java.lang.PathClassLoader Maven / Gradle / Ivy
/*
* Copyright (C) 2007 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.
*/
/*
* Copyright (C) 2012 RoboVM AB
*
* 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 java.lang;
import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.zip.ZipFile;
/**
* Provides a simple {@link ClassLoader} implementation that operates on a list
* of files and directories in the local file system. Most of the code has been
* copied from Android with the exception of the {@link #findClass(String)}
* method which just delegates to {@link Class#forName(String, boolean, ClassLoader)}.
*/
class PathClassLoader extends ClassLoader {
private final String path;
private final String libPath;
/*
* Parallel arrays for jar/apk files.
*
* (could stuff these into an object and have a single array;
* improves clarity but adds overhead)
*/
private String[] mPaths;
private File[] mFiles;
private ZipFile[] mZips;
/**
* Native library path.
*/
private List libraryPathElements;
/**
* Creates a {@code PathClassLoader} that operates on a given list of files
* and directories. This method is equivalent to calling
* {@link #PathClassLoader(String, String, ClassLoader)} with a
* {@code null} value for the second argument (see description there).
*
* @param path
* the list of files and directories
*
* @param parent
* the parent class loader
*/
PathClassLoader(String path, ClassLoader parent, boolean nullAllowed) {
this(path, null, parent, nullAllowed);
}
/**
* Creates a {@code PathClassLoader} that operates on two given
* lists of files and directories. The entries of the first list
* should be one of the following:
*
*
* - Directories containing classes or resources.
*
- JAR/ZIP/APK files, possibly containing a "classes.dex" file.
*
- "classes.dex" files.
*
*
* The entries of the second list should be directories containing
* native library files. Both lists are separated using the
* character specified by the "path.separator" system property,
* which, on Android, defaults to ":".
*
* @param path
* the list of files and directories containing classes and
* resources
*
* @param libPath
* the list of directories containing native libraries
*
* @param parent
* the parent class loader
*/
PathClassLoader(String path, String libPath, ClassLoader parent, boolean nullAllowed) {
super(parent, nullAllowed);
if (path == null)
throw new NullPointerException();
this.path = path;
this.libPath = libPath;
}
private synchronized void init() {
if (mPaths != null) {
return;
}
mPaths = path.split(System.getProperty("path.separator"));
int length = mPaths.length;
//System.out.println("PathClassLoader: " + mPaths);
mFiles = new File[length];
mZips = new ZipFile[length];
/* open all Zip files up front */
for (int i = 0; i < length; i++) {
//System.out.println("My path is: " + mPaths[i]);
File pathFile = new File(mPaths[i]);
mFiles[i] = pathFile;
if (pathFile.isFile()) {
try {
mZips[i] = new ZipFile(pathFile);
}
catch (IOException ioex) {
// expecting IOException and ZipException
//System.out.println("Failed opening '" + pathFile + "': " + ioex);
//ioex.printStackTrace();
}
}
}
/*
* Native libraries may exist in both the system and application library
* paths, so we use this search order for these paths:
* 1. This class loader's library path for application libraries
* 2. The VM's library path from the system property for system libraries
* This order was reversed prior to Gingerbread; see http://b/2933456
*/
libraryPathElements = new ArrayList();
if (libPath != null) {
for (String pathElement : libPath.split(File.pathSeparator)) {
libraryPathElements.add(cleanupPathElement(pathElement));
}
}
String systemLibraryPath = System.getProperty("java.library.path", ".");
if (!systemLibraryPath.isEmpty()) {
for (String pathElement : systemLibraryPath.split(File.pathSeparator)) {
libraryPathElements.add(cleanupPathElement(pathElement));
}
}
}
/**
* Returns a path element that includes a trailing file separator.
*/
private String cleanupPathElement(String path) {
return path.endsWith(File.separator) ? path : (path + File.separator);
}
/**
* Finds a class. This method is called by {@code loadClass()} after the
* parent ClassLoader has failed to find a loaded class of the same name.
*
* @param name
* The "binary name" of the class to search for, in a
* human-readable form like "java.lang.String" or
* "java.net.URLClassLoader$3$1".
* @return the {@link Class} object representing the class
* @throws ClassNotFoundException
* if the class cannot be found
*/
@Override
protected Class findClass(String name) throws ClassNotFoundException {
return VMClassLoader.findClassInClasspathForLoader(this, name);
}
/**
* Finds a resource. This method is called by {@code getResource()} after
* the parent ClassLoader has failed to find a loaded resource of the same
* name.
*
* @param name
* The name of the resource to find
* @return the location of the resource as a URL, or {@code null} if the
* resource is not found.
*/
@Override
protected URL findResource(String name) {
init();
//java.util.logging.Logger.global.severe("findResource: " + name);
int length = mPaths.length;
for (int i = 0; i < length; i++) {
URL result = findResource(name, i);
if(result != null) {
return result;
}
}
return null;
}
/**
* Finds an enumeration of URLs for the resource with the specified name.
*
* @param resName
* the name of the resource to find.
* @return an enumeration of {@code URL} objects for the requested resource.
*/
@Override
protected Enumeration findResources(String resName) {
init();
int length = mPaths.length;
ArrayList results = new ArrayList();
for (int i = 0; i < length; i++) {
URL result = findResource(resName, i);
if(result != null) {
results.add(result);
}
}
return new EnumerateListArray(results);
}
private URL findResource(String name, int i) {
File pathFile = mFiles[i];
ZipFile zip = mZips[i];
if (zip != null) {
if (isInArchive(zip, name)) {
//System.out.println(" found " + name + " in " + pathFile);
try {
// File.toURL() is compliant with RFC 1738 in always
// creating absolute path names. If we construct the
// URL by concatenating strings, we might end up with
// illegal URLs for relative names.
return new URL("jar:" + pathFile.toURI() + "!/" + name);
}
catch (MalformedURLException e) {
throw new RuntimeException(e);
}
}
} else if (pathFile.isDirectory()) {
File dataFile = new File(mPaths[i] + "/" + name);
if (dataFile.exists()) {
//System.out.println(" found resource " + name);
try {
// Same as archive case regarding URL construction.
return dataFile.toURI().toURL();
}
catch (MalformedURLException e) {
throw new RuntimeException(e);
}
}
} else if (pathFile.isFile()) {
} else {
System.err.println("PathClassLoader: can't find '"
+ mPaths[i] + "'");
}
return null;
}
/*
* Figure out if "name" is a member of "archive".
*/
private boolean isInArchive(ZipFile zip, String name) {
return zip.getEntry(name) != null;
}
/**
* Finds a native library. This class loader first searches its own library
* path (as specified in the constructor) and then the system library path.
* In Android 2.2 and earlier, the search order was reversed.
*
* @param libname
* The name of the library to find
* @return the complete path of the library, or {@code null} if the library
* is not found.
*/
public String findLibrary(String libname) {
init();
String fileName = System.mapLibraryName(libname);
for (String pathElement : libraryPathElements) {
String pathName = pathElement + fileName;
File test = new File(pathName);
if (test.exists()) {
return pathName;
}
}
return null;
}
/**
* Returns package information for the given package. Unfortunately, the
* PathClassLoader doesn't really have this information, and as a non-secure
* 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
* myClass.getPackage().getName() happy. Thus we construct a
* Package object the first time it is being requested and fill most of the
* fields with dummy values. The Package object is then put into the
* ClassLoader's Package cache, so we see the same one next time. We don't
* create Package objects for null arguments or for the default package.
*
* There a limited chance that we end up with multiple Package objects
* representing the same package: It can happen when when a package is
* scattered across different JAR files being loaded by different
* ClassLoaders. Rather unlikely, and given that this whole thing is more or
* less a workaround, probably not worth the effort.
*
* @param name
* the name of the class
* @return the package information for the class, or {@code null} if there
* is not package information available for it
*/
@Override
protected Package getPackage(String name) {
if (name != null && !name.isEmpty()) {
synchronized(this) {
Package pack = super.getPackage(name);
if (pack == null) {
pack = definePackage(name, "Unknown", "0.0", "Unknown", "Unknown", "0.0", "Unknown", null);
}
return pack;
}
}
return null;
}
/*
* Create an Enumeration for an ArrayList.
*/
private static class EnumerateListArray implements Enumeration {
private final ArrayList mList;
private int i = 0;
EnumerateListArray(ArrayList list) {
mList = list;
}
public boolean hasMoreElements() {
return i < mList.size();
}
public T nextElement() {
if (i >= mList.size())
throw new NoSuchElementException();
return (T) mList.get(i++);
}
};
public String toString () {
return getClass().getName() + "[" + path + "]";
}
}