谁能告诉我，为什么上传图片时进度条不显示。我从我工作的旧项目中复制了 asynctask 结构。在我的旧项目中，我使用 asynctask 从 Web 服务器下载图片，并在下载时显示进度条。这是我的代码：
public class PreviewPostActivity extends Activity {
ImageView imageView;
TextView tvComment;
Button submit;
MyLocationListener locationListener;
List<NameValuePair> list = new ArrayList<NameValuePair>();
private final String url = "***"; //Url of php script
ProgressDialog pDialog;
String responseMessage="";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.preview_post);
Intent intent = this.getIntent();
imageView = (ImageView)findViewById(R.id.imgPerview);
tvComment = (TextView)findViewById(R.id.txtPreviewComment);
submit = (Button)findViewById(R.id.btnPreviewSubmit);
Bitmap image = (Bitmap)intent.getParcelableExtra("picture");
String comment = intent.getStringExtra("comment");
locationListener = (MyLocationListener)intent.getSerializableExtra("location");
String imagePath = intent.getStringExtra("imagePath");
String date = intent.getStringExtra("date");
imageView.setImageBitmap(image);
tvComment.setText(comment);
//tvComment.append("\n"+locationListener.latitude + "\n"+locationListener.longitude);
list.add(new BasicNameValuePair("image", imagePath));
list.add(new BasicNameValuePair("comment", comment));
list.add(new BasicNameValuePair("longitude", Double.toString(locationListener.longitude)));
list.add(new BasicNameValuePair("latitude", Double.toString(locationListener.latitude)));
list.add(new BasicNameValuePair("date", date));
submit.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
new uploadPost().execute();
}
});
}
public void post(List<NameValuePair> nameValuePairs) {
HttpParams httpParameters = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpParameters, 100000);
HttpConnectionParams.setSoTimeout(httpParameters, 200000);
HttpClient httpClient = new DefaultHttpClient(httpParameters);
HttpContext localContext = new BasicHttpContext();
HttpPost httpPost = new HttpPost(url);
try {
MultipartEntity entity = new MultipartEntity();
for(int index=0; index < nameValuePairs.size(); index++) {
if(nameValuePairs.get(index).getName().equalsIgnoreCase("image")) {
// If the key equals to "image", we use FileBody to transfer the data
entity.addPart(nameValuePairs.get(index).getName(), new FileBody(new File(nameValuePairs.get(index).getValue()),"image/jpeg"));
} else {
// Normal string data
entity.addPart(nameValuePairs.get(index).getName(), new StringBody(nameValuePairs.get(index).getValue()));
}
}
httpPost.setEntity(entity);
HttpResponse response = httpClient.execute(httpPost, localContext);
HttpEntity httpEntity = response.getEntity();
String responseMessage = EntityUtils.toString(httpEntity);
tvComment.setText(responseMessage);
} catch (IOException e) {
e.printStackTrace();
}
}
class uploadPost extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(PreviewPostActivity.this);
pDialog.setMessage("Uploading post. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
/**
* Getting product details in background thread
* */
protected String doInBackground(String... params) {
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
//post(list);
HttpParams httpParameters = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpParameters, 100000);
HttpConnectionParams.setSoTimeout(httpParameters, 200000);
HttpClient httpClient = new DefaultHttpClient(httpParameters);
HttpContext localContext = new BasicHttpContext();
HttpPost httpPost = new HttpPost(url);
try {
MultipartEntity entity = new MultipartEntity();
for(int index=0; index < list.size(); index++) {
if(list.get(index).getName().equalsIgnoreCase("image")) {
// If the key equals to "image", we use FileBody to transfer the data
entity.addPart(list.get(index).getName(), new FileBody(new File(list.get(index).getValue()),"image/jpeg"));
} else {
// Normal string data
entity.addPart(list.get(index).getName(), new StringBody(list.get(index).getValue()));
}
}
httpPost.setEntity(entity);
HttpResponse response = httpClient.execute(httpPost, localContext);
HttpEntity httpEntity = response.getEntity();
responseMessage = EntityUtils.toString(httpEntity);
//tvComment.setText(responseMessage);
} catch (IOException e) {
e.printStackTrace();
}
}
});
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once got all details
tvComment.setText(responseMessage);
pDialog.dismiss();
}
}
因此，当我点击上传按钮时，屏幕冻结并保持冻结状态，直到上传完成，并且根本不显示进度条。有时它会显示，但它的后部很稳定，我不知道为什么。我已经尝试从 doInBackground 主体中的类调用 Post() 方法，插入整个代码（主体中的代码与 post() 方法中的代码相同）但效果是一样的，所以我想我在创建进度条时没有做正确的事情。但是我再次说我从旧项目中复制了整个 asynctask 代码，它运行良好。
编辑：
我只是尝试在 PreviewPostActivity.class 的构造函数中创建进度条，之后我为 asynctask 类创建了构造函数，但它仍然有效。我很困惑，因为它在我的旧程序中工作。这是他的代码：
class GetSlike extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(KlubSlikeActivity.this);
pDialog.setMessage("Ucitavanje u toku. Molimo vas sacekajte...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
/**
* Getting product details in background thread
* */
protected String doInBackground(String... params) {
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
String id = Integer.toString(k.getId());
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("klub",id));
slikeUrl = JSONAdapter.getSlike(params);
gv.setAdapter(new SlikeAdapter(slikeUrl,KlubSlikeActivity.this));
}
});
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once got all details
pDialog.dismiss();
}
}
唯一改变的是 doInBackground 身体......
编辑：
执行后显示对话框runOnUiThread()。