我的类使用http连接时遇到问题。这个错误是针对连接的，我读到这个错误意味着我必须使用AsyncTask，但我使用了它，我的应用程序仍然无法工作。这里有代码：
@Override
public void onCreate(Bundle savedInstanceState) {
...
new GetCoursesDetails().execute();
}
class GetCoursesDetails extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(InfoCorsi.this);
pDialog.setMessage("Loading courses details. 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() {
// Check for success tag
int success;
try {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("pid", pid));
// getting product details by making HTTP request
// Note that product details url will use GET request
JSONObject json = jParser.makeHttpRequest(
url_info_corsi, "GET", params);
// check your log for json response
Log.d("Single course Details", json.toString());
// json success tag
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// successfully received product details
JSONArray productObj = json
.getJSONArray(TAG_COURSES); // JSON Array
// get first product object from JSON Array
JSONObject product = productObj.getJSONObject(0);
}else{
// product with pid not found
}
} catch (JSONException 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
pDialog.dismiss();
}
}
类jSONParser之所以工作，是因为我用它来连接另一个类，在这种情况下，错误类型为android.os.NetworkOnMainThreadException：
1-18 13:44:46.478 23304-23318/? E/art: Failed sending reply to debugger: Broken pipe
11-18 13:44:53.635 23304-E/AndroidRuntime: FATAL EXCEPTION: main
11-18 13:44:53.635 23304-E/AndroidRuntime: Process: com.piemonteorientale.cus.cuspo, PID: 23304
11-18 13:44:53.635 23304-E/AndroidRuntime: android.os.NetworkOnMainThreadException
11-18 13:44:53.635 23304-E/AndroidRuntime: at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147)
11-18 13:44:53.635 23304-E/AndroidRuntime: at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:110)
11-18 13:44:53.635 23304-E/AndroidRuntime: at libcore.io.IoBridge.connectErrno(IoBridge.java:137)
11-18 13:44:53.635 23304-E/AndroidRuntime: at libcore.io.IoBridge.connect(IoBridge.java:122)
11-18 13:44:53.635 23304-E/AndroidRuntime: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)
11-18 13:44:53.635 23304-E/AndroidRuntime: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:456)
11-18 13:44:53.635 23304-E/AndroidRuntime: at java.net.Socket.connect(Socket.java:882)
11-18 13:44:53.635 23304-E/AndroidRuntime: at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:124)
11-18 13:44:53.635 23304-E/AndroidRuntime: at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:149)
11-18 13:44:53.635 23304-E/AndroidRuntime: at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:169)
11-18 13:44:53.635 23304-E/AndroidRuntime: at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:124)
11-18 13:44:53.635 23304-E/AndroidRuntime: at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:365)
11-18 13:44:53.635 23304-E/AndroidRuntime: at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:560)
11-18 13:44:53.635 23304-E/AndroidRuntime: at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:492)
11-18 13:44:53.635 23304-E/AndroidRuntime: at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:470)
11-18 13:44:53.635 23304-E/AndroidRuntime: at com.piemonteorientale.cus.cuspo.JSONParser.makeHttpRequest(JSONParser.java:62)
11-18 13:44:53.635 23304-E/AndroidRuntime: at com.piemonteorientale.cus.cuspo.InfoCorsi$GetCoursesDetails$1.run(InfoCorsi.java:89)
11-18 13:44:53.635 23304-E/AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:739)
11-18 13:44:53.635 23304-E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:95)
11-18 13:44:53.635 23304-E/AndroidRuntime: at android.os.Looper.loop(Looper.java:135)
11-18 13:44:53.635 23304-E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5290)
11-18 13:44:53.635 23304-E/AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
11-18 13:44:53.635 23304-E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:372)
11-18 13:44:53.635 23304-E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
11-18 13:44:53.635 23304-E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
从doInBackground()方法中删除runOnUiThread()。
如果要显示进度，可以使用AsyncTask.onProgressUpdate (Progress...)。此方法将在UI线程上运行。不要从它进行任何网络调用。使用AsyncTask.doInBackground (Params...)方法中的AsyncTask.publishProgress (Progress...)来调用进度更新。
请参阅AsyncTask API文档