Android 控件 RecyclerView 的使用

一、RecyclerView是什么

从Android 5.0开始，谷歌公司推出了一个用于大量数据展示的新控件RecylerView，可以用来代替传统的ListView，更加强大和灵活。RecyclerView是support-v7包中的新组件，是一个强大的滑动组件，与经典的ListView相比，同样拥有item回收复用的功能，这一点从它的名字Recyclerview即回收view也可以看出。

二、基本使用

1.引入依赖

implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support:recyclerview-v7:28.0.0'
implementation 'jp.wasabeef:recyclerview-animators:2.2.7'

2.主布局（activity_main.xml）

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/id_add"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="增加" />

    <Button
        android:id="@+id/id_del"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="删除" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/id_recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

3.item布局（activity_itemview.xml）

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:background="@color/colorAccent"
    android:layout_height="72dp">

    <TextView
        android:id="@+id/id_tv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center" />

</FrameLayout>

4.自定义分割线，在res/drawable下新建divider.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <size android:height="2dp" />

    <gradient
        android:centerColor="@color/colorCenter"
        android:endColor="@color/colorEnd"
        android:startColor="@color/colorStart"
        android:type="linear"></gradient>

</shape>

5.将自定义的分割线在style.xml里进行应用

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <item name="android:listDivider">@drawable/divider</item>
    </style>

</resources>

6.自定义分割线的工具类

package com.chen.recyclerviewtest;

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.util.Log;
import android.view.View;

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;
	
	

	private 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);
		}
	}
}

7.MainActivity主界面

package com.chen.recyclerviewtest;

import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

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


public class MainActivity extends AppCompatActivity {

    private List<String> mData;
    private RecyclerView recyclerView;
    private SimpleAdapter simpleAdapter;
    private Button btn_add;
    private Button btn_del;


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

        initData();
        initView();
        simpleAdapter=new SimpleAdapter(this,mData);
        recyclerView.setAdapter(simpleAdapter);

        //设置RecyclerView布局管理器
        LinearLayoutManager linearLayoutManager=new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);
        recyclerView.setLayoutManager(linearLayoutManager);
        //recyclerView.setLayoutManager(new GridLayoutManager(this,2));
        //设置分分割线
        recyclerView.addItemDecoration(new DividerItemDecoration(this,DividerItemDecoration.VERTICAL_LIST));
        //设置动画效果
        recyclerView.setItemAnimator(new DefaultItemAnimator());

        btn_add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                simpleAdapter.addData(mData.size());
            }
        });

        btn_del.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                simpleAdapter.deleteData(mData.size()-1);
            }
        });

        simpleAdapter.setOnItemClickListener(new SimpleAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(MainActivity.this,"点击"+position,Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onItemLongClick(View view, int position) {
                Toast.makeText(MainActivity.this,"长按"+position,Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void initView(){
        recyclerView=findViewById(R.id.id_recyclerView);
        btn_add=findViewById(R.id.id_add);
        btn_del=findViewById(R.id.id_del);
    }

    private void initData(){
        mData=new ArrayList<String>();

        for (int i='A';i<='z';i++){
            mData.add(""+(char)i);
        }
    }
}

8.设置适配器

package com.chen.recyclerviewtest;

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

import java.util.List;

public class SimpleAdapter extends RecyclerView.Adapter<MyViewHolder> {

    private LayoutInflater mInflater;
    private Context mContext;
    private List<String> mData;

    public interface OnItemClickListener{
        void onItemClick(View view,int position);
        void onItemLongClick(View view,int position);
    }

    private OnItemClickListener onItemClickListener;

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

    public SimpleAdapter(Context context,List<String> datas) {
        this.mContext=context;
        this.mData=datas;
        mInflater=LayoutInflater.from(context);
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {

        View view=mInflater.inflate(R.layout.activity_itemview,viewGroup,false);
        MyViewHolder viewHolder=new MyViewHolder(view);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull final MyViewHolder myViewHolder, final int i) {
        myViewHolder.tv.setText(mData.get(i));

        if(onItemClickListener!=null){
            myViewHolder.itemView.setOnClickListener(new View.OnClickListener(){
                public void onClick(View v){
                    onItemClickListener.onItemClick(myViewHolder.itemView,i);
                }
            });
            myViewHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    onItemClickListener.onItemLongClick(myViewHolder.itemView,i);
                    return false;
                }
            });
        }

    }

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

    public void addData(int pos){
        mData.add(pos,"哈哈哈");
        notifyItemInserted(pos);
    }

    public void deleteData(int pos){
        mData.remove(pos);
        notifyItemRemoved(pos);
    }
}

class MyViewHolder extends RecyclerView.ViewHolder {

    TextView tv;
    public MyViewHolder(@NonNull View itemView) {
        super(itemView);
        tv=itemView.findViewById(R.id.id_tv);
    }
}

实现效果：