Android在ListView异步线程获取网络图片

根据目前服务器的设置，我需要先发一些信息，去获取图片的名称。然后再发信息到服务器，获取各个图片，我目前所有图片只会在最后一行循环刷新这几天也试了很多方法，一直不成功。求指教了。
public class FileListAdapter extends BaseAdapter {
        private Context context; // 运行上下文
        private List<Files> groupList = new ArrayList<Files>(); // 所有文件及文件夹
        // private List<List<String>> childList = new
        // ArrayList<List<String>>();//文件集合
        private LayoutInflater listContainer; // 视图容器
        private Files files;
        private boolean isOk;
        private boolean isFirst = true;
        private Handler handler;
        private ImageView imgfile;
        private ListItemView listItemView;
 
        public final class ListItemView { // 自定义控件集合
                public Button downButton, friendButton, shareButton, renameButton;
                public Button deleteButton;
                private Button select_img;
                public ImageView img_isView;
                public TextView fileName, fileDate;
        }
 
        public FileListAdapter(Context context, List<Files> groups) {
                this.context = context;
                this.groupList = groups;
                listContainer = LayoutInflater.from(context);
                listItemView = new ListItemView();
                handler = new Handler() {
 
                        @Override
                        public void handleMessage(Message msg) {
                                // TODO Auto-generated method stub
                                switch (msg.what) {
 
                                case 2:
                                        notifyDataSetChanged();
                                        break;
 
                                default:
                                        break;
                                }
                                super.handleMessage(msg);
                        }
 
                };
 
        }
 
        @Override
        public int getCount() {
                // TODO Auto-generated method stub
                return groupList.size();
        }
 
        @Override
        public Object getItem(int position) {
                // TODO Auto-generated method stub
                return groupList.get(position);
        }
 
        @Override
        public long getItemId(int position) {
                // TODO Auto-generated method stub
                return position;
        }
 
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
                // TODO Auto-generated method stub
 
                if (convertView == null) {
                        convertView = listContainer.inflate(R.layout.item_filelist, null);
                }
                imgfile = (ImageView) convertView.findViewById(R.id.img_fileimg);
                // 初始化绑定控件
                listItemView.deleteButton = (Button) convertView
                                .findViewById(R.id.btn_delete);
                listItemView.downButton = (Button) convertView
                                .findViewById(R.id.btn_download);
                listItemView.friendButton = (Button) convertView
                                .findViewById(R.id.btn_friend);
                listItemView.renameButton = (Button) convertView
                                .findViewById(R.id.btn_rename);
                listItemView.shareButton = (Button) convertView
                                .findViewById(R.id.btn_share);
                listItemView.fileName = (TextView) convertView
                                .findViewById(R.id.txt_fileName);
                listItemView.fileDate = (TextView) convertView
                                .findViewById(R.id.txt_fileDate);
                listItemView.select_img = (Button) convertView
                                .findViewById(R.id.btn_select);
 
                listItemView.img_isView = (ImageView) convertView
                                .findViewById(R.id.img_checkimg);
 
                // 进行初始化赋值
                initData(convertView, position);
                setListener(convertView, position, parent);
 
                return convertView;
        }
 
        private void setListener(final View convertView, final int position,
                        final ViewGroup parent) {
                // TODO Auto-generated method stub
                final Files Cur_file = groupList.get(position);
                final String Cur_fileName = groupList.get(position).getFileName();
               
 
        }
 
        private void initData(View convertView, final int position) {
                // TODO Auto-generated method stub
                Files files = new Files();
                files = groupList.get(position);
                listItemView.fileName.setText(files.getFileName());
 
                // 判断是文件
                if (files.isFile()) {
                        String fileType = files.getFileName().substring(
                                        files.getFileName().lastIndexOf("."),
                                        files.getFileName().length());
                        listItemView.fileDate.setText(files.getLastModified() + " "
                                        + files.getLength());
                        listItemView.downButton.setText("下载");
                        listItemView.downButton.setTag("下载");
                        if (fileType.equals(".jpg") || fileType.equals(".png")
                                        || fileType.equals(".gif") || fileType.equals(".Jpeg")
                                        || fileType.equals(".bmp")) {
//我现在就是要在这里，如果是图片。我就要去服务器获取文件名，文件名的获取是通过
//HttpCookieUtils httpCookieUtils = new HttpCookieUtils(); 
//httpCookieUtils.preview( groupList.get(position).getPath(),
// "40", "40"); 
//这个返回的是一个字符串，就是文件名。然后再设置缩略图，但是一直不成功，只会在最后一行循环刷新图片。而且线程一直在跑
//下面注释的都是我之前写的代码
 
                                /*
                                 * new Thread() {
                                 * 
                                 * @Override public void run() { // TODO Auto-generated method
                                 * stub HttpCookieUtils httpCookieUtils = new HttpCookieUtils();
                                 * String msg = null; Bitmap bitmap = null; try { msg =
                                 * httpCookieUtils.preview( groupList.get(position).getPath(),
                                 * "40", "40"); bitmap = BitmapUtils
                                 * .getHttpBitmap(Constants.API_HOST + Constants.API_SHOW +
                                 * msg); } catch (NotLoginException e) { // TODO Auto-generated
                                 * catch block e.printStackTrace(); } catch (IOException e) { //
                                 * TODO Auto-generated catch block e.printStackTrace(); }
                                 * Message m = handler.obtainMessage(1, 1, 1, bitmap);
                                 * handler.sendMessage(m); super.run(); }
                                 * 
                                 * 
                                 * }.start();
                                 */
 
                        }
 
                } else {
                        listItemView.fileDate.setText(files.getLastModified());
                        listItemView.downButton.setText("打开");
                        listItemView.downButton.setTag("打开");
                        groupList.get(position).setFileImg("file");
                        imgfile.setBackgroundResource(R.drawable.img_filelist);
                }
        }Android多线程listview