Android:更改列表视图中特定项目的图像 [英] Android: Change image for a particular item in listview
问题描述
在上图中，有一个列表视图，其中包含用户可以下载的项目列表. 这是告诉用户他可以下载文件的图像.下载完成后，图像将更改为 .我的问题是，当我下载文件时，状态图像(表示下载已完成)会更改为另一行，相反，它应该更改为我选择的行.目前，如果我下载列表中的第一个文件，图像将更改为列表中的第 4 项或第 5 项.此外，当我尝试从列表中下载任何其他文件时.它打开上次下载的文件(这是应用程序的功能，如果文件已经下载，则在 pdf 阅读器中打开它)，即，如果我下载列表中的第一个文件，然后转到第二个项目，那么而不是下载第二个文件，它会打开上次下载的文件.此外，如果我滚动列表视图，列表中其他项目的下载状态也会发生变化.下面是我的适配器代码:
In the above image, there is a list view which contains list of items that the user can download. This is the image which tells user that he can download the file. On completion of download, the image will change to . My problem is when I download a file, the status image(which denotes that download has completed) gets changed for another row, instead, it should change for the row that I had selected. At present, if I download first file in the list, the image gets changed for 4th or 5th item in the list. Also, when I try to download any other file from the list. it opens up last downloaded file(This is functionality of the app that if file is already downloaded, then open it in pdf reader),i.e., if I download 1st file in the list and then go for second item,then instead of downloading 2nd file, it opens up last downloaded file. More over, if I scroll the listview, the status of download gets changed for other items in the list also. Below,is my adapter code:
public class DownloadListAdapter extends BaseAdapter {
Context ctx;
public ArrayList<DownloadListDao> mDownloadList;
String readMoreLink;
public static final String TAG = "DownloadListAdapter";
ProgressDialog mProgressDialog;
private boolean isSDCardPresent;
File tieDir;
int downloadState[];
public DownloadListAdapter(Context ctx,
ArrayList<DownloadListDao> mDownloadList) {
this.ctx = ctx;
this.mDownloadList = mDownloadList;
downloadState = new int [mDownloadList.size()];
for(int i = 0; i < mDownloadList.size(); i++) {
downloadState[i] = 0;
}
tieDir = new File(Environment.getExternalStorageDirectory().toString()
+ "/tie");
}// Constructor
public int getCount() {
return this.mDownloadList.size();
}// getCount
public Object getItem(int position) {
return this.mDownloadList.get(position);
}// getItem
public long getItemId(int position) {
return 0;
}// getItemId
static class ViewHolder {
TextView txtTitle, txtTheme, txtDate;
ImageView imgDownload;
}// ViewHolder
ViewHolder holder;
public View getView(final int position, View convertView, ViewGroup parent) {
final String url = mDownloadList.get(position).getUrl();
if (convertView == null) {
convertView = LayoutInflater.from(parent.getContext()).inflate(
R.layout.downlist_adapter, null);
holder = new ViewHolder();
holder.txtTitle = (TextView) convertView
.findViewById(R.id.txtTitle);
holder.txtTheme = (TextView) convertView
.findViewById(R.id.txtTheme);
holder.txtDate = (TextView) convertView.findViewById(R.id.txtDate);
holder.imgDownload = (ImageView) convertView
.findViewById(R.id.imgDload);
holder.imgDownload.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
File mediaFile = null;
if (url != null && !url.equals("null") && !url.equals("")) {
String fileName = url.toString().substring(
url.toString().lastIndexOf("/") + 1,
url.toString().length());
mediaFile = new File(tieDir, fileName);
}
processFile(mediaFile, url, position);
int pos = (Integer)v.getTag();
downloadState[pos] = 1;
}
});
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
if (mDownloadList != null && mDownloadList.size() > 0) {
if (mDownloadList.get(position).getTitle() != null
&& !mDownloadList.get(position).getTitle().equals("null")
&& !mDownloadList.get(position).getTitle().equals("")) {
holder.txtTitle.setText(mDownloadList.get(position).getTitle());
}
if (mDownloadList.get(position).getTheme() != null
&& !mDownloadList.get(position).getTheme().equals("null")
&& !mDownloadList.get(position).getTheme().equals("")) {
holder.txtTheme.setText(mDownloadList.get(position).getTheme());
}
if (mDownloadList.get(position).getDate() != null
&& !mDownloadList.get(position).getDate().equals("null")
&& !mDownloadList.get(position).getDate().equals("")) {
holder.txtDate.setText(mDownloadList.get(position).getDate());
}
if (downloadState[position] == 1) {
holder.imgDownload.setImageDrawable(ctx.getResources()
.getDrawable(R.drawable.ic_dloaded));
} else {
holder.imgDownload.setImageDrawable(ctx.getResources()
.getDrawable(R.drawable.ic_dload));
}
}
holder.imgDownload.setTag(position);
return convertView;
}// getView
protected void downloadFile(String url, int position, String fileName) {
Log.v(TAG, "Preparing to download");
mProgressDialog = new ProgressDialog(ctx);
mProgressDialog.setMessage("Dowloading...");
mProgressDialog.setIndeterminate(false);
mProgressDialog.setMax(100);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
isSDCardPresent = Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED);
if (!isSDCardPresent) {
noSDCardAlert(ctx);
} else {
if ((tieDir.exists()) && (tieDir != null)) {
if (NetworkConnection.isOnline(ctx)) {
if (tieDir.isDirectory()) {
Log.v(TAG, "if tie dir URL:::" + url);
new DownloadAudioAsync(ctx, position, fileName).execute(url);
}
} else {
((DownloadListActivity) ctx)
.OpenNetErrDialog("Please check your internet connection...");
}
} else {
boolean isDirectoryCreated = tieDir.mkdirs();
if (isDirectoryCreated) {
Log.v(TAG, "if tie not dir URL:::" + url);
if (NetworkConnection.isOnline(ctx)) {
new DownloadAudioAsync(ctx, position, fileName).execute(url);
} else {
((DownloadListActivity) ctx)
.OpenWiFiDialog("Please check your internet connection...");
}
}
}
}
}
private void noSDCardAlert(Context ctx) {
AlertDialog.Builder ad = new AlertDialog.Builder(ctx);
ad.setMessage("No sd card present..");
ad.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
if (!((DownloadDetail) ctx).isFinishing()) {
ad.show();
}
}
public void OpenDialog(String messageID) {
final Dialog dialog = new Dialog(ctx,
android.R.style.Theme_Translucent_NoTitleBar);
dialog.setContentView(R.layout.dialog_base);
dialog.getWindow().getAttributes().windowAnimations = android.R.style.Animation_Dialog;
dialog.setCancelable(false);
TextView alertMessage = (TextView) dialog.findViewById(R.id.txtMessage);
Button btnOK = (Button) dialog.findViewById(R.id.btnOk);
btnOK.setText("Show");
alertMessage.setText(messageID);
dialog.show();
btnOK.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
}
});
}
protected void showPdf(File mediaFile) {
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(mediaFile), "application/pdf");
intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
ctx.startActivity(intent);
}
public class DownloadAudioAsync extends AsyncTask<String, String, String> {
Context ctx;
int pos;
private ProgressDialog pd;
String fileName;
public DownloadAudioAsync(Context ctx, int pos, String fileName) {
this.ctx = ctx;
this.pos = pos;
this.fileName = fileName;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
Log.v(TAG, "inside on pre execute");
pd = new ProgressDialog(ctx);
pd.setMessage("Downloading...
Please wait..");
pd.show();
}
@Override
protected String doInBackground(String... aurl) {
int count;
try {
Log.v(TAG,
"inside do in background with url::"
+ aurl[0].toString());
aurl[0] = aurl[0].replaceAll(" ", "%20");
URL url = new URL(aurl[0]);
URLConnection conexion = url.openConnection();
conexion.connect();
int lenghtOfFile = conexion.getContentLength();
fileName = URLDecoder.decode(fileName, "UTF-8");
InputStream input = new BufferedInputStream(url.openStream());
OutputStream output = new FileOutputStream(tieDir + "/"
+ fileName);
byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
publishProgress("" + (int) ((total * 100) / lenghtOfFile));
output.write(data, 0, count);
}
output.flush();
output.close();
input.close();
} catch (Exception e) {
}
return null;
}
@Override
protected void onPostExecute(String unused) {
if (!((DownloadListActivity) ctx).isFinishing()) {
pd.dismiss();
updateView(pos);
}
}
private void updateView(int pos) {
View v = ((DownloadListActivity) ctx).menuListView.getChildAt(pos
- ((DownloadListActivity) ctx).menuListView
.getFirstVisiblePosition());
ImageView imgDloadBtn = (ImageView) v.findViewById(R.id.imgDload);
imgDloadBtn.setImageDrawable(ctx.getResources().getDrawable(
R.drawable.ic_dloaded));
notifyDataSetChanged();
}
}
private void processFile(File mediaFile, String url, int pos) {
if (url != null && !url.equals("null") && !url.equals("")) {
if (mediaFile != null) {
Log.v(TAG, "in processFile FileName " + mediaFile.getName());
Log.v(TAG, "in processFile Position " + pos);
if(!mediaFile.exists()) {
Log.v(TAG, "in processFile Media file doesn't exists");
downloadFile(url, pos, mediaFile.getName());
} else {
Log.v(TAG, "in processFile Media file exists");
try {
showPdf(mediaFile);
} catch (ActivityNotFoundException anfe) {
OpenDialog("PDF Reader is not installed on your device.");
}
}
}
}
}
}// DownloadAdapter
我已经阅读了这篇文章用于回收视图(感谢 Knickedi 的深入解释).但是，我无法弄清楚实际问题在哪里.
I had read this post for recycling the view(Thanks to Knickedi for in depth explaination). But, I can't figure out where is actual problem.
推荐答案
Issue with getview 每当你滚动视图时不断重新创建的方法，以处理你必须使用 setTag 播放的确切位置&getTag，查看下面几个 stackvoerflow 答案以了解 setTag &getTag:
Issue with getview Method which keep recreating whenever you scroll your view, to handle exact position you have to play with setTag & getTag,check below few stackvoerflow answers to understand setTag & getTag:
甚至将下载的状态存储到一个 booleanarray 中，如下所示:
and even store downloaded state into one booleanarray like below:
int boxState[];
在适配器构造函数中，最初设置为零:
within adapter constructor, set zero initially:
for (int i = 0; i < getData.size(); i++) {
boxState[i] = 0;
}
在适配器 getview 方法中:
within adapter getview method:
holder.imgDownload.setTag(position);
现在你点击下载按钮设置值为1(在按钮的onclick里面):
Now you click on download button set value as 1 (Inside onclick of button):
pos = (Integer) v.getTag();
boxState[pos]=1;
最后，当您将视图检查条件滚动到以下方式时(将下面的代码放在 getview 方法中):
At last when you scroll your view check condition into following way(put below code inside getview method):
if (boxState[position] == 0) {
holder.imgDownload.setImageDrawable(ctx.getResources()
.getDrawable(R.drawable.ic_dloaded)); //which aren't downloaded
} else {
holder.imgDownload.setImageDrawable(ctx.getResources()
.getDrawable(R.drawable.ic_dload)); // which are downloaded.
}
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