Android Baseadapter를 사용하여 이미지를로드하는 방법은 무엇입니까?

내 프로젝트는 오류없이 작동하지만로드시 이미지가 Listview에로드되지 않습니다.

다음은 샘플 이미지입니다.

첫 번째 작업 이미지의 샘플

그러나 ListView를 드래그하면 모든 이미지가로드됩니다.

드래그 생성 된 이미지로드 샘플

도와주세요. 나쁜 영어 죄송합니다.

Categoryadapter.java

package com.medyasef.dernek.tjod;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.http.AndroidHttpClient;
import android.os.AsyncTask;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.HttpGet;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

/**
 * Created by olkunmustafa on 26.09.2013.
 */
public class CategoryAdapter extends BaseAdapter {
    private String LOG_NAME = "HATA";
    private List<Categoryicerikler> list_view;
    private HashMap<Integer,Bitmap> bitmaplist;
    private Context mContext;
    private Categories categories = new Categories();


    public CategoryAdapter(List<Categoryicerikler> list_view, Context mContext) {
        this.list_view = list_view;
        this.mContext = mContext;
        bitmaplist = new HashMap<Integer, Bitmap>();

        for (int i = 0; i < list_view.size() ; i++) {
            Categoryicerikler bitmap_icerikler = list_view.get(i);
            setBitmapFromURL(bitmap_icerikler.getCategory_post_image(),i);
        }
    }
    /*
    Burada resimleri çekmek için thread oluşturuyoruz.
    Resim linkini ve ImageView'i veriyoruz ve ekrana basmasını sağlıyoruz.
     */
    public void setBitmapFromURL(final String src,final int value) {
        new Thread(
                new Runnable()
                {
                    @Override
                    public void run() {
                        HttpURLConnection connection= null;
                        try {
                            URL url = new URL(src);
                            connection = (HttpURLConnection) url.openConnection();
                            connection.setRequestMethod("GET");
                            connection.setDoInput(true);
                            connection.setDoOutput(true);
                            connection.connect();
                            InputStream input = connection.getInputStream();
                            final Bitmap myBitmap = BitmapFactory.decodeStream(input);
                            try {
                                bitmaplist.put(value,myBitmap);
                            }
                            catch (Exception e){
                                Log.d(LOG_NAME,e.getMessage());
                                Log.d(LOG_NAME,"Resim ekleme işlemi başarısız.");
                            }


                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                        finally {
                            connection.disconnect();
                        }
                    }
                }).start();
    }

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

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

    @Override
    public long getItemId(int position) {
        return list_view.indexOf(getItem(position));
    }

    @Override
    public View getView(int position, View convertview, ViewGroup viewGroup) {
        Categoryicerikler categoryicerikler = list_view.get(position);
        ViewHolder holder = null;

        if(convertview==null){
            Log.d(LOG_NAME,"sonuc");
            convertview = LayoutInflater.from(mContext).inflate(R.layout.categories,viewGroup,false);
            holder = new ViewHolder();
            holder.txtTitle = (TextView) convertview.findViewById(R.id.category_posttitle);
            holder.txtDate  = (TextView) convertview.findViewById(R.id.category_postdate);
            holder.imageView  = (ImageView) convertview.findViewById(R.id.category_image);
            convertview.setTag(holder);
            Categories.categoryAdapter.notifyDataSetChanged();
        }
        else {
            holder = (ViewHolder) convertview.getTag();
        }

        holder.txtTitle.setText(categoryicerikler.getCategory_posttitle());
        holder.txtDate.setText(categoryicerikler.getCategory_postdate());
        try {
        holder.imageView.setImageBitmap(bitmaplist.get(position));
        }
        catch (Exception e){

        }

        return convertview;
    }

    /*private view holder class*/
    private class ViewHolder {
        ImageView imageView;
        TextView txtTitle;
        TextView txtDate;
    }
}

Categoryicerikler.java

    package com.medyasef.dernek.tjod;

import android.graphics.Bitmap;
import android.widget.ImageView;

/**
 * Created by olkunmustafa on 26.09.2013.
 */
public class Categoryicerikler {
    private String category_posttitle;
    private String category_postdate;
    private String category_post_content;
    private String category_post_image;

    public Categoryicerikler( String category_posttitle, String category_postdate, String category_post_content,String post_image) {
        this.category_posttitle = category_posttitle;
        this.category_postdate = category_postdate;
        this.category_post_content = category_post_content;
        this.category_post_image = post_image;
    }

    public String getCategory_posttitle() {
        return category_posttitle;
    }

    public void setCategory_posttitle(String category_posttitle) {
        this.category_posttitle = category_posttitle;
    }

    public String getCategory_postdate() {
        return category_postdate;
    }

    public void setCategory_postdate(String category_postdate) {
        this.category_postdate = category_postdate;
    }

    public String getCategory_post_content() {
        return category_post_content;
    }

    public void setCategory_post_content(String category_post_content) {
        this.category_post_content = category_post_content;
    }

    public String getCategory_post_image() {
        return category_post_image;
    }

    public void setCategory_post_image(String category_post_image) {
        this.category_post_image = category_post_image;
    }
}

Categories.java

package com.medyasef.dernek.tjod;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.text.Html;
import android.util.Log;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONException;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.List;

/**
 * Created by olkunmustafa on 25.09.2013.
 */
public class Categories extends Activity {
    private List<Categoryicerikler> content_list;
    public static CategoryAdapter categoryAdapter;
    private ListView main_category;
    private static HashMap<Integer,Bitmap> bitmaplist;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_categories);
        main_category = (ListView) findViewById(R.id.main_category);
        new GetCategory().execute();
    }

    private class GetCategory extends AsyncTask<Void,Void,String> {

        @Override
        protected void onPreExecute() {
            Toast.makeText(Categories.this, "İslem Baslıyor Bekleyiniz", Toast.LENGTH_SHORT).show();
        }

        @Override
        protected String doInBackground(Void... voids) {
            /*
            Burada internete bağlanıp json veriyi string cinsinden çekiyoruz.
             */
            InternetConnection internetcon = new InternetConnection();
            String json_result = internetcon.get_json_data();
            return json_result;
        }

        @Override
        protected void onPostExecute(String data) {
            /*
            Gelen string veriyi json_to_list_view metoduna veriyorum
            Bu metot gelen json verisinin içeriklerini doldurarak bana birt liste dönderir.
             */
            try {
                content_list = GetJson.json_to_list_view(data);
            } catch (JSONException e) {
                Log.d("Json_Error","Json çekilirken hata oluştu");
            }
            categoryAdapter = new CategoryAdapter(content_list,Categories.this);
            main_category.setAdapter(categoryAdapter);
        }
    }
}