我遇到了一个问题。我需要使用 asynctask 来检索 JSON 数据，并且在移动到程序的下一部分之前我需要这些数据。但是，当使用 AsyncTask 的 get() 方法时，在看到数据显示之前，我有 5 到 8 秒的黑屏。我想在数据检索期间显示进度对话框，但由于黑屏，我无法执行此操作。有没有办法放入另一个线程？这是一些代码
异步任务
public class DataResponse extends AsyncTask<String, Integer, Data> {
AdverData delegate;
Data datas= new Data();
Reader reader;
Context myContext;
ProgressDialog dialog;
String temp1;
public DataResponse(Context appcontext) {
myContext=appcontext;
}
@Override
protected void onPreExecute()
{
dialog= new ProgressDialog(myContext);
dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
dialog.setCancelable(false);
dialog.setMessage("Retrieving...");
dialog.show();
};
@Override
protected Data doInBackground(String... params) {
temp1=params[0];
try
{
InputStream source = retrieveStream(temp1);
reader = new InputStreamReader(source);
}
catch (Exception e)
{
e.printStackTrace();
}
Gson gson= new Gson();
datas= gson.fromJson(reader, Data.class);
return datas;
}
@Override
protected void onPostExecute(Data data)
{
if(dialog.isShowing())
{
dialog.dismiss();
}
}
private InputStream retrieveStream(String url) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet getRequest = new HttpGet(url);
try {
HttpResponse getResponse = client.execute(getRequest);
final int statusCode = getResponse.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
Log.w(getClass().getSimpleName(),
"Error " + statusCode + " for URL " + url);
return null;
}
HttpEntity getResponseEntity = getResponse.getEntity();
return getResponseEntity.getContent();
}
catch (IOException e) {
getRequest.abort();
Log.w(getClass().getSimpleName(), "Error for URL " + url, e);
}
return null;
}
}
显示信息
public class DisplayInfo extends Activity implements AdverData {
public static Data data;
public ProjectedData attup;
public ProjectedData attdown;
public ProjectedData sprintup;
public ProjectedData sprintdown;
public ProjectedData verizionup;
public ProjectedData veriziondown;
public ProjectedData tmobileup;
public ProjectedData tmobiledown;
public ProjectedAll transfer;
private ProgressDialog dialog;
public DataResponse dataR;
Intent myIntent; // gets the previously created intent
double x; // will return "x"
double y; // will return "y"
int spatial; // will return "spatial"
//public static Context appContext;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
StrictMode.ThreadPolicy policy = new StrictMode.
ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
dialog= new ProgressDialog(DisplayInfo.this);
dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
dialog.setCancelable(false);
dialog.setMessage("Retrieving...");
dialog.show();
myIntent= getIntent(); // gets the previously created intent
x = myIntent.getDoubleExtra("x",0); // will return "x"
y = myIntent.getDoubleExtra("y", 0); // will return "y"
spatial= myIntent.getIntExtra("spatial", 0); // will return "spatial"
String URL = "Some URL"
dataR=new DataResponse().execute(attUp).get();
@Override
public void onStart()
{more code}