You can connect using a TaskClient and get the tasks using the method suggested above :
//Connect with the Human Task handler using the task client
//Create a list of status of the tasks you are interested in.
statusList.add(Status.Completed);
statusList.add(Status.Reserved);
statusList.add(Status.Ready);
client.getTasksByStatusByProcessId(processInstanceId,statusList, "en-UK", responseHandler);
List<TaskSummary> taskSummaryList = responseHandler.getResults();
for(TaskSummary taskSummary : taskSummaryList)
{
//retrieve the details
taskSummary.getId();
taskSummary.getName();
taskSummary.getCreatedOn();
taskSummary.getActualOwner();
taskSummary.getStatus();
}