001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.discovery.jdk; 018 019 import java.io.IOException; 020 import java.net.URL; 021 import java.util.Enumeration; 022 023 /** 024 * JDK Hooks to extract properties/resources. 025 */ 026 public abstract class JDKHooks { 027 028 private static final JDKHooks jdkHooks; 029 030 static { 031 jdkHooks = new JDK12Hooks(); 032 } 033 034 /** 035 * Hidden constructor, this class can't be directly instantiated. 036 */ 037 protected JDKHooks() { } 038 039 /** 040 * Return singleton object representing JVM hooks/tools. 041 * 042 * TODO: add logic to detect JDK level. 043 * 044 * @return The detected {@code JDKHooks} 045 */ 046 public static final JDKHooks getJDKHooks() { 047 return jdkHooks; 048 } 049 050 /** 051 * Get the system property 052 * 053 * @param propName name of the property 054 * @return value of the property 055 */ 056 public abstract String getSystemProperty(final String propName); 057 058 /** 059 * The thread context class loader is available for JDK 1.2 060 * or later, if certain security conditions are met. 061 * 062 * @return The thread context class loader, if available. 063 * Otherwise return null. 064 */ 065 public abstract ClassLoader getThreadContextClassLoader(); 066 067 /** 068 * The system class loader is available for JDK 1.2 069 * or later, if certain security conditions are met. 070 * 071 * @return The system class loader, if available. 072 * Otherwise return null. 073 */ 074 public abstract ClassLoader getSystemClassLoader(); 075 076 /** 077 * Resolve resource with given names and make them available in 078 * the returned iterator. 079 * 080 * @param loader The class loader used to resolve resources 081 * @param resourceName The resource name to resolve 082 * @return The iterator over the URL resolved resources 083 * @throws IOException if any error occurs while loading the resource 084 */ 085 public abstract Enumeration<URL> getResources(ClassLoader loader, String resourceName) throws IOException; 086 087 }