工作流引擎activiti 获取下一节点

最近公司需要使用工作流引擎，选用了activiti。需求中提到的流程比较简单，也就3级审核，送审时需要选择下一节点的用户，所以必须在流程中需要获取当前节点的下一个节点。代码如下：
      

/**
	 * 根据实例编号查找下一个任务节点
	 * @param String procInstId ：实例编号
	 * @return
	 */
	public TaskDefinition nextTaskDefinition(String procInstId){
		//流程标示
		String processDefinitionId = historyService.createHistoricProcessInstanceQuery().processInstanceId(procInstId).singleResult().getProcessDefinitionId();
		
		ProcessDefinitionEntity def = (ProcessDefinitionEntity) ((RepositoryServiceImpl)repositoryService).getDeployedProcessDefinition(processDefinitionId);
		//执行实例
		ExecutionEntity execution = (ExecutionEntity) runtimeService.createProcessInstanceQuery().processInstanceId(procInstId).singleResult();
		//当前实例的执行到哪个节点
		String activitiId = execution.getActivityId();
		//获得当前任务的所有节点
		List<ActivityImpl> activitiList = def.getActivities();
		String id = null;
		for(ActivityImpl activityImpl:activitiList){  
			id = activityImpl.getId(); 
			if(activitiId.equals(id)){
				System.out.println("当前任务："+activityImpl.getProperty("name"));
				return nextTaskDefinition(activityImpl, activityImpl.getId(),"${iscorrect==1}");
//				System.out.println(taskDefinition.getCandidateGroupIdExpressions().toArray()[0]);
//				return taskDefinition;
			}
		}
		return null;
	}
	
	/**
	 * 下一个任务节点
	 * @param activityImpl
	 * @param activityId
	 * @param elString
	 * @return
	 */
	private TaskDefinition nextTaskDefinition(ActivityImpl activityImpl, String activityId, String elString){
			if("userTask".equals(activityImpl.getProperty("type")) && !activityId.equals(activityImpl.getId())){
				TaskDefinition taskDefinition = ((UserTaskActivityBehavior)activityImpl.getActivityBehavior()).getTaskDefinition();
//				taskDefinition.getCandidateGroupIdExpressions().toArray();
				return taskDefinition;
			}else{
				List<PvmTransition> outTransitions = activityImpl.getOutgoingTransitions();
				List<PvmTransition> outTransitionsTemp = null;
				for(PvmTransition tr:outTransitions){  
					PvmActivity ac = tr.getDestination(); //获取线路的终点节点  
					if("exclusiveGateway".equals(ac.getProperty("type"))){
						outTransitionsTemp = ac.getOutgoingTransitions();
						if(outTransitionsTemp.size() == 1){
							return nextTaskDefinition((ActivityImpl)outTransitionsTemp.get(0).getDestination(), activityId, elString);
						}else if(outTransitionsTemp.size() > 1){
							for(PvmTransition tr1 : outTransitionsTemp){
								Object s = tr1.getProperty("conditionText");
								if(elString.equals(StrUtils.trim(s.toString()))){
									return nextTaskDefinition((ActivityImpl)tr1.getDestination(), activityId, elString);
								}
							}
						}
					}else if("userTask".equals(ac.getProperty("type"))){
						return ((UserTaskActivityBehavior)((ActivityImpl)ac).getActivityBehavior()).getTaskDefinition();
					}else{
						logger.debug(ac.getProperty("type"));
					}
				} 
			return null;
		}
	}

思路是通过实例ID获取当前节点，然后查找当前节点后后面所有的活动，主要查找的活动是exclusiveGateway和userTask，如果exclusiveGateway中的条件符合${iscorrect==1}就直接查找exclusiveGateway后的活动，直到找到userTask为止。如果当前节点后的活动是userTask，说明这个userTask就是你想要的。


代码中${iscorrect==1}表达式是流程中定义，表示审核通过。当时对于在java中解析表达式遇到困难，所以使用字符串来比较，代码

if(elString.equals(StrUtils.trim(s.toString())))

就是用于判断表达式。后来发现可以通说juel来解析，以下是解析的代码：

ExpressionFactory factory = new ExpressionFactoryImpl();
		SimpleContext context = new SimpleContext();
		context.setVariable("count", factory.createValueExpression(10000, String.class));
		ValueExpression e = factory.createValueExpression(context, "${count>=1000}", boolean.class);
		System.out.println(e.getValue(context));