Cglib学习报错 java.lang.reflect.InvocationTargetException-->null

package javacore.testForCglibProxy;

import java.lang.reflect.Method;

import net.sf.cglib.proxy.Enhancer;

import net.sf.cglib.proxy.MethodInterceptor;

import net.sf.cglib.proxy.MethodProxy;

public class GetNewBook {

public static void main(String[] args) {

cglibProxy cp = new cglibProxy();

gg gnb1 = (gg)cp.getProxy(new gg());

gnb1.GetBook();

}

}

class cglibProxy implements MethodInterceptor{

Object target ;

public Object getProxy(Object target){

this.target=target;

Enhancer ch = new Enhancer();

ch.setSuperclass(this.target.getClass());

ch.setCallback(this);

return ch.create();

}

@Override

public Object intercept(Object obj, Method method, Object[] args,

MethodProxy proxy) throws Throwable {

// TODO Auto-generated method stub

System.out.println("开始");

proxy.invokeSuper(obj, args);

System.out.println("结束");

return null;

}

}

class gg{

public void GetBook() {

// TODO Auto-generated method stub

System.out.println("get book");

}

}

当Class  gg 的修饰符非public的时候 会报错 cannot access its superclass

Exception in thread "main" net.sf.cglib.core.CodeGenerationException: java.lang.reflect.InvocationTargetException-->null

at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:237)

at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:377)

at net.sf.cglib.proxy.Enhancer.create(Enhancer.java:285)

at javacore.testForCglibProxy.cglibProxy.getProxy(GetNewBook.java:25)

at javacore.testForCglibProxy.GetNewBook.main(GetNewBook.java:13)

Caused by: java.lang.reflect.InvocationTargetException

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:497)

at net.sf.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:384)

at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:219)

... 4 more

Caused by: java.lang.IllegalAccessError: class $javacore.testForCglibProxy.gg1$$EnhancerByCGLIB$$bf75381d cannot access its superclass javacore.testForCglibProxy.gg1

at java.lang.ClassLoader.defineClass1(Native Method)

at java.lang.ClassLoader.defineClass(ClassLoader.java:760)

... 10 more