| Clover coverage report - PLT Utilities Test Coverage (plt-20120304-r5436) |
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| Source file | Conditionals | Statements | Methods | TOTAL | |||||||||||||||
| ShadowingClassLoader.java | 100% | 100% | 100% | 100% |
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| 1 | /*BEGIN_COPYRIGHT_BLOCK* | |
| 2 | ||
| 3 | PLT Utilities BSD License | |
| 4 | ||
| 5 | Copyright (c) 2007-2010 JavaPLT group at Rice University | |
| 6 | All rights reserved. | |
| 7 | ||
| 8 | Developed by: Java Programming Languages Team | |
| 9 | Rice University | |
| 10 | http://www.cs.rice.edu/~javaplt/ | |
| 11 | ||
| 12 | Redistribution and use in source and binary forms, with or without modification, are permitted | |
| 13 | provided that the following conditions are met: | |
| 14 | ||
| 15 | - Redistributions of source code must retain the above copyright notice, this list of conditions | |
| 16 | and the following disclaimer. | |
| 17 | - Redistributions in binary form must reproduce the above copyright notice, this list of | |
| 18 | conditions and the following disclaimer in the documentation and/or other materials provided | |
| 19 | with the distribution. | |
| 20 | - Neither the name of the JavaPLT group, Rice University, nor the names of the library's | |
| 21 | contributors may be used to endorse or promote products derived from this software without | |
| 22 | specific prior written permission. | |
| 23 | ||
| 24 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR | |
| 25 | IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND | |
| 26 | FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS AND | |
| 27 | CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 28 | DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 29 | DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER | |
| 30 | IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT | |
| 31 | OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 32 | ||
| 33 | *END_COPYRIGHT_BLOCK*/ | |
| 34 | ||
| 35 | package edu.rice.cs.plt.reflect; | |
| 36 | ||
| 37 | import java.net.URL; | |
| 38 | import edu.rice.cs.plt.iter.IterUtil; | |
| 39 | ||
| 40 | import static edu.rice.cs.plt.debug.DebugUtil.debug; | |
| 41 | ||
| 42 | /** | |
| 43 | * A class loader that hides a set of classes and related resources. This allows classes | |
| 44 | * with the same name (but perhaps a different implementation) to be cleanly loaded by a child loader. | |
| 45 | */ | |
| 46 | public class ShadowingClassLoader extends ClassLoader { | |
| 47 | ||
| 48 | private final Iterable<? extends String> _prefixes; | |
| 49 | private final boolean _blackList; | |
| 50 | private final boolean _filterBootClasses; | |
| 51 | ||
| 52 | /** | |
| 53 | * Create a ShadowingClassLoader that will hide non-bootstrap classes matching the given prefixes. | |
| 54 | * @param parent The parent loader | |
| 55 | * @param excludePrefixes A set of class name prefixes to match. Each prefix must be a package or class | |
| 56 | * name (partial names, like {@code "java.lang.Stri"}, will not match the full class | |
| 57 | * name). | |
| 58 | */ | |
| 59 | 4 | public static ShadowingClassLoader blackList(ClassLoader parent, String... excludePrefixes) { |
| 60 | 4 | return new ShadowingClassLoader(parent, true, IterUtil.asIterable(excludePrefixes), false); |
| 61 | } | |
| 62 | ||
| 63 | /** | |
| 64 | * Create a ShadowingClassLoader that will hide all non-bootstrap classes except those matching the | |
| 65 | * given prefixes. | |
| 66 | * @param parent The parent loader | |
| 67 | * @param includePrefixes A set of class name prefixes to match. Each prefix must be a package or class | |
| 68 | * name (partial names, like {@code "java.lang.Stri"}, will not match the full class | |
| 69 | * name). | |
| 70 | */ | |
| 71 | 2 | public static ShadowingClassLoader whiteList(ClassLoader parent, String... includePrefixes) { |
| 72 | 2 | return new ShadowingClassLoader(parent, false, IterUtil.asIterable(includePrefixes), false); |
| 73 | } | |
| 74 | ||
| 75 | /** | |
| 76 | * @param parent The parent loader | |
| 77 | * @param blackList If {@code true}, classes matching {@code prefixes} are prevented from loading; otherwise, | |
| 78 | * all classes <em>except</em> those matching {@code prefixes} are prevented from loading. | |
| 79 | * @param prefixes A set of class name prefixes to which class names will be compared. Each prefix must | |
| 80 | * be a package or class name (partial names, like {@code "java.lang.Stri"}, will not | |
| 81 | * match the full class name). | |
| 82 | * @param filterBootClasses Whether classes and resources available to the bootstrap class loader should | |
| 83 | * be hidden. If {@code true}, care must be taken to ensure that essential | |
| 84 | * classes (like {@code java.lang.Object}) are available when needed. | |
| 85 | */ | |
| 86 | 7 | public ShadowingClassLoader(ClassLoader parent, boolean blackList, Iterable<? extends String> prefixes, |
| 87 | boolean filterBootClasses) { | |
| 88 | 7 | super(parent); |
| 89 | 7 | _blackList = blackList; |
| 90 | 7 | _prefixes = prefixes; |
| 91 | 7 | _filterBootClasses = filterBootClasses; |
| 92 | } | |
| 93 | ||
| 94 | /** | |
| 95 | * If the given class is shadowed, a {@code ClassNotFoundException} will | |
| 96 | * occur; otherwise, the method delegates to the parent class loader. | |
| 97 | */ | |
| 98 | 15 | @Override protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException { |
| 99 | 15 | if ((_filterBootClasses || !isBootClass(name)) && matchesPrefixes(name) == _blackList) { |
| 100 | 6 | throw new ClassNotFoundException(name + " is being shadowed"); |
| 101 | } | |
| 102 | else { | |
| 103 | // can't use getParent().loadClass(name) because parent may be null | |
| 104 | 9 | return super.loadClass(name, resolve); |
| 105 | } | |
| 106 | } | |
| 107 | ||
| 108 | 2 | @Override public URL getResource(String name) { |
| 109 | 2 | if ((_filterBootClasses || !isBootResource(name)) && |
| 110 | matchesPrefixes(name.replace('/', '.')) == _blackList) { | |
| 111 | 1 | return null; |
| 112 | } | |
| 113 | else { | |
| 114 | // can't use getParent().getResource(name) because parent may be null | |
| 115 | 1 | return super.getResource(name); |
| 116 | } | |
| 117 | } | |
| 118 | ||
| 119 | // Ideally, we should override getResources() as well. Unfortunately, it's final in Java 1.4. | |
| 120 | ||
| 121 | /** As a side effect, loads the given class in the bootstrap class loader. */ | |
| 122 | 13 | private boolean isBootClass(String name) { |
| 123 | 3 | try { ReflectUtil.BOOT_CLASS_LOADER.loadClass(name); return true; } |
| 124 | 10 | catch (ClassNotFoundException e) { return false; } |
| 125 | } | |
| 126 | ||
| 127 | 2 | private boolean isBootResource(String name) { |
| 128 | 2 | return ReflectUtil.BOOT_CLASS_LOADER.getResource(name) != null; |
| 129 | } | |
| 130 | ||
| 131 | 14 | private boolean matchesPrefixes(String name) { |
| 132 | // TODO: improve efficiency by using a sorted data structure | |
| 133 | 14 | for (String p : _prefixes) { |
| 134 | 19 | if (name.startsWith(p)) { |
| 135 | 8 | if (name.equals(p) || name.startsWith(p + ".") || name.startsWith(p + "$")) { |
| 136 | 7 | return true; |
| 137 | } | |
| 138 | } | |
| 139 | } | |
| 140 | 7 | return false; |
| 141 | } | |
| 142 | ||
| 143 | } |
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