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网站每天更新的内容是内链吗,最新域名查询ip,发卡平台wordpress,网站制作性价比哪家好为什么80%的码农都做不了架构师？>>> 1、问题排查出现的场景： 服务端通过springmvc写了一个对外的接口，返回一个json字符串，其中该json带有日期，格式为yyyy-MM-dd HH:mm:ss 客户端通过feign调用该http接口…

为什么80%的码农都做不了架构师？>>>

1、问题排查

出现的场景：
- 服务端通过springmvc写了一个对外的接口，返回一个json字符串，其中该json带有日期，格式为yyyy-MM-dd HH:mm:ss
- 客户端通过feign调用该http接口，指定返回值为一个Dto，Dto中日期的字段为Date类型
- 客户端调用该接口后抛异常了。

异常如下：

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)
Caused by: org.springframework.http.converter.HttpMessageNotReadableException: 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.XxxDto["createTime"])at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:238)at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:223)at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:96)at org.springframework.cloud.netflix.feign.support.SpringDecoder.decode(SpringDecoder.java:59)at org.springframework.cloud.netflix.feign.support.ResponseEntityDecoder.decode(ResponseEntityDecoder.java:47)at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:165)... 45 more
Caused by: 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.XxxDto["createTime"])at com.fasterxml.jackson.databind.exc.InvalidFormatException.from(InvalidFormatException.java:74)at com.fasterxml.jackson.databind.DeserializationContext.weirdStringException(DeserializationContext.java:1410)at com.fasterxml.jackson.databind.DeserializationContext.handleWeirdStringValue(DeserializationContext.java:926)at com.fasterxml.jackson.databind.deser.std.StdDeserializer._parseDate(StdDeserializer.java:819)at com.fasterxml.jackson.databind.deser.std.StdDeserializer._parseDate(StdDeserializer.java:788)at com.fasterxml.jackson.databind.deser.std.DateDeserializers$DateBasedDeserializer._parseDate(DateDeserializers.java:172)at com.fasterxml.jackson.databind.deser.std.DateDeserializers$DateDeserializer.deserialize(DateDeserializers.java:259)at com.fasterxml.jackson.databind.deser.std.DateDeserializers$DateDeserializer.deserialize(DateDeserializers.java:242)at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:504)at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:104)at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:357)at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:148)at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:287)at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:259)at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:26)at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:504)at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:104)at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:357)at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:148)at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3814)at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2938)at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:235)... 50 more

从异常信息中我们可以看出，是在AbstractJackson2HttpMessageConverter类中调用了readJavaType方法之后抛的异常
一步一步往下深入，我们找到了最关键的地方，在DeserializationContext类的_parseDate方法中，执行了df.parse(dateStr)之后抛异常了

public Date parseDate(String dateStr) throws IllegalArgumentException
{try {DateFormat df = getDateFormat();// 这行代码报错了return df.parse(dateStr);} catch (ParseException e) {throw new IllegalArgumentException(String.format("Failed to parse Date value '%s': %s", dateStr, e.getMessage()));}
}

DeserializationContext是jackson的一个反序列化的一个上下文，那么它的DateFormat是从哪来的呢?我们再来看下getDateFormat的源码

protected DateFormat getDateFormat()
{if (_dateFormat != null) {return _dateFormat;}DateFormat df = _config.getDateFormat();_dateFormat = df = (DateFormat) df.clone();return df;
}

DateFormat又是从MapperConfig而来，我们再看下config.getDateFormat()的源码

```
public final DateFormat getDateFormat() { return _base.getDateFormat(); }
```
我们知道，SpringMvc就是通过AbstractJackson2HttpMessageConverter类来整合jackson的，该类维护jackson的ObjectMapper，而ObjectMapper又是通过MapperConfig来进行配置的
由此可见，本异常就是因为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

2、问题处理

异常说的值服务器返回了一个带有日期的json，日期的形式是字符串2018-03-07 16:18:35，jackson无法将该字符串转成一个Date对象，网上查资料，上面说的是jackson只支持以下几种日期格式：
- "yyyy-MM-dd'T'HH:mm:ss.SSSZ"；
- "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"；
- "yyyy-MM-dd";
- "EEE, dd MMM yyyy HH:mm:ss zzz";
- long类型的时间戳
去掉服务端的以下两个配置，让日期返回时间戳，结果就没报错了

#spring.jackson.date-format=yyyy-MM-dd HH:mm:ss
#spring.jackson.time-zone=Asia/Chongqing

由于服务端在其他的地方有可能和这里的配置耦合了，也就是说其他地方有可能要用到的是yyyy-MM-dd HH:mm:ss这一日期格式而不是时间戳的格式，所以这个配置肯定是不能修改的。
jackson竟然不支持yyyy-MM-dd HH:mm:ss的这种格式，肯定很不爽啦，所以下面就要开始来研究怎么让jackson支持这种格式了。
要让jackson支持这种格式，那么就必须修改ObjectMapper中的DateFormat，因为在ObjectMapper中，DateFormat的默认实现类是StdDateFormat，StdDateFormat也就只兼容了我们上述所说的几种格式
首先我们先使用装饰模式来创建一个支持yyyy-MM-dd HH:mm:ss格式的DateFormat如下

 
import java.text.DateFormat;
import java.text.FieldPosition;
import java.text.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Date;public class MyDateFormat extends DateFormat {private DateFormat dateFormat;private SimpleDateFormat format1 = new SimpleDateFormat("yyy-MM-dd HH:mm:ss");public MyDateFormat(DateFormat dateFormat) {this.dateFormat = dateFormat;}@Overridepublic StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition) {return dateFormat.format(date, toAppendTo, fieldPosition);}@Overridepublic Date parse(String source, ParsePosition pos) {Date date = null;try {date = format1.parse(source, pos);} catch (Exception e) {date = dateFormat.parse(source, pos);}return date;}// 主要还是装饰这个方法@Overridepublic Date parse(String source) throws ParseException {Date date = null;try {// 先按我的规则来date = format1.parse(source);} catch (Exception e) {// 不行，那就按原先的规则吧date = dateFormat.parse(source);}return date;}// 这里装饰clone方法的原因是因为clone方法在jackson中也有用到@Overridepublic Object clone() {Object format = dateFormat.clone();return new MyDateFormat((DateFormat) format);}
}

DateFormat有了，接下来的任务就是让ObjectMapper使用我的这个DateFormat了，在config类中定义如下（本案例基于springboot）

@Configuration
public class WebConfig {@Autowiredprivate Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder;@Beanpublic MappingJackson2HttpMessageConverter MappingJsonpHttpMessageConverter() {ObjectMapper mapper = jackson2ObjectMapperBuilder.build();// ObjectMapper为了保障线程安全性，里面的配置类都是一个不可变的对象// 所以这里的setDateFormat的内部原理其实是创建了一个新的配置类DateFormat dateFormat = mapper.getDateFormat();mapper.setDateFormat(new MyDateFormat(dateFormat));MappingJackson2HttpMessageConverter mappingJsonpHttpMessageConverter = new MappingJackson2HttpMessageConverter(mapper);return mappingJsonpHttpMessageConverter;}
}

配置了上述代码之后，问题成功解决。

3、为什么往spring容器中注入MappingJackson2HttpMessageConverter，springMvc就会用这个Converter呢？

查看springboot的源代码如下：

@Configuration
class JacksonHttpMessageConvertersConfiguration {@Configuration@ConditionalOnClass(ObjectMapper.class)@ConditionalOnBean(ObjectMapper.class)@ConditionalOnProperty(name = HttpMessageConvertersAutoConfiguration.PREFERRED_MAPPER_PROPERTY, havingValue = "jackson", matchIfMissing = true)protected static class MappingJackson2HttpMessageConverterConfiguration {@Bean@ConditionalOnMissingBean(value = MappingJackson2HttpMessageConverter.class, ignoredType = {"org.springframework.hateoas.mvc.TypeConstrainedMappingJackson2HttpMessageConverter","org.springframework.data.rest.webmvc.alps.AlpsJsonHttpMessageConverter" })public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter(ObjectMapper objectMapper) {return new MappingJackson2HttpMessageConverter(objectMapper);}}

默认配置为，当spring容器中没有MappingJackson2HttpMessageConverter这个实例的时候才会被创建
springboot的思想是约定优于配置，也就是说，springboot默认帮我们配好了spring mvc的Converter，如果我们没有自定义Converter的话，那么框架就会帮我们创建一个，如果我们有自定义的话，那么springboot就直接使用我们所注册的bean进行绑定
以上摘自https://blog.csdn.net/qq906627950/article/details/79503801
补充：
使用JsonFormat注解的时候需要加上时区
- ```
import com.fasterxml.jackson.annotation.JsonFormat;
@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss",timezone = "GMT+8")
```
  中国的时区东8区，timezone="GMT+8" 是必须加上去的不然转换后的时间和数据库里的时间是不一样的。
补充摘自 https://blog.csdn.net/wxlhdm/article/details/45073393