Question

所以我正在尝试加载我在Parse服务器上的一些缩略图，但它不是很有效。

我遇到的问题是在for循环之外将图像加载到GridView中。由于某种原因，未在列表中添加位图。

这是我的代码：

private void getUserThumbs(){
    Log.i("thumbs", "ThumbnailsFragment executed.");
    thumbItemsList = new ArrayList<ThumbnailItems>();
    final String userObjectID = ProfileActivity.objectID;
    ParseQuery<ParseUser> query = ParseUser.getQuery();
    query.getInBackground(userObjectID, new GetCallback<ParseUser>() {
        @Override
        public void done(ParseUser parseUser, ParseException e) {
            if (e == null) {
                try {
                    ParseQuery<ParseObject> postQuery = new ParseQuery<ParseObject>(
                            "Post");
                    postQuery.whereEqualTo("user", parseUser);
                    postQuery.orderByDescending("createdAt");
                    objectList = postQuery.find();
                    for (ParseObject parseObject : objectList) {
                        final ThumbnailItems thumbItems = new ThumbnailItems();
                        ParseFile image = (ParseFile) parseObject.get("image");
                        if (image != null) {
                            image.getDataInBackground(new GetDataCallback() {
                                @Override
                                public void done(byte[] bytes, ParseException e) {
                                    if (e == null) {
                                        Bitmap userImage = BitmapFactory.decodeByteArray(bytes, 0
                                                , bytes.length);
                                        thumbItems.setThumb(userImage);
                                    } else {
                                        Log.d("ParseException", "Error: " + e.getMessage());
                                        e.printStackTrace();
                                    }
                                }
                            });
                        }
                        thumbItemsList.add(thumbItems);
                    }
                    gridViewAdapter = new GridViewAdapter(getContext()
                            , thumbItemsList);
                    gridView.setAdapter(gridViewAdapter);
                    swipeRefreshLayout.setRefreshing(false);

                } catch (ParseException e1) {
                    e1.printStackTrace();
                }
            } else {
                e.printStackTrace();
                Log.i("ParseException", e.getMessage());
            }
        }
    });
}

这是我的适配器：

package co.eshg.limo4.adapter;

import android.content.Context;
import android.graphics.Bitmap;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import java.util.ArrayList;
import java.util.List;
import co.eshg.limo4.R;
import co.eshg.limo4.data.ThumbnailItems;

public class GridViewAdapter extends BaseAdapter {
    Context context;
    LayoutInflater inflater;
    private List<ThumbnailItems> thumbnailsItemsList = null;
    private ArrayList<ThumbnailItems> arrayList;

public GridViewAdapter(Context context, List<ThumbnailItems> thumbnailItemsList) {
    this.context = context;
    this.thumbnailsItemsList = thumbnailItemsList;
    inflater = LayoutInflater.from(context);
    this.arrayList = new ArrayList<>();
    this.arrayList.addAll(thumbnailItemsList);
}

public class ViewHolder {
    ImageView imgThumb;
}

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

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

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

@Override
public View getView(int position, View view, ViewGroup parent) {
    ViewHolder holder;
    if (view == null) {
        holder = new ViewHolder();
        view = inflater.inflate(R.layout.profile_viewpager_tab1_children, null);
        holder.imgThumb = (ImageView) view.findViewById(R.id.imgThumb);
        view.setTag(holder);
    } else {
        holder = (ViewHolder) view.getTag();
    }
    Bitmap image = thumbnailsItemsList.get(position).getThumb();
    holder.imgThumb.setImageBitmap(image);

    return view;
}
}

修改

所以我一直试图搞砸它，我已经让它上班了。我现在的问题是，在我点击屏幕之前图像不会加载。我不知道为什么会这样。

解决方法是将thumbItemsList.add(thumbItems)置于if条件（if (e == null)）内，我不知道为什么它不起作用。

Answer 1

看起来不知道为什么会发生这种情况..

但我建议您使用此库here

它使用了LazyLoad

的概念

在您的gradle文件中

compile 'com.nostra13.universalimageloader:universal-image-loader:1.9.5'

您只需要设置一次（打开项目时执行）

private void ConfigureImageLoader(){
DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder()
                .resetViewBeforeLoading(true)
                .cacheOnDisk(true)
                .cacheInMemory(true)
                .imageScaleType(ImageScaleType.EXACTLY)
                .displayer(new FadeInBitmapDisplayer(300))
                .build();


        ImageLoaderConfiguration.Builder config = new ImageLoaderConfiguration.Builder(getApplicationContext());
        config.defaultDisplayImageOptions(defaultOptions);
        config.memoryCache(new WeakMemoryCache());
        config.threadPriority(Thread.NORM_PRIORITY - 2);
        config.denyCacheImageMultipleSizesInMemory();
        //config.diskCacheFileNameGenerator(new Md5FileNameGenerator());
        config.diskCacheSize(10 * 1024 * 1024); // 10 MiB
        config.tasksProcessingOrder(QueueProcessingType.LIFO);
        config.writeDebugLogs(); // Remove for release app

        ImageLoader.getInstance().init(config.build());
}

您的适配器

private DisplayImageOptions options;
public GridViewAdapter(Context context, List<ThumbnailItems> thumbnailItemsList) {
    options = new DisplayImageOptions.Builder()
                    .showImageOnLoading(R.drawable.naodisponivel)
                    .showImageForEmptyUri(R.drawable.naodisponivel)
                    .showImageOnFail(R.drawable.naodisponivel)
                    .cacheInMemory(true)
                    .cacheOnDisk(true)
                    .considerExifParams(true)
                    .imageScaleType(ImageScaleType.IN_SAMPLE_INT)
                    .displayer(new SimpleBitmapDisplayer())
                    .build();

}

你的getView中的

@Override
public View getView(int position, View view, ViewGroup parent) {
    ViewHolder holder;
    if (view == null) {
        //
    } else {
       //
    }
            ImageLoader imageLoader = ImageLoader.getInstance();
            final String finalImgURL = "www.mysite.com/myimage.jpg" //change url here
            imageLoader.displayImage(finalImgURL, holder.imgThumb, options);

    return view;
}

下载LazyLoad中的图像，下次使用celuar中的缓存时不需要再次下载图像，当然您配置选项

我帮了。

解析 - 将图像加载到GridView中

1 个答案: