//验证是否成功启动
assertNotNull(processInstanceId);
TaskQuery taskQuery = taskService.createTaskQuery();
// 查找 1200119390 的这个流程实例的当前独占任务
TaskInstance taskInstance = taskQuery.taskAssignee("1200119390").processInstanceId(processInstanceId).taskNotEnd().list().get(0);
String taskId = taskInstance.getId();
taskService.setAssignee(taskId, "121231231");
taskQuery = taskService.createTaskQuery();
taskInstance = taskQuery.taskId(taskId).singleResult();