Question

I’m having problems deploying a Spring web app to Tomcat 6.0. I want to deploy some jars to the shared/lib (catalina.properties is correctly configured); these jars contain various bean definitions. The main application, deployed to the webapps directory, uses:

<import resource="classpath*:com/**/*.xml"/>

to pick up the bean definitions in the jars deployed to shared/lib.

Some of the beans deployed to shared/lib have been updated and now implement the MessageSourceAware interface; when the app now starts, I get the following error:

Caused by: java.lang.NoClassDefFoundError: org/springframework/context/MessageSourceAware
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1667)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
    at org.springframework.util.ClassUtils.forName(ClassUtils.java:257)
    at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:408)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doResolveBeanClass(AbstractBeanFactory.java:1282)
    at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1253)
    ... 72 more
Caused by: java.lang.ClassNotFoundException: org.springframework.context.MessageSourceAware
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
    ... 89 more

If the jars are moved from shared/lib to the WEB-INF/lib directory of the app, obviously everything works OK, but I’d like to keep the jars in shared/lib if at all possible.

This looks like a classloader issue, but hasn’t the spring-context.jar in WEB-INF/lib already been loaded by the time Spring tries to create the beans in the shared/lib jars?

I’m confused; any help would be much appreciated.

Answer 1

Realised in the end that the shared/lib folder is exactly the wrong place to put these extension jars, owing to the hierarchical nature of the classloaders in Tomcat.

Instead, I wrote my own class loader that extends Tomcat’s WebappClassLoader:

public class CustomWebappClassLoader extends WebappClassLoader {

    public CustomWebappClassLoader() {
        super();
        addCustomRepository();
    }

    public CustomWebappClassLoader(ClassLoader parent) {
        super(parent);
        addCustomRepository();
    }

    private void addCustomRepository() {
        String catalinaHome = System.getProperty("catalina.home");
        File dir = new File(catalinaHome, String.format("extensions%slib", File.separator));
        for (File file : dir.listFiles()) {
            if (file.getName().endsWith(".jar")) {
                String repository = String.format("file:/%s", file.getAbsolutePath());
                addRepository(repository);
            }
        }
    }
}

This adds any jars in %CATALINA_HOME%/extensions/lib to the classpath (along with WEB-INF/classes and WEB-INF/lib for the application).

The following line is then needed in context.xml:

<Loader loaderClass="com.test.CustomWebappClassLoader" delegate="true"/>