【发布时间】：2012-06-08 18:23:48
【问题描述】：
在我的应用程序中，我连接到一个网站以从 AsyncTask 开始收集一些信息，使用 try catch，从这里我可以在我的目录日志中显示连接时的错误（如果有），但我一直在尝试没有运气显示一个对话框，显示连接失败以及重新连接或退出的选项，请检查我的代码并告诉我我做错了什么或如何完成此操作的想法
//this is our download file asynctask
class DownloadFileAsync extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
showDialog(DIALOG_DOWNLOAD_PROGRESS);
}
@Override
protected String doInBackground(String... aurl) {
try {
String result = "";
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://mywebsiteaddress");
// httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
InputStream webs = entity.getContent();
// convert response to string
try {
BufferedReader reader = new BufferedReader(
new InputStreamReader(webs, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
webs.close();
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
// parse json data
try {
JSONArray jArray = new JSONArray(result);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
webResult resultRow = new webResult();
//infotodownload
arrayOfWebData.add(resultRow);
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
} catch (Exception e) {
// this is the line of code that sends a real error message to the
// log
Log.e("ERROR", "ERROR IN CODE: " + e.toString());
// this is the line that prints out the location in
// the code where the error occurred.
e.printStackTrace();
}
return null;
}
protected void onProgressUpdate(String... progress) {
Log.d(LOG_TAG,progress[0]);
mProgressDialog.setProgress(Integer.parseInt(progress[0]));
}
@Override
protected void onPostExecute(String unused) {
//dismiss the dialog after the file was downloaded
dismissDialog(DIALOG_DOWNLOAD_PROGRESS);
}
}
//our progress bar settings
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DIALOG_DOWNLOAD_PROGRESS: //we set this to 0
mProgressDialog = new ProgressDialog(this);
mProgressDialog.setTitle("Conectando al Servidor");
mProgressDialog.setMessage("Cargando informacion...");
mProgressDialog.setIndeterminate(false);
mProgressDialog.setMax(100);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
mProgressDialog.setCancelable(true);
mProgressDialog.show();
return mProgressDialog;
default:
return null;
}
}
编辑： 然后我尝试按照 Arun 的建议添加下一个代码
catch (Exception e) {
// this is the line of code that sends a real error message to the
// log
Log.e("ERROR", "ERROR IN CODE: " + e.toString());
// this is the line that prints out the location in
// the code where the error occurred.
e.printStackTrace();
return "ERROR_IN_CODE";
}
return null; // if I place here return "ERROR_IN_CODE" it calls the dialog but it gets always called so I don't need it here
}
@Override
protected void onPostExecute(String unused) {
//dismiss the dialog after the file was downloaded
dismissDialog(DIALOG_DOWNLOAD_PROGRESS);
if(unused.equals("ERROR_IN_CODE")){ //I get a system crash here!
errornote();
}
}
}
public void errornote() {
AlertDialog.Builder alt_bld = new AlertDialog.Builder(this);
alt_bld.setMessage("No se a podido descargar la informacion de los medios, deseas reintentarlo, o salir?").setCancelable(false)
.setPositiveButton("Conectar de Nuevo", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
new DownloadFileAsync().execute();
}
})
.setNegativeButton("Salir", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// Action for 'NO' Button
finish();
}
});
AlertDialog alert = alt_bld.create();
// Title for AlertDialog
alert.setTitle("Error en la Conexion!");
// Icon for AlertDialog
alert.setIcon(android.R.drawable.ic_dialog_alert);
alert.show();
}
但也不工作，我的应用程序在 onPostExecute 的 if 语句行中崩溃。我仍然需要帮助。
【问题讨论】：
-
doInBackground() 的 Catch 块中无法显示对话框，因为此函数在非 UI 线程中运行
-
看看答案here有没有帮助。
-
@yorkw，不显示对话框。
-
根据你上次编辑，似乎代码执行没有遇到catch块，确保你的catch块被正确触发，换句话说，确保try块中的代码失败并抛出实际异常。
-
@ yorkw，我所做的测试只是断开我的互联网与计算机的连接，当模拟器尝试连接以下载它无法下载的信息时，它会得到一个连接错误。你是这个意思吗？
标签： java android eclipse try-catch