微服务中怎么通过feignClient调用接口

微服务中怎么通过feignClient调用接口，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。

服务端

客户端

错误显示

feign.codec.DecodeException: Type definition error: [simple type, class com.baomidou.mybatisplus.core.metadata.IPage]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.baomidou.mybatisplus.core.metadata.IPage` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information at [Source: (PushbackInputStream); line: 1, column: 1]        at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:174)        at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:134)        at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:77)        at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:102)        at com.sun.proxy.$Proxy101.getGoodList(Unknown Source)        at cpm.leyou.search.client.BrandClientTest.getSpu(BrandClientTest.java:53)        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)        at java.lang.reflect.Method.invoke(Method.java:498)        at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)        at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)        at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)        at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)        at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:73)        at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:83)        at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)        at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)        at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)        at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)        at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)        at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)        at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)        at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)        at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)        at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)        at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)        at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)        at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)        at org.junit.runners.ParentRunner.run(ParentRunner.java:363)        at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)        at org.junit.runner.JUnitCore.run(JUnitCore.java:137)        at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)        at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)        at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)        at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)Caused by: org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class com.baomidou.mybatisplus.core.metadata.IPage]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.baomidou.mybatisplus.core.metadata.IPage` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information at [Source: (PushbackInputStream); line: 1, column: 1]        at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:240)        at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:225)        at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:100)        at org.springframework.cloud.openfeign.support.SpringDecoder.decode(SpringDecoder.java:60)        at org.springframework.cloud.openfeign.support.ResponseEntityDecoder.decode(ResponseEntityDecoder.java:45)        at feign.optionals.OptionalDecoder.decode(OptionalDecoder.java:36)        at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:170)        ... 35 moreCaused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.baomidou.mybatisplus.core.metadata.IPage` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information at [Source: (PushbackInputStream); line: 1, column: 1]        at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)        at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1452)        at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1028)        at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserialize(AbstractDeserializer.java:265)        at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013)        at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3084)        at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:237)        ... 41 more

正确操作

将服务端的返回值由IPage转为Page

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