SpringFactoriesLoader.instantiateFactory(…) should report offending class on error

[odrotbohm]

SpringFactoriesLoader.instantiateFactory(…) reports the name of the interface that implementations are looked up for. However, it does not report the name of the actual implementation class whose failed creation is likely to have caused the exception.

[jhoeller]

Isn't the implementation class name usually part of the nested exception anyway?

[odrotbohm]

It is indeed. I just thought that the primary exception message could reveal the original offender, especially as it states "Unable to instantiate factory class" but then prints the interface name.

[sbrannen]

@jhoeller, are you actively working on this? If not, I'd be happy to pick it up.

[sbrannen]

I actually did something similar for the TestContext framework which uses SpringFactoriesLoader behind the scenes to find the factory class names:

spring-framework/spring-test/src/main/java/org/springframework/test/context/support/AbstractTestContextBootstrapper.java

Lines 216 to 231 in 777b4c8

	protected Set<Class<? extends TestExecutionListener>> getDefaultTestExecutionListenerClasses() {
	Set<Class<? extends TestExecutionListener>> defaultListenerClasses = new LinkedHashSet<>();
	ClassLoader cl = getClass().getClassLoader();
	for (String className : getDefaultTestExecutionListenerClassNames()) {
	try {
	defaultListenerClasses.add((Class<? extends TestExecutionListener>) ClassUtils.forName(className, cl));
	}
	catch (Throwable ex) {
	if (logger.isDebugEnabled()) {
	logger.debug("Could not load default TestExecutionListener class [" + className +
	"]. Specify custom listener classes or make the default listener classes available.", ex);
	}
	}
	}
	return defaultListenerClasses;
	}

So I'll improve the exception message in SpringFactoriesLoader.instantiateFactory(…) in a similar fashion.

[sbrannen]

@odrotbohm, are you satisfied with the outcome in f087fd5?

[odrotbohm]

LGTM.