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动态生成BPMN流程模型的实现步骤

随着技术的不断进步，生成BPMN流程模型的方式也在不断演变。通过代码实现BPMN模型的动态生成，开发人员可以更加灵活地构建和部署流程模型，而不需要依赖工具如Activiti Designer进行图形化绘制。

以下是一个使用Java代码实现动态生成BPMN流程模型的示例：

1. 创建BPMN模型

BpmnModel model = new BpmnModel();
Process process = new Process();
model.addProcess(process);
process.setId("my-process");

2. 添加BPMN流程元素

process.addFlowElement(createStartEvent());
process.addFlowElement(createUserTask("task1", "First task", "fred"));
process.addFlowElement(createUserTask("task2", "Second task", "john"));
process.addFlowElement(createEndEvent());

3. 创建流程路径

process.addFlowElement(createSequenceFlow("start", "task1"));
process.addFlowElement(createSequenceFlow("task1", "task2"));
process.addFlowElement(createSequenceFlow("task2", "end"));

4. 自动布局BPMN模型

new BpmnAutoLayout(model).execute();

5. 部署流程模型

Deployment deployment = activitiRule.getRepositoryService().createDeployment()
    .addBpmnModel("dynamic-model.bpmn", model)
    .name("Dynamic process deployment")
    .deploy();

6. 启动流程实例

ProcessInstance processInstance = activitiRule.getRuntimeService()
    .startProcessInstanceByKey("my-process");

7. 创建任务并验证

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());

8. 保存BPMN图表

InputStream processDiagram = activitiRule.getRepositoryService()
    .getProcessDiagram(processInstance.getProcessDefinitionId());
FileUtils.copyInputStreamToFile(processDiagram, new File("target/diagram.png"));

9. 生成BPMN文件

InputStream processBpmn = activitiRule.getRepositoryService()
    .getResourceAsStream(deployment.getId(), "dynamic-model.bpmn");
FileUtils.copyInputStreamToFile(processBpmn, 
    new File("target/process.bpmn20.xml"));

创建任务和流程元素

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;
}

通过以上代码，可以实现从代码层面动态生成BPMN流程模型的功能，从而灵活管理和部署流程。

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