| // 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); |
| } |
| } |