How to know which message converter is used by spring boot? - spring-boot

Question

For some reason I decided to change to another message converter, my code is below
#Bean
public HttpMessageConverters customConverters() {
HttpMessageConverter<?> additional = new FastJsonHttpMessageConverter();
return new HttpMessageConverters(additional);
}
Now I'd like to know how to check whether this custom converter is in effect? I tried to access /beans but only got this
{
bean: "customConverters",
scope: "singleton",
type: "org.springframework.boot.autoconfigure.web.HttpMessageConverters",
resource: "com.foo.BarApplication",
dependencies: [ ]
}
So does exist some manner to know which message converter is used by spring boot?

Answer 1

Because I'm not very sure if my custom converter works, so I have to track source code. I cloned spring framework then attached it in eclipse, then debug step by step and found something.
In AbstractMessageConverterMethodProcessor.writeWithMessageConverters
for (HttpMessageConverter<?> messageConverter : this.messageConverters)
when watch this.messageConverters got below output
[org.springframework.hateoas.mvc.TypeConstrainedMappingJackson2HttpMessageConverter#1eb0d2e8, com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter#2026476b, org.springframework.http.converter.ByteArrayHttpMessageConverter#3287cbc7, org.springframework.http.converter.StringHttpMessageConverter#2c19dd3, org.springframework.http.converter.ResourceHttpMessageConverter#1afe28f1, org.springframework.http.converter.xml.SourceHttpMessageConverter#87129da, org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter#4a412e0, org.springframework.http.converter.json.MappingJackson2HttpMessageConverter#a8528a2, org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter#61d720a3]
and actually it used com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter#2026476b

Answer 2

Only injected dependencies are shown in the dependencies array. If you do something like
#Bean
public FastJsonHttpMessageConverter fastJsonHttpMessageConverter() {
return new FastJsonHttpMessageConverter();
}
#Bean
#Autowired
public HttpMessageConverters convertersToBeUsed(FastJsonHttpMessageConverter converter) {
return new HttpMessageConverters(converter);
}
you will see the FastJsonHttpMessageConverter in the list.
If you want to see all registered converters, look for HttpMessageConvertersAutoConfiguration in the bean list. It should look similar to this:
{
bean: "org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration",
scope: "singleton",
type: "org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration$$EnhancerBySpringCGLIB$$9e15b021",
resource: "null",
dependencies: [
"fastJsonHttpMessageConverter",
"stringHttpMessageConverter"
]
}