@Override
    @Transactional(rollbackFor = Exception.class)
    public int callBack(String processId) {

        //通过流程id查找到当前的任务
        List<Task> tasks= taskService.createTaskQuery()
                .processInstanceId(processId)
                .list();
        //如果为空或者小于等于0则证明没有可查看到的任务
        if (tasks == null||tasks.size()<=0) {
            System.out.println("当前没有任务或者任务已执行完了");
            return -1;
        }
        //查看所有走过的历史任务
        List<HistoricTaskInstance> htlist = historyService.createHistoricTaskInstanceQuery()
                .processInstanceId(processId)
                .finished()
                .list();
        if (htlist == null||htlist.size()<=0) {
            System.out.println("请先提交任务");
        }
        String myTaskId = null;
        HistoricTaskInstance myTask = null;
        //前一个任务节点,也就是提交人 拿到前一个任务
        for (HistoricTaskInstance hti : htlist) {
            //回退到zhangsan也就是任务A,业务中这里就是当前登录的用户名 TODO:从登录名拿
            if (hti.getAssignee().equals("1")) {
                myTaskId = hti.getId();

                myTask = hti;
                break;
            }
        }

        if (myTask == null) {
            System.out.println("这个任务不是你的任务");
        }
        //流程定义id
        String processDefinitionId = myTask.getProcessDefinitionId();

        //整个流程节点对象
        BpmnModel bpmnModel = repositoryService.getBpmnModel(processDefinitionId);

        //我的节点
        String myActivityId = null;
        //历史节点完成节点
        List<HistoricActivityInstance> haiList =
                historyService
                        .createHistoricActivityInstanceQuery()
                        .executionId(myTask.getExecutionId())
                        .finished()
                        .list();
        //拿到我的节点 _3
        for (HistoricActivityInstance hai : haiList) {
            if (myTaskId.equals(hai.getTaskId())) {
                myActivityId = hai.getActivityId();
                break;
            }
        }
        //我的流程节点
        FlowNode myFlowNode =
                (FlowNode) bpmnModel.getMainProcess().getFlowElement(myActivityId);
        //当前执行对象
        Execution execution = runtimeService.createExecutionQuery()
                .executionId(tasks.get(0).getExecutionId()).singleResult();
        //当任务执行节点_4
        String activityId = execution.getActivityId();

        System.out.println(activityId);
        //当前流程节点对象
        FlowNode flowNode = (FlowNode) bpmnModel.getMainProcess()
                .getFlowElement(activityId);

        //记录原活动方向出方向
        List<SequenceFlow> oriSequenceFlows = new ArrayList<SequenceFlow>();
        oriSequenceFlows.addAll(flowNode.getOutgoingFlows());

        //清理活动方向
        flowNode.getOutgoingFlows().clear();

        //建立新方向
        List<SequenceFlow> newSequenceFlowList = new ArrayList<SequenceFlow>();
        SequenceFlow newSequenceFlow = new SequenceFlow();
        newSequenceFlow.setId("newSequenceFlowId");
        newSequenceFlow.setSourceFlowElement(flowNode);
        newSequenceFlow.setTargetFlowElement(myFlowNode);
        newSequenceFlowList.add(newSequenceFlow);
        flowNode.setOutgoingFlows(newSequenceFlowList);
        //设置操作人记录 和备注信息
        Authentication.setAuthenticatedUserId("zhangsan");
        taskService.addComment(tasks.get(0).getId(), tasks.get(0).getProcessInstanceId(), "撤回");
        String taskId= tasks.get(0).getId();
        //完成任务
        if (tasks.size() > 1) {
            //会签撤回
            HashMap<String, Object> variables = new HashMap<>();
            variables.put("pass",true);
//            variables.put("param","y");
            taskService.complete(taskId,variables);
            //恢复原方向
            flowNode.setOutgoingFlows(oriSequenceFlows);
            ProcessInstance processInstance = runtimeService.createProcessInstanceQuery().processInstanceId(tasks.get(0).getProcessInstanceId()).singleResult();
            //更新数据库 从新设置state为未提交状态
            Apply apply = new Apply();
            apply.setCode(processInstance.getBusinessKey());
            apply.setState(0);


            return applyService.updateByCode(apply);
        }
        //普通撤回
        taskService.complete(taskId);
        //恢复原方向
        flowNode.setOutgoingFlows(oriSequenceFlows);
        ProcessInstance processInstance = runtimeService.createProcessInstanceQuery().processInstanceId(tasks.get(0).getProcessInstanceId()).singleResult();
        //更新数据库 从新设置state为未提交状态
        Apply apply = new Apply();
        apply.setCode(processInstance.getBusinessKey());
        apply.setState(0);


        return applyService.updateByCode(apply);
    }

actviti7撤回操作