spring-framework

Spring Framework

Chris Beams 807d612978 Determine FactoryBean object type via generics For the particular use case detailed in SPR-8514, with this change we now attempt to determine the object type of a FactoryBean through its generic type parameter if possible. For (a contrived) example: @Configuration public MyConfig { @Bean public FactoryBean<String> fb() { return new StringFactoryBean("foo"); } } The implementation will now look at the <String> generic parameter instead of attempting to instantiate the FactoryBean in order to call its #getObjectType() method. This is important in order to avoid the autowiring lifecycle issues detailed in SPR-8514. For example, prior to this change, the following code would fail: @Configuration public MyConfig { @Autowired Foo foo; @Bean public FactoryBean<String> fb() { Assert.notNull(foo); return new StringFactoryBean("foo"); } } The reason for this failure is that in order to perform autowiring, the container must first determine the object type of all configured FactoryBeans. Clearly a chicken-and-egg issue, now fixed by this change. And lest this be thought of as an obscure bug, keep in mind the use case of our own JPA support: in order to configure and return a LocalContainerEntityManagerFactoryBean from a @Bean method, one will need access to a DataSource, etc -- resources that are likely to be @Autowired across @Configuration classes for modularity purposes. Note that while the examples above feature methods with return types dealing directly with the FactoryBean interface, of course the implementation deals with subclasses/subinterfaces of FactoryBean equally as well. See ConfigurationWithFactoryBeanAndAutowiringTests for complete examples. There is at least a slight risk here, in that the signature of a FactoryBean-returing @Bean method may advertise a generic type for the FactoryBean less specific than the actual object returned (or than advertised by #getObjectType for that matter). This could mean that an autowiring target may be missed, that we end up with a kind of autowiring 'false negative' where FactoryBeans are concerned. This is probably a less common scenario than the need to work with an autowired field within a FactoryBean-returning @Bean method, and also has a clear workaround of making the generic return type more specific. Issue: SPR-8514		15 years ago
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.settings	Merge 3.1.0 development branch into trunk	15 years ago
src	Determine FactoryBean object type via generics	15 years ago
.classpath	Polishing Eclipse classpath settings	15 years ago
.project	adding eclipse project meta-data, .classpath file is based on dependencies listed in ivy.xml	17 years ago
beans.iml	Merge 3.1.0 development branch into trunk	15 years ago
build.xml	+ upgrade to AspectJ 1.6.8	16 years ago
ivy.xml	shortened build properties "org.junit.version" to "junit.version" and "org.testng.version" to "testng.version"; reverted SLF4J version back to 1.5.3 (for Hibernate 3.3.1 compatibility)	15 years ago
pom.xml	Add hamcrest to beans pom in the right place to make tests compile	15 years ago
template.mf	+ make use or property placeholders inside template.mf	16 years ago