jakarta.activation.ServiceLoaderUtil Maven / Gradle / Ivy
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/*
* Copyright (c) 2021 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package jakarta.activation;
import java.util.ServiceLoader;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Shared ServiceLoader/FactoryFinder Utils shared among JAF, MAIL, SAAJ, JAXB and JAXWS
* Class duplicated to all those projects.
*
* @author [email protected]
*/
class ServiceLoaderUtil {
static P firstByServiceLoader(Class spiClass,
Logger logger,
ExceptionHandler handler) throws T {
logger.log(Level.FINE, "Using java.util.ServiceLoader to find {0}", spiClass.getName());
// service discovery
try {
ServiceLoader serviceLoader = ServiceLoader.load(spiClass);
for (P impl : serviceLoader) {
logger.log(Level.FINE, "ServiceProvider loading Facility used; returning object [{0}]", impl.getClass().getName());
return impl;
}
} catch (Throwable t) {
throw handler.createException(t, "Error while searching for service [" + spiClass.getName() + "]");
}
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));
}
}
}
@SuppressWarnings({"unchecked"})
static
Class
nullSafeLoadClass(String className, ClassLoader classLoader) throws ClassNotFoundException {
if (classLoader == null) {
return (Class
) Class.forName(className);
} else {
return (Class
) 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 P newInstance(String className,
String defaultImplClassName, ClassLoader classLoader,
final ExceptionHandler handler) throws T {
try {
Class cls = safeLoadClass(className, defaultImplClassName, classLoader);
return cls.getConstructor().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);
}
}
@SuppressWarnings({"unchecked"})
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
) Class.forName(className);
}
// not platform default implementation ...
throw se;
}
return nullSafeLoadClass(className, classLoader);
}
static ClassLoader contextClassLoader(ExceptionHandler exceptionHandler) throws T {
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);
}
}