1 /* 2 * Copyright (c) 2009, 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 sun.misc; 27 28 import java.io.File; 29 import java.io.IOException; 30 import java.net.URLStreamHandlerFactory; 31 import sun.misc.URLClassPath; 32 33 /** 34 * BootClassLoaderHook defines an interface for a hook to inject 35 * into the bootstrap class loader. 36 * 37 * In jkernel build, the sun.jkernel.DownloadManager is set as 38 * a BootClassLoaderHook by the jkernel VM after the VM is initialized. 39 * 40 * In other JDK builds, no hook is set. 41 */ 42 public abstract class BootClassLoaderHook { 43 private static BootClassLoaderHook bootLoaderHook = null; 44 public static synchronized BootClassLoaderHook getHook() { 45 return bootLoaderHook; 46 } 47 48 public static synchronized void setHook(BootClassLoaderHook hook) { 49 if (!VM.isBooted()) { 50 throw new InternalError("hook can only be set after VM is booted"); 51 } 52 if (bootLoaderHook != null) { 53 throw new InternalError("hook should not be reinitialized"); 54 } 55 bootLoaderHook = hook; 56 } 57 58 protected BootClassLoaderHook() { 59 } 60 61 /** 62 * A method to be invoked before a class loader loads 63 * a bootstrap class. 64 * 65 * @param classname the binary name of the class 66 */ 67 public static void preLoadClass(String classname) { 68 BootClassLoaderHook hook = getHook(); 69 if (hook != null) { 70 hook.loadBootstrapClass(classname); 71 } 72 } 73 74 /** 75 * A method to be invoked before a class loader loads 76 * a resource. 77 * 78 * @param resourcename the resource name 79 */ 80 public static void preLoadResource(String resourcename) { 81 BootClassLoaderHook hook = getHook(); 82 if (hook != null) { 83 hook.getBootstrapResource(resourcename); 84 } 85 } 86 87 /** 88 * A method to be invoked before a library is loaded. 89 * 90 * @param libname the name of the library 91 */ 92 public static void preLoadLibrary(String libname) { 93 BootClassLoaderHook hook = getHook(); 94 if (hook != null) { 95 hook.loadLibrary(libname); 96 } 97 } 98 99 /** 100 * Returns a pathname of a JAR or class that the hook loads 101 * per this loadClass request; or null. 102 * 103 * @param classname the binary name of the class 104 */ 105 public abstract String loadBootstrapClass(String className); 106 107 /** 108 * Returns a pathname of a resource file that the hook loads 109 * per this getResource request; or null. 110 * 111 * @param resourceName the resource name 112 */ 113 public abstract String getBootstrapResource(String resourceName); 114 115 /** 116 * Returns true if the hook successfully performs an operation per 117 * this loadLibrary request; or false if it fails. 118 * 119 * @param libname the name of the library 120 */ 121 public abstract boolean loadLibrary(String libname); 122 123 /** 124 * Returns a bootstrap class path constructed by the hook. 125 * 126 * @param bcp VM's bootstrap class path 127 * @param factory Launcher's URL stream handler 128 */ 129 public abstract URLClassPath getBootstrapClassPath(URLClassPath bcp, 130 URLStreamHandlerFactory factory); 131 132 /** 133 * Returns true if the current thread is in the process of doing 134 * a prefetching operation. 135 */ 136 public abstract boolean isCurrentThreadPrefetching(); 137 138 /** 139 * Returns true if the hook successfully prefetches the specified file. 140 * 141 * @param name a platform independent pathname 142 */ 143 public abstract boolean prefetchFile(String name); 144 }