apache karaf中的activemq，使用xbean加載配置

Question

我想使用在Apache Karaf上運行的OSGi捆綁包內的xbean配置創建嵌入式ActiveMQ代理。 這段代碼：

brokerService = BrokerFactory.createBroker("xbean:file:etc/config.xml");

失敗，但以下異常：

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to load type: org.apache.activemq.xbean.XBeanBrokerService. Reason: java.lang.ClassNotFoundException: org.apache.activemq.xbean.XBeanBrokerService not found by org.apache.xbean.spring [81]; nested exception is java.lang.ClassNotFoundException: org.apache.activemq.xbean.XBeanBrokerService not found by org.apache.xbean.spring [81]
        at org.apache.xbean.spring.context.v2c.XBeanQNameHelper.getBeanInfo(XBeanQNameHelper.java:75)
        at org.apache.xbean.spring.context.v2c.XBeanQNameHelper.coerceNamespaceAwarePropertyValues(XBeanQNameHelper.java:54)
        at org.apache.xbean.spring.context.v2c.XBeanBeanDefinitionParserDelegate.parseBeanDefinitionElement(XBeanBeanDefinitionParserDelegate.java:59)
        at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseBeanDefinitionElement(BeanDefinitionParserDelegate.java:396)
        at org.apache.xbean.spring.context.v2c.XBeanNamespaceHandler.parseBeanFromExtensionElement(XBeanNamespaceHandler.java:224)
        at org.apache.xbean.spring.context.v2c.XBeanNamespaceHandler.parseBeanFromExtensionElement(XBeanNamespaceHandler.java:276)
        at org.apache.xbean.spring.context.v2c.XBeanNamespaceHandler.parse(XBeanNamespaceHandler.java:156)
        at org.apache.xbean.spring.context.v2.XBeanNamespaceHandler.parse(XBeanNamespaceHandler.java:49)
        at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1338)
        at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1328)
        at org.apache.xbean.spring.context.v2.XBeanBeanDefinitionDocumentReader.parseBeanDefinitions(XBeanBeanDefinitionDocumentReader.java:84)
        at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:93)
        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
        at org.apache.xbean.spring.context.v2.XBeanXmlBeanDefinitionReader.registerBeanDefinitions(XBeanXmlBeanDefinitionReader.java:79)
        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
        at org.apache.xbean.spring.context.ResourceXmlApplicationContext.loadBeanDefinitions(ResourceXmlApplicationContext.java:111)
        at org.apache.xbean.spring.context.ResourceXmlApplicationContext.loadBeanDefinitions(ResourceXmlApplicationContext.java:104)
        at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
        at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:467)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:397)
        at org.apache.xbean.spring.context.ResourceXmlApplicationContext.<init>(ResourceXmlApplicationContext.java:64)
        at org.apache.xbean.spring.context.ResourceXmlApplicationContext.<init>(ResourceXmlApplicationContext.java:52)
        at org.apache.activemq.xbean.XBeanBrokerFactory$1.<init>(XBeanBrokerFactory.java:114)
        at org.apache.activemq.xbean.XBeanBrokerFactory.createApplicationContext(XBeanBrokerFactory.java:114)
        at org.apache.activemq.xbean.XBeanBrokerFactory.createBroker(XBeanBrokerFactory.java:70)
        at org.apache.activemq.broker.BrokerFactory.createBroker(BrokerFactory.java:71)
        at org.apache.activemq.broker.BrokerFactory.createBroker(BrokerFactory.java:54)
        at org.apache.activemq.broker.BrokerFactory.createBroker(BrokerFactory.java:85)
        at jmstest.bundle.TestActivator.start(TestActivator.java:18)
        at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:629)
        at org.apache.felix.framework.Felix.activateBundle(Felix.java:1842)
        at org.apache.felix.framework.Felix.startBundle(Felix.java:1759)
        at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1163)
        at org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:264)
        at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ClassNotFoundException: org.apache.activemq.xbean.XBeanBrokerService not found by org.apache.xbean.spring [81]
        at org.apache.felix.framework.ModuleImpl.findClassOrResourceByDelegation(ModuleImpl.java:787)
        at org.apache.felix.framework.ModuleImpl.access$400(ModuleImpl.java:71)
        at org.apache.felix.framework.ModuleImpl$ModuleClassLoader.loadClass(ModuleImpl.java:1768)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
        at org.apache.xbean.spring.context.v2c.XBeanQNameHelper.loadClass(XBeanQNameHelper.java:107)
        at org.apache.xbean.spring.context.v2c.XBeanQNameHelper.getBeanInfo(XBeanQNameHelper.java:72)
        ... 36 more

所有需要的捆綁包（activemq，activemq-spring，xbean-spring）均已加載並正在運行，而我的捆綁包中的所有捆綁包均位於Import-Package 。

從獨立ActiveMQ代理加載的相同配置文件可以正常工作。

我相信這是因為xbean無法從未導入的包中訪問類而引起的。 有沒有解決的辦法？

Answer 1

我自己解決了這個問題，但看起來像是駭客。 欣賞是否有人告訴自己如何做到這一點。

這個想法是用加載當前類的類替換默認的類加載器（在我的例子中是捆綁激活器）：

ClassLoader c = Thread.currentThread().getContextClassLoader();
Thread.currentThread().setContextClassLoader(this.getClass().getClassLoader());

brokerService = BrokerFactory.createBroker("xbean:file:etc/config.xml");
brokerService.start();

Thread.currentThread().setContextClassLoader(c);

XBean在加載類時會嘗試幾種類加載器，包括線程上下文類加載器。 當然， getClass().getClassLoader()加載器知道我的包的導入，因此XBean設法加載所有需要的類（前提是它們在Import-Package頭中）。 也許這也會對其他人有所幫助。