activiti 生成当前任务图片PNG

/**生成当前任务节点流程图片PNG
   * @param PROC_INST_ID_ //流程实例ID
   * @param FILENAME    //图片名称
   * @from fhadmin.cn 
   */
  protected void createXmlAndPngAtNowTask(String PROC_INST_ID_, String FILENAME) throws IOException{
    DelFileUtil.delFolder(PathUtil.getProjectpath()+"uploadFiles/activitiFile");  //生成先清空之前生成的文件
        InputStream in = getResourceDiagramInputStream(PROC_INST_ID_); 
        FileUpload.copyFile(in,PathUtil.getProjectpath()+Const.FILEACTIVITI,FILENAME);//把文件上传到文件目录里面
        in.close();  
  }
  /**获取当前任务流程图片的输入流
   * @param PROC_INST_ID_ //流程实例ID
   * @from fhadmin.cn 
   */
  private InputStream getResourceDiagramInputStream(String PROC_INST_ID_){
        try {
            HistoricProcessInstance hip = historyService.createHistoricProcessInstanceQuery().processInstanceId(PROC_INST_ID_).singleResult();      //获取历史流程实例
            List<HistoricActivityInstance> hai = 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
            List<String> executedActivityIdList = new ArrayList<String>();            // 构造已执行的节点ID集合
            for (HistoricActivityInstance activityInstance : hai) {
                executedActivityIdList.add(activityInstance.getActivityId());
            }
            BpmnModel bpmnModel = repositoryService.getBpmnModel(hip.getProcessDefinitionId()); // 获取bpmnModel
            List<String> flowIds = this.getExecutedFlows(bpmnModel, hai);           // 获取流程已发生流转的线ID集合
            ProcessDiagramGenerator processDiagramGenerator = processEngine.getProcessEngineConfiguration().getProcessDiagramGenerator(); 
            InputStream imageStream = processDiagramGenerator.generateDiagram(bpmnModel, "png", executedActivityIdList, flowIds, "宋体", "微软雅黑", "黑体", null, 2.0);  //使用默认配置获得流程图表生成器，并生成追踪图片字符流
            return imageStream;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }