckListener;

    public void setOnItemCheckListener(OnItemCheckListener mOnItemCheckListener)
    {
        this.mOnItemCheckListener = mOnItemCheckListener;
    }
}

三、使用方法

在MainActivity中添加OnItemCheckListener监听事件

package com.why.project.recyclerviewselectableadapterdemo;

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

import com.why.project.recyclerviewselectableadapterdemo.adapter.ChannelAdapter;
import com.why.project.recyclerviewselectableadapterdemo.adapter.base.OnItemCheckListener;
import com.why.project.recyclerviewselectableadapterdemo.bean.Photo;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private ArrayList<Photo> mPhotoArrayList;
    private ChannelAdapter mChannelAdapter;

    private int maxCount = 1;//如果值为1，代表单选；如果值>1，代表多选且设置了最大数目


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initViews();
        initDatas();
        initEvents();

    }

    private void initViews() {
        mRecyclerView = findViewById(R.id.recycler_view);
    }

    private void initDatas() {
        //初始化集合
        mPhotoArrayList = new ArrayList<Photo>();
        for(int i=0; i<10;i++){
            Photo photo = new Photo();
            photo.setId("img"+i);
            int imgIndex = 1 + new Random().nextInt(3) % (1 + (3 - 1));
            photo.setPath("item_img" + imgIndex + ".jpg");

            mPhotoArrayList.add(photo);
        }

        //设置布局管理器
        GridLayoutManager gridLayoutManager = new GridLayoutManager(this,3);
        mRecyclerView.setLayoutManager(gridLayoutManager);

        //设置适配器
        if(mChannelAdapter == null){
            //设置适配器
            mChannelAdapter = new ChannelAdapter(this, mPhotoArrayList);
            mRecyclerView.setAdapter(mChannelAdapter);
            //添加分割线
            //设置添加删除动画
            //调用ListView的setSelected(!ListView.isSelected())方法，这样就能及时刷新布局
            mRecyclerView.setSelected(true);
        }else{
            mChannelAdapter.notifyDataSetChanged();
        }
    }

    private void initEvents() {
        //列表适配器的点击监听事件
        mChannelAdapter.setOnItemClickLitener(new ChannelAdapter.OnItemClickLitener() {
            @Override
            public void onItemClick(View view, int position) {

            }

            @Override
            public void onItemLongClick(View view, int position) {

            }
        });

        //列表适配器的选择监听事件
        mChannelAdapter.setOnItemCheckListener(new OnItemCheckListener() {
            @Override
            public boolean onItemCheck(int position, Photo photo, int selectedItemCount) {
                //如果单选，那么选中的图片路径集合肯定只有一个
                if (maxCount <= 1) {
                    List<Photo> selectedPhotos = mChannelAdapter.getSelectedPhotos();
                    if (!mChannelAdapter.containsThisImg(photo,selectedPhotos)) {//如果点击的不是当前选中的图片，则取消选中状态，重新设置选中状态
                        selectedPhotos.clear();//清空选中的图片集合
                        mChannelAdapter.notifyDataSetChanged();
                    }
                    return true;
                }
                //如果多选，则特殊处理超过最大数目的情况
                if (selectedItemCount > maxCount) {
                    Toast.makeText(MainActivity.this,String.format("最多可选择%1$d张图片",maxCount),Toast.LENGTH_SHORT).show();
                    return false;//超过多选的最大数目，就不能选择了，所以需要返回false
                }
                return true;
            }
        });
    }
}

如果想要获取选中的图片的集合，则使用List<Photo> selectedPhotos = mChannelAdapter.getSelectedPhotos();