CGLIB `BeanCopier` falls back to `ClassLoader.defineClass` for public target

[SuperEdison]

springframework.version 5.3.21
jdk.version 17

old issue #28530
I find this error still happening that is fault way to use?

public static void main(String[] args) { BeanCopier beanCopier = BeanCopier.create(A.class, B.class, false); }

Exception in thread "main" org.springframework.cglib.core.CodeGenerationException: java.lang.reflect.InaccessibleObjectException-->Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @32cf48b7
at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:589)
at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:363)
at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:110)
at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:108)
at org.springframework.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54)
at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61)
at org.springframework.cglib.core.internal.LoadingCache.get(LoadingCache.java:34)
at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:134)
at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:319)
at org.springframework.cglib.beans.BeanCopier$Generator.create(BeanCopier.java:98)
at org.springframework.cglib.beans.BeanCopier.create(BeanCopier.java:52)
at club.edm.bscwallet.server.BscWalletApplication.main(BscWalletApplication.java:17)
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @32cf48b7
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:354)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:199)
at java.base/java.lang.reflect.Method.setAccessible(Method.java:193)
at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:553)
... 13 more

    public static void main(String[] args) {
        BeanCopier beanCopier = BeanCopier.create(A.class, B.class, false);
        System.out.println(beanCopier);
        A a = new A();
    }

    static public class A {

    }

    static public class B {

    }

@jhoeller

[livk-cloud]

This didn't happen with any errors,I tried using spring-core 6.0.0M4 and spring-core 5.3.21,didn't get any errors

public class AppTest {

    @Test
    public void test() {
        BeanCopier copier = BeanCopier.create(A.class, B.class, false);
        System.out.println("copier:" + copier);
    }
}

class A {

}

class B {

}

[SuperEdison]

这没有发生任何错误，我尝试使用 spring-core 6.0.0M4 和 spring-core 5.3.21，没有收到任何错误

public class AppTest {

    @Test
    public void test() {
        BeanCopier copier = BeanCopier.create(A.class, B.class, false);
        System.out.println("copier:" + copier);
    }
}

class A {

}

class B {

}

because your class not public class, you can try create public class A and B

[livk-cloud]

这没有发生错误，我试用使用 spring-core 6.0.0M4 和 spring-core 5.3.21，没有收到任何错误

public class AppTest {

    @Test
    public void test() {
        BeanCopier copier = BeanCopier.create(A.class, B.class, false);
        System.out.println("copier:" + copier);
    }
}

class A {

}

class B {

}

因为您的课程不是公共课程，您可以尝试创建公共课程 A 和 B

Obviously there is no problem

spring6.0.0-M4 result

spring5.3.21 result

[SuperEdison]

这没有发生错误，我试用使用 spring-core 6.0.0M4 和 spring-core 5.3.21，没有收到任何错误

public class AppTest {

    @Test
    public void test() {
        BeanCopier copier = BeanCopier.create(A.class, B.class, false);
        System.out.println("copier:" + copier);
    }
}

class A {

}

class B {

}

因为您的课程不是公共课程，您可以尝试创建公共课程 A 和 B

Obviously there is no problem

spring6.0.0-M4 result

spring5.3.21 result

so, i wanna know that you add some param?
there are pic to tell you my env and spring.verison.

[livk-cloud]

class A and class B is empty
I am using oracle jdk17.0.2
spring version has been said before

[SuperEdison]

class A and class B is empty

I am using oracle jdk17.0.2

spring version has been said before

can you show me the A class code ?

[livk-cloud]

A类和B类为空

我正在使用 oracle jdk17.0.2

spring 版本之前已经说过了

你能告诉我A类代码吗？

[SuperEdison]

A类和B类为空

我正在使用 oracle jdk17.0.2

spring 版本之前已经说过了

你能告诉我A类代码吗？

i had change oracle jdk17,still error.
i have no idea to solve it.
do you add --add-opens java.base/java.lang=ALL-UNNAMED param?

[livk-cloud]

A类和B类为空

我正在使用 oracle jdk17.0.2

spring 之前已经知道了

你能告诉我一个类代码吗？

我改变了oracle jdk17，仍然错误。 我不知道解决它。 你添加--add-opens java.base/java.lang=ALL-UNNAMED 参数吗？

No, I use the default parameters of the idea, I think you should use @test instead of the Main method

[SuperEdison]

i try many way to solve this problem, but any way had fail

[funky-eyes]

i try many way to solve this problem, but any way had fail

me too

[mazhewei]

Same issue.
Here is minimize steps:

1. create empty springboot project using spring initializr(in IDEA)
   Project SDK: openjdk 17.0.3
   Java: 17
   SpringBoot Version 2.7.3
   SpringFramework Version 5.3.22
2. create two entity class, Person.class / PersonVO.class for example

public class Person {
    String name;
    Integer age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

import java.util.List;

public class PersonVO extends Person {
    List<String> hobbies;

    public List<String> getHobbies() {
        return hobbies;
    }

    public void setHobbies(List<String> hobbies) {
        this.hobbies = hobbies;
    }
}

3. use BeanCopier

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cglib.beans.BeanCopier;

@SpringBootApplication
public class BeanCopierDemoApplication {
    private static final Log logger = LogFactory.getLog(BeanCopierDemoApplication.class);

    public static void main(String[] args) {
        PersonVO personVO = testBeanCopy();
        logger.info(personVO);
        SpringApplication.run(BeanCopierDemoApplication.class, args);
    }

    public static PersonVO testBeanCopy() {
        Person person = new Person();
        person.setName("nico");
        person.setAge(18);
        PersonVO personVO = new PersonVO();
        final BeanCopier beanCopier = BeanCopier.create(Person.class, PersonVO.class, false);
        beanCopier.copy(person, personVO, null);
        personVO.setHobbies(null);
        return personVO;
    }
}

4. start springboot application and error occurred

Exception in thread "main" org.springframework.cglib.core.CodeGenerationException: java.lang.reflect.InaccessibleObjectException-->Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @7920ba90
	at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:598)
	at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:363)
	at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:110)
	at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:108)
	at org.springframework.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61)
	at org.springframework.cglib.core.internal.LoadingCache.get(LoadingCache.java:34)
	at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:134)
	at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:319)
	at org.springframework.cglib.beans.BeanCopier$Generator.create(BeanCopier.java:98)
	at org.springframework.cglib.beans.BeanCopier.create(BeanCopier.java:52)
	at com.example.beancopierdemo.BeanCopierDemoApplication.testBeanCopy(BeanCopierDemoApplication.java:24)
	at com.example.beancopierdemo.BeanCopierDemoApplication.main(BeanCopierDemoApplication.java:14)
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @7920ba90
	at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:354)
	at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
	at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:199)
	at java.base/java.lang.reflect.Method.setAccessible(Method.java:193)
	at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:552)
	... 13 more

In my case, to resolve it, just add vm options "--add-opens java.base/java.lang=ALL-UNNAMED"

So i think maybe it's a compatibility issue with CGLIB?
If there are other solutions or information, that will be very grateful.

[invzbl3]

@mazhewei, thank you, your post was very helpful for me!