我有一种方法需要定期更新其状态到服务器。
我正在使用AsyncTask在后台运行HTTP调用。
问题：在检查AsyncTask.getStatus时的onPostExecute方法中，它显示上一个仍在运行的任务，导致错误。
错误：java.lang.IllegalStateException：无法执行任务：任务已在运行。
用于解决问题但尚未运作的不同策略
1. Before Relaunching AsyncTask, checked the status, it is showing the thread is RUNNING.
2. Called the AsyncTask.cancel(true), immediately before calling the AsyncTask.execute if it is still running. It turns out AsyncTask still RUNNING and taking more than 3 mins to get cancel.
注意：我在这里检查了很多类似的问题，但没有找到帮助。
如果你们中的任何一个人给我一个解决这个问题的例子，我真的很认真，感谢百万提前......
public class MainActivity extends Activity implements AsyncResponse{
ConnectServer asyncTask =new ConnectServer();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
asyncTask.delegate = this;
setContentView(R.layout.activity_main);
//Start updating server using below method
loop();
}
public void processFinish(String output){
//this you will received result fired from async class of onPostExecute(result) method.
//Log.v(TAG, output);
if(output != null){
//not using this at this point
}
}
//Method that will call Async method to reach server
public void loop(){
TextView b = (TextView) findViewById(R.id.mField);
String str;
try {
str = asyncTask.execute(true).get();
b.setText(str);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// START SERVER CONNECTION
class ConnectServer extends AsyncTask<Boolean, String, String> {
public AsyncResponse delegate=null;
public int i = 0;
private Activity activity;
public void MyAsyncTask(Activity activity) {
this.activity = activity;
}
@Override
protected String doInBackground(Boolean... params) {
String result = null;
StringBuilder sb = new StringBuilder();
try {
// http post
HttpClient httpclient = new DefaultHttpClient();
HttpGet httppost = new HttpGet("http://192.168.0.21:8080");
HttpResponse response = httpclient.execute(httppost);
if (response.getStatusLine().getStatusCode() != 200) {
Log.d("GPSApp", "Server encountered an error");
}
BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF8"));
sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
return result;
}
@Override
protected void onPostExecute(String result) {
TextView mField = (TextView) findViewById(R.id.mField);
mField.setText(result+i);
try {
Thread.sleep(10000);
//asyncTask =new ConnectServer();
i++;
String str = asyncTask.execute(true).get();
mField.setText(str+i);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
protected void onPreExecute() {}
}
}