android - 列表视图不显示远程图像

Question

我正在使用 HashMap 通过 simpleAdapter 在列表视图中显示图像和文本。现在这适用于我的 R.drawable 中的图像。但是，一旦我从远程源检索图像作为位图，它就不会显示图像。图像正在正确下载，当我在图像视图上显示它时显示正常。这是我检索图像并将其存储在位图变量中的代码：

   user_picture=(ImageView)findViewById(R.id.widget89);
    java.net.URL img_value = null;
    try {
        img_value = new java.net.URL("http://graph.facebook.com/XXXXXXX/picture?type=small");
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    try {
        mIcon1 = BitmapFactory.decodeStream(img_value.openConnection().getInputStream());
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    user_picture.setImageBitmap(mIcon1);

任何想法为什么会发生这种情况？

提前感谢詹尼克

Answer 1

在最近的项目中，我使用下面的类来获取位图并将它们存储在自定义对象中，并使用这些类来使用适配器填充 ListView：

package com.octoshape.android.octopocplayer.playlist;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;

public class BitmapDownloader extends AsyncTask<String, Void, Bitmap>{

    @Override
    protected Bitmap doInBackground(String... urls) {
        try {
            URL url = new URL(urls[0]); 
            URLConnection conn = url.openConnection();
            conn.connect();
            BufferedInputStream bis = new BufferedInputStream(conn.getInputStream());
            Bitmap bm = BitmapFactory.decodeStream(bis);
            bis.close();
            return bm;
        } catch (IOException e) {}
            return null;
    }
}

这是适配器：

private class VideoAdapter extends BaseAdapter {

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

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

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

        @Override
        public int getViewTypeCount() {
            return ITEM_VIEW_TYPE_COUNT;
        }

        @Override
        public int getItemViewType(int position) {
            return (playList.get(position) instanceof String) ? ITEM_VIEW_TYPE_CHANNELSET
                    : ITEM_VIEW_TYPE_CHANNEL;
        }

        @Override
        public boolean isEnabled(int position) {
            // A separator cannot be clicked !
            return getItemViewType(position) != ITEM_VIEW_TYPE_CHANNELSET;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            final int type = getItemViewType(position);

            // First, let's create a new convertView if needed. You can also
            // create a ViewHolder to speed up changes if you want ;)
            if (convertView == null) {
                final LayoutInflater inflater = LayoutInflater
                        .from(DemoPlayer.this);
                final int layoutID = type == ITEM_VIEW_TYPE_CHANNELSET ? R.layout.separator_list_item
                        : R.layout.video_list_item;
                convertView = inflater.inflate(layoutID, parent, false);
            }

            // We can now fill the list item view with the appropriate data.
            if (type == ITEM_VIEW_TYPE_CHANNELSET) {
                ((TextView) convertView).setText((String) getItem(position));
            } else {
                final Channel channel = (Channel) getItem(position);
                ((TextView) convertView.findViewById(R.id.name))
                        .setText(channel.getName());
                ((ImageView) convertView.findViewById(R.id.logo))
                        .setImageResource(R.drawable.default);

                if (channel.getChannelImage() != null)
                    ((ImageView) convertView.findViewById(R.id.channellogo))
                            .setImageBitmap(channel.getChannelImage());
            }
            return convertView;
        }
    }