ProcessInstance processInstance=runtimeService.startProcessInstanceByKey(processKey,businessKey,params);

map中的param引數或存放在activiti提供的act_ru_variable表中；

class MyTaskListener implements TaskListener{

      public void notify(DelegateTask dTask) {

                  String groupId= (String) runtimeService.getVariable(delegateTask.getExecutionId(), "dgroup");

       }

}