android 从 url 加载图像

Question

我使用 universal image loader 库加载了从 url 到 listview 的大约 50 张图像。这是活页夹数据。

public class BinderDataImg extends BaseAdapter {
    static final String KEY_IMG = "img";
    LayoutInflater inflater;
    List<HashMap<String,String>> imgHashmap;
    ViewHolder holder;
    public BinderDataImg() {
        // TODO Auto-generated constructor stub
    }
    public BinderDataImg(Activity act, List<HashMap<String,String>> map) {
        this.imgHashmap = map;
        inflater = (LayoutInflater) act
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }
    public int getCount() {
        // TODO Auto-generated method stub
        return imgHashmap.size();
    }
    public Object getItem(int arg0) {
        // TODO Auto-generated method stub
        return null;
    }
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return 0;
    }
    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;
        if(convertView==null){
            vi = inflater.inflate(R.layout.list_img, null);
            holder = new ViewHolder();
            holder.iv_img =(ImageView)vi.findViewById(R.id.imageViewImg);
            vi.setTag(holder);
        }
        else{
            holder = (ViewHolder)vi.getTag();
        }
        String uri = imgHashmap .get(position).get(KEY_IMG);
        ImageLoader imageLoader = ImageLoader.getInstance();
        DisplayImageOptions options = new DisplayImageOptions.Builder().cacheInMemory(true)
                .cacheOnDisc(true).resetViewBeforeLoading(true).build();
        imageLoader.displayImage(uri, holder.iv_img, options);
        return vi;
    }
    static class ViewHolder{
        ImageView iv_img;
    }
}

activity.

DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder()
            .cacheOnDisc(true).cacheInMemory(true)
            .imageScaleType(ImageScaleType.EXACTLY)
            .displayer(new FadeInBitmapDisplayer(300)).build();

    ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(
            getApplicationContext())
            .defaultDisplayImageOptions(defaultOptions)
            .memoryCache(new WeakMemoryCache())
            .discCacheSize(100 * 1024 * 1024).build();

    ImageLoader.getInstance().init(config);

几乎，但并非所有图像都加载，并且在 logcat 中有一个 OutOfMemoryError。如何解决？

更新：

这是来自 Picasso 库的 Binderdata。

public class BinderDataImg extends BaseAdapter {
    static final String KEY_IMG = "img";
    LayoutInflater inflater;
    List<HashMap<String,String>> imgHashmap;
    ViewHolder holder;
    public BinderDataImg() {
        // TODO Auto-generated constructor stub
    }
    Activity act;
    public BinderDataImg(Activity act, List<HashMap<String,String>> map) {
        this.imgHashmap = map;
        inflater = (LayoutInflater) act
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                this.act = act;
    }
    public int getCount() {
        // TODO Auto-generated method stub
        return imgHashmap.size();
    }
    public Object getItem(int arg0) {
        // TODO Auto-generated method stub
        return null;
    }
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return 0;
    }
    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;
        if(convertView==null){
            vi = inflater.inflate(R.layout.list_img, null);
            holder = new ViewHolder();
            holder.iv_img =(ImageView)vi.findViewById(R.id.imageViewImg);
            vi.setTag(holder);
        }
        else{
            holder = (ViewHolder)vi.getTag();
        }
        String uri = imgHashmap .get(position).get(KEY_IMG);
        Picasso.with(act).load(uri).into(holder.iv_img);
        return vi;
    }
    static class ViewHolder{
        ImageView iv_img;
    }
}

这可以正常加载图像，但是向上或向下滚动时图像会再次重新加载。

Answer 1

好的，这是我使用 picasso 实现的代码，它对我来说工作顺利

public class MyFragmentAdapter extends ArrayAdapter<Video> {
    private Context mContext;
    private LayoutInflater mInflater;
    private Bitmap mBitmap;

    public MyFragmentAdapter(Context context, int resource, List<Video> objects) {
        super(context, resource, objects);
        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        this.mContext = context;
    }


    public View getView(int position, View convertView, ViewGroup parent) {
        final ViewHolder holder;
        if (convertView == null) {
            holder = new ViewHolder();
            convertView = mInflater.inflate(
                    R.layout.item_gallery, null);
            holder.imageview = (ImageView) convertView.findViewById(R.id.iv_thumbImage);
            holder.pb = (ProgressBar) convertView.findViewById(R.id.iv_progressbar);
            convertView.setTag(holder);

        } else {
            holder = (ViewHolder) convertView.getTag();
        }
        holder.pb.setVisibility(View.VISIBLE);
        String url="Url here";
            Picasso.with(mContext).load(thumbnail_path).placeholder(R.drawable.icon_video).into(holder.imageview, new Callback() {
                @Override
                public void onSuccess() {
                    holder.pb.setVisibility(View.INVISIBLE);
                }

                @Override
                public void onError() {
                    holder.pb.setVisibility(View.INVISIBLE);
                }
            });
        }
        return convertView;
    }

    public static class ViewHolder {
        ImageView imageview;
        ProgressBar pb;
    }
}

Answer 2

尝试使用对我有用的 Aquery Image 加载库

public class CustomAdapterAccept extends BaseAdapter {

        private Context context;
        private ArrayList<HashMap<String,String>> listData;


        private static final String TAG_NAME="brandname";
        private static final String TAG_IMAGE="brandimg";
        public CustomAdapterAccept(Context context,ArrayList<HashMap<String,String>> listData) {
            this.context = context;
            this.listData=listData;
            aQuery = new AQuery(this.context);
        }

        @Override
        public int getCount() {
            return listData.size();
        }

        @Override
        public Object getItem(int position) {
            return listData.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(final int position, View convertView, ViewGroup parent) {
            ViewHolder holder;
            if (convertView == null) {
                holder = new ViewHolder();
                convertView = LayoutInflater.from(context).inflate(R.layout.list_item_cat, null);
                holder.propic = (ImageView) convertView.findViewById(R.id.brndimage);
                holder.txtproname = (TextView) convertView.findViewById(R.id.txtcatname);


                convertView.setTag(holder);
            }else{
                holder = (ViewHolder) convertView.getTag();
            }

            holder.txtproname.setText(listData.get(position).get(TAG_NAME));

            aQuery.id(holder.propic).image(listData.get(position).get(TAG_IMAGE), true, true, 0, R.drawable.ic_launcher);


            aQuery.id(holder.propic).image(listData.get(position).get(TAG_IMAGE),true,true,0,R.drawable.ic_launcher);

            // image parameter : 1 : memory cache,2:file cache,3:target width,4:fallback image
            return convertView;
        }
        class ViewHolder{
            ImageView propic;
            TextView txtproname;
            TextView txtproid;
            TextView txtprofilecast;
            TextView txtprofileage;
            TextView txtprofileplace;
        }

    }

详情请见this

android 从 url 加载图像

android load image from url

android

listview

universal-image-loader