zookeeper服务端使用3.4.x版本的话需要修改pom文件，排除<exclusions>
                <exclusion>
                    <groupId>org.apache.zookeeper</groupId>
                    <artifactId>zookeeper</artifactId>
                </exclusion>
            </exclusions>
重新添加zookeeper 3.4.x版本就不会报错了

Sleep extension too large (1050). Pinning to 500
Opening socket connection to server 127.0.0.1/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error)
Socket connection established to 127.0.0.1/127.0.0.1:2181, initiating session
Client session timed out, have not heard from server in 30001ms for sessionid 0x0, closing socket connection and attempting reconnect
Sleep extension too large (1500). Pinning to 500
Opening socket connection to server 0:0:0:0:0:0:0:1/0:0:0:0:0:0:0:1:2181. Will not attempt to authenticate using SASL (unknown error)
Socket connection established to 0:0:0:0:0:0:0:1/0:0:0:0:0:0:0:1:2181, initiating session
Client session timed out, have not heard from server in 30001ms for sessionid 0x0, closing socket connection and attempting reconnect

丁老师， waiter-server 已经正常注册，但是customer-server启动时无法访问，一直循环报这个

java.net.ConnectException: Connection refused: no further information
百度说三种可能：
1 网络不通，端口不可用等；
2 zookeeper服务程序未正常启动；
3 防火墙未关闭；
我都解决了。但是还是报这个错误，对着视频步骤复制的。希望能有人帮我早点解决，真的怒了

把zk-waiter-service 扩展了一下，CoffeeOrderController 提供获取订单列表的接口：

@GetMapping(value = "/", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    @ResponseBody
    public List<CoffeeOrder> listOrder() {
        log.info("List order");
        List<CoffeeOrder> order = orderService.list();
        return order;
    }

CoffeeOrderService 提供了实现：

    public List<CoffeeOrder> list() {
        return orderRepository.findAll(Sort.by("id"));
    }

zk-customer-service 在按id查询一个订单后，再执行一下查询所有订单的接口：

    private void queryAllOrder() {
        ParameterizedTypeReference<List<CoffeeOrder>> ptr = new ParameterizedTypeReference<List<CoffeeOrder>>() {};
        ResponseEntity<List<CoffeeOrder>> list = restTemplate.exchange("http://waiter-service/order/", HttpMethod.GET, null, ptr);
        list.getBody().forEach(o -> log.info("itr order: {}", o));
    }

问题来了，获取订单列表的时候，每个订单输出的信息并没有包含具体的咖啡信息（可以看到下面items字段都是null）：

itr order: CoffeeOrder(id=1, customer=Lily, items=null, state=INIT, createTime=Mon Jun 24 15:12:21 CST 2019, updateTime=Mon Jun 24 15:12:21 CST 2019)
itr order: CoffeeOrder(id=2, customer=Lily, items=null, state=INIT, createTime=Mon Jun 24 15:14:26 CST 2019, updateTime=Mon Jun 24 15:14:26 CST 2019)
itr order: CoffeeOrder(id=3, customer=Li Lei, items=null, state=INIT, createTime=Mon Jun 24 15:16:48 CST 2019, updateTime=Mon Jun 24 15:16:48 CST 2019)

看WaiterServiceApplication输出的日志，可以看到并没有执行关联查询查具体的coffee信息：

Hibernate:
    select
        coffeeorde0_.id as id1_1_,
        coffeeorde0_.create_time as create_t2_1_,
        coffeeorde0_.update_time as update_t3_1_,
        coffeeorde0_.customer as customer4_1_,
        coffeeorde0_.state as state5_1_
    from
        t_order coffeeorde0_
    order by
        coffeeorde0_.id asc

这是为什么呢？我自己新建工程重写一遍也是如此，同样的代码逻辑，按照本章之前的教程做下来、不做服务化改造的时候都是正常的。