Question

我有一个ListView，我想在其中显示一些图像。显示一些图像我有网址数组。我使用凌空库下载图像。但问题是，当我第一次运行应用程序时，它只显示我的图像。但当我再次访问屏幕时，它会显示所有图像。我无法认识到这个问题，请帮帮我。

适配器

public CategoryListAdapter(Context context, ArrayList<Category> categories) {
        mContext = context;
        mCategories = categories;
        mImageLoader = VolleySingleton.getInstance().getImageLoader();
    } 

    @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView = inflater.inflate(R.layout.category_list_item, parent, false);
                mViewHolder = new ViewHolder();
                mViewHolder.mCategoryLogo = (ImageView) convertView.findViewById(R.id.category_image);
                mViewHolder.mCategoryName = (TextView) convertView.findViewById(R.id.category_name);
                convertView.setTag(mViewHolder);
            } else {
                mViewHolder = (ViewHolder) convertView.getTag();
            }

            mViewHolder.mCategoryName.setText(mCategories.get(position).getCategory_name());

            if (TextUtils.isEmpty(mCategories.get(position).getCategory_logo())) {
                mViewHolder.mCategoryLogo.setImageResource(R.drawable.ic_launcher);
            } else {
                mImageLoader.get(mCategories.get(position).getCategory_logo(),this);
            }
            return convertView;
        }

@Override
    public void onErrorResponse(VolleyError error) {
        mViewHolder.mCategoryLogo.setImageResource(R.drawable.ic_launcher);
    }
    @Override
    public void onResponse(ImageContainer response, boolean isImmediate) {
        mViewHolder.mCategoryLogo.setImageBitmap(response.getBitmap());
    }

Answer 1

onResponse将被异步调用。这意味着mViewHolder可能会引用与当前图像下载无关的其他持有者。

我建议您使用NetworkImageView，这是Volley库的一部分。

布局：

<com.android.volley.toolbox.NetworkImageView
    android:id="@+id/category_image"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
 />

在适配器中：

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.category_list_item, parent, false);
            mViewHolder = new ViewHolder();
            mViewHolder.mCategoryLogo = (NetworkImageView) convertView.findViewById(R.id.category_image);
            mViewHolder.mCategoryName = (TextView) convertView.findViewById(R.id.category_name);
            convertView.setTag(mViewHolder);
        } else {
            mViewHolder = (ViewHolder) convertView.getTag();
        }

        mViewHolder.mCategoryName.setText(mCategories.get(position).getCategory_name());

        if (TextUtils.isEmpty(mCategories.get(position).getCategory_logo())) {
            mViewHolder.mCategoryLogo.setImageResource(R.drawable.ic_launcher);
        } else {
            mViewHolder.mCategoryLogo.setImageUrl(mCategories.get(position).getCategory_logo(),mImageLoader);
        }
        return convertView;
    }

Volley Library没有显示图像

1 个答案: