1 /* 2 * Copyright (C) 2008 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 21 /** 22 * A class loader that loads classes from {@code .jar} and {@code .apk} files 23 * containing a {@code classes.dex} entry. This can be used to execute code not 24 * installed as part of an application. 25 * 26 * <p>This class loader requires an application-private, writable directory to 27 * cache optimized classes. Use {@code Context.getCodeCacheDir()} to create 28 * such a directory: <pre> {@code 29 * File dexOutputDir = context.getCodeCacheDir(); 30 * }</pre> 31 * 32 * <p><strong>Do not cache optimized classes on external storage.</strong> 33 * External storage does not provide access controls necessary to protect your 34 * application from code injection attacks. 35 */ 36 public class DexClassLoader extends BaseDexClassLoader { 37 /** 38 * Creates a {@code DexClassLoader} that finds interpreted and native 39 * code. Interpreted classes are found in a set of DEX files contained 40 * in Jar or APK files. 41 * 42 * <p>The path lists are separated using the character specified by the 43 * {@code path.separator} system property, which defaults to {@code :}. 44 * 45 * @param dexPath the list of jar/apk files containing classes and 46 * resources, delimited by {@code File.pathSeparator}, which 47 * defaults to {@code ":"} on Android 48 * @param optimizedDirectory directory where optimized dex files 49 * should be written; must not be {@code null} 50 * @param librarySearchPath the list of directories containing native 51 * libraries, delimited by {@code File.pathSeparator}; may be 52 * {@code null} 53 * @param parent the parent class loader 54 */ DexClassLoader(String dexPath, String optimizedDirectory, String librarySearchPath, ClassLoader parent)55 public DexClassLoader(String dexPath, String optimizedDirectory, 56 String librarySearchPath, ClassLoader parent) { 57 super(dexPath, new File(optimizedDirectory), librarySearchPath, parent); 58 } 59 } 60