Classloaders

Articles

• Internals of Java Class Loading
• Inside Class Loaders
• Inside Class Loaders: debugging
• Understanding Network Class loaders
• Understanding Class.forName
• Get a load of that name!
• Find a way out of the ClassLoader maze
• Create a custom Java 1.2-style classloader
• J2EE Classloading Demystified
• BEA WebLogic Server classloading
• Understanding J2EE Application Server Class Loading Architectures
• Advanced Classloading in J2EE
• Tyler Jewel's article about EJB classloading schemes
• Class Loading in J2EE and Oracle9iAS Environments -PART II
• Classloading best practices
• Managing Component Dependencies Using ClassLoaders
• Websphere 6.1 classloaders

Open source projects

• http://classworlds.codehaus.org/ - a classloader framework
• http://which4j.dev.java.net/ - trouble shooting tool for "where am I getting this class from?" issue.

Class loader hints

If you want to load a given class from a dynamically determined jar file, here's the recipe:

    import java.net.*;

    String jarName = "/somedir/.../package.jar";
    URL url = new java.io.File(jarName).toURI().toURL();
    ClassLoader cl = URLClassLoader.newInstance(new URL[] {url});
    String clsName = "package.package.ClassName";
    Class cls = Class.forName(clsName, true, cl);

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