ListView图片下载优化造成的跳变怎么解决

本篇内容主要讲解“ListView图片下载优化造成的跳变怎么解决”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“ListView图片下载优化造成的跳变怎么解决”吧!

public class MainActivity extends Activity {

HashMap map = new HashMap();

private ListView listview;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

listview = (ListView)findViewById(R.id.listView1);

MyApapter myApapter = new MyApapter();

        listview.setAdapter(myApapter);

}

class User

{

ImageView p_w_picpathview;

ProgressBar pb;

TextView tv;

Button button;

}

 class MyApapter extends BaseAdapter

 {

@Override

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

     View view = null;

 User user = new User();

LayoutInflater inflater = getLayoutInflater();

if(cOnvertView==null)

{

 view = inflater.inflate(R.layout.itmp, null);

 user.p_w_picpathview = (ImageView)view.findViewById(R.id.p_w_picpathView1);

 user.pb = (ProgressBar)view.findViewById(R.id.progressBar1);

 user.button = (Button)view.findViewById(R.id.button1); 

 user.tv = (TextView)view.findViewById(R.id.textView1);

 view.setTag(user);

}else

{

view = convertView;

user = (User)view.getTag();

}

//下载图片

//设置图片还未开始下载时的状态

user.p_w_picpathview.setImageResource(R.drawable.ic_launcher);

Bitmap bitmap = map.get(position);

if (bitmap==null) 

{

MyAsyncTask myp_w_picpathview = new MyAsyncTask(user.p_w_picpathview,position,user.pb);

myp_w_picpathview.execute("http://192.168.56.1:8080/service/qq"+position+".png");

}else

{

user.p_w_picpathview.setImageBitmap(bitmap);

}

return view;

 }

@Override

public int getCount() {

// TODO Auto-generated method stub

return 10;

}

@Override

public Object getItem(int position) {

// TODO Auto-generated method stub

return null;

}

@Override

public long getItemId(int position) {

// TODO Auto-generated method stub

return 0;

}

 }

 class MyAsyncTask extends AsyncTask

 {

        int position;

        ImageView p_w_picpathview;

        ProgressBar pb;

public MyAsyncTask(ImageView p_w_picpathview,int position,ProgressBar pb) {

this.p_w_picpathview = p_w_picpathview;

this.position = position;

this.pb = pb;

}

@Override

protected Bitmap doInBackground(String... params) {

Bitmap bitmap = null;

            try {

URL url = new URL(params[0]);

URLConnection cOnnection= url.openConnection();

InputStream is = connection.getInputStream();

bitmap = BitmapFactory.decodeStream(is);

} catch (MalformedURLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return bitmap;

}

         @Override

        protected void onPostExecute(Bitmap result) {

        //得到当前屏幕可见第一行

         int fvb = listview.getFirstVisiblePosition();

         int lvp = listview.getLastVisiblePosition();

         if (position>=fvb&&position<=lvp) 

         {

         p_w_picpathview.setImageBitmap(result);

 }

         map.put(position, result);

              super.onPostExecute(result);

        }  

 }

@Override

public boolean onCreateOptionsMenu(Menu menu) {

getMenuInflater().inflate(R.menu.main, menu);

return true;

}

}

到此，相信大家对“ListView图片下载优化造成的跳变怎么解决”有了更深的了解，不妨来实际操作一番吧！这里是编程笔记网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！