获取flowable流程图资源

@PostMapping(value = "/flow/resource")
    public FlowResultVO getFlowResource(@RequestBody HashMap<String, String> map) throws IOException {
        String pId = map.get("pId");
        String instId = map.get("instId");
        List<String> highLightedActivities = new ArrayList<>();
        List<String> highLightedFlows = new ArrayList<>();
        BpmnModel bpmnModel = repositoryService.getBpmnModel(pId);

        if (instId != null && instId != "") {
            List<HistoricActivityInstance> historyProcess = historyService // 历史相关Service
                    .createHistoricActivityInstanceQuery() // 创建历史活动实例查询
                    .processInstanceId(instId) // 执行流程实例id
                    .finished()
                    .list();
            for (HistoricActivityInstance hi : historyProcess) {
                String activityType = hi.getActivityType();
                if (activityType.equals("sequenceFlow") || activityType.equals("exclusiveGateway")) {
                    highLightedFlows.add(hi.getActivityId());
                } else if (activityType.equals("userTask") || activityType.equals("startEvent")) {
                    highLightedActivities.add(hi.getActivityId());
                }
            }
        }
        ProcessEngine processEngine = ProcessEngines.getDefaultProcessEngine();
        ProcessEngineConfiguration engConf = processEngine.getProcessEngineConfiguration();
        ProcessDiagramGenerator processDiagramGenerator = engConf.getProcessDiagramGenerator();
        runtimeService.createProcessInstanceQuery().processInstanceId(pId).singleResult();

        FlowResultVO flowResultVO = new FlowResultVO();
        InputStream in = processDiagramGenerator.generateDiagram(bpmnModel, "PNG", highLightedActivities,
                highLightedFlows,
                "宋体", "宋体", "宋体", null, 1.0D, true);
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        try {
            byte[] b = new byte[1024];
            int len = -1;
            while ((len = in.read(b, 0, 1024)) != -1) {
                out.write(b, 0, len);
            }
            String resource = new BASE64Encoder().encode(out.toByteArray());
            flowResultVO.setRetCode(MetaStatus.BIZ_SUCCESS);
            flowResultVO.setRetMsg("获取流程资源成功");
            flowResultVO.setResource(resource);
        } catch (Exception e) {
            flowResultVO.setRetCode(MetaStatus.BIZ_FAIL);
            flowResultVO.setRetMsg("获取流程资源失败:" + e.getMessage());
            log.error("获取流程资源失败:" + e.getMessage());
        } finally {
            if (in != null) {
                in.close();
            }
            if (out != null) {
                out.close();
            }
        }
        return flowResultVO;
    }