Question

我正在从JSON文档提供的url下载图像。起初我的应用程序似乎正常工作，拉入并放置图像并捕获异常，当数组元素中没有图像网址但突然崩溃，我的错误日志显示的东西调整到引起：java.lang.RuntimeException：java.net.MalformedURLException：找不到协议：问题是我已经发现了这个错误，如下所示。

如果有人能向我解释为什么会发生这种情况并指出我正确的方向，我将非常感激。

Image DwnLdr class

 public Drawable loadImage (BaseAdapter adapt, ImageView view)
{
    this.adapter = adapt;
    String url = (String) view.getTag();
    if (imageCache.containsKey(url))
    {
        return imageCache.get(url);
    }
    else {
        new ImageTask().execute(url);
        return DEFAULT_ICON;
    }
}

private class ImageTask extends AsyncTask<String, Void, Drawable>
{
    private String s_url;

    @Override
    protected Drawable doInBackground(String... params) {
        s_url = params[0];
        InputStream inStream;
        try {
            Log.v(debugTag, "Fetching: " + s_url);
            URL url = new URL(s_url);
            inStream = url.openStream();
        } catch (MalformedURLException e) {
            Log.v(debugTag, "Malformed: " + e.getMessage());
            throw new RuntimeException(e);
        } catch (IOException e)
        {
            Log.d(debugTag, "I/O : " + e.getMessage());
            throw new RuntimeException(e);

        }
        return Drawable.createFromStream(inStream, "src");
    }

    @Override
    protected void onPostExecute(Drawable result) {
        super.onPostExecute(result);
        synchronized (this) {
            imageCache.put(s_url, result);
        }
        adapter.notifyDataSetChanged();
    }

}

查看适配器类

 ListData data = topics.get(position);
    try {
        long lg = Long.valueOf(data.getPostTime())*1000;
        Date date = new  Date(lg);
        String postTime = new SimpleDateFormat("MM dd, yyyy hh:mma").format(date);

        holder.data = data;
        holder.listName.setText(data.getTitle());
        holder.authorName.setText(data.getAuthor());
        holder.postTime.setText(postTime);
        holder.redditScore.setText(data.getrScore());

        Log.v(DEBUG_TAG, "Cell Created");
    }catch (Exception e){
        e.printStackTrace();
        Log.v(DEBUG_TAG,"Cell Not Created Due to: ",e);
    }

    if(data.getImageUrl()!=null){
        try {
            holder.thumbnail.setTag(data.getImageUrl());


            Drawable drawable = imgGet.loadImage(this, holder.thumbnail);
      if (drawable != null) {
                holder.thumbnail.setImageDrawable(drawable);
            } else {
                holder.thumbnail.setImageResource(R.drawable.filler_icon);
            }
        }catch (Exception e){
            e.printStackTrace();
            Log.v(DEBUG_TAG,"no image: ",e);

        }

        return convertView;
    }

主类适配器集

public static class MyViewHolder {
    public TextView listName, authorName, redditScore, postTime;
    public Button goButton;
    public ImageView thumbnail;
    public ListData data;
}
public void setTopics(ArrayList<ListData> data) {
    this.data = data;
    this.postList.setAdapter(new RedditDataAdapter(this, this.getImg, this.layoutInflater,this.data));

}

错误记录

 Caused by: java.lang.RuntimeException: java.net.MalformedURLException: Protocol not found:
        at Tasks.RedditIconTask$ImageTask.doInBackground(RedditIconTask.java:60)
        at Tasks.RedditIconTask$ImageTask.doInBackground(RedditIconTask.java:46)
        at android.os.AsyncTask$2.call(AsyncTask.java:287)

Answer 1

看起来图片网址是一个空字符串。调试代码以了解其原因。您发布的代码并未真正显示URL值的来源。

为什么你得到异常是因为你重新抛出它，包裹在RuntimeException中：

throw new RuntimeException(e);

Answer 2

我能够通过使用laatlto所说的内容并将代码更改为以下内容来解决我的问题。

protected Drawable doInBackground(String... params) {
        s_url = params[0];
        InputStream inStream;
        Drawable picture=null;
        try {
            Log.v(debugTag, "Fetching: " + s_url);


            URL url = new URL(s_url);
            inStream = url.openStream();
            picture= Drawable.createFromStream(inStream, "src");

        } catch (MalformedURLException e) {
            Log.v(debugTag, "Malformed: " + e.getMessage());
        } catch (IOException e)
        {
            Log.d(debugTag, "I/O : " + e.getMessage());

        }
        return picture;
    }

Android JSON图像下载抛出已捕获的MalformedURLException

2 个答案: