I have posted several question related to javassit linkage error spring Exception when running application on WebSphere with java 8 . Now after some research work around this topics and error, i have got some useful information about bytecode manipulation with Javassist to solve linkage error .
For your reference ( Already posted this stack trace in another questions here )
[10/13/17 ] 00000089 webapp E com.ibm.ws.webcontainer.webapp.WebApp logServletError SRVE0293E: [Servlet Error]-[weblge]: java.lang.ExceptionInInitializerError
at java.lang.J9VMInternals.ensureError(J9VMInternals.java:134)
at java.lang.J9VMInternals.recordInitializationFailure(J9VMInternals.java:123)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:83)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:57)
at java.lang.reflect.Constructor.newInstance(Constructor.java:437)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:163)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:120)
at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:345)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:278)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:103)
at com.ibm.ws.webcontainer.webapp.WebApp.notifyServletContextCreated(WebApp.java:1826)
at com.ibm.ws.webcontainer.webapp.WebAppImpl.initialize(WebAppImpl.java:442)
at com.ibm.ws.webcontainer.webapp.WebGroupImpl.addWebApplication(WebGroupImpl.java:88)
at com.ibm.ws.webcontainer.VirtualHostImpl.addWebApplication(VirtualHostImpl.java:171)
at com.ibm.ws.webcontainer.WSWebContainer.addWebApp(WSWebContainer.java:904)
at com.ibm.ws.webcontainer.WSWebContainer.addWebApplication(WSWebContainer.java:789)
at com.ibm.ws.webcontainer.component.WebContainerImpl.install(WebContainerImpl.java:427)
at com.ibm.ws.webcontainer.component.WebContainerImpl.start(WebContainerImpl.java:719)
at com.ibm.ws.runtime.component.ApplicationMgrImpl.start(ApplicationMgrImpl.java:1247)
at com.ibm.ws.runtime.component.DeployedApplicationImpl.fireDeployedObjectStart(DeployedApplicationImpl.java:1514)
at com.ibm.ws.runtime.component.DeployedModuleImpl.start(DeployedModuleImpl.java:704)
at com.ibm.ws.runtime.component.DeployedApplicationImpl.start(DeployedApplicationImpl.java:1096)
at com.ibm.ws.runtime.component.ApplicationMgrImpl.startApplication(ApplicationMgrImpl.java:799)
at com.ibm.ws.runtime.component.ApplicationMgrImpl$5.run(ApplicationMgrImpl.java:2315)
at com.ibm.ws.security.auth.ContextManagerImpl.runAs(ContextManagerImpl.java:5488)
at com.ibm.ws.security.auth.ContextManagerImpl.runAsSystem(ContextManagerImpl.java:5614)
at com.ibm.ws.security.core.SecurityContext.runAsSystem(SecurityContext.java:255)
at com.ibm.ws.runtime.component.ApplicationMgrImpl.start(ApplicationMgrImpl.java:2320)
at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.start(CompositionUnitMgrImpl.java:436)
at com.ibm.ws.runtime.component.CompositionUnitImpl.start(CompositionUnitImpl.java:123)
at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.start(CompositionUnitMgrImpl.java:379)
at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.access$500(CompositionUnitMgrImpl.java:127)
at com.ibm.ws.runtime.component.CompositionUnitMgrImpl$CUInitializer.run(CompositionUnitMgrImpl.java:985)
at com.ibm.wsspi.runtime.component.WsComponentImpl$_AsynchInitializer.run(WsComponentImpl.java:524)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1909)
Caused by: java.lang.IllegalStateException: javassist.CannotCompileException: by java.lang.LinkageError: org.springframework.aop.framework.ProxyCreatorSupport
at org.springframework.aop.framework.JavassistApplicationContext.<clinit>(JavassistApplicationContext.java:36)
... 34 more
Caused by: javassist.CannotCompileException: by java.lang.LinkageError: org.springframework.aop.framework.ProxyCreatorSupport
at javassist.ClassPool.toClass(ClassPool.java:1170)
at javassist.ClassPool.toClass(ClassPool.java:1113)
at javassist.ClassPool.toClass(ClassPool.java:1071)
at javassist.CtClass.toClass(CtClass.java:1275)
at org.springframework.aop.framework.JavassistApplicationContext.<clinit>(JavassistApplicationContext.java:34)
... 34 more
Caused by: java.lang.LinkageError: org.springframework.aop.framework.ProxyCreatorSupport
at java.lang.ClassLoader.defineClassImpl(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:357)
at java.lang.ClassLoader.defineClass(ClassLoader.java:293)
at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:508)
at javassist.ClassPool.toClass2(ClassPool.java:1183)
at javassist.ClassPool.toClass(ClassPool.java:1164)
... 38 more
and i am getting this error on this java file , when i am trying do operation on org.springframework.aop.framework.ProxyCreatorSupport
package org.spring.aop.framework;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtConstructor;
import javassist.LoaderClassPath;
import org.springframework.web.context.support.XmlWebApplicationContext;
public class JavassistApplicationContext extends XmlWebApplicationContext {
static {
ClassPool classPool = ClassPool.getDefault();
try {
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
classPool.appendClassPath(new LoaderClassPath(classLoader));
CtClass cc = classPool.get("org.spring.aop.framework.ProxyCreatorSupport");
CtConstructor c = cc.getConstructors()[0];
c.insertAfter("$0.aopProxyFactory = new org.spring.aop.framework.JavassistAopProxyFactory();");
cc.toClass();
} catch (Exception e) {
throw new IllegalStateException(e);
}
}
}
on the line cc.toClass();
, i am getting this exception . I have tried different class loader methods on WebSphere to solve this exception and getting same error .
Now i understood that linkage problem is occur when tries to modify the class already loaded by referenced classloader .
being able to solve this error , i should unload the class first from the reference classloader
and i think it's difficult .
You need to write a Java agent and attach it dynamically to transform a class at load time. You can find a cool tutorial here that explains how to do it.
Note that this method allows you to intercept the class while it's loaded by the JVM and modify it after this loading is actually done.