| /* |
| * Copyright (c) 2006, 2012, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| |
| |
| package com.sun.org.glassfish.gmbal.util; |
| |
| import java.lang.reflect.Constructor ; |
| import java.security.AccessController; |
| import java.security.PrivilegedExceptionAction; |
| import java.util.logging.Level; |
| import java.util.logging.Logger; |
| |
| /** Class that allows any class to be instantiated via any accessible constructor. |
| * Really a short hand to avoid writing a bunch of reflective code. |
| */ |
| public class GenericConstructor<T> { |
| private final Object lock = new Object() ; |
| |
| private String typeName ; |
| private Class<T> resultType ; |
| private Class<?> type ; |
| private Class<?>[] signature ; |
| |
| // Use the raw type of the constructor here, because |
| // MethodInfo can only return a raw type for a constructor. |
| // It is not possible to have MethodInfo return a |
| // Constructor<T> because T may not be known at compile time. |
| private Constructor constructor ; |
| |
| /** Create a generic of type T for the untyped class cls. |
| * Generally cls is a class that has been generated and loaded, so |
| * no compiled code can depend on the class directly. However, the |
| * generated class probably implements some interface T, represented |
| * here by Class<T>. |
| * @param type The expected type of a create call. |
| * @param className The name of the class to use for a constructor. |
| * @param signature The signature of the desired constructor. |
| * @throws IllegalArgumentException if cls is not a subclass of type. |
| */ |
| public GenericConstructor( final Class<T> type, final String className, |
| final Class<?>... signature ) { |
| this.resultType = type ; |
| this.typeName = className ; |
| this.signature = signature.clone() ; |
| } |
| |
| @SuppressWarnings("unchecked") |
| private void getConstructor() { |
| synchronized( lock ) { |
| if ((type == null) || (constructor == null)) { |
| try { |
| type = (Class<T>)Class.forName( typeName ) ; |
| constructor = AccessController.doPrivileged( |
| new PrivilegedExceptionAction<Constructor>() { |
| public Constructor run() throws Exception { |
| synchronized( lock ) { |
| return type.getDeclaredConstructor( signature ) ; |
| } |
| } |
| } ) ; |
| } catch (Exception exc) { |
| // Catch all for several checked exceptions: ignore findbugs |
| Logger.getLogger( "com.sun.org.glassfish.gmbal.util" ).log( Level.FINE, |
| "Failure in getConstructor", exc ) ; |
| } |
| } |
| } |
| } |
| |
| /** Create an instance of type T using the constructor that |
| * matches the given arguments if possible. The constructor |
| * is cached, so an instance of GenericClass should always be |
| * used for the same types of arguments. If a call fails, |
| * a check is made to see if a different constructor could |
| * be used. |
| * @param args The constructor arguments. |
| * @return A new instance of the object. |
| */ |
| public synchronized T create( Object... args ) { |
| synchronized(lock) { |
| T result = null ; |
| |
| for (int ctr=0; ctr<=1; ctr++) { |
| getConstructor() ; |
| if (constructor == null) { |
| break ; |
| } |
| |
| try { |
| result = resultType.cast( constructor.newInstance( args ) ) ; |
| break ; |
| } catch (Exception exc) { |
| // There are 4 checked exceptions here with identical handling. |
| // Ignore FindBugs complaints. |
| constructor = null ; |
| Logger.getLogger("com.sun.org.glassfish.gmbal.util"). |
| log(Level.WARNING, "Error invoking constructor", exc ); |
| } |
| } |
| |
| return result ; |
| } |
| } |
| } |