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javaxmlspringclassloaderkotlin

Load spring xml config dynamically

At the startup time of a spring app, I want to scan a path on the computer, find the jar files and build a spring application context from an xml config files inside them. Every thing is OK to add jar file to the classpath and making an ApplicationContext. But I can't find any beans from new context. All of needed dependencies are available in the jar files in the specific path on computer (via a maven copier plugin) expect those dependencies which are in the base spring project (for example spring dependency itself). The code is (In Kotlin language):

var loader = URLClassLoader(arrayOf(entry.toFile().toURL()), Thread.currentThread().contextClassLoader)
...
val context = ClassPathXmlApplicationContext("classpath*:/$name")//name is xml file. I'm sure the address in classpath is right. context is not creating when the address in wrong. for example: classpath://$name
val services = context.getBeanNamesForType(IService::class.java)//services is empty

I have tried many other ways to load the xml but none of them was successful. for example:

val beans = DefaultListableBeanFactory(applicationContext)
val reader = XmlBeanDefinitionReader(beans)
reader.beanClassLoader = loader
reader.resourceLoader = resourceLoader
reader.setValidationMode(XmlBeanDefinitionReader.VALIDATION_XSD)
jarFile.getInputStream(jarEntry).use {
    reader.loadBeanDefinitions(EncodedResource(InputStreamResource(it)))
}
beans.preInstantiateSingletons()

the xml inside jar file looks like this:

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xsi:schemaLocation="http://www.springframework.org/schema/context
      http://www.springframework.org/schema/context/spring-context-3.0.xsd
      http://www.springframework.org/schema/beans
      http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<import resource="classpath*:/xxx-logic-context.xml"/>
<context:annotation-config/>
<context:component-scan base-package="aa.bbb.ccc.server"/>
</beans>

It's really interesting: When I define regular Beans instead using package scaning feature, I can get the bean in a sort of code

Solution

  • Great answer from @talex guided me. I fixed it by setting the current class loader:

    val loader = URLClassLoader(arrayOf(entry.toFile().toURL()), Thread.currentThread().contextClassLoader)
Thread.currentThread().contextClassLoader = loader