Android使用Recyclerview实现图片水平自动循环滚动效果

简介：

本篇博客主要介绍的是如何使用recyclerview实现图片水平方向自动循环（跑马灯效果）

效果图： 　　

思路：

1.准备m张图片

1.使用recyclerview实现，返回无数个（实际interge.maxvalue）item，第n个item显示第n%m张图片

3.使用recyclerview.scrollby  每个一段时间水平滚动一段距离

4.通过layoutmanager.findfirstvisibleitemposition()获取当前显示的第一个view是第几个item,上面的imageview显示对应de图片

实现代码：

xml文件

1.activity布局文件activity_recy.xml　　

<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">
  <imageview
    android:layout_width="300dp"
    android:layout_height="350dp"
    android:layout_gravity="center_horizontal"
    android:id="@+id/img"
    android:src="@drawable/p5"
    android:scaletype="fitxy"
    />

    <android.support.v7.widget.recyclerview
      android:layout_width="match_parent"
      android:layout_height="150dp"
      android:layout_margintop="10dp"
      android:id="@+id/recyclerview"
      ></android.support.v7.widget.recyclerview>



</linearlayout>

2.适配器布局item_horizon.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"

  >
  <imageview
    android:layout_width="100dp"
    android:layout_height="match_parent"
    android:id="@+id/img"
    android:layout_marginleft="5dp"
    android:layout_marginright="5dp"
    android:scaletype="fitxy"
    />

</linearlayout>

activity　　

public class horizontalactivity extends appcompatactivity implements recyadapter.onitemclicklistener {
  private string tag="horizontalactivity";

  @bindview(r.id.img)
  imageview img;
  @bindview(r.id.recyclerview)
  recyclerview recyclerview;


  private integer[] mimgids = {r.drawable.p1, r.drawable.p2, r.drawable.p3, r.drawable.p4, r.drawable.p5,
      r.drawable.pic1, r.drawable.pic5, r.drawable.pic6};
  private list<integer> datas;
  private recyadapter recyadapter;
  private handler mhandler=new handler();
  private linearlayoutmanager layoutmanager;

  private int olditem=0;


  @override
  protected void oncreate(@nullable bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.activity_recy);
    butterknife.bind(this);
    initdata();
    initrecy();
    img.setimageresource(datas.get(0));
    recyadapter.setonitemclicklistener(this);
  }


  runnable scrollrunnable=new runnable() {
    @override
    public void run() {
      recyclerview.scrollby(3,0);

//      int firstitem = layoutmanager.findfirstvisibleitemposition();
      int firstitem=layoutmanager.findfirstvisibleitemposition();
      if(firstitem!=olditem&&firstitem>0){
        olditem=firstitem;
        img.setimageresource(datas.get(olditem%datas.size()));
      }

      log.e(tag, "run: firstitem:"+firstitem );


      mhandler.postdelayed(scrollrunnable,10);
    }
  };

  private void initrecy() {
    recyadapter=new recyadapter(this,datas);

    layoutmanager = new linearlayoutmanager(this);
    layoutmanager.setorientation(linearlayoutmanager.horizontal);
    recyclerview.setlayoutmanager(layoutmanager);
    recyclerview.setadapter(recyadapter);
  }

  private void initdata() {
    datas=new arraylist<>();
    for (int i = 0; i <mimgids.length ; i++) {
      datas.add(mimgids[i]);
    }
  }

  @override
  protected void onresume() {
    super.onresume();
    mhandler.postdelayed(scrollrunnable,10);
  }

  @override
  protected void onstop() {
    super.onstop();
    mhandler.removecallbacks(scrollrunnable);
  }

  @override
  public void onitemclick(view view, int tag) {
    toast.maketext(this,"第"+tag+"张图片被点击了",toast.length_short).show();
  }
}

适配器recyadapter

public class recyadapter extends recyclerview.adapter<recyadapter.viewholder> implements view.onclicklistener {

  private context context;
  private list<integer> datas;
  private onitemclicklistener onitemclicklistener;

  public recyadapter(context context, list<integer> datas) {
    this.context = context;
    this.datas = datas;
  }

  @override
  public viewholder oncreateviewholder(viewgroup parent, int viewtype) {
    view view = layoutinflater.from(context).inflate(r.layout.item_horizontal, parent, false);
    viewholder vh=new viewholder(view);
    view.setonclicklistener(this);
    return vh;
  }


  @override
  public void onbindviewholder(viewholder holder, int position) {
    int newpos=position%datas.size();

    holder.img.setimageresource(datas.get(newpos));

    holder.itemview.settag(position);


  }

  @override
  public int getitemcount() {
    return integer.max_value;
  }

  @override
  public void onclick(view view) {
    if(onitemclicklistener!=null){
      onitemclicklistener.onitemclick(view, (integer) view.gettag());
    }
  }


  class viewholder extends recyclerview.viewholder {
     imageview img;
    public viewholder(view itemview) {
      super(itemview);
      img=itemview.findviewbyid(r.id.img);
    }
  }

  public void setonitemclicklistener(onitemclicklistener listener){
    this.onitemclicklistener=listener;

  }
  interface onitemclicklistener{
    void onitemclick(view view,int tag);
  }

}

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