Activiti6.0版本流程撤回、跳转、回退等操作

如题，实现思路：
1、获取当前任务所在的节点
2、获取所在节点的流出方向
3、记录所在节点的流出方向，并将所在节点的流出方向清空
4、获取目标节点
5、创建新的方向
6、将新的方向set到所在节点的流出方向
7、完成当前任务

8、还原所在节点的流出方向

public void revoke(String objId) throws Exception {
		
		Task task = taskService.createTaskQuery().processInstanceBusinessKey(objId).singleResult();
		if(task==null) {
			throw new ServiceException("流程未启动或已执行完成，无法撤回");
		}
		
		LoginUser loginUser = SessionContext.getLoginUser();
		List htiList = historyService.createHistoricTaskInstanceQuery()
				.processInstanceBusinessKey(objId)
				.orderByTaskCreateTime()
				.asc()
				.list();
		String myTaskId = null;
		HistoricTaskInstance myTask = null;
		for(HistoricTaskInstance hti : htiList) {
			if(loginUser.getUsername().equals(hti.getAssignee())) {
				myTaskId = hti.getId();
				myTask = hti;
				break;
			}
		}
		if(null==myTaskId) {
			throw new ServiceException("该任务非当前用户提交，无法撤回");
		}
		
		String processDefinitionId = myTask.getProcessDefinitionId();
		ProcessDefinitionEntity processDefinitionEntity = (ProcessDefinitionEntity) repositoryService.createProcessDefinitionQuery().processDefinitionId(processDefinitionId).singleResult();
		BpmnModel bpmnModel = repositoryService.getBpmnModel(processDefinitionId);
		
		//变量
//		Map variables = runtimeService.getVariableInstances(currentTask.getExecutionId());
		String myActivityId = null;
		List haiList = historyService.createHistoricActivityInstanceQuery()
				.executionId(myTask.getExecutionId()).finished().list();
		for(HistoricActivityInstance hai : haiList) {
			if(myTaskId.equals(hai.getTaskId())) {
				myActivityId = hai.getActivityId();
				break;
			}
		}
		FlowNode myFlowNode = (FlowNode) bpmnModel.getMainProcess().getFlowElement(myActivityId);
		
		
		Execution execution = runtimeService.createExecutionQuery().executionId(task.getExecutionId()).singleResult();
		String activityId = execution.getActivityId();
		logger.warn("------->> activityId:" + activityId);
		FlowNode flowNode = (FlowNode) bpmnModel.getMainProcess().getFlowElement(activityId);
		
		//记录原活动方向
		List oriSequenceFlows = new ArrayList();
		oriSequenceFlows.addAll(flowNode.getOutgoingFlows());
		
		//清理活动方向
		flowNode.getOutgoingFlows().clear();
		//建立新方向
		List newSequenceFlowList = new ArrayList();
		SequenceFlow newSequenceFlow = new SequenceFlow();
		newSequenceFlow.setId("newSequenceFlowId");
		newSequenceFlow.setSourceFlowElement(flowNode);
		newSequenceFlow.setTargetFlowElement(myFlowNode);
		newSequenceFlowList.add(newSequenceFlow);
		flowNode.setOutgoingFlows(newSequenceFlowList);
		
		Authentication.setAuthenticatedUserId(loginUser.getUsername());
		taskService.addComment(task.getId(), task.getProcessInstanceId(), "撤回");
		
		Map currentVariables = new HashMap();
		currentVariables.put("applier", loginUser.getUsername());
		//完成任务
		taskService.complete(task.getId(),currentVariables);
		//恢复原方向
		flowNode.setOutgoingFlows(oriSequenceFlows);
	}