如果在我的AsyncTask中doInBackground发生任何异常，我将无法解除进度对话，因为它永远不会到达onPostExecute，并且永远不会关闭进行ANR的进度对话框。
以下是AsyncTask的代码
private class checkAS extends AsyncTask<Void, Void, Void>
{
ProgressDialog dialogue;
@Override
protected void onPostExecute() {
// TODO Auto-generated method stub
super.onPostExecute();
dialogue.dismiss();
}
@Override
protected Void doInBackground(Void... params) {
//Long Network Task
return null;
}
@Override
protected void onPreExecute(Void result) {
// TODO Auto-generated method stub
super.onPreExecute(result);
dialogue = new ProgressDialog(MainActivity.this);
dialogue.setTitle("Processing");
dialogue.setMessage("Getting Profile Information");
dialogue.setIndeterminate(true);
dialogue.setCancelable(false);
dialogue.show();
}
}
我的问题是，如果在doInBackground发生任何异常，我将如何处理它以及如何调用onPostExecute来解除对话？我不能在doInBackground上解雇它。如何同步？
答案 0 :(得分：1)
试试这个..
从doInBackground返回类似字符串的内容。如果Exception来catch分配字符串值error，否则返回success
private class checkAS extends AsyncTask<Void, Void, String>
{
ProgressDialog dialogue;
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
dialogue = new ProgressDialog(MainActivity.this);
dialogue.setTitle("Processing");
dialogue.setMessage("Getting Profile Information");
dialogue.setIndeterminate(true);
dialogue.setCancelable(false);
dialogue.show();
}
@Override
protected String doInBackground(Void... params) {
//Long Network Task
String result;
try{
result = "success"
}
catch(Exception e){
result = "error";
}
return result;
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
if(result.equals("error"))
dialogue.dismiss();
else
// do something
}
}
答案 1 :(得分：0)
您正在onPostExecute方法中创建对话框对话框，它应该在onPreExecute方法中。 试试这个。
private class checkAS extends AsyncTask<Void, Void, Void>
{
ProgressDialog dialogue;
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
dialogue = new ProgressDialog(MainActivity.this);
dialogue.setTitle("Processing");
dialogue.setMessage("Getting Profile Information");
dialogue.setIndeterminate(true);
dialogue.setCancelable(false);
dialogue.show();
}
@Override
protected Void doInBackground(Void... params) {
//Long Network Task
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
dialogue.dismiss();
}
}
答案 2 :(得分：0)
@Override
protected String doInBackground(String... params)
{
System.out.println("check user profile");
try
{
}
catch (Exception e)
{
e.printStackTrace();
publishProgress((e.getMessage()));
}
return result;
}
@Override
protected void onProgressUpdate(String... values)
{
// TODO Auto-generated method stub
super.onProgressUpdate(values);
Toast.makeText(activity, values[0], Toast.LENGTH_LONG);
if(dialog != null && dialog.isShowing())
dialog.dismiss();
}
@SuppressLint("InlinedApi")
@Override
protected void onPostExecute(String result)
{
super.onPostExecute(result);
if(dialog != null && dialog.isShowing())
{
dialog.dismiss();
}
}
答案 3 :(得分：0)
您可能希望忽略finally构建的try catch块中的对话框。
即
try {
...
} catch {
...
finally{
//dismiss dialog here.
}
答案 4 :(得分：0)
首先使用您可以检查的代码检查对话框是否显示
if(dialog.isShowing())
dialog.dismiss();
并使用异常处理来避免未知的异常
答案 5 :(得分：0)
private class checkAS extends AsyncTask<String, Integer, String> {
public static final int POST_TASK = 1;
private static final String TAG = "checkAS";
// connection timeout, in milliseconds (waiting to connect)
private static final int CONN_TIMEOUT = 12000;
// socket timeout, in milliseconds (waiting for data)
private static final int SOCKET_TIMEOUT = 12000;
private int taskType = POST_TASK;
private Context mContext = null;
private String processMessage = "Processing...";
private ArrayList<NameValuePair> params = new ArrayList<NameValuePair>();
private ProgressDialog pDlg = null;
public checkAS(int taskType, Context mContext, String processMessage) {
this.taskType = taskType;
this.mContext = mContext;
this.processMessage = processMessage;
}
public void addNameValuePair(String name, String value) {
params.add(new BasicNameValuePair(name, value));
}
@SuppressWarnings("deprecation")
private void showProgressDialog() {
pDlg = new ProgressDialog(mContext);
pDlg.setMessage(processMessage);
pDlg.setProgressDrawable(mContext.getWallpaper());
pDlg.setProgressStyle(ProgressDialog.STYLE_SPINNER);
pDlg.setCancelable(false);
pDlg.show();
}
@Override
protected void onPreExecute() {
showProgressDialog();
}
protected String doInBackground(String... urls) {
String url = urls[0];
String result = "";
HttpResponse response = doResponse(url);
if (response == null) {
return result;
} else {
try {
result = inputStreamToString(response.getEntity().getContent());
} catch (IllegalStateException e) {
Log.e(TAG, e.getLocalizedMessage(), e);
} catch (IOException e) {
Log.e(TAG, e.getLocalizedMessage(), e);
}
}
return result;
}
@Override
protected void onPostExecute(String response) {
handleResponse(response);
pDlg.dismiss();
}
private HttpParams getHttpParams() {
HttpParams htpp = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(htpp, CONN_TIMEOUT);
HttpConnectionParams.setSoTimeout(htpp, SOCKET_TIMEOUT);
return htpp;
}
private HttpResponse doResponse(String url) {
// Use our connection and data timeouts as parameters for our
// DefaultHttpClient
HttpClient httpclient = new DefaultHttpClient(getHttpParams());
HttpResponse response = null;
try {
switch (taskType) {
case POST_TASK:
HttpPost httppost= new HttpPost(url);
httppost.setEntity(new UrlEncodedFormEntity(params));
response = httpclient.execute(httppost);
break;
}
}
catch (Exception e) {
// display("Remote DataBase can not be connected.\nPlease check network connection.");
Log.e(TAG, e.getLocalizedMessage(), e);
return null;
}
return response;
}
private String inputStreamToString(InputStream is) {
String line = "";
StringBuilder total = new StringBuilder();
// Wrap a BufferedReader around the InputStream
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
// Read response until the end
while ((line = rd.readLine()) != null) {
total.append(line);
}
} catch (IOException e) {
Log.e(TAG, e.getLocalizedMessage(), e);
}
catch(Exception e)
{
Log.e(TAG, e.getLocalizedMessage(), e);
}
// Return full string
return total.toString();
}
}
public void handleResponse(String response)
{
//display("Response:"+response);
if(!response.equalsIgnoreCase(""))
{
JSONObject jso;
try {
//do your stuff
}
catch (JSONException e1) {
Log.e(TAG, e1.getLocalizedMessage(), e1);
}
catch(Exception e)
{
Log.e(TAG, e.getLocalizedMessage(), e);
}
}
else
{
display("Could not able to reach Server!");
}
}
答案 6 :(得分：0)
试试这个：
private class checkAS extends AsyncTask<Void, Void, Boolean> {
ProgressDialog dialogue;
@Override
protected void onPostExecute(Boolean result) {
super.onPostExecute(result);
dialogue.dismiss();
}
@Override
protected Boolean doInBackground(Void... params) {
try {
Thread.sleep(15000);
} catch (Exception e) {}
return true;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
dialogue = new ProgressDialog(Main.this);
dialogue.setTitle("Processing");
dialogue.setMessage("Getting Profile Information");
dialogue.setIndeterminate(true);
dialogue.setCancelable(false);
dialogue.show();
}
}