因为返回结果对象中没有无参构造方法，导致微服务调用失败

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我是靠谱客的博主谦让皮卡丘，最近开发中收集的这篇文章主要介绍因为返回结果对象中没有无参构造方法，导致微服务调用失败，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

微服务调用失败，弹出错误，超时或未收到返回信息
1.确认了被调用方，postman调用时，能够返回正确结果
2.确认了 FeignClient 的类型，以及服务名称，在gateway中也存在，并且拼写正确
3.打印的日志中，显示信息如下。断点跟踪后，发现错误是 missing default constructor or creator, or perhaps need to add/enable type information?。
尝试增加无参构造方法后，成功解决问题。

    2020-04-24 13:11:49.888 cc8d76f4 com.netflix.hystrix.exception.HystrixRuntimeException: EquipmentManager#syncEquipmentInfo(SyncEquipmentInfoDTO) timed-out and no fallback available.
    2020-04-24 13:11:49.888 cc8d76f4    at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:140)
    2020-04-24 13:11:49.888 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
    2020-04-24 13:11:49.889 cc8d76f4    at com.netflix.hystrix.AbstractCommand$FallbackHookApplication$1.onError(AbstractCommand.java:1397)
    2020-04-24 13:11:49.889 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
    2020-04-24 13:11:49.889 cc8d76f4    at rx.observers.Subscribers$5.onError(Subscribers.java:230)
    2020-04-24 13:11:49.889 cc8d76f4    at rx.internal.operators.OnSubscribeThrow.call(OnSubscribeThrow.java:28)
    2020-04-24 13:11:49.890 cc8d76f4    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51)
    2020-04-24 13:11:49.890 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
    2020-04-24 13:11:49.890 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    2020-04-24 13:11:49.891 cc8d76f4    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    2020-04-24 13:11:49.891 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
    2020-04-24 13:11:49.891 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    2020-04-24 13:11:49.892 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
    2020-04-24 13:11:49.892 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    2020-04-24 13:11:49.892 cc8d76f4    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    2020-04-24 13:11:49.892 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    2020-04-24 13:11:49.893 cc8d76f4    at rx.Observable.unsafeSubscribe(Observable.java:10211)
    2020-04-24 13:11:49.893 cc8d76f4    at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:142)
    2020-04-24 13:11:49.893 cc8d76f4    at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
    2020-04-24 13:11:49.893 cc8d76f4    at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:45)
    2020-04-24 13:11:49.893 cc8d76f4    at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:41)
    2020-04-24 13:11:49.894 cc8d76f4    at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable.run(HystrixContextRunnable.java:61)
    2020-04-24 13:11:49.894 cc8d76f4    at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$1.tick(AbstractCommand.java:1159)
    2020-04-24 13:11:49.894 cc8d76f4    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    2020-04-24 13:11:49.894 cc8d76f4    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
    2020-04-24 13:11:49.895 cc8d76f4    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    2020-04-24 13:11:49.895 cc8d76f4    at java.lang.Thread.run(Thread.java:748)

JSON parse error: Can not construct instance of com.XXX.service.dto.sync.SyncResult:
no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?);
nested exception is com.fasterxml.jackson.databind.JsonMappingException:
Can not construct instance of com.XXX.service.dto.sync.SyncResult:
no suitable constructor found, can not deserialize from Object value
(missing default constructor or creator, or perhaps need to add/enable type information?)
at [Source: java.io.PushbackInputStream@6d1705d9; line: 2, column: 3]