为Spring Cloud Finchley的Feign 配置 FastJson_feign fastjson

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错误

feign.codec.DecodeException: Could not extract response: no suitable HttpMessageConverter found for response type [com.garea.api.dto.BaiduResponse<com.garea.dto.baidu.ReverseGeocoding>] and content type [text/javascript;charset=utf-8]

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一、相关环境

Spring Boot：2.0.5.RELEASE
Spring Cloud ：Finchley.RELEASE
FastJson：1.2.54

二、配置代码

/**
 * 单独为feign配置fastjson
 */

@SpringBootConfiguration
public class FeignConfig {

    @Bean
    public EncoderfeignEncoder() {
        return new SpringEncoder(feignHttpMessageConverter());
    }
    @Bean
    public DecoderfeignDecoder() {
        return new ResponseEntityDecoder(new SpringDecoder(feignHttpMessageConverter()));
    }
    private ObjectFactoryfeignHttpMessageConverter() {
        final HttpMessageConverters httpMessageConverters =
                new HttpMessageConverters(getFastJsonConverter());
        return () -> httpMessageConverters;
    }

    private FastJsonHttpMessageConvertergetFastJsonConverter() {
        FastJsonHttpMessageConverter converter =
                new FastJsonHttpMessageConverter();
        List supportedMediaTypes = new ArrayList<>();
//        MediaType mediaTypeJson =
//                MediaType.valueOf(MediaType.APPLICATION_JSON_UTF8_VALUE);
//        supportedMediaTypes.add(mediaTypeJson);
        MediaType mediaTypeJson =
                MediaType.valueOf(MediaType.TEXT_PLAIN_VALUE + ";charset=UTF-8");
        supportedMediaTypes.add(mediaTypeJson);
        converter.setSupportedMediaTypes(supportedMediaTypes);
        FastJsonConfig config = new FastJsonConfig();
        config.getSerializeConfig()
                .put(JSON.class, new SwaggerJsonSerializer());
        config.setSerializerFeatures(
                SerializerFeature.DisableCircularReferenceDetect);
        converter.setFastJsonConfig(config);
        return converter;
    }
}
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三、原因

我想大家对fastJsonHttpMessageConverters的配置应该很熟悉了，网上的文章也是一大片，而我一开始也是如此只进行了全局配置。然后在使用Feign调用服务测试时，报错了：

feign.codec.DecodeException: Could not extract response: no suitable HttpMessageConverter found for response type [class java.lang.Object] and content type [text/plain;charset=UTF-8]
at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:169)
at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:133)
at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:76)
at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103)
at com.sun.proxy.$Proxy92.hello(Unknown Source)
at com.example.test.TestDB.test(TestDB.java:26)
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.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [class java.lang.Object] and content type [text/plain;charset=UTF-8]

at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:119)
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:23)
at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:165)
... 35 more
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后来百度发现是Feign不和SpringMvc共用一个HttpMessageConverter，所以需要单独配置。因为SpringMvc默认使用的Jackson，所以我便看到了

@SpringBootConfiguration

public class FeignByJacksonConfig {

@Bean
public DecoderfeignDecoder() {
		return new ResponseEntityDecoder(new SpringDecoder(feignHttpMessageConverter()));
}
	public ObjectFactoryfeignHttpMessageConverter() {
		final HttpMessageConverters httpMessageConverters =new HttpMessageConverters(new 					PhpMappingJackson2HttpMessageConverter());
        return new ObjectFactory() {
	@Override
	public HttpMessageConvertersgetObject()throws BeansException {
		return httpMessageConverters;
	}
	};
}

public class PhpMappingJackson2HttpMessageConverterextends MappingJackson2HttpMessageConverter {
		PhpMappingJackson2HttpMessageConverter(){
		List mediaTypes =new ArrayList<>();
		            mediaTypes.add(MediaType.valueOf(MediaType.TEXT_PLAIN_VALUE +";charset=UTF-8")); //关键
		            setSupportedMediaTypes(mediaTypes);

        }

	}
}
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FeignClientsConfiguration初始化配置中：
默认Encoder类型为SpringEncoder，功能为调用Spring的HttpMessageConverters处理参数。
默认Decoder类型为ResponseEntityDecoder，它包装了SpringDecoder，做的事情也就是调用Spring的HttpMessageConverters处理接口返回值。
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@Bean
public EncoderfeignEncoder() {
return new SpringEncoder(feignHttpMessageConverter());

}
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原来一开始配置的SpringEncoder只处理了请求时的参数，对于返回值仍未作更改，所以后来我加上了SpringDecoder后就成功了：
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@Bean
public DecoderfeignDecoder() {
return new ResponseEntityDecoder(new SpringDecoder(feignHttpMessageConverter()));
}
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