<userTask id="writeReportTask" name="Write monthly financial report" >
            <documentation>
              Write monthly financial report for publication to shareholders.
            </documentation>

<potentialOwner>
     <resourceAssignmentExpression>
        <formalExpression>accountancy</formalExpression>什么意思？用户组？
     </resourceAssignmentExpression>
</potentialOwner>

</userTask>

We can now retrieve this task through the TaskService by adding the following logic:

List<Task> tasks = taskService.createTaskQuery().taskCandidateUser("kermit").list();

Note that the user we pass to this operation needs to be a member of the accountancy group, since that was declared in the process definition:

<potentialOwner>
  <resourceAssignmentExpression>
    <formalExpression>accountancy</formalExpression>
  </resourceAssignmentExpression>
</potentialOwner>

We could also use the task query API to get the same results using the name of the group. We can now add the following logic to our code:

TaskService taskService = processEngine.getTaskService();
List<Task> tasks = taskService.createTaskQuery().taskCandidateGroup("accountancy").list();

Since we‘ve configured our ProcessEngine to use the same database as the demo setup is using, we can now log intoActiviti Explorer. By default, no user is in the accountancy group. Login with kermit/kermit, click Groups and then "Create group". Then click Users and add the group to fozzie. Now login with fozzie/fozzie, and we will find that we can start our business process after selecting the Processes page and and clicking on the ‘Start Process‘ link in the ‘Actions‘ column corresponding to the ‘Monthly financial report‘ process.（这里的创建组，怎么在XML中体现……）