图像在从上到下滚动时显示但在我在gridview中从下到上滚动时删除？

Question

我的图片值显示在logcat中但不在屏幕上显示，我在2天内挣扎了吗？

public class MyFragment extends Fragment {
int mCurrentPage;
Context c;
GridView mListView;
String id, cat;
String strUrl;
TextView tvtitle;
TextView tv_id, tv_rating, tv_url;

private ImageLoader imageLoader;
private DisplayImageOptions options;
private ProgressDialog progressDialog;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Bundle data = getArguments();
    mCurrentPage = data.getInt("current_page", 0);
    imageLoader=ImageLoader.getInstance();

    options = new DisplayImageOptions.Builder()
    .showImageOnLoading(R.drawable.empty_photo)
    .showImageForEmptyUri(R.drawable.empty_photo)
    .showImageOnFail(R.drawable.empty_photo)
    .cacheInMemory(true)
    .cacheOnDisc(true)
    .displayer(new RoundedBitmapDisplayer(20))
    .build();
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View v = null;
    DownloadTask downloadTask = new DownloadTask();
    v = inflater.inflate(R.layout.starters, container, false);
    tv_id = (TextView) v.findViewById(R.id.tv_starter_hide_id);
    tv_rating = (TextView) v.findViewById(R.id.tv_starter_hide_ratinf);
    tv_url = (TextView) v.findViewById(R.id.tv_starter_hide_url);
    cat = Category.Main_Cat;
    Log.i("Logcat Cat1", cat);
    switch (mCurrentPage) {
    case 1:
        Log.v("MyFragment Heap", "Max Mem in MB:"
                + (Runtime.getRuntime().maxMemory() / 1024 / 1024));
        // strUrl =
        // "http://vaibhavtech.com/work/android/get_json.php?cat="+cat+"&subcat=1";
        //strUrl = " http://vaibhavtech.com/work/android/movie_list.php?category=BollyWood%20&sub_category=top";
strUrl="http://vaibhavtech.com/work/android/json_topdownload.php?cat=Nature";       
        downloadTask.execute(strUrl);
        mListView = (GridView) v.findViewById(R.id.lv_countries);
        mListView.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1,
                    int pos, long arg3) {
                // TODO Auto-generated method stub
                Intent i = new Intent(getActivity().getBaseContext(),
                        Starter_info.class);
                i.putExtra("clicked_position", pos);
                startActivity(i);
            }
        });
        break;
    case 2:
        // strUrl =
        // "http://vaibhavtech.com/work/android/get_json.php?cat="+cat+"&subcat=1";
        strUrl="http://vaibhavtech.com/work/android/json_topdownload.php?cat=Nature";   
        //strUrl = " http://vaibhavtech.com/work/android/movie_list.php?category=BollyWood%20&sub_category=top";
        downloadTask.execute(strUrl);
        Log.v("Splash Heap", "Max Mem in MB:"
                + (Runtime.getRuntime().maxMemory() / 1024 / 1024));
        mListView = (GridView) v.findViewById(R.id.lv_countries);
        mListView.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1,
                    int pos, long arg3) {
                // TODO Auto-generated method stub
                Intent i = new Intent(getActivity().getBaseContext(),
                        Starter_info.class);
                i.putExtra("clicked_position", pos);
                startActivity(i);
            }
        });
        break;
    default:
        Log.i("Cat IS", Category.Main_Cat);
        // strUrl =
        strUrl="http://vaibhavtech.com/work/android/json_topdownload.php?cat=Nature";   
        // "http://vaibhavtech.com/work/android/get_json.php?cat="+cat+"&subcat=1";
        //strUrl = " http://vaibhavtech.com/work/android/movie_list.php?category=BollyWood%20&sub_category=top";
        downloadTask.execute(strUrl);
        Log.v("Splash Heap", "Max Mem in MB:"
                + (Runtime.getRuntime().maxMemory() / 1024 / 1024));
        mListView = (GridView) v.findViewById(R.id.lv_countries);
        mListView.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1,
                    int pos, long arg3) {
                // TODO Auto-generated method stub
                Intent i = new Intent(getActivity().getBaseContext(),
                        Starter_info.class);
                i.putExtra("clicked_position", pos);
                startActivity(i);
            }
        });
        break;
    }
    return v;
}

private String downloadUrl(String strUrl) throws IOException {
    String data = "";
    InputStream iStream = null;
    try {
        URL url = new URL(strUrl);
        // Creating an http connection to communicate with url
        HttpURLConnection urlConnection = (HttpURLConnection) url
                .openConnection();
        // Connecting to url
        urlConnection.connect();
        // Reading data from url
        iStream = urlConnection.getInputStream();
        BufferedReader br = new BufferedReader(new InputStreamReader(
                iStream));
        StringBuffer sb = new StringBuffer();
        String line = "";
        while ((line = br.readLine()) != null) {
            sb.append(line);
        }
        data = sb.toString();
        br.close();

    } catch (Exception e) {
        Log.d("Exception while downloading url", e.toString());
    } finally {
        iStream.close();
    }

    return data;
}

private class DownloadTask extends AsyncTask<String, Integer, String> {
    String data = null;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog=ProgressDialog.show(getActivity(), "", "Loading...");
    }
    @Override
    protected String doInBackground(String... url) {
        try {
            data = downloadUrl(url[0]);
            return data;
        } catch (Exception e) {
            Log.d("Background Task", e.toString());
            return null;
        }
    }

    @Override
    protected void onPostExecute(String result) {
        if(result!=null)
        {
            ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
            listViewLoaderTask.execute(result);
        }
        else
        {
            if(progressDialog!=null)
                progressDialog.dismiss();
            Log.d("Data Returns Null"," DownloadTask Terminated");
        }
    }
}

private class ListViewLoaderTask extends
        AsyncTask<String, Void, Boolean> {
    JSONObject jObject;
    @Override
    protected Boolean doInBackground(String... strJson) {

        try {
            jObject = new JSONObject(strJson[0]);
            // Getting the parsed data as a List construct
            StarterParser countryJsonParser = new StarterParser();
            MainActivity.WALL_PAPER_RESPONSE= countryJsonParser.parse(jObject);
        } catch (Exception e) {
            Log.d("Exception", e.toString());
        }
        return true;
    }

    @Override
    protected void onPostExecute(Boolean result) {
        if(progressDialog!=null)
            progressDialog.dismiss();
        if(result)
            mListView.setAdapter(new WallPaperAdapter(MainActivity.WALL_PAPER_RESPONSE));
    }
}

public class WallPaperAdapter extends BaseAdapter {

    private LayoutInflater mInflater = null;
    private List<HashMap<String, Object>> wall_paper_response = null;
    public WallPaperAdapter(List<HashMap<String, Object>> countries) {
        mInflater = LayoutInflater.from(getActivity());
        this.wall_paper_response=countries;
    }

    public int getCount() {
        return wall_paper_response.size();
    }

    public Object getItem(int position) {
        return position;
    }

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

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

        ViewHolder holder;
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.lv_layout,
                    null);
            holder = new ViewHolder();

            holder.txtId = (TextView) convertView
                    .findViewById(R.id.tv_starter_hide_id);
            //holder.txtDuration = (TextView) convertView
                //  .findViewById(R.id.tv_starter_hide_ratinf);
            holder.txtTitle= (TextView) convertView
                    .findViewById(R.id.tv_starter_hide_imagename);
            holder.txtYear = (TextView) convertView
                    .findViewById(R.id.tv_starter_hide_url);
            holder.imgPoster= (ImageView) convertView
                    .findViewById(R.id.iv_flag);
            convertView.setTag(holder);

        } else {
            holder = (ViewHolder) convertView.getTag();
        }
        try {
            holder.txtId.setText(wall_paper_response.get(position)
                            .get("id").toString());
            //holder.txtDuration.setText(wall_paper_response.get(position)
                //  .get("duration").toString());
            holder.txtTitle.setText(wall_paper_response.get(position)
                    .get("title").toString());
            holder.txtYear.setText(wall_paper_response.get(position)
                    .get("year").toString());
            Log.v("Image Loader URL",wall_paper_response.get(position)
                    .get("flag_path").toString());
            imageLoader.displayImage(wall_paper_response.get(position)
                            .get("flag_path").toString(),holder.imgPoster,options);

        } catch (Exception e) {
        }
        return convertView;
    }

    class ViewHolder {

        public TextView txtId;
    //  public TextView txtDuration;
        public TextView txtTitle;
        public TextView txtYear;
        public ImageView imgPoster;
    }
}
 }

我正在制作壁纸应用程序，我的图像来自gridview中的json，它的值显示在logcat上但不在屏幕上显示我做什么？

Answer 1

我已经检查过JSON响应，它只包含Image名称。而它应该包含图像的完整路径。然后，只有这样它才能获得图像的实际位置并加载图像。

您需要修改图像值的json响应，并提供除title值的图像名称之外的图像的完整路径。

尝试更新您的JSON响应，如下所示：

{ "Demo": [ { "id": "1" ,"title": "http://www.vaibhavtech.com/work/android/1000.jpg" } ,
           { "id": "2" ,"title": "http://www.vaibhavtech.com/work/android/1001.jpg" } , 
          { "id": "3" ,"title": "http://www.vaibhavtech.com/work/android/1002.jpg" } ]}

Answer 2

由于您的json响应包含字符串url.thus，您需要从该URL下载图像，而不仅仅是您可以显示它

试试这段代码，

你的班级

ImageView lrImageView=(ImageView)findViewById(R.id.YOUR_IMAGE_ID);
ImageLoader task = new ImageLoader()
{
 @Override
 protected void onPostExecute(Bitmap result) 
 {
   lrImageView.setImageBitmap(result);
  }
};

task.execute(new String[]{strUrl});

和ImageLoader类的内容是

public class ImageLoader extends AsyncTask<String,Void,Bitmap> 
{
@Override
protected Bitmap doInBackground(String... urls) 
{
    Bitmap map = null;
    for (String url : urls) 
    {
        map = downloadImage(url);
    }
    return map;
}

private Bitmap downloadImage(String url) 
{
    Bitmap bitmap = null;
    InputStream stream = null;
    BitmapFactory.Options bmOptions = new BitmapFactory.Options();
    bmOptions.inSampleSize = 1;
    try 
    {
        stream = getHttpConnection(url);
        bitmap = BitmapFactory.decodeStream(stream, null, bmOptions);
        stream.close();
    } 
    catch (IOException ex) {}
    return bitmap;
}

private InputStream getHttpConnection(String urlString)throws IOException 
{
    InputStream stream = null;
    URL url = new URL(urlString);
    URLConnection connection = url.openConnection();
    try 
    {
        HttpURLConnection httpConnection = (HttpURLConnection) connection;
        httpConnection.setRequestMethod("GET");
        httpConnection.connect();

        if (httpConnection.getResponseCode() == HttpURLConnection.HTTP_OK) 
        {
            stream = httpConnection.getInputStream();
        }
    } 
    catch (Exception ex) 
    {
        ex.printStackTrace();
    }
    return stream;
}

}