我对Android开发和Java一般都非常陌生。以下是基本设置:我有一个启动屏幕,其中AsyncTask
用于检查服务器的可用性。正在关注this线程我在我的活动中进行了回调。这比在OnPostExecute()
中进行工作更有意义,因为我想在不同的活动中重复使用此任务。Android从匿名类中获取活动
但是,在我的回调中,我会检查状态是否正常。如果是,它应该启动下一个活动。但从我的回调中,我不明白我能如何获得我的Activity
参考,我需要它作为Intent的参数。
这是在OnCreate下在我的活动代码:
//Check server status
CheckServiceTask t = new CheckServiceTask(new OnTaskCompleted<ShaggyServiceStatus>() {
@Override
public void onTaskCompleted(ShaggyServiceStatus result) {
Log.i(TAG, "Callback. Result: " + result.getStatus());
ProgressBar pb = (ProgressBar) findViewById(R.id.splash_progress);
pb.setVisibility(View.INVISIBLE);
if (result.getStatusCode() == 999){
TextView t = (TextView) findViewById(R.id.splash_status_text);
t.setText(result.getStatus());
return;
}
Intent i = new Intent(getActivity(), LoginActivity.class);
startActivity(i);
finish();
}
});
t.execute();
哪里失败是getActivity()
的一部分。该呼叫不可用。使用this
会抛出一个错误(我知道,因为我在OnTaskCompleted
的上下文中)。
为了完整,这是OnTaskCompleted接口:
public interface OnTaskCompleted<T> {
public void onTaskCompleted(T result);
}
这是CheckServiceTask类:
public class CheckServiceTask extends AsyncTask<Void, Void, ShaggyServiceStatus>{
private static final String TAG = "coo";
public OnTaskCompleted<ShaggyServiceStatus> listener;
public CheckServiceTask (OnTaskCompleted<ShaggyServiceStatus> l){
this.listener = l;
}
@Override
protected ShaggyServiceStatus doInBackground(Void... params) {
try {
Log.i(TAG, "Connecting to server...");
//TODO: Make this a setting
final String url = "https://someplace.com/status";
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
//restTemplate.postForObject("url", bodyObject, ShaggySer.class);
ShaggyServiceStatus sss = restTemplate.getForObject(url, ShaggyServiceStatus.class);
Log.d(TAG, "Got the status.");
return sss;
} catch (Exception e) {
//TODO: Exception handling
Log.e(TAG, e.getMessage(), e);
}
//If we're here, it's not okay.
ShaggyServiceStatus r = new ShaggyServiceStatus("Cannot connect to server", 999, "none");
return r;
}
@Override
protected void onPostExecute(ShaggyServiceStatus result) {
super.onPostExecute(result);
listener.onTaskCompleted(result);
}
}
是啊,这确实诀窍! 'SplashActivity.this' – Coo