dalvik.system.BaseDexClassLoader Maven / Gradle / Ivy
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/*
* Copyright (C) 2011 The Android Open Source Project
*
* 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 dalvik.system;
//import dalvik.annotation.compat.UnsupportedAppUsage;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Enumeration;
import java.util.List;
/**
* Base class for common functionality between various dex-based
* {@link ClassLoader} implementations.
*/
public class BaseDexClassLoader extends ClassLoader {
/**
* Hook for customizing how dex files loads are reported.
*
* This enables the framework to monitor the use of dex files. The
* goal is to simplify the mechanism for optimizing foreign dex files and
* enable further optimizations of secondary dex files.
*
* The reporting happens only when new instances of BaseDexClassLoader
* are constructed and will be active only after this field is set with
* {@link BaseDexClassLoader#setReporter}.
*/
/* @NonNull */ private static volatile Reporter reporter = null;
// //@UnsupportedAppUsage
private final DexPathList pathList;
/**
* Array of ClassLoaders that can be used to load classes and resources that the code in
* {@code pathList} may depend on. This is used to implement Android's
*
* shared libraries feature.
* The shared library loaders are always checked before the {@code pathList} when looking
* up classes and resources.
*
*
{@code null} if the class loader has no shared library.
*
* @hide
*/
protected final ClassLoader[] sharedLibraryLoaders;
/**
* Constructs an instance.
* Note that all the *.jar and *.apk files from {@code dexPath} might be
* first extracted in-memory before the code is loaded. This can be avoided
* by passing raw dex files (*.dex) in the {@code dexPath}.
*
* @param dexPath the list of jar/apk files containing classes and
* resources, delimited by {@code File.pathSeparator}, which
* defaults to {@code ":"} on Android.
* @param optimizedDirectory this parameter is deprecated and has no effect since API level 26.
* @param librarySearchPath the list of directories containing native
* libraries, delimited by {@code File.pathSeparator}; may be
* {@code null}
* @param parent the parent class loader
*/
public BaseDexClassLoader(String dexPath, File optimizedDirectory,
String librarySearchPath, ClassLoader parent) {
this(dexPath, librarySearchPath, parent, null, false);
}
/**
* @hide
*/
//@UnsupportedAppUsage
public BaseDexClassLoader(String dexPath, File optimizedDirectory,
String librarySearchPath, ClassLoader parent, boolean isTrusted) {
this(dexPath, librarySearchPath, parent, null, isTrusted);
}
/**
* @hide
*/
public BaseDexClassLoader(String dexPath,
String librarySearchPath, ClassLoader parent, ClassLoader[] libraries) {
this(dexPath, librarySearchPath, parent, libraries, false);
}
/**
* BaseDexClassLoader implements the Android
*
* shared libraries feature by changing the typical parent delegation mechanism
* of class loaders.
*
Each shared library is associated with its own class loader, which is added to a list of
* class loaders this BaseDexClassLoader tries to load from in order, immediately checking
* after the parent.
* The shared library loaders are always checked before the {@code pathList} when looking
* up classes and resources.
*
* @hide
*/
public BaseDexClassLoader(String dexPath,
String librarySearchPath, ClassLoader parent, ClassLoader[] sharedLibraryLoaders,
boolean isTrusted) {
super(parent);
// Setup shared libraries before creating the path list. ART relies on the class loader
// hierarchy being finalized before loading dex files.
this.sharedLibraryLoaders = sharedLibraryLoaders == null
? null
: Arrays.copyOf(sharedLibraryLoaders, sharedLibraryLoaders.length);
this.pathList = new DexPathList(this, dexPath, librarySearchPath, null, isTrusted);
if (reporter != null) {
reportClassLoaderChain();
}
}
/**
* Reports the current class loader chain to the registered {@code reporter}.
*/
private void reportClassLoaderChain() {
throw new UnsupportedOperationException("STUB");
}
/**
* Constructs an instance.
*
* dexFile must be an in-memory representation of a full dexFile.
*
* @param dexFiles the array of in-memory dex files containing classes.
* @param librarySearchPath the list of directories containing native
* libraries, delimited by {@code File.pathSeparator}; may be {@code null}
* @param parent the parent class loader
*
* @hide
*/
public BaseDexClassLoader(ByteBuffer[] dexFiles, String librarySearchPath, ClassLoader parent) {
super(parent);
this.pathList = new DexPathList(this, dexFiles, librarySearchPath);
this.sharedLibraryLoaders = null;
}
@Override
protected Class findClass(String name) throws ClassNotFoundException {
// First, check whether the class is present in our shared libraries.
if (sharedLibraryLoaders != null) {
for (ClassLoader loader : sharedLibraryLoaders) {
try {
return loader.loadClass(name);
} catch (ClassNotFoundException ignored) {
}
}
}
// Check whether the class in question is present in the dexPath that
// this classloader operates on.
List suppressedExceptions = new ArrayList();
Class c = pathList.findClass(name, suppressedExceptions);
if (c == null) {
ClassNotFoundException cnfe = new ClassNotFoundException(
"Didn't find class \"" + name + "\" on path: " + pathList);
for (Throwable t : suppressedExceptions) {
cnfe.addSuppressed(t);
}
throw cnfe;
}
return c;
}
/**
* @hide
*/
//@UnsupportedAppUsage
//@libcore.api.CorePlatformApi
public void addDexPath(String dexPath) {
addDexPath(dexPath, false /*isTrusted*/);
}
/**
* @hide
*/
//@UnsupportedAppUsage
public void addDexPath(String dexPath, boolean isTrusted) {
pathList.addDexPath(dexPath, null /*optimizedDirectory*/, isTrusted);
}
/**
* Adds additional native paths for consideration in subsequent calls to
* {@link #findLibrary(String)}
* @hide
*/
//@libcore.api.CorePlatformApi
public void addNativePath(Collection libPaths) {
pathList.addNativePath(libPaths);
}
@Override
protected URL findResource(String name) {
if (sharedLibraryLoaders != null) {
for (ClassLoader loader : sharedLibraryLoaders) {
URL url = loader.getResource(name);
if (url != null) {
return url;
}
}
}
return pathList.findResource(name);
}
@Override
protected Enumeration findResources(String name) {
throw new UnsupportedOperationException("STUB");
}
@Override
public String findLibrary(String name) {
return pathList.findLibrary(name);
}
/**
* Returns package information for the given package.
* Unfortunately, instances of this class don't really have this
* information, and as a non-secure {@code ClassLoader}, it isn't
* even required to, according to the spec. Yet, we want to
* provide it, in order to make all those hopeful callers of
* {@code myClass.getPackage().getName()} happy. Thus we construct
* a {@code Package} object the first time it is being requested
* and fill most of the fields with dummy values. The {@code
* Package} object is then put into the {@code ClassLoader}'s
* package cache, so we see the same one next time. We don't
* create {@code Package} objects for {@code null} arguments or
* for the default package.
*
* There is a limited chance that we end up with multiple
* {@code Package} objects representing the same package: It can
* happen when when a package is scattered across different JAR
* files which were loaded by different {@code ClassLoader}
* instances. This is rather unlikely, and given that this whole
* thing is more or less a workaround, probably not worth the
* effort to address.
*
* @param name the name of the class
* @return the package information for the class, or {@code null}
* if there is no package information available for it
*/
@Override
protected synchronized Package getPackage(String name) {
if (name != null && !name.isEmpty()) {
Package pack = super.getPackage(name);
if (pack == null) {
pack = definePackage(name, "Unknown", "0.0", "Unknown",
"Unknown", "0.0", "Unknown", null);
}
return pack;
}
return null;
}
/**
* @hide
*/
//@UnsupportedAppUsage
//@libcore.api.CorePlatformApi
public String getLdLibraryPath() {
StringBuilder result = new StringBuilder();
for (File directory : pathList.getNativeLibraryDirectories()) {
if (result.length() > 0) {
result.append(':');
}
result.append(directory);
}
return result.toString();
}
@Override public String toString() {
return getClass().getName() + "[" + pathList + "]";
}
/**
* Sets the reporter for dex load notifications.
* Once set, all new instances of BaseDexClassLoader will report upon
* constructions the loaded dex files.
*
* @param newReporter the new Reporter. Setting null will cancel reporting.
* @hide
*/
//@libcore.api.CorePlatformApi
public static void setReporter(Reporter newReporter) {
reporter = newReporter;
}
/**
* @hide
*/
public static Reporter getReporter() {
return reporter;
}
/**
* @hide
*/
//@libcore.api.CorePlatformApi
public interface Reporter {
/**
* Reports the construction of a BaseDexClassLoader and provides information about the
* class loader chain.
*
* @param classLoadersChain the chain of class loaders used during the construction of the
* class loader. The first element is the BaseDexClassLoader being constructed,
* the second element is its parent, and so on.
* @param classPaths the class paths of the class loaders present in
* {@param classLoadersChain}. The first element corresponds to the first class
* loader and so on. A classpath is represented as a list of dex files separated by
* {@code File.pathSeparator}. If the class loader is not a BaseDexClassLoader the
* classpath will be null.
*/
//@libcore.api.CorePlatformApi
void report(List classLoadersChain, List classPaths);
}
}