Inadequate implementation of GenericConversionService.findConverterByClassPair(Class, Class) [SPR-6297]

[spring-projects-issues]

Oliver Becker opened SPR-6297 and commented

The algorithm implemented in GenericFormatterRegistry.findConverterByClassPair(Class, Class) apparently goes up the superinterface and superclass hierarchy to find a proper converter for a given source type. However, since the DefaultConversionService registers an ObjectToStringConverter, this converter will be preferred over specialized converters for interfaces.

Consider the following situation: class X implements the interface I which in turn is a subinterface of J. There is a special converter for J-to-String.
The classQueue will be filled in this case with

• X
• I (from X.getInterfaces())
• Object (from X.getSuperclass())
• J (from I.getInterfaces())

Since Object appears before J the generic ObjectToStringConverter will be used here instead of the more specific converter for J.

A more appropriate algorithm should probably consider first all interfaces before using the superclasses. In any case the ObjectToStringConverter should always be the last converter to be used.

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Affects: 3.0 RC1

Sub-tasks:

• Optimize GenericConversionService.findConverterForClassPair [SPR-6749] #11415 Optimize GenericConversionService.findConverterForClassPair

Issue Links:

• Review Converter resolution algorithm [SPR-6314] #10980 Review Converter resolution algorithm

Referenced from: commits 010e72c

[spring-projects-issues]

Juergen Hoeller commented

Good point. I've revised this to consider all interfaces (including inherited interfaces) before going up the superclass hierarchy. This will be available in tonight's snapshot already.

Juergen