每次滚动时，毕加索都会在 ListView 中刷新图像

Question

我有一个 ListView，每次我上下滚动时都会刷新图像

我正在从我提供给毕加索的 JSON 中挑选图片网址。

我正在使用 Picasso 加载图像。

所有图像的总大小为 516kb，知道这一点，我不认为这是缓存问题，因为图像大小实际上很小。

老实说，我已经在 S.O 上研究过这个问题，但还没有看到任何好的解决方案。

也许这个问题与毕加索无关，也许我的实现实际上是错误的。请我需要更多这方面的知识。

这是我下面的代码。

public class ImageAdapter extends ArrayAdapter<Genres> {

    ArrayList<Genres> movieList;
    TextView movietitle, moviecategory;

    LayoutInflater vi;
    int Resource;
    ViewHolder holder;

    private Context mContext;

    public ImageAdapter(Context context, int resource, ArrayList<Genres> objects) {
        super(context, resource, objects);
        vi = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        Resource = resource;
        movieList = objects;
        mContext = context;
    }

    // create a new ImageView for each item referenced by the Adapter
    public View getView(int position, View convertView, ViewGroup parent) {
        View v = convertView;
        ImageView imageView;
        if (v == null) {
            holder = new ViewHolder();
            v = vi.inflate(Resource, null);

            holder.imageview = (ImageView) v.findViewById(R.id.movieimage);

            LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(96, 128);
            holder.imageview.setLayoutParams(layoutParams);
            holder.imageview.setScaleType(ImageView.ScaleType.CENTER_CROP);
            holder.imageview.setPadding(4, 4, 4, 4);
            holder.imageview.setAdjustViewBounds(true);

            holder.movietitle = (TextView) v.findViewById(R.id.movietitle);
            holder.moviecategory = (TextView) v.findViewById(R.id.moviecategory);

            v.setTag(holder);

        } else {
            holder = (ViewHolder) v.getTag();
        }

        Picasso.with(mContext)
        .load(movieList.get(position).getImage())
        .noFade()
        .into(holder.imageview);

        holder.movietitle.setText(movieList.get(position).getMoviename());
        holder.moviecategory.setText(movieList.get(position).getCategory());

        return v;
    }

    static class ViewHolder {
        public ImageView imageview;
        public TextView movietitle;
        public TextView moviecategory;
    }

}

Answer 1

我认为您在这里遇到的问题是您将持有人对象设为适配器类的实例变量，因此实际上您只有一个视图持有人。

尝试删除你的实例变量声明

LayoutInflater vi;
int Resource;
ViewHolder holder;    // remove or comment out this line 

private Context mContext;

然后创建新的视图持有者和getTag()返回的持有者

局部变量。

所以这两个变化：

第一：

if (v == null) {
   // holder = new ViewHolder();
   ViewHolder holder = new ViewHolder();  // replace above commented line with this line
   v = vi.inflate(Resource, null);

然后在你的 else 子句中：

    } else {
    //    holder = (ViewHolder) v.getTag();
          ViewHolder holder = (ViewHolder) v.getTag(); // replace above commented line with this one.
    }

现在布局存储的持有者将是不同的视图，而不是您当前拥有的唯一一个。

作为参考，这里是我与毕加索一起使用的适配器。有几个不同之处，但我认为主要是您对 viewHolder 变量使用单个实例变量。

public class FollowedUsersListAdapter extends ArrayAdapter<UserListItem> {
    private final Context context;
    private final ArrayList<UserListItem> values;

    public FollowedUsersListAdapter(Context context, ArrayList<UserListItem> values) {
        super(context, R.layout.row_layout, values);
        this.context = context;
        this.values = values;
    }

    static class ViewHolder {
        public TextView userNameView;
        public TextView lastPostView;
        public TextView postedTimeAgoView;
        public ImageView imageView;
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        View followedUserView = convertView;
        if (followedUserView == null) {
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            followedUserView = inflater.inflate(R.layout.followed_user_item_layout, parent, false);
            ViewHolder viewHolder = new ViewHolder();
            viewHolder.userNameView = (TextView) followedUserView.findViewById(R.id.user_name);
            viewHolder.lastPostView = (TextView) followedUserView.findViewById(R.id.last_post);
            viewHolder.postedTimeAgoView = (TextView) followedUserView.findViewById(R.id.posted_time_ago);
            viewHolder.imageView = (ImageView) followedUserView.findViewById(R.id.user_icon);
            followedUserView.setTag(viewHolder);
        }

        ViewHolder holder = (ViewHolder) followedUserView.getTag();
        holder.userNameView.setText(values.get(position).getName());
        holder.lastPostView.setText(values.get(position).getLastMicropost());
        holder.postedTimeAgoView.setText(values.get(position).getPostedTimeAgo());
        ImageView imageView = holder.imageView;
        String gravatarURL = "http://www.gravatar.com/avatar/"
                + values.get(position).getGravatarId();
        Picasso.with(context).load(gravatarURL).into(imageView);


        return followedUserView;
    }

}