// Copyright 2014 The Bazel Authors. All rights reserved. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package com.google.devtools.build.android.incrementaldeployment; import android.util.Log; import dalvik.system.BaseDexClassLoader; import java.io.File; import java.lang.reflect.Field; import java.util.List; /** * A class loader that loads classes from any .dex file in a particular directory on the SD card. * * <p>Used to implement incremental deployment to Android phones. */ public class IncrementalClassLoader extends ClassLoader { private final DelegateClassLoader delegateClassLoader; public IncrementalClassLoader(ClassLoader original, String packageName, File codeCacheDir, String nativeLibDir, List<String> dexes) { super(original.getParent()); // TODO(bazel-team): For some mysterious reason, we need to use two class loaders so that // everything works correctly. Investigate why that is the case so that the code can be // simplified. delegateClassLoader = createDelegateClassLoader(codeCacheDir, nativeLibDir, dexes, original); } @Override public Class<?> findClass(String className) throws ClassNotFoundException { return delegateClassLoader.findClass(className); } /** * A class loader whose only purpose is to make {@code findClass()} public. */ private static class DelegateClassLoader extends BaseDexClassLoader { private DelegateClassLoader( String dexPath, File optimizedDirectory, String libraryPath, ClassLoader parent) { super(dexPath, optimizedDirectory, libraryPath, parent); } @Override public Class<?> findClass(String name) throws ClassNotFoundException { return super.findClass(name); } } private static DelegateClassLoader createDelegateClassLoader( File codeCacheDir, String nativeLibDir, List<String> dexes, ClassLoader original) { StringBuilder pathBuilder = new StringBuilder(); boolean first = true; for (String dex : dexes) { if (first) { first = false; } else { pathBuilder.append(File.pathSeparator); } pathBuilder.append(dex); } Log.v("IncrementalClassLoader", "Incremental dex path is " + pathBuilder); Log.v("IncrementalClassLoader", "Native lib dir is " + nativeLibDir); return new DelegateClassLoader(pathBuilder.toString(), codeCacheDir, nativeLibDir, original); } private static void setParent(ClassLoader classLoader, ClassLoader newParent) { try { Field parent = ClassLoader.class.getDeclaredField("parent"); parent.setAccessible(true); parent.set(classLoader, newParent); } catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException e) { throw new RuntimeException(e); } } public static void inject( ClassLoader classLoader, String packageName, File codeCacheDir, String nativeLibDir, List<String> dexes) { IncrementalClassLoader incrementalClassLoader = new IncrementalClassLoader(classLoader, packageName, codeCacheDir, nativeLibDir, dexes); setParent(classLoader, incrementalClassLoader); } }