activiti 获取当前任务流程图片的输入流

	/**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;
        }
    }