如何在Spring Boot wicket应用程序中注入RequestScope bean

Question

In my Wicket page I have:

@SpringBean
protected J2EContext j2EContext;

In Configuration I have:

@Bean
@RequestScope
public J2EContext getWebContext() {
    return new J2EContext(request, response, getSessionStore());
}


@Bean
public RequestContextListener requestContextListener() {
    return new RequestContextListener();
}

application starts OK but when I go to home page I got exception:

Caused by: java.lang.IllegalArgumentException: Superclass has no null constructors but no arguments were given
    at net.sf.cglib.proxy.Enhancer.emitConstructors(Enhancer.java:931)
    at net.sf.cglib.proxy.Enhancer.generateClass(Enhancer.java:631)
    at net.sf.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25)
    at net.sf.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:

329)
    at net.sf.cglib.proxy.Enhancer.generate(Enhancer.java:492)
    at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:93)
    at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:91)
    at net.sf.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)

when wicket want to inject J2EContext bean. I think this is because page is rendering before @RequestScope create this bean. Any idea how to fix this problem ?

Answer 1

to inject beans Wicket creates a proxy in two different ways:

• If bean is an interface a standard java.lang.reflect.Proxy is created
• If bean is a class cglib is used by default

Unfortunately cglib can not create proxy for classes without a default constructor. There is however a third way that can solve the problem. Just add objenesis as dependency to your project and Wicket will use it instead of cglib.