Date类型参数报错
在Spring cloud feign接口中传递Date类型参数时报错,报错信息。场景:
客户端传递一个new Date()的参数,服务端接受的参数和客户端有时间差。
客户端打印格式化的new Date():
2018-05-11 10:23:36
而服务端接收到的参数是:
2018-05-12 00:23:36
我们从Feign启动的源码可以看出,Feign在encode和decode时会用SpringEncoder类来实现:
@Bean
@ConditionalOnMissingBean
public Decoder feignDecoder() {
return new ResponseEntityDecoder(new SpringDecoder(this.messageConverters));
}
@Bean
@ConditionalOnMissingBean
public Encoder feignEncoder() {
return new SpringEncoder(this.messageConverters);
}
而SpringEncoder的HttpMessageConverters使用的是Jackson默认模板,该模板来自基类WebMvcConfigurationSupport.java:
[image:FDEB2409-A536-465C-9229-B65B23F4EFA9-340-0000031DA8363321/4A0D3ACD-13DE-45C3-B7E3-3C7E0CF03A1D.png]
protected final List<HttpMessageConverter<?>> getMessageConverters() {
if (this.messageConverters == null) {
this.messageConverters = new ArrayList<HttpMessageConverter<?>>();
configureMessageConverters(this.messageConverters);
if (this.messageConverters.isEmpty()) {
addDefaultHttpMessageConverters(this.messageConverters);
}
extendMessageConverters(this.messageConverters);
}
return this.messageConverters;
}
而WebMvcConfigurationSupport.java最终使用的是默认的ObjectMapper生成的MappingJackson2HttpMessageConverter。至此可以看出该问题的产生并不是Feign的问题,而是Feign实现中使用的Spring MVC中的Jackson转换参数问题,默认的TimeZone并不是东八区,而是UTC。
/**
* Override the default {@link TimeZone} to use for formatting.
* Default value used is UTC (NOT local timezone).
* @since 4.1.5
*/
public Jackson2ObjectMapperBuilder timeZone(TimeZone timeZone) {
this.timeZone = timeZone;
return this;
}
这个问题,在Spring MVC中可以在接口或者字段上添加注解来解决,但在Feign中使用GET请求的接口添加注解是不行的。debug发现,Spring MVC在处理Date的时候,调用了sun.reflect.ConstructorAccessor#newInstance(Object[] var1),时间会加14个小时。具体实现没看到源码,后续再研究。需要说明的是,加JsonFormat注解对于Feign接口没生效,但Spring MVC是可以的。
OK,回到正题。要解决这个问题,最好的办法是自定义ObjectMapper。即使是加了注解可以解决问题,也依然推荐使用自定义ObjectMapper,因为大量的接口每个都添加注解太繁琐了。
@Bean
@Primary
public ObjectMapper objectMapper() {
return Jackson2ObjectMapperBuilder.json()
.serializationInclusion(JsonInclude.Include.NON_NULL)
.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
.timeZone(TimeZone.getTimeZone("Asia/Shanghai"))
.build();
}
这样注解进去的ObjectMapper就带了时区。
LocalDate类型报错
报错详情:
Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Can not construct instance of java.time.LocalDate: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of java.time.LocalDate: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?)
at [Source: java.io.PushbackInputStream@3ce2b1e2; line: 1, column: 44] (through reference chain: com.chunrun.user.param.UserParams[“localDate”])
这是因为LocalDate没有提供默认的构造器,而Jackson还不支持Java8的特征。这时候只需要加上依赖,ObjectMapper加一行代码即可:
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-jsr310</artifactId>
<version>2.4.0</version>
</dependency>
@Bean
@Primary
public ObjectMapper objectMapper() {
return Jackson2ObjectMapperBuilder.json()
.serializationInclusion(JsonInclude.Include.NON_NULL)
.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
.timeZone(TimeZone.getTimeZone("Asia/Shanghai"))
.modules(new JSR310Module())
.build();
}
以上配置调用方也需要。
以上。