1 /* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package dalvik.system; 18 19 import java.io.File; 20 import java.net.URL; 21 import java.nio.ByteBuffer; 22 import java.util.ArrayList; 23 import java.util.Enumeration; 24 import java.util.List; 25 26 /** 27 * Base class for common functionality between various dex-based 28 * {@link ClassLoader} implementations. 29 */ 30 public class BaseDexClassLoader extends ClassLoader { 31 32 /** 33 * Hook for customizing how dex files loads are reported. 34 * 35 * This enables the framework to monitor the use of dex files. The 36 * goal is to simplify the mechanism for optimizing foreign dex files and 37 * enable further optimizations of secondary dex files. 38 * 39 * The reporting happens only when new instances of BaseDexClassLoader 40 * are constructed and will be active only after this field is set with 41 * {@link BaseDexClassLoader#setReporter}. 42 */ 43 /* @NonNull */ private static volatile Reporter reporter = null; 44 45 private final DexPathList pathList; 46 47 /** 48 * Constructs an instance. 49 * Note that all the *.jar and *.apk files from {@code dexPath} might be 50 * first extracted in-memory before the code is loaded. This can be avoided 51 * by passing raw dex files (*.dex) in the {@code dexPath}. 52 * 53 * @param dexPath the list of jar/apk files containing classes and 54 * resources, delimited by {@code File.pathSeparator}, which 55 * defaults to {@code ":"} on Android. 56 * @param optimizedDirectory this parameter is deprecated and has no effect 57 * @param librarySearchPath the list of directories containing native 58 * libraries, delimited by {@code File.pathSeparator}; may be 59 * {@code null} 60 * @param parent the parent class loader 61 */ 62 public BaseDexClassLoader(String dexPath, File optimizedDirectory, 63 String librarySearchPath, ClassLoader parent) { 64 super(parent); 65 this.pathList = new DexPathList(this, dexPath, librarySearchPath, null); 66 67 if (reporter != null) { 68 reporter.report(this.pathList.getDexPaths()); 69 } 70 } 71 72 /** 73 * Constructs an instance. 74 * 75 * dexFile must be an in-memory representation of a full dexFile. 76 * 77 * @param dexFiles the array of in-memory dex files containing classes. 78 * @param parent the parent class loader 79 * 80 * @hide 81 */ 82 public BaseDexClassLoader(ByteBuffer[] dexFiles, ClassLoader parent) { 83 // TODO We should support giving this a library search path maybe. 84 super(parent); 85 this.pathList = new DexPathList(this, dexFiles); 86 } 87 88 @Override 89 protected Class<?> findClass(String name) throws ClassNotFoundException { 90 List<Throwable> suppressedExceptions = new ArrayList<Throwable>(); 91 Class c = pathList.findClass(name, suppressedExceptions); 92 if (c == null) { 93 ClassNotFoundException cnfe = new ClassNotFoundException( 94 "Didn't find class \"" + name + "\" on path: " + pathList); 95 for (Throwable t : suppressedExceptions) { 96 cnfe.addSuppressed(t); 97 } 98 throw cnfe; 99 } 100 return c; 101 } 102 103 /** 104 * @hide 105 */ 106 public void addDexPath(String dexPath) { 107 pathList.addDexPath(dexPath, null /*optimizedDirectory*/); 108 } 109 110 @Override 111 protected URL findResource(String name) { 112 return pathList.findResource(name); 113 } 114 115 @Override 116 protected Enumeration<URL> findResources(String name) { 117 return pathList.findResources(name); 118 } 119 120 @Override 121 public String findLibrary(String name) { 122 return pathList.findLibrary(name); 123 } 124 125 /** 126 * Returns package information for the given package. 127 * Unfortunately, instances of this class don't really have this 128 * information, and as a non-secure {@code ClassLoader}, it isn't 129 * even required to, according to the spec. Yet, we want to 130 * provide it, in order to make all those hopeful callers of 131 * {@code myClass.getPackage().getName()} happy. Thus we construct 132 * a {@code Package} object the first time it is being requested 133 * and fill most of the fields with dummy values. The {@code 134 * Package} object is then put into the {@code ClassLoader}'s 135 * package cache, so we see the same one next time. We don't 136 * create {@code Package} objects for {@code null} arguments or 137 * for the default package. 138 * 139 * <p>There is a limited chance that we end up with multiple 140 * {@code Package} objects representing the same package: It can 141 * happen when when a package is scattered across different JAR 142 * files which were loaded by different {@code ClassLoader} 143 * instances. This is rather unlikely, and given that this whole 144 * thing is more or less a workaround, probably not worth the 145 * effort to address. 146 * 147 * @param name the name of the class 148 * @return the package information for the class, or {@code null} 149 * if there is no package information available for it 150 */ 151 @Override 152 protected synchronized Package getPackage(String name) { 153 if (name != null && !name.isEmpty()) { 154 Package pack = super.getPackage(name); 155 156 if (pack == null) { 157 pack = definePackage(name, "Unknown", "0.0", "Unknown", 158 "Unknown", "0.0", "Unknown", null); 159 } 160 161 return pack; 162 } 163 164 return null; 165 } 166 167 /** 168 * @hide 169 */ 170 public String getLdLibraryPath() { 171 StringBuilder result = new StringBuilder(); 172 for (File directory : pathList.getNativeLibraryDirectories()) { 173 if (result.length() > 0) { 174 result.append(':'); 175 } 176 result.append(directory); 177 } 178 179 return result.toString(); 180 } 181 182 @Override public String toString() { 183 return getClass().getName() + "[" + pathList + "]"; 184 } 185 186 /** 187 * Sets the reporter for dex load notifications. 188 * Once set, all new instances of BaseDexClassLoader will report upon 189 * constructions the loaded dex files. 190 * 191 * @param newReporter the new Reporter. Setting null will cancel reporting. 192 * @hide 193 */ 194 public static void setReporter(Reporter newReporter) { 195 reporter = newReporter; 196 } 197 198 /** 199 * @hide 200 */ 201 public static Reporter getReporter() { 202 return reporter; 203 } 204 205 /** 206 * @hide 207 */ 208 public interface Reporter { 209 public void report(List<String> dexPaths); 210 } 211 } 212
