Android打造万能适配器--RecyclerView

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一、通常RecyclerView的Adapter写法

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在使用RecyclerView之前我们还需要导入依赖库，在build.gradle中的dependencies下添加：

compile 'com.android.support:recyclerview-v7:24.2.1'

通常情况下的RecyclerView的Adapter:

package com.gcy.universal_adapter_recyclerview.adapter;

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

import com.gcy.universal_adapter_recyclerview.Entity.Bean;
import com.gcy.universal_adapter_recyclerview.R;

import java.util.List;

/**
 * Created by gcy71 on 2016/9/28.
 */

public class MyAdapter extends RecyclerView.Adapter.MyViewHolder> {

    private Context mContext;
    private List mDatas;
    private LayoutInflater mInflater;

    public MyAdapter(Context context , List datas) {
        this.mContext = context;
        this.mDatas = datas;
        this.mInflater = LayoutInflater.from(mContext);
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new MyViewHolder(mInflater.inflate(R.layout.item_recyclerview, parent, false));
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        holder.mTilte.setText(mDatas.get(position).getTitle());
        holder.mInfo.setText(mDatas.get(position).getInfo());
        holder.mTime.setText(mDatas.get(position).getTime());
    }

    @Override
    public int getItemCount() {
        return mDatas.size();
    }

    class MyViewHolder extends RecyclerView.ViewHolder{
        TextView mTilte;
        TextView mInfo;
        TextView mTime;
        public MyViewHolder(View itemView) {
            super(itemView);
            mTilte = (TextView) itemView.findViewById(R.id.id_title);
            mInfo = (TextView) itemView.findViewById(R.id.id_info);
            mTime = (TextView) itemView.findViewById(R.id.id_time);
        }

    }
}

观察发现，RecycleView已经强制我们使用ViewHolder，我们在这里仅仅只发现了getItemCount和onCreateViewHolder两个函数存在重复的代码

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二、封装ViewHolder

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1. 同样我们需要一个SparseArray作为我们存放控件的容器，还需要一个itemView用来获取RecyclerView的Item包含的控件
2. 用户需要在onBindViewHolder方法中对不同的空间实现数据绑定，所以我们需要一个抛出一个getView给用户获取控件
3. 为了减少用户为控件设置值的代码，还可以添加一些辅助方法，例如本例中的setText2TextView，用户在使用的过程中可根据需要自行添加

BaseViewHolder.java

package com.gcy.universal_adapter_recyclerview.utils;

import android.support.v7.widget.RecyclerView;
import android.util.SparseArray;
import android.view.View;
import android.widget.TextView;


/**
 * Created by gcy71 on 2016/9/28.
 */

public class BaseViewHolder extends RecyclerView.ViewHolder {

    /*用于存储各类控件的容器*/
    private SparseArray mViews;

    private View itemView;


    public BaseViewHolder(View itemView) {
        super(itemView);
        mViews = new SparseArray();
        this.itemView = itemView;
        itemView.setTag(this);
    }

    //通过ViewID在容器中获取控件，若在容器中没有该控件就通过ID获取，然后存储到容器中
    public  T getView(int ViewID){
        View view = mViews.get(ViewID);
        if(view == null){
            view = itemView.findViewById(ViewID);
            mViews.put(ViewID , view);
        }
        return (T) view;
    }


    /**
     * 辅助方法，减少用户为控件设置值的代码
     */
    //返回值设置为BaseViewHolder类型是为了实现链式编程
    public BaseViewHolder setText2TextView(int ViewID , String text){
        ((TextView)getView(ViewID)).setText(text);
        return this;
    }

}

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三、封装Adapter

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分析第一步里的MyAdapter可以看出在Adapter里我们至少需要一个Context和一个数据集还有Item的布局文件ID，和ListView的万能适配器类似，我们也定义一个为控件绑定数据的抽象方法，让用户自己实现。
MyBaseAdapter.java

package com.gcy.universal_adapter_recyclerview.utils;

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


import java.util.List;


/**
 * Created by gcy71 on 2016/9/28.
 */

public abstract class MyBaseAdapter extends RecyclerView.Adapter {

    private int LayoutID;
    private Context mContext;
    private List mDatas;

    public MyBaseAdapter(int layoutID, Context mContext , List datas) {
        this.LayoutID = layoutID;
        this.mContext = mContext;
        this.mDatas = datas;
    }

    @Override
    public BaseViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        BaseViewHolder holder = new BaseViewHolder(LayoutInflater.from(mContext).inflate(LayoutID, parent , false));
        return holder;
    }

    @Override
    public void onBindViewHolder(BaseViewHolder holder, int position) {
        blindViewHolder(holder , mDatas.get(position));
    }

    @Override
    public int getItemCount() {
        return mDatas.size();
    }

    public abstract void blindViewHolder(BaseViewHolder holder , T t);
}

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四、工具类

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RecyclerView并未给我们提供Item之间的分割线，所以需要我们自己定义分割线，这里我们直接引用网上的一个工具类DividerItemDecoration

package com.gcy.universal_adapter_recyclerview.utils;/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * limitations under the License.
 */

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;


/**
 * This class is from the v7 samples of the Android SDK. It's not by me!
 * 

 * See the license above for details.
 */
public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{
            android.R.attr.listDivider
    };

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;

    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

    protected Drawable mDivider;

    private int mOrientation;

    public DividerItemDecoration(Context context, int orientation) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(orientation);
    }

    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("invalid orientation");
        }
        mOrientation = orientation;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent) {

        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }

    }


    public void drawVertical(Canvas c, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            //RecyclerView v = new RecyclerView(parent.getContext());
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getHeight() - parent.getPaddingBottom();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }
}

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五、测试

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Bean.java（本例中所使用的实体类）

package com.gcy.universal_adapter_recyclerview.Entity;

/**
 * Created by gcy71 on 2016/9/26.
 */

public class Bean {

    private String title;
    private String info;
    private String time;

    public Bean(String title, String info, String time) {
        this.title = title;
        this.info = info;
        this.time = time;
    }

    public Bean() {
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getInfo() {
        return info;
    }

    public void setInfo(String info) {
        this.info = info;
    }

    public String getTime() {
        return time;
    }

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

item_recyclerview.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin">
    <TextView
        android:id="@+id/id_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="16sp"
        android:text="我是标题"
        android:textColor="#444"/>
    <TextView
        android:id="@+id/id_info"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/id_title"
        android:minLines="1"
        android:maxLines="2"
        android:text="Android打造万能的ListView和GridView适配器"
        android:textColor="#898989"
        android:textSize="16sp"/>

    <TextView
        android:id="@+id/id_time"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/id_info"
        android:minLines="1"
        android:maxLines="2"
        android:text="2016-09-26"
        android:textColor="#898989"
        android:textSize="12sp"/>

RelativeLayout>

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/id_recyclerview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    android.support.v7.widget.RecyclerView>
LinearLayout>

MainActivity.java

package com.gcy.universal_adapter_recyclerview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

import com.gcy.universal_adapter_recyclerview.Entity.Bean;
import com.gcy.universal_adapter_recyclerview.utils.BaseViewHolder;
import com.gcy.universal_adapter_recyclerview.utils.DividerItemDecoration;
import com.gcy.universal_adapter_recyclerview.utils.MyBaseAdapter;

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

public class MainActivity extends AppCompatActivity {

    private List mDatas;
    private RecyclerView mRecyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initData();
        initRecyclerView();
    }

    private void initRecyclerView() {
        mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
        //此处我们使用匿名内部类的方式来为mRecyclerView设置Adapter
        mRecyclerView.setAdapter(new MyBaseAdapter(R.layout.item_recyclerview , this , mDatas) {
            @Override
            public void blindViewHolder(BaseViewHolder holder, Bean bean) {
                holder.setText2TextView(R.id.id_title , bean.getTitle())
                        .setText2TextView(R.id.id_info , bean.getInfo())
                        .setText2TextView(R.id.id_time,bean.getTime());
            }
        });
        mRecyclerView.addItemDecoration(new DividerItemDecoration(this , DividerItemDecoration.VERTICAL_LIST));
    }

    private void initData() {
        mDatas = new ArrayList();
        for(int i=1 ; i<=10 ; i++){
            mDatas.add(new Bean("我是标题 " + i, "Android打造ListView和GridView万能适配器" , "2016-09-28"));
        }
    }
}

测试效果：

项目源码：
https://github.com/Sunrise7878/Universal_adapter/tree/master/universal_adapter_recyclerview