RecyclerView的简要学习与常用方法

看了hongyang大神的慕课网教学视屏，记录一下，毕竟记忆这种东西，我只有7秒
在android5.0之后，谷歌推出了一款View，叫RecyclerView，谷歌也提供了兼容库，供5.0一下的设备兼容它。

为什么叫RecyclerView？

与设计思路有关。他与ListView与GirdView的设计思想不同
它不关心Item是否显示在正确的位置，如何显示。
不关心Item间如何分割。
不关心Item增加与删除的动画效果。
仅仅关注如何回收和服用View。
所以叫RecyclerView。

如何控制RecyclerView的显示风格？

引入类LayoutManager。通过LayoutManager去控制RecyclerView的显示风格。比如需要一个ListView的显示风格。就可以调用

mRecyclerView.setLayoutManager(new LinearLayoutManager(this));

如果需要GridView的风格，就传入GirdView
它的显示风格完全交由LayoutManager去管理

如何控制Item间分隔的效果？

引入类ItemDecoration
如果需要定义Item间的分隔效果，可以通过实现ItemDecoration的子类，通过它提供的OnDraw（），onOverDraw（）去绘制item间的分隔情况。如果仅仅关注背景色的间距，通过设置margin或padding去实现分隔。

如何控制item的增加和删除效果？

通过引入ItemAnimator来实现item间的增加与删除的动画效果。
通过设置不同的ItemAnimator的子类，去实现不同的动画效果。
采用插件式的架构，通过设置LayoutManager。ItemDecoration。ItemAnimator去组合实现我们的需求。

RecyclerView相关的重要类
Adapter
ViewHolder
LayoutManager
ItemDecoration
ItemAnimator

RecyclerView强制开发者去使用ViewHolder的模式。

RecyclerView能干什么？

Just like ListView
Just like GirdView
横向 ListView
横向GirdView
瀑布流
定制Item增加与删除动画
等基于LauoutManager的自定义效果

编写的一般步骤

依赖

compile 'com.android.support:recyclerview-v7:23.4.0'

activity xml文件

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

item xml文件

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:background="#44ff0000"
    android:layout_height="72dp">

    <TextView
        android:id="@+id/id_tv"

        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"/>
</FrameLayout>

package com.example.administrator.myrecycle;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.widget.GridLayout;
import android.widget.LinearLayout;


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

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private List<String> mDatas ;
    private SimpleAdapter mAdapter;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        intiDatas();
        initViews();
                //删除或增加
//        mAdapter.addDate(1);
//        mAdapter.deleteDate(1);
        mAdapter = new SimpleAdapter(this,mDatas);
        mRecyclerView.setAdapter(mAdapter);
        //设置RecycleView的布局管理
        //GirdView
        //mRecyclerView.setLayoutManager(new GridLayoutManager(this,3));
        //hor_girdview
        //mRecyclerView.setLayoutManager(new              StaggeredGridLayoutManager(5,StaggeredGridLayoutManager.HORIZONTAL));
        //listview
          mRecyclerView.setLayoutManager(new linearLayoutManager(this));
        //设置RecycleView的Item间分割线

        mRecyclerView.addItemDecoration(new DividerItemDecoration(this,
                DividerItemDecoration.VERTICAL_LIST));
    }

    private void initViews() {
        mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerView);

    }

    private void intiDatas() {
        mDatas = new ArrayList<String>();

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

package com.example.administrator.myrecycle;

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * 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.util.Log;
import android.view.View;

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



    private Drawable mDivider; //item间隔图片资源

    private int mOrientation; //方向，水平或垂直
     //构造方法
    public DividerItemDecoration(Context context, int orientation)
    {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        //mDivider的获取
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(orientation);
    }
   // 设置方向
    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)
    {
        Log.v("recyclerview - itemdecoration", "onDraw()");
        //判断方向，绘制divider
         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);//设置绘制的范围
            mDivider.draw(c);//绘制
        }
    }

    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);
        }
    }

    //提供绘制divider的间隙
    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);
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <size android:height="4dp"/>
    <gradient
        android:centerColor="#ff00ff00"
        android:endColor="#ff0000ff"
        android:startColor="#ffff0000"
        android:type="linear"/>
</shape>

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- 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_02</item>
    </style>

</resources>

package com.example.administrator.myrecycle;

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 java.util.List;

/**
 * Created by Administrator on 2016/10/16.
 */
public class SimpleAdapter extends RecyclerView.Adapter<MyViewHolder>{

    private LayoutInflater mInflater;
    private Context mContext;
    private List<String> mDatas;
    public interface OnItemClickListener
    {
        void onItemClick(View view,int position);
        void onItemLongClick(View view,int position);
    }
    private OnItemClickListener mOnItemClickListener;

    public void setmOnItemClickListener(OnItemClickListener listener)
    {
        this.mOnItemClickListener = listener;
    }
    public SimpleAdapter(Context mContext, List<String> datas) {
        this.mContext = mContext;
        this.mDatas = datas;
        mInflater = LayoutInflater.from(mContext);
    }
   //创建viewHolder
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mInflater.inflate(R.layout.item_single_textview,parent,false);
        MyViewHolder viewHolder = new MyViewHolder(view);
        return viewHolder;
    }
     public void addDate(int pos){
         mDatas.add(pos,"insert");
         notifyItemInserted(pos);
     }
    public void deleteDate(int pos){
        mDatas.remove(pos);
        notifyItemRemoved(pos);


    }
    //绑定ViewHolder
    public void onBindViewHolder(final MyViewHolder holder, final int position) {
        holder.textView.setText(mDatas.get(position));

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

    }

    @Override
    public int getItemCount() {
        return mDatas.size();
    }
}
    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView textView;
        public MyViewHolder(View itemView) {
            super(itemView);
            textView = (TextView) itemView.findViewById(R.id.id_tv);
        }
    }