英文:
DocumentBuilder.class operator loads the class in System Classloader
问题
我们正在使用子优先（Child first）类加载器来避免JAR冲突，并从特定路径加载类。通过服务加载器和xml-apis JAR在子类加载器的类路径中，我们遇到了问题。
xerces2 JAR的服务加载器会使用org.apache.xerces.jaxp.DocumentBuilderFactoryImpl来创建javax.xml.parsers.DocumentBuilderFactory的对象，如果类路径中不存在DocumentBuilderFactoryImpl，则会加载rt.jar中的备用类。在正常情况下，代码可以正常运行。
在System类加载器的基础上使用子优先类加载器时，我们在以下代码行中遇到了问题。
DocumentBuilderFactory newInstance()
上面的代码用于创建对象。该方法的详细信息如下：
public static DocumentBuilderFactory newInstance() {
return (DocumentBuilderFactory)FactoryFinder.find(DocumentBuilderFactory.class, "com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl");
}
find方法的第一个参数，
DocumentBuilderFactory.class
创建了javax.xml.parsers.DocumentBuilderFactory类的类对象。但是，即使我们已经将类加载器设置为子类加载器，.class 操作符仍会使用System类加载器加载类并创建类对象，而不是当前子类加载器。
在服务加载器内部，使用子类加载器为org.apache.xerces.jaxp.DocumentBuilderFactoryImpl创建对象，而子优先类加载器会加载javax.xml.parsers.DocumentBuilderFactory类。
由于DocumentBuilderFactory.class加载在系统类加载器中，而org.apache.xerces.jaxp.DocumentBuilderFactoryImpl类加载在顶层子类加载器中，两者不能相互赋值，因为javax.xml.parsers.DocumentBuilderFactory是在不同的类加载器中创建的。
我的问题是，
有没有办法避免DocumentBuilder.class加载到系统类加载器中？
对于子优先类加载器，我们正在使用以下库：
https://github.com/kamranzafar/JCL/
英文:
We are using Child first classloader to avoid jar conflicts and load the classes from a particular path. With the service loader and the xml-apis jar in the child classloader's classpath, we are facing issues.
xerces2 jars service loader creates an object of javax.xml.parsers.DocumentBuilderFactory with org.apache.xerces.jaxp.DocumentBuilderFactoryImpl if DocumentBuilderFactoryImpl not present in the classpath, It loads the fallback class present in the rt.jar. Under normal circumstances, the code works fine.
With using child first classloader on top of System classloader, we facing issues in the following lines.
DocumentBuilderFactory newInstance()
the above line is used for creating the object. The method details are,
public static DocumentBuilderFactory newInstance() {
return (DocumentBuilderFactory)FactoryFinder.find(DocumentBuilderFactory.class, "com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl");
}
The first argument to the find method,
> DocumentBuilderFactory.class
>
> creates a class object for javax.xml.parsers.DocumentBuilderFactory
> class. but even we have set the classloader with child classloader,
> .class operator loads the class with System classloader and creates a
> class object, not with the current child classloader on top
.
Inside the service loader, creates an object for org.apache.xerces.jaxp.DocumentBuilderFactoryImpl with child classloader and the child first classloader loads the javax.xml.parsers.DocumentBuilderFactory class.
As the DocumentBuilderFactory.class loaded in the system classloader and the org.apache.xerces.jaxp.DocumentBuilderFactoryImpl class loaded in the top child classloaders are not assignable to each other as both javax.xml.parsers.DocumentBuilderFactory is created in separate classloaders.
My question is,
Is there any way to avoid the DocumentBuilder.class from loading to the system classloader?
For child first classloader we are using the following library
https://github.com/kamranzafar/JCL/
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