Java – Interface is not visible from ClassLoader when using a proxy

dynamicjavaproxy

I am seeing following exception when I try to use dynamic proxy

 com.intellij.rt.execution.application.AppMain DynamicProxy.DynamicProxy
Exception in thread "main" java.lang.IllegalArgumentException: interface Interfaces.IPerson is not visible from class loader
    at java.lang.reflect.Proxy.getProxyClass(Proxy.java:353)
    at java.lang.reflect.Proxy.newProxyInstance(Proxy.java:581)
    at DynamicProxy.Creator.getProxy(Creator.java:18)
    at DynamicProxy.DynamicProxy.main(DynamicProxy.java:54)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

Any idea what I need to do to resolve it

Best Solution

If this is web application, then you should use the web application classloader when creating dynamic proxy. So, for example instead of:

Proxy.newProxyInstance(
  ClassLoader.getSystemClassLoader(),
  new Class < ? >[] {MyInterface.class},
  new InvocationHandler() {
    // (...)
});

try:

Proxy.newProxyInstance(
  this.getClass().getClassLoader(), // here is the trick
  new Class < ? >[] {MyInterface.class},
  new InvocationHandler() {
    // (...)
});

For instance, hierarchy of tomcat class loaders (other web containers have similar) is following:

      Bootstrap
          |
       System
          |
       Common
       /     \
  Webapp1   Webapp2 ... 

And it is the webapp classloader which contains classes and resources in the /WEB-INF/classes directory of your web application, plus classes and resources in JAR files under the /WEB-INF/lib directory of your web application.

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