如何显示jBPM流程图

    jbpmconsole流程图采用的是jBPM自定义的标签,我没有研究过如何部署,因为我添加了几次没成功就放弃了,自定义标签的方法也许引用简单,但是部署麻烦,而且不够灵活,所以最好是自己从jBPM的附件表中调出图片,并自己绘制出当前节点和已经过节点.甚至可以在节点上提示审批意见,点击当前节点打开审批窗口等.
    先说说jBPM的附件表,默认发布时包含了流程定义和坐标两个xml文件和一个流程截图的jpg图片,流程图显示就是构建一个action,在action中读取jpg图片并输出,然后客户端用一个img指向改action就可以了,当前节点和历史节点可以自行读取并利用div或者vml叠加到图片上.
//读取附件的内容

	public byte[] getFile(String processName,int version, String fileName) throws Exception{
		byte[] bytes = null;
		JbpmContext jbpmContext = this.getContext();
		try {			
			GraphSession graphSession = jbpmContext.getGraphSession();
			ProcessDefinition pd = getDefinition(processName, version);
			if(pd==null) throw new Exception("Process not found!");
			FileDefinition fileDef = pd.getFileDefinition();
			if(fileDef==null) throw new Exception("Process filedefinition not found!");
			
			bytes = fileDef.getBytes(fileName);
		} finally { 
			closeContext();
		}
		
		return bytes;
	}

//获取图片的action

    public ModelAndView handleRequest(HttpServletRequest request,
            HttpServletResponse response) throws Exception {
        request.setCharacterEncoding("UTF-8");
        String name = request.getParameter("name");
        int version = 0;
        try {
        	version = Integer.valueOf(request.getParameter("version"));
        } catch(Exception e) { }
        		
        response.setContentType("text/xml");
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Charset", "UTF-8"); //default is UTF-8        
        
        log.info("get process:" + name+"/"+version);
        
        Service jbpmSvr = new Service();
        byte[] bytes = jbpmSvr.getFile(name, version, name+".xml");
        ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
        OutputStream out = response.getOutputStream(); 
        IoUtil.transfer(bais,out);
        out.flush();
        out.close();

        return null;
    }

在图片上叠加当前节点的图层需要先获取节点的坐标和大小

 	public int[] GetTaskinstanceBox(Long piID) throws DocumentException, UnsupportedEncodingException {
		JbpmContext jbpmContext=this.getContext(); 
		Session session = getSession(jbpmContext);
		try {
			List<String> aryToken = getProcessToken(session, piID);
			int[] ret = new int[aryToken.size()*4+2];
			ProcessInstance pi = jbpmContext.getProcessInstance(piID);
			FileDefinition fd = pi.getProcessDefinition().getFileDefinition();
			byte[] gpdBytes = fd.getBytes("gpd.xml");
			String s = new String(gpdBytes,"UTF-8");
			Document document = DocumentHelper.parseText(s);
			document.setXMLEncoding("UTF-8");
			Element root = document.getRootElement();
			ret[0] = Integer.valueOf(root.attribute("width").getValue()).intValue();
			ret[1] = Integer.valueOf(root.attribute("height").getValue()).intValue();
			for(int i=0;i<aryToken.size();i++){
				String nodeName = aryToken.get(i);
				XPath xPath = new DefaultXPath("//node[@name='" + nodeName + "']");
				Element node = (Element) xPath.selectSingleNode(root);
				
				ret[i*4+2] = Integer.valueOf(node.attribute("x").getValue()).intValue();
				ret[i*4+3] = Integer.valueOf(node.attribute("y").getValue()).intValue();
				ret[i*4+4] = Integer.valueOf(node.attribute("width").getValue()).intValue();
				ret[i*4+5] = Integer.valueOf(node.attribute("height").getValue()).intValue();
			}
			return ret;
		} finally {
			jbpmContext.close();
		}
	}

    可以看到用XPath xPath = new DefaultXPath("//node[@name='" + nodeName + "']");在xml中查找节点,所以jBPM的节点名称不能重名,一个有意思的现象,如果你手动修改流程定义的xml文件,让其中两个节点重名,打开流程图后发现同名其中一个节点连接都跑到另外一个节点上了,这说明jBPM是按节点名称查找xml中的第一个节点,要解决这个问题就只能自定义流程样式,用自己顶一个的属性来显示节点名称,并且自己编写流程设计器和流程图显示.