我有一个自定义Listview，其中每个项目都包含一个进度条。但是当列表包含许多项目，并且我使用滚动条浏览列表视图时，一些ProgressBars消失并面临与imageview相同的问题，以显示上传图像的状态，可能是什么原因以及如何解决此问题？看下面的代码
static class ViewHolder {
public ViewHolder(View convertView) {
// TODO Auto-generated constructor stub
}
TextView imageNameTextView;
ImageView sdCardImageView, statusImageView;
ProgressBar uploadProgressBar;
ImageButton uploadImageButton, dataImageButton, printImageButton, viewImageButton, deleteImageButton ;
}
public class ImageAdapter extends BaseAdapter
{
public ImageAdapter(Context c)
{
}
public int getCount() {
// TODO Auto-generated method stub
return ImageList.size();
}
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
public View getView(final int position, View convertView, ViewGroup parent) {
// Avoid unneccessary calls to findViewById() on each row, which is expensive!
holder = null;
// If this item is to be synced
if(flags.get(position)) {
startUpload(position);
// Mark as synced
flags.put(position, false);
}
/*
* If convertView is not null, we can reuse it directly, no inflation required!
* We only inflate a new View when the convertView is null.
*/
if (convertView == null) {
convertView = getLayoutInflater().inflate(R.layout.list_upload, null);
holder = new ViewHolder(convertView);
// Create a ViewHolder and store references to the children views
holder.imageNameTextView = (TextView) convertView.findViewById(R.id.ColImgName);
holder.sdCardImageView = (ImageView) convertView.findViewById(R.id.ColImgPath);
holder.statusImageView = (ImageView) convertView.findViewById(R.id.ColStatus);
holder.uploadProgressBar = (ProgressBar) convertView.findViewById(R.id.progressBar);
holder.uploadImageButton = (ImageButton) convertView.findViewById(R.id.btnUpload);
holder.dataImageButton = (ImageButton) convertView.findViewById(R.id.btnData);
holder.printImageButton = (ImageButton) convertView.findViewById(R.id.btnPrint);
holder.viewImageButton = (ImageButton) convertView.findViewById(R.id.btnView);
holder.deleteImageButton = (ImageButton) convertView.findViewById(R.id.btnDelete);
// The tag can be any Object, this just happens to be the ViewHolder
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
strPath = ImageList.get(position).toString();
// Get File Name
fileName = strPath.substring( strPath.lastIndexOf('_')+1, strPath.length() );
file = new File(strPath);
@SuppressWarnings("unused")
long length = file.length();
holder.imageNameTextView.setText(fileName);
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 8;
Bitmap bm = BitmapFactory.decodeFile(strPath,options);
holder.sdCardImageView.setImageBitmap(bm);
holder.statusImageView.setImageResource(R.drawable.bullet_button);
holder.uploadProgressBar.setVisibility(View.GONE);
//btnUpload
holder.uploadImageButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Upload
cd = new ConnectionDetector(getApplicationContext());
// Check for internet connection
if (!cd.isConnectingToInternet()) {
// Internet Connection is not present
alert.showAlertDialog(UploadActivity.this, "Internet not available",
"Please connect to working Internet connection", false);
// stop executing code by return
return;
}
startUpload(position);
}
});
//Upload
public void startUpload(final int position) {
Runnable runnable = new Runnable() {
public void run() {
handler.post(new Runnable() {
public void run() {
v = lstView.getChildAt(position - lstView.getFirstVisiblePosition());
holder.uploadProgressBar.setVisibility(View.VISIBLE);
holder.statusImageView.setImageResource(R.drawable.bullet_button);
new UploadFileAsync().execute(String.valueOf(position));
}
});
}
};
new Thread(runnable).start();
}
// Async Upload
public class UploadFileAsync extends AsyncTask<String, Void, Void> {
String resServer;
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(String... params) {
// TODO Auto-generated method stub
position = Integer.parseInt(params[0]);
int bytesRead, bytesAvailable, bufferSize;
byte[] buffer;
int maxBufferSize = 1 * 1024 * 1024;
int resCode = 0;
String resMessage = "";
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
// File Path
String strSDPath = ImageList.get(position).toString();
// Upload to PHP Script
String strUrlServer = "http://domein/fiile.php";
try {
/** Check file on SD Card ***/
File file = new File(strSDPath);
if(!file.exists())
{
resServer = "{\"StatusID\":\"0\",\"Error\":\"Please check path on SD Card\"}";
return null;
}
FileInputStream fileInputStream = new FileInputStream(new File(strSDPath));
URL url = new URL(strUrlServer);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("Content-Type",
"multipart/form-data;boundary=" + boundary);
DataOutputStream outputStream = new DataOutputStream(conn
.getOutputStream());
outputStream.writeBytes(twoHyphens + boundary + lineEnd);
outputStream
.writeBytes("Content-Disposition: form-data; name=\"filUpload\";filename=\""
+ strSDPath + "\"" + lineEnd);
outputStream.writeBytes(lineEnd);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
// Read file
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
while (bytesRead > 0) {
outputStream.write(buffer, 0, bufferSize);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
}
outputStream.writeBytes(lineEnd);
outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
// Response Code and Message
resCode = conn.getResponseCode();
if(resCode == HttpURLConnection.HTTP_OK)
{
InputStream is = conn.getInputStream();
ByteArrayOutputStream bos = new ByteArrayOutputStream();
int read = 0;
while ((read = is.read()) != -1) {
bos.write(read);
}
byte[] result = bos.toByteArray();
bos.close();
resMessage = new String(result);
}
Log.d("resCode=",Integer.toString(resCode));
Log.d("resMessage=",resMessage.toString());
fileInputStream.close();
outputStream.flush();
outputStream.close();
resServer = resMessage.toString();
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
protected void onPostExecute(Void unused) {
statusWhenFinish(position,resServer);
}
}
// When UPload Finish
@SuppressWarnings("unused")
protected void statusWhenFinish(int position, String resServer) {
View v = lstView.getChildAt(position - lstView.getFirstVisiblePosition());
// hide ProgressBar
holder.uploadProgressBar.setVisibility(View.GONE);
/*** Default Value ***/
String strStatusID = "0" ;
String strError = "" ;
try {
JSONObject c = new JSONObject(resServer);
strStatusID = c.getString("StatusID");
strError = c.getString("Message");
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// using if - else if
if(strStatusID.equals("0"))
{
// already exist
holder.statusImageView.setImageResource(R.drawable.already_exist);
}
else if(strStatusID.equals("1")) {
// upload done
holder.statusImageView.setImageResource(R.drawable.upload_done);
}
else // if upload failed
{
// upload failed
holder.statusImageView.setImageResource(R.drawable.upload_failed);
}
}
}
答案 0 :(得分：3)
所以对你的ProgressBar。
每当调用getView（）时，都会将其可见性设置为GONE。
holder.uploadProgressBar.setVisibility(View.GONE);
因此，当开始上传某些内容（并将uploadProgressBar设置为VISIBLE），然后向下滚动（使列表项不可见），然后向上滚动，将再次调用getView（），它将使您的ProgressBar不可见。< / p>
因此，您需要将状态包装在对象中，或使用列表记录每个项目状态。例如，在ImageAdapter
boolean[] uploadings = new boolean[getCount()];
Arrays.fill(uploadings, false);
在getView()
if (uploadings[position]) {
// You need this, since you are not sure whether you are
// using newly inflated view or ConvertView
holder.uploadProgressBar.setVisibility(View.VISIBLE);
} else {
holder.uploadProgressBar.setVisibility(View.GONE);
}
在startUpload()方法中，每当您将prograss栏设置为GONE或VISIBILE时，请将uploadings[position]设置为false或true。
我认为您的ImageView可能存在同样的问题。
答案 1 :(得分：3)
在ViewHolder课程中：
static class ViewHolder {
//...
boolean isUploading = false;
//...
}
在getView()：
public View getView(final int position, View convertView, ViewGroup parent) {
//...
if(holder.isUploading) {
holder.uploadProgressBar.setVisibility(View.VISIBLE);
} else {
holder.uploadProgressBar.setVisibility(View.GONE);
}
//...
}
在startUpload()：
public void startUpload(final int position) {
//...
holder.uploadProgressBar.setVisibility(View.VISIBLE);
holder.isUploading = true;
//...
}
希望它能奏效。
答案 2 :(得分：1)
尝试使用持有人进行单元格视图
将此类放在适配器的末尾
class ViewHolder {
TextView txtName,txtStatus;
ImageView imageView;
public ViewHolder(View convertview) {
txtName = (TextView) convertview.findViewById(R.id.txtName );
imageView = (ImageView) convertview.findViewById(R.id.ColImgPath);
//and so on...
}
}
取代：
if (convertView == null) {
convertView = inflater.inflate(R.layout.list_upload, null);
}
使用：
if (convertview == null) {
convertview = activity.getLayoutInflater().inflate(R.layout.list_upload, null);
holder = new ViewHolder(convertview);
convertview.setTag(holder);
} else {
holder = (ViewHolder) convertview.getTag();
}
之后与持有人一起做你的工作......
holder.imageView代替所有视图的imageView等等
答案 3 :(得分：1)
您必须在getView()方法中设置进度状态，因为android重用ListView项。
为了解你如何解决这个问题：
`
public View getView(final int position, View convertView, ViewGroup parent) {
.
.
.
Int rowId = holder.id;
UploadTask task = Uploader.getTaskById(rowId);
if (task == null) {
holder.progressBar.setVisibility(View.Gone);
} else {
int progress = task.getUploadProgress();
holder.progressBar.setVisibility(View.Visible);
holder.progressBar.setProgress(progress);
}
}
P.S。你应该看一下Google IO video about listviewListView
答案 4 :(得分：1)
查看可能对您有用的Listview with ProgressBar