我正在制作一个更新的Android应用程序。为此，我需要一个简单的函数，可以下载文件并在ProgressDialog中显示当前进度。我知道如何下载文件，但我不知道如何显示当前进度。我使用以下方法下载图像。
public Bitmap DownloadFile(String url){
URL myFileUrl;
Bitmap bitmap=null;
try {
myFileUrl = new URL(imageUrl);
HttpURLConnection conn= (HttpURLConnection)myFileUrl.openConnection();
conn.setDoInput(true);
conn.setConnectTimeout(10000);
conn.setReadTimeout(10000);
conn.connect();
InputStream is = conn.getInputStream();
bmImg = BitmapFactory.decodeStream(is);
bitmap = BitmapFactory.decodeStream((InputStream) new URL(
imageUrl).getContent());
bitmap = Bitmap.createScaledBitmap(bitmap,80 , 80, true);
System.out.println("name of butmap"+bitmap.toString());
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return bitmap;
}
以下是我的异步任务类：
public class BackgroundAsyncTask extends AsyncTask<String, Integer, Bitmap> {
int myProgress;
@Override
protected void onPostExecute(Bitmap result) {
dialog.dismiss();
iv.setVisibility(View.VISIBLE);
iv.setImageBitmap(result);
System.out.println("bbbbbbbbb");
System.out.println("post execute");
}
@Override
protected void onPreExecute() {
System.out.println("pre execute");
dialog = ProgressDialog.show(ProfileNormalUserPhotos.this, "Loading...", "Please wait...");
}
@Override
protected Bitmap doInBackground(String...paths) {
System.out.println(imageUrl+" imageurl");
return DownloadFile(imageUrl);
}
@Override
protected void onProgressUpdate(Integer... values) {
// TODO Auto-generated method stub
progressBar.setProgress(values[0]);
}
}
我正在调用以下适配器类中的方法：
public class ImageAdapter extends BaseAdapter {
Context mContext;
public String[] stringOnTextView;
public ImageAdapter(Context c) {
mContext = c;
}
public ImageAdapter(Context Context,
String[] stringOnTextView) {
this.mContext=Context;
this.stringOnTextView=stringOnTextView;
}
public int getCount() {
return stringOnTextView.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
View v = null;
if(convertView==null){
try{
{
LayoutInflater li = getLayoutInflater();
v = li.inflate(R.layout.icon, null);
TextView tv = (TextView)v.findViewById(R.id.text);
tv.setText("Profile Image "+(position+1));
iv= (ImageView)v.findViewById(R.id.image);
imageUrl = "http://ondamove.it/English/images/users/";
imageUrl=imageUrl+stringOnTextView[position];
new BackgroundAsyncTask().execute(imageUrl);
}
}catch (Exception e) {
e.printStackTrace();
System.out.println(e);
}
}
else
{
try{
v = convertView;}
catch(Exception e){
System.out.println(e);
}
}
return v;
}
}
我需要下载9张图片，但我遇到的问题是它只显示最后一张图片，进度对话框进入无限循环。
任何人都可以告诉我如何解决thios问题。
由于
答案 0 :(得分：4)
如果你还记得，我已经建议你先前使用AsyncTask来解决你的问题。
完成此示例并了解并以您的方式实施：AsyncTask with Progress Dialog
答案 1 :(得分：3)
我通过研究得到了解决方案，以下应该是解决方案：
class DownloadFileAsync extends AsyncTask<String, String, String>
{
int count;
URL myFileUrl;
ImageView imageview;
Bitmap bp;
public DownloadFileAsync(ImageView iv, URL uu)
{
this.imageview = iv;
this.myFileUrl = uu;
}
@Override
protected void onPreExecute()
{
super.onPreExecute();
showDialog(DIALOG_DOWNLOAD_PROGRESS);
}
@Override
protected String doInBackground(String... aurl)
{
for (int i = 0; i < aurl.length; i++)
System.out.println("----------" + i + "------" + aurl[i]);
try
{
HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();
conn.setConnectTimeout(10000);
conn.setReadTimeout(10000);
conn.connect();
InputStream is = conn.getInputStream();
bmImg = BitmapFactory.decodeStream(is);
bp = BitmapFactory.decodeStream((InputStream) (myFileUrl).getContent());
bp = Bitmap.createScaledBitmap(bp, 70, 70, true);
}
catch (Exception e)
{
System.out.println(e);
e.printstacktrace();
}
return null;
}
protected void onProgressUpdate(String... progress)
{
dialog.setProgress(Integer.parseInt(progress[0]));
}
@Override
protected void onPostExecute(String unused)
{
try
{
imageview.setImageBitmap(bp);
System.out.println("this is" + this);
// dialog.dismiss();
dismissDialog(DIALOG_DOWNLOAD_PROGRESS);
}
catch (Exception e)
{
System.out.println(e);
}
}
}
答案 2 :(得分：0)
您必须使用AssyncTask才能轻松地将进度传达给UI线程。
对于对话框，请使用ProgressDialog：
private void downloadFile(URL fileUrl) {
if (myProgressDialog == null) {
new DownloadFilesTask().execute(fileUrl);
myProgressDialog = ProgressDialog.show(this, "Downloading file " + fileUrl.toString(), "Wait patiently, your download is in progress.", true /*You wont have a time estimate*/, false /*Download cannot be canceled*/);
} else {
Log.e(LOG_TAG, "A download is already in progress");
}
}
private void hideDialog() {
if (myProgressDialog != null) {
myProgressDialog.cancel();
}
}
对于AssycTask，在Activity中使用内部类：
private class DownloadFilesTask extends AsyncTask<URL, Integer, Boolean> {
protected Long doInBackground(URL... urls) {
// TODO Download file here
return true;
}
protected void onProgressUpdate(Integer... progress) {
// TODO nothing to do here, you don't have download details
}
protected void onPostExecute(Boolean result) {
MyActivity.this.hideProgressDialog();
}
}
答案 3 :(得分：0)
您必须为适配器使用持有者类型的结构。
，对于listView中的每个项目，imageView应该是不同的。基本上，你必须将imageView作为参数传递给asyncTask。
我更换了你的适配器，看看它。
static class ViewHolder {
TextView tv;
ImageView iv;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder vh;
View v = null;
if(convertView==null){
vh = new ViewHolder();
LayoutInflater li = getLayoutInflater();
v = li.inflate(R.layout.icon, null);
vh.tv = (TextView)v.findViewById(R.id.text);
vh.iv= (ImageView)v.findViewById(R.id.image);
v.setTag(vh);
}
else
{
vh = (ViewHolder) convertView.getTag();
v = convertView;
}
vh.tv.setText("Profile Image "+(position+1));
imageUrl = "http://ondamove.it/English/images/users/";
imageUrl=imageUrl+stringOnTextView[position];
new BackgroundAsyncTask(vh.iv).execute(imageUrl);
return v;
}
此处还有asyncTask。我创建了一个构造函数并将imageView作为参数传递。
public class BackgroundAsyncTask extends AsyncTask<String, Integer, Bitmap> {
int myProgress;
ImageView iv;
public BackgroundAsyncTask (ImageView imageView) {
iv = imageView;
}
@Override
protected void onPostExecute(Bitmap result) {
dialog.dismiss();
iv.setVisibility(View.VISIBLE);
iv.setImageBitmap(result);
System.out.println("bbbbbbbbb");
System.out.println("post execute");
}
@Override
protected void onPreExecute() {
System.out.println("pre execute");
dialog = ProgressDialog.show(ProfileNormalUserPhotos.this, "Loading...", "Please wait...");
}
@Override
protected Bitmap doInBackground(String...paths) {
System.out.println(imageUrl+" imageurl");
return DownloadFile(imageUrl);
}
@Override
protected void onProgressUpdate(Integer... values) {
// TODO Auto-generated method stub
progressBar.setProgress(values[0]);
}
}
但我仍然无法保证无限循环的解决方案，但修复其他一些问题总是好的：）
HTH。