在Spring Cloud Netflix栈中，各个微服务都是以HTTP接口的形式暴露自身服务的，因此在调用远程服务时就必须使用HTTP客户端。我们可以使用JDK原生的URLConnection、Apache的Http Client、Netty的异步HTTP Client, Spring的RestTemplate。但是，用起来最方便、最优雅的还是要属Feign了。
Feign配合SpringCloud使用是最为方便的，只需要显示的申明调用什么服务，服务的哪些URL，Feign。但是在某些项目中，由于遗留原因，整个系统并不是spring cloud项目，甚至不是spring项目，而使用者关注的重点仅仅是简化http调用代码的编写。
如果采用httpclient或者okhttp这样相对较重的框架，对初学者来说编码量与学习曲线都会是一个挑战，而使用spring中RestTemplate，又没有配置化的解决方案，由此想到是否可以脱离spring cloud，独立使用Feign。

一，添加maven依赖

<dependency>
    <groupId>com.netflix.feign</groupId>
    <artifactId>feign-core</artifactId>
    <version>8.18.0</version>
</dependency>
<dependency>
    <groupId>com.netflix.feign</groupId>
    <artifactId>feign-jackson</artifactId>
     <version>8.18.0</version>
</dependency>

二，添加自定义远程调用服务类

/**
 * @Author: zhoujin
 * @Date: 2018/5/16 18:07
 */
public interface FeignTestService {
    @RequestLine("GET /sys/menu/list")
    List<SysMenuEntity> getMenu();
}

三，在Application中添加配置

  @Bean
  FeignTestService feignTest(){
      return Feign.builder()
          .encoder(new JacksonEncoder())
          .decoder(new JacksonDecoder())
          .options(new Request.Options(2000, 3500))
          .retryer(new Retryer.Default(5000, 5000, 3))
          .target(FeignTestService.class, "http://127.0.0.1:8002/exfresh-address");
  }

四，编写测试类

/**
 * @Author: zhoujin
 * @Date: 2018/5/16 20:09
 */
@RunWith(SpringRunner.class)
@SpringBootTest
public class SqlFilterTest {
    @Autowired
    FeignTestService feignTestService;

    @Test
    void test(){
        feignTestService.getMenu();
    }
}  

调用后报异常

feign.codec.DecodeException: JSON parse error: Can not deserialize value of type java.util.Date from String "2018-03-07 16:18:35": not a valid representation (error: Failed to parse Date value '2018-03-07 16:18:35': Can not parse date "2018-03-07 16:18:35Z": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSS'Z'', parsing fails (leniency? null)); nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Can not deserialize value of type java.util.Date from String "2018-03-07 16:18:35": not a valid representation (error: Failed to parse Date value '2018-03-07 16:18:35': Can not parse date "2018-03-07 16:18:35Z": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSS'Z'', parsing fails (leniency? null))
 at [Source: java.io.PushbackInputStream@4615bc00; line: 1, column: 696] (through reference chain: com.RestfulDataBean["data"]->java.util.ArrayList[0]->com.entity.XxxDto["createTime"])
    at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:169)
    at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:133)
    at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:76)
    at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103)
    at com.sun.proxy.$Proxy138.queryMonitorByTime(Unknown Source)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673)
    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.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:252)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    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:191)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

原因：Jackson进行json转对象时，因为ObjectMapper中的DateFormat无法对yyyy-MM-dd HH:mm:ss格式的字符串进行转换所导致的
解决方法：
新建一个配置

/**
 * @Author: zhoujin
 * @Date: 2018/5/16 18:49
 */
@Configuration
public class WebConfig {

    @Bean
    public MappingJackson2HttpMessageConverter getMappingJackson2HttpMessageConverter() {
        MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
        //设置日期格式  
        ObjectMapper objectMapper = new ObjectMapper();
        SimpleDateFormat smt = new SimpleDateFormat("yyyy-MM-dd");
        objectMapper.setDateFormat(smt);
        mappingJackson2HttpMessageConverter.setObjectMapper(objectMapper);
        //设置中文编码格式  
        List<MediaType> list = new ArrayList<MediaType>();
        list.add(MediaType.APPLICATION_JSON_UTF8);
        mappingJackson2HttpMessageConverter.setSupportedMediaTypes(list);
        return mappingJackson2HttpMessageConverter;
    }
}

添加后，测试类可以正常通过！