javax.xml.bind.ServiceLoaderUtil Maven / Gradle / Ivy
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package javax.xml.bind;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Iterator;
import java.util.ServiceLoader;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Shared ServiceLoader/FactoryFinder Utils shared among SAAJ, JAXB and JAXWS
* - this class must be duplicated to all those projects, but it's
* basically generic code and we want to have it everywhere same.
*
* @author [email protected]
*/
class ServiceLoaderUtil {
private static final String OSGI_SERVICE_LOADER_CLASS_NAME = "org.glassfish.hk2.osgiresourcelocator.ServiceLoader";
private static final String OSGI_SERVICE_LOADER_METHOD_NAME = "lookupProviderClasses";
static P firstByServiceLoader(Class spiClass,
Logger logger,
ExceptionHandler handler) throws T {
// service discovery
try {
ServiceLoader serviceLoader = ServiceLoader.load(spiClass);
for (P impl : serviceLoader) {
logger.fine("ServiceProvider loading Facility used; returning object [" +
impl.getClass().getName() + "]");
return impl;
}
} catch (Throwable t) {
throw handler.createException(t, "Error while searching for service [" + spiClass.getName() + "]");
}
return null;
}
static Object lookupUsingOSGiServiceLoader(String factoryId, Logger logger) {
try {
// Use reflection to avoid having any dependendcy on ServiceLoader class
Class serviceClass = Class.forName(factoryId);
Class target = Class.forName(OSGI_SERVICE_LOADER_CLASS_NAME);
Method m = target.getMethod(OSGI_SERVICE_LOADER_METHOD_NAME, Class.class);
Iterator iter = ((Iterable) m.invoke(null, serviceClass)).iterator();
if (iter.hasNext()) {
Object next = iter.next();
logger.fine("Found implementation using OSGi facility; returning object [" +
next.getClass().getName() + "].");
return next;
} else {
return null;
}
} catch (IllegalAccessException |
InvocationTargetException |
ClassNotFoundException |
NoSuchMethodException ignored) {
logger.log(Level.FINE, "Unable to find from OSGi: [" + factoryId + "]", ignored);
return null;
}
}
static void checkPackageAccess(String className) {
// make sure that the current thread has an access to the package of the given name.
SecurityManager s = System.getSecurityManager();
if (s != null) {
int i = className.lastIndexOf('.');
if (i != -1) {
s.checkPackageAccess(className.substring(0, i));
}
}
}
static Class nullSafeLoadClass(String className, ClassLoader classLoader) throws ClassNotFoundException {
if (classLoader == null) {
return Class.forName(className);
} else {
return classLoader.loadClass(className);
}
}
// Returns instance of required class. It checks package access (security)
// unless it is defaultClassname. It means if you are trying to instantiate
// default implementation (fallback), pass the class name to both first and second parameter.
static Object newInstance(String className,
String defaultImplClassName,
final ExceptionHandler handler) throws T {
try {
return safeLoadClass(className, defaultImplClassName, contextClassLoader(handler)).newInstance();
} catch (ClassNotFoundException x) {
throw handler.createException(x, "Provider " + className + " not found");
} catch (Exception x) {
throw handler.createException(x, "Provider " + className + " could not be instantiated: " + x);
}
}
static Class safeLoadClass(String className,
String defaultImplClassName,
ClassLoader classLoader) throws ClassNotFoundException {
try {
checkPackageAccess(className);
} catch (SecurityException se) {
// anyone can access the platform default factory class without permission
if (defaultImplClassName != null && defaultImplClassName.equals(className)) {
return Class.forName(className);
}
// not platform default implementation ...
throw se;
}
return nullSafeLoadClass(className, classLoader);
}
static ClassLoader contextClassLoader(ExceptionHandler exceptionHandler) throws Exception {
try {
return Thread.currentThread().getContextClassLoader();
} catch (Exception x) {
throw exceptionHandler.createException(x, x.toString());
}
}
static abstract class ExceptionHandler {
public abstract T createException(Throwable throwable, String message);
}
}