Android使用Recyclerview實現圖片水平自動循環滾動效果

簡介：

本篇博客主要介紹的是如何使用RecyclerView實現圖片水平方向自動循環（跑馬燈效果）

效果圖： 　　

思路：

1.准備m張圖片

1.使用Recyclerview實現，返回無數個（實際Interge.MAXVALUE）item，第n個item顯示第n%m張圖片

3.使用recyclerview.scrollBy  每個一段時間水平滾動一段距離

4.通過layoutManager.findFirstVisibleItemPosition()獲取當前顯示的第一個View是第幾個item,上面的ImageView顯示對應de圖片

實現代碼：

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.適配器布局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+"張圖片被點擊了",Toast.LENGTH_SHORT).show();
  }
}

適配器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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