Question

以下代码创建后台任务并执行它。

String dateString = null;
if (dateSelected)
    dateString = Utils.parseDateToMsTimestamp(selectedDate);
final String ori = originCode;
final String dest = destinationCode;
RequestScheduleTask requestScheduleTask = new RequestScheduleTask();
requestScheduleTask
        .execute(ori, dest, dateString);

originCode和destinationCode是实例变量。

以下是后台任务的作用。

private class RequestScheduleTask extends
        AsyncTask<String, Void, List<CUSchedule>> {

    @Override
    protected List<CUSchedule> doInBackground(String... args) {
        List<CUSchedule> cuSchedules = null;

        try {
            cuSchedules = CURestCommunicator
                    .requestSUScheduleByOriginAndDestination(args[0],
                            args[1], args[2]);
        } catch (NetworkException e) {
        }
        return cuSchedules;

    }

    @Override
    protected void onPostExecute(List<CUSchedule> result) {
        if (result == null) {
            raiseError("Server Error");
        }
        InnoBusApplication innoBusApplication = (InnoBusApplication) getApplication();
        innoBusApplication.setCuSchedules(result);
        super.onPostExecute(result);
    }

}

以下是http调用的一部分。

public static List<CUSchedule> requestSUScheduleByOriginAndDestination (
        String origin, String destination, String date) throws NetworkException {

    Log.d("upload", "up");

    origin = Utils.shortNameForCity(origin);
    destination = Utils.shortNameForCity(destination);

    HttpClient client = null;

    String url = "http://" + SVR + "/innobussvr/BusSchedulesSearchByOrgDestStartTimeEndTime/"
            + origin + "/" + destination;

    Log.d("url", url);
            ...
}

以下是产生的网址。

http://192.168.0.150/innobussvr/BusSchedulesSearchByOrgDestStartTimeEndTime/null/null

我知道这是一个线程可见性问题。我该如何解决？

Answer 1

Simple Solution只需为Request Scheduled Task创建一个Constructor，它接受2个String并传递它们，然后在Task class 2本地字符串var中创建。

AsyncTask中的线程可见性

1 个答案: