我有以下课程：
public abstract class AbstractBusinessModule {
}
public class MS3BusinessModule extends AbstractBusinessModule
{
public MS3BusinessModule(SomeOtherClass value)
{
}
}
以及以下 bean 声明：
<bean id="ms3BusinessModule" class="com.hba.MS3BusinessModule" >
<constructor-arg index="0">
<ref bean="someOtherBeanID"/>
</constructor-arg>
<aop:scoped-proxy />
</bean>
启动我的应用程序后，我收到以下错误：
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ms3BusinessModule' defined in BeanDefinition defined in class path resource [spring.xml]: Initialization of bean failed; nested exception is org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class [class com.hba.MS3BusinessModule]: Common causes of this problem include using a final class or a non-visible class; nested exception is java.lang.IllegalArgumentException: Superclass has no null constructors but no arguments were given
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:527)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:293)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:192)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:567)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
at com.hba.EhCacheTest.main(EhCacheTest.java:16)
Caused by: org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class [class com.hba.MS3BusinessModule]: Common causes of this problem include using a final class or a non-visible class; nested exception is java.lang.IllegalArgumentException: Superclass has no null constructors but no arguments were given
at org.springframework.aop.framework.Cglib2AopProxy.getProxy(Cglib2AopProxy.java:212)
at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:112)
at org.springframework.aop.scope.ScopedProxyFactoryBean.setBeanFactory(ScopedProxyFactoryBean.java:109)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeAwareMethods(AbstractAutowireCapableBeanFactory.java:1439)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1408)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
... 11 more
Caused by: java.lang.IllegalArgumentException: Superclass has no null constructors but no arguments were given
at net.sf.cglib.proxy.Enhancer.emitConstructors(Enhancer.java:721)
at net.sf.cglib.proxy.Enhancer.generateClass(Enhancer.java:499)
at net.sf.cglib.transform.TransformingClassGenerator.generateClass(TransformingClassGenerator.java:33)
at net.sf.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25)
at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:216)
at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:377)
at net.sf.cglib.proxy.Enhancer.create(Enhancer.java:285)
at org.springframework.aop.framework.Cglib2AopProxy.getProxy(Cglib2AopProxy.java:200)
... 16 more
可能出了什么问题？
如果我删除<aop:scoped-proxy/>从bean声明来看它是有效的。
更新：如果我将默认构造函数放入MS3BusinessModule， 有用。我不明白为什么需要默认构造函数的原因。有人可以解释一下吗？
如果我在 MS3BusinessModule 中放置默认构造函数，它就可以工作。我不明白为什么需要默认构造函数的原因。有人可以解释一下吗？
The way <aop:scoped-proxy/>工作原理是用不同的名称隐藏“真实”bean，并创建一个 CGLIB 代理类，它是真实 bean 类的子类，并将所有方法调用委托给目标 bean 的正确实例。所以这里有两种不同类型的对象：
-
n的实例
com.hba.MS3BusinessModule对于每个会话/请求/无论范围是什么，以及
- 动态生成的代理类的一个单例实例。
The n目标 bean 是使用带有参数的构造函数构造的，您的<constructor-arg>传递给它的值，但代理类需要一个无参数超类构造函数来调用（当然可以声明protected而不是public）。代理机制永远不会真正调用代理实例上的任何超类方法，因为所有调用都会转到目标实例，但代理类需要扩展目标 bean 类，以便代理成为instanceof正确的类型。
另一种修复方法是提供界面 that M3BusinessModule实现，并使其他 bean 对此 bean 的所有引用都使用接口类型而不是具体类类型。这将允许 Spring 使用java.lang.reflect代理而不是 CGLIB 代理，无需扩展具体类即可实现接口。
本文内容由网友自发贡献，版权归原作者所有，本站不承担相应法律责任。如您发现有涉嫌抄袭侵权的内容，请联系:hwhale#tublm.com(使用前将#替换为@)
