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！
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