代码重构
- - ITeye博客随着程序的演化,我们有必要重新思考早先的决策,并重写部分代码. 代码需要演化;它不是静态的事物. 重写、重做和重新架构代码合起来,称为重构. 当你遇到绊脚石 --- 代码不在合适,你注意到有两样东西其实应该合并或是其他任何对你来说是"错误"的东西 -------- . 如果代码具备以下特征,你都应该考虑重构代码:.
英文原文: Dynamic Process Creation and Deployment in 100 Lines of Code
这是一篇迟到的博文,几个月前我就准备把它整理出来发布,由于时间原因就搁置了。。。
在5.12版本中把各个模块进行了大幅度的划分,值得一提的就是activiti-bpmn-的几个模块(activiti-bpmn-converter、activiti-bpmn-layout、activiti-bpmn-model)。
Activiti团队核心成员 frederikheremans创建了 activiti-dynamic-process项目,该项目利用以上的几个模块演示了如何动态创建流程并部署运行,这几个步骤仅仅用了100行代码(还可以继续精简,但是这不是重点,重点在于体现Activiti的灵活性)。
@Test public void testDynamicDeploy() throws Exception { // 1. Build up the model from scratch BpmnModel model = new BpmnModel(); Process process = new Process(); model.addProcess(process); process.setId("my-process"); process.addFlowElement(createStartEvent()); process.addFlowElement(createUserTask("task1", "First task", "fred")); process.addFlowElement(createUserTask("task2", "Second task", "john")); process.addFlowElement(createEndEvent()); process.addFlowElement(createSequenceFlow("start", "task1")); process.addFlowElement(createSequenceFlow("task1", "task2")); process.addFlowElement(createSequenceFlow("task2", "end")); // 2. Generate graphical information new BpmnAutoLayout(model).execute(); // 3. Deploy the process to the engine Deployment deployment = activitiRule.getRepositoryService().createDeployment() .addBpmnModel("dynamic-model.bpmn", model).name("Dynamic process deployment") .deploy(); // 4. Start a process instance ProcessInstance processInstance = activitiRule.getRuntimeService() .startProcessInstanceByKey("my-process"); // 5. Check if task is available List tasks = activitiRule.getTaskService().createTaskQuery() .processInstanceId(processInstance.getId()).list(); Assert.assertEquals(1, tasks.size()); Assert.assertEquals("First task", tasks.get(0).getName()); Assert.assertEquals("fred", tasks.get(0).getAssignee()); // 6. Save process diagram to a file InputStream processDiagram = activitiRule.getRepositoryService() .getProcessDiagram(processInstance.getProcessDefinitionId()); FileUtils.copyInputStreamToFile(processDiagram, new File("target/diagram.png")); // 7. Save resulting BPMN xml to a file InputStream processBpmn = activitiRule.getRepositoryService() .getResourceAsStream(deployment.getId(), "dynamic-model.bpmn"); FileUtils.copyInputStreamToFile(processBpmn, new File("target/process.bpmn20.xml")); } protected UserTask createUserTask(String id, String name, String assignee) { UserTask userTask = new UserTask(); userTask.setName(name); userTask.setId(id); userTask.setAssignee(assignee); return userTask; } protected SequenceFlow createSequenceFlow(String from, String to) { SequenceFlow flow = new SequenceFlow(); flow.setSourceRef(from); flow.setTargetRef(to); return flow; } protected StartEvent createStartEvent() { StartEvent startEvent = new StartEvent(); startEvent.setId("start"); return startEvent; } protected EndEvent createEndEvent() { EndEvent endEvent = new EndEvent(); endEvent.setId("end"); return endEvent; }
部署后获取流程图如下所示:
按照从代码清单中的7步依次分析:
利用这个Demo可以在不借助可视化流程设计器的情况下动态设计流程,进一步提升了应用的灵活性;当然如果你熟悉了以上的几个模块也可以自己扩展实现特定功能,例如Activiti中的Email Task就是一个特殊的活动类型,它继承于Service Task,所以你也可以参考它做自己的实现。
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