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

spring-issuemaster opened this issue Nov 27, 2018 · 1 comment


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@spring-issuemaster spring-issuemaster 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


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@spring-issuemaster spring-issuemaster 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.

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