如何使用android baseadapter加载图像？

Question

我的项目没有错误，但加载后，图像不会加载到列表视图中。

这里是一个示例图像

sample at the first working image

但在拖动的ListView之后，所有的图像加载。

sample draggened image load

请帮助。对不起，坏英语。

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); 
     } 
    } 
} 

Answer 1

如果你只是想在一个列表视图中加载图像，我会建议你使用Picasso

它的简单，快速，自动为你做几乎一切。您也不必关心取消活动销毁的请求。所以我想这对你来说是最好的开始，如果你只是想将图像加载到ListView中的ImageView中。

例如在您的适配器，您可以使用：

Picasso.with(context) 
    .load(url) 
    .placeholder(R.drawable.placeholder) 
    .error(R.drawable.error) 
    .into(imageView); 

哪里ImageView的是你的ListView细胞的ImageView的

Answer 2

使用通用image loader library，然后按以下方式

--------------------------------------------------------- 
    1 - options = new DisplayImageOptions.Builder() 
      .showStubImage(R.drawable.physicalgift_normal) 
      .cacheInMemory() 
      .cacheOnDisc() 
      .displayer(new RoundedBitmapDisplayer(10)) 
      .build(); 
      imageLoader=ImageLoader.getInstance(); 
      ImageLoaderConfiguration imgconfig=ImageLoaderConfiguration.createDefault(context); 
      imageLoader.init(imgconfig); 
    ---------------------------------------------------------- 

    2 - String url=list.get(position).getThumbUrl(); 
      if(url != null && url !="") 
       imageLoader.displayImage(Utils.getEncodedUrl(url), holder.img, options); 

    ------------------------------------------------------------ 
    3 - SubCatAdapter adapter = new SubCatAdapter(SubCategoryActivity.this, 
        mlist); 
      list.setAdapter(adapter); 
------------------------------------------------------------ 
    full example is here 


    public class SubCatAdapter extends BaseAdapter { 
     private ArrayList<SubcategoryData> list; 
     private LayoutInflater inflator; 
     public ImageLoader imageLoader; 
     private DisplayImageOptions options; 

     public SubCatAdapter(Context context, ArrayList<SubcategoryData> mlist) { 
      super(); 
      this.list = mlist; 
      this.inflator = LayoutInflater.from(context); 
      options = new DisplayImageOptions.Builder() 
      .showStubImage(R.drawable.physicalgift_normal) 
      .cacheInMemory() 
      .cacheOnDisc() 
      .displayer(new RoundedBitmapDisplayer(10)) 
      .build(); 
      imageLoader=ImageLoader.getInstance(); 
      ImageLoaderConfiguration imgconfig=ImageLoaderConfiguration.createDefault(context); 
      imageLoader.init(imgconfig); 
     } 

     public int getCount() { 
      // TODO Auto-generated method stub 
      return list.size(); 
     } 

     public Object getItem(int position) { 
      // TODO Auto-generated method stub 
      return list.get(position); 
     } 

     public long getItemId(int position) { 
      // TODO Auto-generated method stub 
      return position; 
     } 

     public View getView(int position, View convertView, ViewGroup parent) { 
      // TODO Auto-generated method stub 

      View view = convertView; 
      ViewHolder holder = null; 

      if (convertView == null) { 
       view = inflator.inflate(R.layout.row_subcat, null); 

       holder = new ViewHolder(); 
       holder.txt_Name = (TextView) view.findViewById(R.id.txt_name); 
       holder.img=(ImageView)view.findViewById(R.id.img_row); 
       view.setTag(holder); 
      } else { 
       holder = (ViewHolder) view.getTag(); 
      } 
      holder.txt_Name.setText(list.get(position).getName()); 
      String url=list.get(position).getThumbUrl(); 
      if(url != null && url !="") 
       imageLoader.displayImage(Utils.getEncodedUrl(url), holder.img, options); 

      return view; 
     } 

     static class ViewHolder { 
      TextView txt_Name; 
      ImageView img; 

     } 
    }