Support bean disposal on ApplicationContext shutdown for Closeable beans [SPR-10034]

[spring-projects-issues]

Stuart Gunter opened SPR-10034 and commented

When shutting down the ApplicationContext, beans that implement DisposableBean are automatically destroyed. However, not all libraries depend on Spring and instead rely on java.io.Closeable for proper cleanup.

It would be very useful if Spring also called the Closeable.close() method on any bean that implements it.

Is this viable, or would it conflict with other behaviour within the framework?

An example that highlighted this problem is the CouchbaseClient, which is constructed via a FactoryBean, which means the destroy-method cannot be specified on the bean created by the factory. This prevents the app context from shutting down correctly. With the above behaviour, CouchbaseClient could be modified to implement java.io.Closeable and be appropriately destroyed on application termination.

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Affects: 3.2 RC1

Issue Links:

• Support 'destroy method inference' for @Bean methods [SPR-8751] #13393 Support 'destroy method inference' for @Bean methods
• Clarify Bean destroyMethod documentation [SPR-16078] #20627 Clarify Bean destroyMethod documentation

Referenced from: commits 9c6aa3e

[spring-projects-issues]

Juergen Hoeller commented

In case of a FactoryBean, the framework does indeed expect the FactoryBean instance to declare the destroy method, since the framework isn't responsible for managing the lifecycle of the exposed object - it's just responsible for managing the lifecycle of the FactoryBean instance. So for the CouchbaseClient case, the FactoryBean should simply implement DisposableBean and delegate the call to the underlying CouchbaseClient instance.

However, generally speaking, it's a good idea to support java.io.Closeable - and also Java 7's java.lang.AutoCloseable - as destroy methods by default. We do detect methods named "close" for @Bean methods in @Configuration classes but do not do so for XML bean definitions since the defaulting model works differently there. That said - for the Closeable/AutoCloseable case, we may check and support that for XML bean definitions as well.

Juergen

[spring-projects-issues]

Stuart Gunter commented

Thanks for the comments, Juergen. That makes perfect sense, and we've updated our FactoryBean to implement DisposableBean as you suggest.

As per the comments about supporting Closeable/AutoCloseable, I agree this would be useful (even with the presence of duck typing as it currently stands for the @Bean methods).