如何在我在 Camunda 中使用的代码中获取活动任务的列表？

我已经看过这个答案“如何查询流程实例的位置？”但我不明白什么是“processInstanceId”以及我应该在哪里获得它以使此方法工作。

这是我目前正在尝试的代码：

package org.camunda.bpm;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.camunda.bpm.engine.ProcessEngine;
import org.camunda.bpm.engine.RepositoryService;
import org.camunda.bpm.engine.RuntimeService;
import org.camunda.bpm.engine.runtime.ProcessInstance;
import org.camunda.bpm.model.bpmn.BpmnModelInstance;
import org.camunda.bpm.model.xml.instance.ModelElementInstance;

public class AllActiveActivities {

public Map<String, String> getAllActiveActivities(String processInstanceId) {
// get engine services
ProcessEngine processEngine = BpmPlatform.getDefaultProcessEngine()
RuntimeService runtimeService = processEngine.getRuntimeService();
RepositoryService repositoryService = processEngine.getRepositoryService();

// get the process instance
ProcessInstance processInstance =
    runtimeService.createProcessInstanceQuery()
        .processInstanceId(processInstanceId)
        .singleResult();

HashMap<String, String> activityNameByActivityId = new HashMap<String, String>();

// get all active activities of the process instance
List<String> activeActivityIds =
    runtimeService.getActiveActivityIds(processInstance.getId());

// get bpmn model of the process instance
BpmnModelInstance bpmnModelInstance =
    repositoryService.getBpmnModelInstance(processInstance.getProcessDefinitionId());

for (String activeActivityId : activeActivityIds) {
  // get the speaking name of each activity in the diagram
  ModelElementInstance modelElementById =
      bpmnModelInstance.getModelElementById(activeActivityId);
  String activityName = modelElementById.getAttributeValue("name");

  activityNameByActivityId.put(activeActivityId, activityName);
}

// map contains now all active activities
return activityNameByActivityId;
}

}

提前感谢您的帮助。