Injector.java

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package com.sun.xml.ws.model;

import javax.xml.ws.WebServiceException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * A {@link ClassLoader} used to "inject" wrapper and exception bean classes
 * into the VM.
 *
 * @author Jitendra kotamraju
 */
final class Injector {

    private static final Logger LOGGER = Logger.getLogger(Injector.class.getName());

    private static final Method defineClass;
    private static final Method resolveClass;
    private static final Method getPackage;
    private static final Method definePackage;

    static {
        Method[] m = AccessController.doPrivileged(
                new PrivilegedAction<Method[]>() {
                    @Override
                    public Method[] run() {
                        return new Method[]{
                                getMethod(ClassLoader.class, "defineClass", String.class, byte[].class, Integer.TYPE, Integer.TYPE),
                                getMethod(ClassLoader.class, "resolveClass", Class.class),
                                getMethod(ClassLoader.class, "getPackage", String.class),
                                getMethod(ClassLoader.class, "definePackage",
                                        String.class, String.class, String.class, String.class,
                                        String.class, String.class, String.class, URL.class)
                        };
                    }
                }
        );
        defineClass = m[0];
        resolveClass = m[1];
        getPackage = m[2];
        definePackage = m[3];
    }

    private static Method getMethod(final Class<?> c, final String methodname, final Class<?>... params) {
        try {
            Method m = c.getDeclaredMethod(methodname, params);
            m.setAccessible(true);
            return m;
        } catch (NoSuchMethodException e) {
            // impossible
            throw new NoSuchMethodError(e.getMessage());
        }
    }

    static synchronized Class inject(ClassLoader cl, String className, byte[] image) {
        // To avoid race conditions let us check if the classloader
        // already contains the class
        try {
            return cl.loadClass(className);
        } catch (ClassNotFoundException e) {
            // nothing to do
        }
        try {
            int packIndex = className.lastIndexOf('.');
            if (packIndex != -1) {
                String pkgname = className.substring(0, packIndex);
                // Check if package already loaded.
                Package pkg = (Package)getPackage.invoke(cl, pkgname);
                if (pkg == null) {
                    definePackage.invoke(cl, pkgname, null, null, null, null, null, null, null);
                }
            }

            Class c = (Class)defineClass.invoke(cl,className.replace('/','.'),image,0,image.length);
            resolveClass.invoke(cl, c);
            return c;
        } catch (IllegalAccessException e) {
            LOGGER.log(Level.FINE,"Unable to inject "+className,e);
            throw new WebServiceException(e);
        } catch (InvocationTargetException e) {
            LOGGER.log(Level.FINE,"Unable to inject "+className,e);
            throw new WebServiceException(e);
        }
    }

}