activiti 根据 流程实例ID 获取发起人

   /**获取发起人
	 * @param PROC_INST_ID_ //流程实例ID
	 * @from  fhadmin.cn
	 */
   protected String getInitiator(String PROC_INST_ID_) {
		HistoricProcessInstance hip = historyService.createHistoricProcessInstanceQuery().processInstanceId(PROC_INST_ID_).singleResult(); 			//获取历史流程实例
		List<HistoricActivityInstance> hais = historyService.createHistoricActivityInstanceQuery().processInstanceId(PROC_INST_ID_)
		   																						 .orderByHistoricActivityInstanceId().asc().list();	//获取流程中已经执行的节点，按照执行先后顺序排序
		BpmnModel bpmnModel = repositoryService.getBpmnModel(hip.getProcessDefinitionId()); // 获取bpmnModel
		List<FlowNode> historicFlowNodeList = new LinkedList<FlowNode>();					//全部活动实例
		for(HistoricActivityInstance hai : hais) {
		    historicFlowNodeList.add((FlowNode) bpmnModel.getMainProcess().getFlowElement(hai.getActivityId(), true));
		    if(hai.getAssignee() != null) {
		    	return hai.getAssignee();	//不为空的第一个节点办理人就是发起人
		    }
		}
		return null;
    }