Android RecycleView滚动监听，以及view回收的细节

Posted 2023-04-04

参考技术A 主要细节是，如果要在recycleView在回收的同时，做UI调整容易出现的问题。
一、xml可见的最外层设置为margin，view的回收还有添加的时间点可能不好计算，容易出现卡顿的情况，
二、如果是实用方法smoothScrollBy，第一个view刚好滚出可视区的时候是没有被回收的，技巧就是滚动距离加1
没图没真相，以下是业务需求的效果

首先想法是通过behavior解决问题，但是后来发现behavior需要好多个，各种相互观察好麻烦，所以想一下可不可以直接使用RecycleView，通过滚动监听改变图片大小实现功能，初步想法是第一个可视view不断变小，第二个可视的view不断变大，如下图

滚动的初步想法是这样的通过滚动距离dx，来改变view的大小

但是后来发现dx，效果不行，有兴趣的同学自己试一下，所以想了另外一个思路，根据下标为2的view也就是第三本书的位置，修改前面两本书的宽度，所以不需要dx了,这里顺便提一下，书本这个view是重写了ImageView的，把宽高比固定为3:4，所以只需要不断的改变书本的宽度就好了，其中bookWidth 为小书本的原始高度

到这里基本上就实现了滚动效果了，但是业务需求是当手指不在滑动的时候，不允许书本被覆盖的，所以这里就要，监听滚动状态

这个地方必须使用smoothScrollBy，不能是ScrollBy，因为ScrollBy不会回调onScrolled（@NonNull RecyclerView recyclerView, int dx, int dy）这个方法，造成view宽度没有重新设定。
项目地址: https://gitee.com/feng87/BookShelf

RecycleView的使用+自定义监听事件

最近使用了RecycleView，发下这个控件十分好用，替代了listView和GridView,包括适配器都很方便。

效果如下：

 

具体使用如下所示：

 1 compile ‘com.android.support:recyclerview-v7:25.3.1‘

activity_main.xml 

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

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



</LinearLayout>

item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >
    <!--android:orientation="horizontal"-->

    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/txt_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />

</LinearLayout>

　　

MainActivity

package com.bway.recycleviewtest;

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.Toast;

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

public class MainActivity extends AppCompatActivity {

    private List<MyImage> mList;

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

        RecyclerView mRecycler = (RecyclerView) findViewById(R.id.recycler);
        /**
         * listView
         */
        LinearLayoutManager manager = new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);
        mRecycler.setLayoutManager(manager);
        HomeAdapter adapter = new HomeAdapter(this,mList);
        mRecycler.setAdapter(adapter);
        /**
         * GridView
         */
       /* GridLayoutManager manager1 = new GridLayoutManager(this,3,GridLayoutManager.VERTICAL,false);
        mRecycler.setLayoutManager(manager1);
        HomeAdapter adapter = new HomeAdapter(this,mList);
        mRecycler.setAdapter(adapter);*/
        /**
         * 瀑布流
         */
       /* StaggeredGridLayoutManager manager = new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL);
        mRecycler.setLayoutManager(manager);
        HomeAdapter adapter = new HomeAdapter(this,mList);*/

        /**
         * 设置自定义的条目点击事件
         */
        adapter.setOnItemClickLisitenter(new RecycleViewLisitenter.onItemClickLisitenter() {
            @Override
            public void onItemClick(View v, int position) {
                Toast.makeText(MainActivity.this,position+"",Toast.LENGTH_SHORT).show();
            }
        });
        /**
         * 设置自定义的条目长按监听
         */
        adapter.setOnItemLongClickLisitenter(new RecycleViewLisitenter.onItemLongClickLisitenter() {
            @Override
            public void onItemLongClick(View v, int position) {
                Toast.makeText(MainActivity.this,position+"long",Toast.LENGTH_SHORT).show();
            }
        });
        mRecycler.setAdapter(adapter);

    }

    /**
     * 初始化数据
     */
    private void initData() {
        mList = new ArrayList<>();
        mList.add(new MyImage("第一张","https://ss0.bdstatic.com/94oJfD_bAAcT8t7mm9GUKT-xh_/timg?image&quality=100&size=b4000_4000&sec=1497864641&di=7a7a381bca514d830aea92d66a7f9024&src=http://pic.58pic.com/58pic/13/61/00/61a58PICtPr_1024.jpg"));
        mList.add(new MyImage("第二张","https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1497874818536&di=6ddb63c3e66ac32feb5762d8d5c1fd42&imgtype=0&src=http%3A%2F%2Fpic.58pic.com%2F58pic%2F13%2F60%2F97%2F48Q58PIC92r_1024.jpg"));
        mList.add(new MyImage("第三张","https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1497874818535&di=9d786693e181801447e49c37bc2bc627&imgtype=0&src=http%3A%2F%2Fi2.sanwen.net%2Fdoc%2F1608%2F704-160PQ43458.png"));
        mList.add(new MyImage("第四张","https://ss0.bdstatic.com/94oJfD_bAAcT8t7mm9GUKT-xh_/timg?image&quality=100&size=b4000_4000&sec=1497864813&di=64e84994c2f8864a69dab604d6f4d3a0&src=http://p4.gexing.com/qqpifu/20120821/1212/50330ab3e811f.jpg"));
        mList.add(new MyImage("第五张","http://up.qqjia.com/z/18/tu19139_7.jpg"));

    }
}

　　

HomeAdapter

package com.bway.recycleviewtest;

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

import com.bumptech.glide.Glide;

import java.util.List;



public class HomeAdapter extends RecyclerView.Adapter<HomeAdapter.ViewHolder> implements View.OnClickListener, View.OnLongClickListener {

    Context context;
    List<MyImage> mList;
    private RecycleViewLisitenter.onItemClickLisitenter onItem;
    private RecycleViewLisitenter.onItemLongClickLisitenter onLongItem;

    public HomeAdapter(Context context, List<MyImage> mList) {
        this.context = context;
        this.mList = mList;
    }

    public void setOnItemLongClickLisitenter(RecycleViewLisitenter.onItemLongClickLisitenter onLongItem){
        this.onLongItem = onLongItem;
    }
    public void setOnItemClickLisitenter(RecycleViewLisitenter.onItemClickLisitenter onItem){
        this.onItem = onItem;
    }
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View view = View.inflate(context, R.layout.item, null);
        view.setOnClickListener(this);
        view.setOnLongClickListener(this);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        /**
         * 给itemView设置tag
         */
        holder.itemView.setTag(position);
        MyImage myImage = mList.get(position);
        Glide.with(context).load(myImage.getUrl()).into(holder.mImage);
        holder.mTxt.setText(myImage.getTitle());

    }

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

    /**
     * item点击事件
     * @param v
     */
    @Override
    public void onClick(View v) {
        if(onItem!=null){
            onItem.onItemClick(v, (Integer) v.getTag());
        }
    }


    @Override
    public boolean onLongClick(View v) {
        if(onLongItem!=null){
            onLongItem.onItemLongClick(v, (Integer) v.getTag());
        }
        return true;
    }

    class ViewHolder extends RecyclerView.ViewHolder{

        ImageView mImage;
        TextView mTxt;

        public ViewHolder(View itemView) {
            super(itemView);
            mImage = (ImageView) itemView.findViewById(R.id.image);
            mTxt = (TextView) itemView.findViewById(R.id.txt_title);
        }
    }
}

　RecycleViewLisitenter(自定义条目点击事件)

package com.bway.recycleviewtest;

import android.view.View;



public class RecycleViewLisitenter {

    /**
     * RecycleView的条目点击监听
     */
    public interface onItemClickLisitenter{
        void onItemClick(View v,int position);
    };
    /**
     * RecycleView的条目长按点击监听
     */
    public interface onItemLongClickLisitenter{
        void onItemLongClick(View v,int position);
    };
}