Android异步加载图片详解之方式二(1)

MainActivity.java如下:

package com.cn.perfectlistview;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;
//解决的问题:
//1 ListView异步加载网络图片
//2 ListView滑动时,图片错位
public class MainActivity extends Activity {
    private ListView listView;
    MyListViewAdapter adapter;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        initView();
    }


    public void initView(){
		listView = (ListView) findViewById(R.id.listView);
		ArrayList<ListViewItem> arrayList = new ArrayList<ListViewItem>();

		ListViewItem item1 = new ListViewItem
		("xxxx","http://images.csdn.net/20121018/zazhi-68-78-1018.jpg");
		arrayList.add(item1);

		ListViewItem item2 = new ListViewItem
		("xxxx","http://info-database.csdn.net/Upload/2012-10-08/zazhi-210-90-1008.jpg");
		arrayList.add(item2);

		ListViewItem item3 = new ListViewItem
		("xxxx","http://images.csdn.net/20121119/20111211223655841.jpg");
		arrayList.add(item3);

		ListViewItem item4 = new ListViewItem
		("xxxx","http://images.csdn.net/20121119/20120619174604972.jpg");
		arrayList.add(item4);

		ListViewItem item5 = new ListViewItem
		("xxxx","http://csdnimg.cn/www/images/pic_foot_report110.png");
		arrayList.add(item5);

		ListViewItem item6 = new ListViewItem
		("xxxx","http://csdnimg.cn/www/images/pic_foot_report.png");
		arrayList.add(item6);

		ListViewItem item7 = new ListViewItem
		("xxxx","http://csdnimg.cn/www/images/pic_foot_BNIA.png");
		arrayList.add(item7);

		ListViewItem item8 = new ListViewItem
		("xxxx","http://csdnimg.cn/www/images/pic_foot_gongshang.png");
		arrayList.add(item8);

		ListViewItem item9 = new ListViewItem
		("xxxx","http://images.csdn.net/20120803/logo-qixing02.jpg");
		arrayList.add(item9);

		ListViewItem item10 = new ListViewItem
		("xxxx","http://images.csdn.net/20120726/quanjing-logo-shouye.jpg");
		arrayList.add(item10);

		ListViewItem item11 = new ListViewItem
		("xxxx","http://images.csdn.net/20120726/nhn-logo-shouye.jpg");
		arrayList.add(item11);

		ListViewItem item12 = new ListViewItem
		("xxxx","http://images.csdn.net/20120510/shanghai-jiaoda-logo.jpg");
		arrayList.add(item12);

		ListViewItem item13 = new ListViewItem
		("xxxx","http://images.csdn.net/20120312/bigman2.gif");
		arrayList.add(item13);

		ListViewItem item14 = new ListViewItem
		("xxxx","http://images.csdn.net/20120216/csdn2.gif");
		arrayList.add(item14);

		ListViewItem item15 = new ListViewItem
		("xxxx","http://images.csdn.net/20121109/win8_100x74.jpg");
		arrayList.add(item15);

		ListViewItem item16 = new ListViewItem
		("xxxx","http://images.csdn.net/20120816/cf-20120816.jpg");
		arrayList.add(item16);

		ListViewItem item17 = new ListViewItem
		("xxxx","http://images.csdn.net/20120704/bi05.jpg");
		arrayList.add(item17);

		ListViewItem item18 = new ListViewItem
		("xxxx","http://images.csdn.net/20120816/amd-20120816.jpg");
		arrayList.add(item18);

		ListViewItem item19 = new ListViewItem
		("xxxx","http://y2.ifengimg.com/2012/12/08/09383369.jpg");
		arrayList.add(item19);

		ListViewItem item20 = new ListViewItem
		("xxxx","http://y1.ifengimg.com/2012/12/08/09320040.jpg");
		arrayList.add(item20);

		ListViewItem item21 = new ListViewItem
		("xxxx","http://y3.ifengimg.com/4ccd6020154f55cb/2012/1207/2.jpg");
		arrayList.add(item21);

		ListViewItem item22 = new ListViewItem
		("xxxx","http://y2.ifengimg.com/2012/12/08/09425571.jpg");
		arrayList.add(item22);

		ListViewItem item23 = new ListViewItem
		("xxxx","http://y2.ifengimg.com/b19fadab6fcc0645/2012/1011/123.jpg");
		arrayList.add(item23);

		ListViewItem item24 = new ListViewItem
		("xxxx","http://y2.ifengimg.com/2012/11/15/07414772.jpg");
		arrayList.add(item24);

		ListViewItem item25 = new ListViewItem
		("xxxx","http://y2.ifengimg.com/2012/11/15/07532374.jpg");
		arrayList.add(item25);

		ListViewItem item26 = new ListViewItem
		("xxxx","http://y0.ifengimg.com/2012/11/15/07583017.jpg");
		arrayList.add(item26);

		ListViewItem item27 = new ListViewItem
		("xxxx","http://y0.ifengimg.com/2012/02/20/14175732.jpg");
		arrayList.add(item27);

		ListViewItem item28 = new ListViewItem
		("xxxx","http://y2.ifengimg.com/2012/10/29/21175274.jpg");
		arrayList.add(item28);

		ListViewItem item29 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/2727e09814adca26/2011/1221/rdn_4ef0fb0333564.jpg");
		arrayList.add(item29);

		ListViewItem item30 = new ListViewItem
		("xxxx","http://y1.ifengimg.com/2012/12/04/10060551.jpg");
		arrayList.add(item30);

		ListViewItem item31 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec068537d8f6.jpg");
		arrayList.add(item31);

		ListViewItem item32 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec068554fa3f.jpg");
		arrayList.add(item32);

		ListViewItem item33 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec06853bd85b.jpg");
		arrayList.add(item33);

		ListViewItem item34 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec06854ace88.jpg");
		arrayList.add(item34);

		ListViewItem item35 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec06855bad01.jpg");
		arrayList.add(item35);

		ListViewItem item36 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec0685649c4e.jpg");
		arrayList.add(item36);

		ListViewItem item37 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec068562ac3d.jpg");
		arrayList.add(item37);

		ListViewItem item38 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec06854dc836.jpg");
		arrayList.add(item38);

		ListViewItem item39 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec06855ef0ea.jpg");
		arrayList.add(item39);

		ListViewItem item40 = new ListViewItem
		("xxxx","http://res.news.ifeng.com/b77953a0c6aae8fb/2011/1114/rdn_4ec068568beda.jpg");
		arrayList.add(item40);
		

		adapter = new MyListViewAdapter(MainActivity.this, arrayList);
		
		listView.setAdapter(adapter);
	}
}

MyListViewAdapter.java如下:

package com.cn.perfectlistview;
import java.util.ArrayList;
import android.content.Context;
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 com.cn.loadImages.ImageDownloader;
public class MyListViewAdapter extends BaseAdapter{
      private ArrayList<ListViewItem> mArrayList;
      private Context mContext;
      private ImageDownloader imageDownloader;
      public MyListViewAdapter(Context mContext,ArrayList<ListViewItem> mArrayList) {
  		super();
  		this.mArrayList = mArrayList;
  		this.mContext = mContext;
  		String folderNameOnSDCard="images";
  		imageDownloader=new ImageDownloader(mContext, folderNameOnSDCard);
  		
  	  
  	}

	public int getCount() {
		if (mArrayList==null) {
			return 0;
		} else {
			return mArrayList.size();
		}
		
	}

	public Object getItem(int position) {
		if (mArrayList==null) {
			return null;
		} else {
            return mArrayList.get(position);
		}
	}

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

	public View getView(int position, View convertView, ViewGroup parent) {
		ViewHolder holder=null;
		if (convertView==null) {
			holder=new ViewHolder();
			convertView=LayoutInflater.from(this.mContext).inflate(R.layout.listviewitem, null, false);
			holder.textView=(TextView) convertView.findViewById(R.id.textView);
		    holder.imageView=(ImageView) convertView.findViewById(R.id.imageview);
		    convertView.setTag(holder);
		} else {
            holder=(ViewHolder) convertView.getTag();
		}
		
	
		
		if (this.mArrayList!=null) {
			ListViewItem listViewItem=this.mArrayList.get(position);
			if (holder.textView!=null) {
				holder.textView.setText(listViewItem.getContent());
			}
			if (holder.imageView!=null) {
				try {
					String imageUrl=listViewItem.getImageURL();
					//加载网络上的图片
					imageDownloader.download(imageUrl, holder.imageView);
				} catch (Exception e) {
					e.printStackTrace();
				}
					
			}
		}	    
		

		return convertView;
	}

	
	private class ViewHolder{
		ImageView imageView;
		TextView textView;
	}
      
}

ListViewItem.java如下:

package com.cn.perfectlistview;
public class ListViewItem {
	String content;
	String imageURL;

	public ListViewItem(String content, String imageURL) {
		super();
		this.content = content;
		this.imageURL = imageURL;
	}

	public String getContent() {
		return content;
	}

	public void setContent(String content) {
		this.content = content;
	}

	public String getImageURL() {
		return imageURL;
	}

	public void setImageURL(String imageURL) {
		this.imageURL = imageURL;
	}

}