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| 1 | /* | ||
| 2 | * Copyright (c) 2002, 2007, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package javax.management.loading; | ||
| 27 | |||
| 28 | import javax.management.MBeanServer; // for Javadoc | ||
| 29 | |||
| 30 | /** | ||
| 31 | * <p>Instances of this interface are used to keep the list of ClassLoaders | ||
| 32 | * registered in an MBean Server. | ||
| 33 | * They provide the necessary methods to load classes using the registered | ||
| 34 | * ClassLoaders.</p> | ||
| 35 | * | ||
| 36 | * <p>The first ClassLoader in a <code>ClassLoaderRepository</code> is | ||
| 37 | * always the MBean Server's own ClassLoader.</p> | ||
| 38 | * | ||
| 39 | * <p>When an MBean is registered in an MBean Server, if it is of a | ||
| 40 | * subclass of {@link java.lang.ClassLoader} and if it does not | ||
| 41 | * implement the interface {@link PrivateClassLoader}, it is added to | ||
| 42 | * the end of the MBean Server's <code>ClassLoaderRepository</code>. | ||
| 43 | * If it is subsequently unregistered from the MBean Server, it is | ||
| 44 | * removed from the <code>ClassLoaderRepository</code>.</p> | ||
| 45 | * | ||
| 46 | * <p>The order of MBeans in the <code>ClassLoaderRepository</code> is | ||
| 47 | * significant. For any two MBeans <em>X</em> and <em>Y</em> in the | ||
| 48 | * <code>ClassLoaderRepository</code>, <em>X</em> must appear before | ||
| 49 | * <em>Y</em> if the registration of <em>X</em> was completed before | ||
| 50 | * the registration of <em>Y</em> started. If <em>X</em> and | ||
| 51 | * <em>Y</em> were registered concurrently, their order is | ||
| 52 | * indeterminate. The registration of an MBean corresponds to the | ||
| 53 | * call to {@link MBeanServer#registerMBean} or one of the {@link | ||
| 54 | * MBeanServer}<code>.createMBean</code> methods.</p> | ||
| 55 | * | ||
| 56 | * @see javax.management.MBeanServerFactory | ||
| 57 | * | ||
| 58 | * @since 1.5 | ||
| 59 | */ | ||
| 60 | public interface ClassLoaderRepository { | ||
| 61 | |||
| 62 | /** | ||
| 63 | * <p>Load the given class name through the list of class loaders. | ||
| 64 | * Each ClassLoader in turn from the ClassLoaderRepository is | ||
| 65 | * asked to load the class via its {@link | ||
| 66 | * ClassLoader#loadClass(String)} method. If it successfully | ||
| 67 | * returns a {@link Class} object, that is the result of this | ||
| 68 | * method. If it throws a {@link ClassNotFoundException}, the | ||
| 69 | * search continues with the next ClassLoader. If it throws | ||
| 70 | * another exception, the exception is propagated from this | ||
| 71 | * method. If the end of the list is reached, a {@link | ||
| 72 | * ClassNotFoundException} is thrown.</p> | ||
| 73 | * | ||
| 74 | * @param className The name of the class to be loaded. | ||
| 75 | * | ||
| 76 | * @return the loaded class. | ||
| 77 | * | ||
| 78 | * @exception ClassNotFoundException The specified class could not be | ||
| 79 | * found. | ||
| 80 | */ | ||
| 81 | public Class<?> loadClass(String className) | ||
| 82 | throws ClassNotFoundException; | ||
| 83 | |||
| 84 | /** | ||
| 85 | * <p>Load the given class name through the list of class loaders, | ||
| 86 | * excluding the given one. Each ClassLoader in turn from the | ||
| 87 | * ClassLoaderRepository, except <code>exclude</code>, is asked to | ||
| 88 | * load the class via its {@link ClassLoader#loadClass(String)} | ||
| 89 | * method. If it successfully returns a {@link Class} object, | ||
| 90 | * that is the result of this method. If it throws a {@link | ||
| 91 | * ClassNotFoundException}, the search continues with the next | ||
| 92 | * ClassLoader. If it throws another exception, the exception is | ||
| 93 | * propagated from this method. If the end of the list is | ||
| 94 | * reached, a {@link ClassNotFoundException} is thrown.</p> | ||
| 95 | * | ||
| 96 | * <p>Be aware that if a ClassLoader in the ClassLoaderRepository | ||
| 97 | * calls this method from its {@link ClassLoader#loadClass(String) | ||
| 98 | * loadClass} method, it exposes itself to a deadlock if another | ||
| 99 | * ClassLoader in the ClassLoaderRepository does the same thing at | ||
| 100 | * the same time. The {@link #loadClassBefore} method is | ||
| 101 | * recommended to avoid the risk of deadlock.</p> | ||
| 102 | * | ||
| 103 | * @param className The name of the class to be loaded. | ||
| 104 | * @param exclude The class loader to be excluded. May be null, | ||
| 105 | * in which case this method is equivalent to {@link #loadClass | ||
| 106 | * loadClass(className)}. | ||
| 107 | * | ||
| 108 | * @return the loaded class. | ||
| 109 | * | ||
| 110 | * @exception ClassNotFoundException The specified class could not | ||
| 111 | * be found. | ||
| 112 | */ | ||
| 113 | public Class<?> loadClassWithout(ClassLoader exclude, | ||
| 114 | String className) | ||
| 115 | throws ClassNotFoundException; | ||
| 116 | |||
| 117 | /** | ||
| 118 | * <p>Load the given class name through the list of class loaders, | ||
| 119 | * stopping at the given one. Each ClassLoader in turn from the | ||
| 120 | * ClassLoaderRepository is asked to load the class via its {@link | ||
| 121 | * ClassLoader#loadClass(String)} method. If it successfully | ||
| 122 | * returns a {@link Class} object, that is the result of this | ||
| 123 | * method. If it throws a {@link ClassNotFoundException}, the | ||
| 124 | * search continues with the next ClassLoader. If it throws | ||
| 125 | * another exception, the exception is propagated from this | ||
| 126 | * method. If the search reaches <code>stop</code> or the end of | ||
| 127 | * the list, a {@link ClassNotFoundException} is thrown.</p> | ||
| 128 | * | ||
| 129 | * <p>Typically this method is called from the {@link | ||
| 130 | * ClassLoader#loadClass(String) loadClass} method of | ||
| 131 | * <code>stop</code>, to consult loaders that appear before it | ||
| 132 | * in the <code>ClassLoaderRepository</code>. By stopping the | ||
| 133 | * search as soon as <code>stop</code> is reached, a potential | ||
| 134 | * deadlock with concurrent class loading is avoided.</p> | ||
| 135 | * | ||
| 136 | * @param className The name of the class to be loaded. | ||
| 137 | * @param stop The class loader at which to stop. May be null, in | ||
| 138 | * which case this method is equivalent to {@link #loadClass(String) | ||
| 139 | * loadClass(className)}. | ||
| 140 | * | ||
| 141 | * @return the loaded class. | ||
| 142 | * | ||
| 143 | * @exception ClassNotFoundException The specified class could not | ||
| 144 | * be found. | ||
| 145 | * | ||
| 146 | */ | ||
| 147 | public Class<?> loadClassBefore(ClassLoader stop, | ||
| 148 | String className) | ||
| 149 | throws ClassNotFoundException; | ||
| 150 | |||
| 151 | } | ||