http内容转换器
默认添加
ByteArrayHttpMessageConverter
StringHttpMessageConverter
ResourceHttpMessageConverter
SourceHttpMessageConverter
AllEncompassingFormHttpMessageConverter
根据jar包添加
MappingJacksonHttpMessageConverter
MappingJackson2HttpMessageConverter
Jaxb2RootElementHttpMessageConverter
RssChannelHttpMessageConverter
AtomFeedHttpMessageConverter