Support OSGi

Signed-off-by: Jorge Bescos Gascon <jorge.bescos.gascon@oracle.com>

api/pom.xml

@@ -350,6 +350,10 @@
                         <Implementation-Title>${project.name}</Implementation-Title>
                         <Implementation-Vendor>${project.organization.name}</Implementation-Vendor>
                         <Implementation-Build-Id>${buildNumber}</Implementation-Build-Id>
+                        <Import-Package>
+                            !org.glassfish.hk2.osgiresourcelocator,
+                            *
+                        </Import-Package>
                     </instructions>
                 </configuration>
                 <executions>
@@ -404,6 +408,7 @@ Use is subject to <a href="{@docRoot}/doc-files/speclicense.html" target="_top">
                 <configuration>
                     <forkCount>2</forkCount>
                     <reuseForks>false</reuseForks>
+                    <trimStackTrace>false</trimStackTrace>
                 </configuration>
             </plugin>
             <plugin>

api/src/main/java/jakarta/mail/util/FactoryFinder.java

@@ -0,0 +1,151 @@
+/*
+ * 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 Public License v. 2.0, which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the
+ * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
+ * version 2 with the GNU Classpath Exception, which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ */
+
+package jakarta.mail.util;
+
+import java.lang.reflect.Method;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.Iterator;
+import java.util.ServiceLoader;
+
+class FactoryFinder {
+
+    /**
+     * Finds the implementation {@code Class} object for the given
+     * factory type.
+     * The arguments supplied must be used in order
+     * This method is package private so that this code can be shared.
+     *
+     * @return the {@code Class} object of the specified message factory
+     *
+     * @param factoryClass          factory abstract class or interface to be found
+     * @exception RuntimeException if there is an error
+     */
+    static <T> T find(Class<T> factoryClass) throws RuntimeException {
+
+        String factoryId = factoryClass.getName();
+
+        // Use the system property first
+        String className = fromSystemProperty(factoryId);
+        if (className != null) {
+            T result = newInstance(className);
+            if (result != null) {
+                return result;
+            }
+        }
+
+        // standard services: java.util.ServiceLoader
+        T factory = factoryFromServiceLoader(factoryClass);
+        if (factory != null) {
+            return factory;
+        }
+
+        // handling Glassfish/OSGi (platform specific default)
+        if (isOsgi()) {
+            T result = lookupUsingOSGiServiceLoader(factoryId);
+            if (result != null) {
+                return result;
+            }
+        }
+        throw new IllegalStateException("Not provider of " + factoryClass.getName() + " was found");
+    }
+
+    private static <T> T newInstance(String className) throws RuntimeException {
+        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+        checkPackageAccess(className);
+        Class<T> clazz = null;
+        try {
+            if (classLoader == null) {
+                clazz = (Class<T>) Class.forName(className);
+            } else {
+                clazz = (Class<T>) classLoader.loadClass(className);
+            }
+            return clazz.getConstructor().newInstance();
+        } catch (ReflectiveOperationException e) {
+            throw new IllegalArgumentException("Cannot instance " + className, e);
+        }
+    }
+
+    private static String fromSystemProperty(String factoryId) {
+        String systemProp = getSystemProperty(factoryId);
+        return systemProp;
+    }
+
+    private static String getSystemProperty(final String property) {
+        String value = AccessController.doPrivileged(new PrivilegedAction<String>() {
+            @Override
+            public String run() {
+                return System.getProperty(property);
+            }
+        });
+        return value;
+    }
+
+    private static final String OSGI_SERVICE_LOADER_CLASS_NAME = "org.glassfish.hk2.osgiresourcelocator.ServiceLoader";
+
+    private static boolean isOsgi() {
+        try {
+            Class.forName(OSGI_SERVICE_LOADER_CLASS_NAME);
+            return true;
+        } catch (ClassNotFoundException ignored) {
+        }
+        return false;
+    }
+
+    @SuppressWarnings({"unchecked"})
+    private static <T> T lookupUsingOSGiServiceLoader(String factoryId) {
+        try {
+            // Use reflection to avoid having any dependency on HK2 ServiceLoader class
+            Class<?> serviceClass = Class.forName(factoryId);
+            Class<?>[] args = new Class<?>[]{serviceClass};
+            Class<?> target = Class.forName(OSGI_SERVICE_LOADER_CLASS_NAME);
+            Method m = target.getMethod("lookupProviderInstances", Class.class);
+            Iterator<?> iter = ((Iterable<?>) m.invoke(null, (Object[]) args)).iterator();
+            return iter.hasNext() ? (T) iter.next() : null;
+        } catch (Exception ignored) {
+            // log and continue
+            return null;
+        }
+    }
+
+    private static <T> T factoryFromServiceLoader(Class<T> factory) {
+        try {
+            ServiceLoader<T> sl = ServiceLoader.load(factory);
+            Iterator<T> iter = sl.iterator();
+            if (iter.hasNext()) {
+                return iter.next();
+            } else {
+                return null;
+            }
+        } catch (Throwable t) {
+            // For example, ServiceConfigurationError can be thrown if the factory class is not declared with 'uses' in module-info
+            throw new IllegalStateException("Cannot load " + factory + " as ServiceLoader", t);
+        }
+    }
+
+    private 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));
+            }
+        }
+    }
+}
+

api/src/main/java/jakarta/mail/util/StreamProvider.java

@@ -174,12 +174,6 @@ public String getEncoder() {
      * @return a stream provider
      */
     public static StreamProvider provider() {
-        ServiceLoader<StreamProvider> sl = ServiceLoader.load(StreamProvider.class);
-        Iterator<StreamProvider> iter = sl.iterator();
-        if (iter.hasNext()) {
-            return iter.next();
-        } else {
-            throw new IllegalStateException("Not provider of " + StreamProvider.class.getName() + " was found");
-        }
+        return FactoryFinder.find(StreamProvider.class);
     }
 }

api/src/main/java/module-info.java

@@ -27,4 +27,6 @@
 
     uses jakarta.mail.Provider;
     uses jakarta.mail.util.StreamProvider;
+    //reflective call to java.beans.Beans.instantiate
+    requires static java.desktop;
 }

api/src/test/java/jakarta/mail/util/FactoryFinderTest.java

@@ -0,0 +1,62 @@
+/*
+ * 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 Public License v. 2.0, which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the
+ * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
+ * version 2 with the GNU Classpath Exception, which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ */
+
+package jakarta.mail.util;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.fail;
+
+import java.util.ServiceConfigurationError;
+
+import org.junit.Test;
+
+public class FactoryFinderTest {
+
+    @Test
+    public void specifiedInSystemProperty() {
+        System.setProperty(Class1.class.getName(), Class2.class.getName());
+        Class1 impl = FactoryFinder.find(Class1.class);
+        assertEquals(Class2.class, impl.getClass());
+    }
+
+    @Test
+    public void specifiedInServiceLoader() {
+        StreamProvider impl = FactoryFinder.find(StreamProvider.class);
+        assertEquals(DummyStreamProvider.class, impl.getClass());
+    }
+
+    @Test
+    public void doesNotExist() {
+        try {
+            FactoryFinder.find(Class2.class);
+            fail("IllegalStateException is expected");
+        } catch (IllegalStateException e) {
+            assertNull(e.getCause());
+        }
+        try {
+            FactoryFinder.find(Class3.class);
+            fail("IllegalStateException is expected");
+        } catch (IllegalStateException e) {
+            // java.util.ServiceConfigurationError: jakarta.mail.util.FactoryFinderTest$Class3: module jakarta.mail does not declare `uses`
+            assertEquals(ServiceConfigurationError.class, e.getCause().getClass());
+        }
+    }
+
+    public static class Class1 {}
+    public static class Class2 extends Class1 {}
+    public static class Class3 {}
+}

api/src/test/java/module-info.java

@@ -28,5 +28,6 @@
 
     uses jakarta.mail.Provider;
     uses jakarta.mail.util.StreamProvider;
+    uses jakarta.mail.util.FactoryFinderTest.Class2;
     provides jakarta.mail.util.StreamProvider with jakarta.mail.util.DummyStreamProvider;
 }