Question

我有一个ListView，每次我上下滚动时都会保持刷新图像

我正在从毕加索提供的JSON中挑选图片网址。

我正在使用Picasso来加载图片。

图像的总大小一起是516kb，我知道，我不认为它是一个缓存问题，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没有关系，也许我的实施实际上是错误的。我需要更多的知识。

这是我的代码。

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

我认为你在这里遇到的问题是你的持有者对象是你的适配器类的实例变量，所以实际上你只有一个视图持有者。

尝试删除实例变量声明

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

private Context mContext;

然后同时制作新的视图持有者和getTag()

返回的视图持有者

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视图。

作为参考，这里是我与Picasso一起使用的适配器。有几个不同但我认为主要的是你使用viewHolder变量的单个实例变量。

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;
    }

}

毕加索每次滚动时都会在ListView中刷新图像

1 个答案: