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Allow parameters in FactoryBean-returning @Bean methods

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Prior to this change, an assumption was made in
AbstractAutowireCapableBeanFactory that any factory-method would have
zero parameters.  This may not be the case in @Bean methods.

We now look for the factory-method by name in a more flexible fashion
that accomodates the possibility of method parameters.

There remains at least one edge cases here where things could still fail,
for example a @Configuration class could have two FactoryBean-returning
methods of the same name, but each with different generic FactoryBean
types and different parameter lists. In this case, the implementation
may infer and return the wrong object type, as it currently returns
the first match for the given factory-method name.  The complexity cost
of ensuring that this never happens is not likely worth the trouble
given the very low likelihood of such an arrangement.

Issue: SPR-8762
This commit is contained in:
Chris Beams
2011-12-10 19:32:02 +00:00
parent 866999764d
commit 48836e2ebb
3 changed files with 99 additions and 10 deletions
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31
org.springframework.beans/src/main/java/org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java
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@@ -1,5 +1,5 @@
/*
* Copyright 2002-2010 the original author or authors.
* Copyright 2002-2011 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -105,6 +105,7 @@ import org.springframework.util.StringUtils;
* @author Rob Harrop
* @author Mark Fisher
* @author Costin Leau
* @author Chris Beams
* @since 13.02.2004
* @see RootBeanDefinition
* @see DefaultListableBeanFactory
@@ -663,9 +664,10 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
*/
@Override
protected Class<?> getTypeForFactoryBean(String beanName, RootBeanDefinition mbd) {
Class<?> objectType = null;
class Holder { Class<?> value = null; }
final Holder objectType = new Holder();
String factoryBeanName = mbd.getFactoryBeanName();
String factoryMethodName = mbd.getFactoryMethodName();
final String factoryMethodName = mbd.getFactoryMethodName();
if (factoryBeanName != null && factoryMethodName != null) {
// Try to obtain the FactoryBean's object type without instantiating it at all.
BeanDefinition fbDef = getBeanDefinition(factoryBeanName);
@@ -675,10 +677,19 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
// CGLIB subclass methods hide generic parameters. look at the superclass.
fbClass = fbClass.getSuperclass();
}
Method m = ReflectionUtils.findMethod(fbClass, factoryMethodName);
objectType = GenericTypeResolver.resolveReturnTypeArgument(m, FactoryBean.class);
if (objectType != null) {
return objectType;
// find the given factory method, taking into account that in the case of
// @Bean methods, there may be parameters present.
ReflectionUtils.doWithMethods(fbClass,
new ReflectionUtils.MethodCallback() {
public void doWith(Method method) throws IllegalArgumentException, IllegalAccessException {
if (method.getName().equals(factoryMethodName) &&
FactoryBean.class.isAssignableFrom(method.getReturnType())) {
objectType.value = GenericTypeResolver.resolveReturnTypeArgument(method, FactoryBean.class);
}
}
});
if (objectType.value != null) {
return objectType.value;
}
}
}
@@ -689,9 +700,9 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
if (fb != null) {
// Try to obtain the FactoryBean's object type from this early stage of the instance.
objectType = getTypeForFactoryBean(fb);
if (objectType != null) {
return objectType;
objectType.value = getTypeForFactoryBean(fb);
if (objectType.value != null) {
return objectType.value;
}
}