Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

ResponseBodyAdvice should ignore non-match type instead throw exception [SPR-17539] #22071

spring-projects-issues opened this issue Nov 27, 2018 · 1 comment
in: web status: declined type: enhancement


Copy link

@spring-projects-issues spring-projects-issues commented Nov 27, 2018

abccbaandy opened SPR-17539 and commented

When I use 

public class MyAdvice implements ResponseBodyAdvice<MyVo>

and my response data is


ResponseBodyAdvice will throw ClassCastException, because we can't use "supports" to check the type. It make type declare in ResponseBodyAdvice interface useless.


Currently, there is a workaround, use Object


and check the type in beforeBodyWrite, like this

public Object beforeBodyWrite(Object o, MethodParameter returnType, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
    if (!(o instanceof MyVo)) {
        return o;
    // do rest things here

but it doesn't look like a best practice.



after study the source, I found there is a class cast before call beforeBodyWrite


private <T> Object processBody(@Nullable Object body, MethodParameter returnType, MediaType contentType,
      Class<? extends HttpMessageConverter<?>> converterType,
      ServerHttpRequest request, ServerHttpResponse response) {

   for (ResponseBodyAdvice<?> advice : getMatchingAdvice(returnType, ResponseBodyAdvice.class)) {
      if (advice.supports(returnType, converterType)) {
         body = ((ResponseBodyAdvice<T>) advice).beforeBodyWrite((T) body, returnType,
               contentType, converterType, request, response);
   return body;

Can we check body is T before call beforeBodyWrite?

Affects: 5.0.9

Copy link
Collaborator Author

@spring-projects-issues spring-projects-issues commented Nov 28, 2018

Rossen Stoyanchev commented

ResponseBodyAdvice will throw ClassCastException, because we can't use "supports" to check the type.

You can use the supports method to check. MethodParameter has the generic type information, e.g.:

boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
    Class<?> targetType = ResolvableType.forMethodParameter(returnType).getGeneric(0);
    // ...


Can we check body is T before call beforeBodyWrite?

Not really. We don't have generic type information for the advice bean at that point.

@spring-projects-issues spring-projects-issues added status: declined type: enhancement in: web labels Jan 11, 2019
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
in: web status: declined type: enhancement
None yet

No branches or pull requests

2 participants