Question

* 已更新* 嘿家伙我用自己的问题解决了我的问题https://github.com/koush/UrlImageViewHelper/blob/master/README.md 并传递UrlImageViewHelper.setUrlDrawable（image，ei.img_url）;来自我的Entryadapter课程，它运作良好。

我想在列表中显示带有3个文本和一个带有分隔符/部分的imageview的Listview。所以我按照本教程http://bartinger.at/listview-with-sectionsseparators/？

比我面临加载图片（位图）的问题，所以我使用file和bitmapfactory通过使用AsyncTask在listview上显示位图。

但问题是它每次我向上或向下滚动时都会加载。我想显示列表一次所以我试图为我的列表实现视图持有者但是因为我对android和Java更新我不知道我怎么能实现这是我的代码。

谁能帮助我吗？我附上了所有代码文件，所以这段代码对我这样的学生和新手都有帮助。

这是我的Entryadaptor.java

public class EntryAdapter extends ArrayAdapter<Item> {
private Context context;
private ArrayList<Item> items;
private LayoutInflater vi;
Uri myurl;
ImageView image;
public EntryAdapter(Context context,ArrayList<Item> items) {
    super(context,0, items);
    this.context = context;
    this.items = items;
    vi = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View v = convertView;
    final Item i = items.get(position);
    if (i != null) {
        if(i.isSection()){
            SectionItem si = (SectionItem)i;
            v = vi.inflate(R.layout.list_item_section, null);
            v.setOnClickListener(null);
            v.setOnLongClickListener(null);
            v.setLongClickable(false);
            final TextView sectionView = (TextView) v.findViewById(R.id.list_item_section_text);
            sectionView.setText(si.getTitle());
        }else
          {
            EntryItem ei = (EntryItem)i;
            v = vi.inflate(R.layout.list_item_entry, null);
            final TextView title = (TextView)v.findViewById(R.id.list_item_entry_title);
            final TextView subtitle = (TextView)v.findViewById(R.id.list_item_entry_summary);
            image = (ImageView)v.findViewById(R.id.showlist_item_entry_drawable);
            if (title != null) 
                title.setText(ei.title);
            if(subtitle != null)
                subtitle.setText(ei.subtitle);
                 if(image !=null)
                 { 
                 try {
                      URL onLineURL = new URL(ei.img_url);
                       new MyNetworkTask(image).execute(onLineURL);
                      } catch (MalformedURLException e) {
                       e.printStackTrace();
                      }}}}
    return v;
    }
  private class MyNetworkTask extends AsyncTask<URL, Void, Bitmap>{
         ImageView tIV;
         public MyNetworkTask(ImageView iv){
          tIV = iv;
         }
      @Override
      protected Bitmap doInBackground(URL... urls) {
       Bitmap networkBitmap = null;
       URL networkUrl = urls[0]; //Load the first element
       try {
        networkBitmap = BitmapFactory.decodeStream(
          networkUrl.openConnection().getInputStream());
       } catch (IOException e) {
        e.printStackTrace();
       }
       return networkBitmap;
      }
      @Override
      protected void onPostExecute(Bitmap result) {
       tIV.setImageBitmap(result);
      }
        }

}

这是片段代码

public class ShowsFragment extends SherlockListFragment { ArrayList<Item> items = new ArrayList<Item>();
@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
     items.add(new SectionItem("Today"));
        items.add(new EntryItem("Item 1", "This is item 1.2","http://pierre.chachatelier.fr/programmation/images/mozodojo-original-image.jpg"));
        items.add(new EntryItem("Item 2", "This is item 1.3","http://upload.wikimedia.org/wikipedia/commons/8/85/Image-New_Delhi_Lotus.jpg"));
        items.add(new SectionItem("This Week"));
        items.add(new EntryItem("Item 4", "This is item 2.1","https://twimg0-a.akamaihd.net/profile_images/1080041262/VMIX_logo_zoom_bkbg1_normal.png")); EntryAdapter adapter = new EntryAdapter(getActivity(), items);
        setListAdapter(adapter);
    }
    public void onListItemClick(ListView l, View v, int position, long id) {
        if(!items.get(position).isSection()){
            EntryItem item = (EntryItem)items.get(position);
            Toast.makeText(getActivity(), "You clicked " + item.title , Toast.LENGTH_SHORT).show();
        }
        super.onListItemClick(l, v, position, id);
    }
}

sectionItem代码

public class SectionItem implements Item{
private final String title;
public SectionItem(String title) {
    this.title = title;
}
public String getTitle(){
    return title;
}
public boolean isSection() {
    return true;
}

}

输入项目类代码

public class EntryItem implements Item{
public final String title;
public final String subtitle;
public final String img_url;
public EntryItem(String title, String subtitle,String Image_url) {
    this.title = title;
    this.subtitle = subtitle;
    this.img_url = Image_url;
}
public boolean isSection() {
    return false;
}

}

Answer 1

我建议将加载的位图缓存到某处，以便在向上和向下滚动时避免服务器调用（例如使用Map）。此外，由于您正在异步加载位图，因此一旦加载了数据，请确保视图仍然是设置图像的正确视图，因为视图在Listview中被回收（因此名称为“convertView”）。 e.g。

    if (item.equals(imageView.getTag())) {
        // only set image if Tag is still valid
        imageView.setImageDrawable(drawable);
    }

Answer 2

对于KoljaTM赞不绝口。它解决了我的同类问题。我使用线程加速gridview，我有一些图片位置相互混合的问题。采用KoljaTM的方法后，没有发生任何扭曲。感谢。

Answer 3

嘿伙计这个lib进入你的项目并传递图像视图对象和url并完成 https://github.com/koush/UrlImageViewHelper/blob/master/README.md

如何将视图持有者实现到数组适配器中

3 个答案: