/*
* Copyright (C) 2008 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.
*/
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
/**
* A class loader with atypical behavior: we try to load a private
* class implementation before asking the system or boot loader. This
* is used to create multiple classes with identical names in a single VM.
*
* If DexFile is available, we use that; if not, we assume we're not in
* Dalvik and instantiate the class with defineClass().
*
* The location of the DEX files and class data is dependent upon the
* test framework.
*/
public class FancyLoader extends ClassLoader {
/* this is where the "alternate" .class files live */
static final String CLASS_PATH = "classes-ex/";
/* this is the "alternate" DEX/Jar file */
static final String DEX_FILE = System.getenv("DEX_LOCATION") + "/068-classloader-ex.jar";
/* on Dalvik, this is a DexFile; otherwise, it's null */
private Class mDexClass;
private Object mDexFile;
/**
* Construct FancyLoader, grabbing a reference to the DexFile class
* if we're running under Dalvik.
*/
public FancyLoader(ClassLoader parent) {
super(parent);
try {
mDexClass = parent.loadClass("dalvik.system.DexFile");
} catch (ClassNotFoundException cnfe) {
// ignore -- not running Dalvik
}
}
/**
* Finds the class with the specified binary name.
*
* We search for a file in CLASS_PATH or pull an entry from DEX_FILE.
* If we don't find a match, we throw an exception.
*/
protected Class<?> findClass(String name) throws ClassNotFoundException
{
if (mDexClass != null) {
return findClassDalvik(name);
} else {
return findClassNonDalvik(name);
}
}
/**
* Finds the class with the specified binary name, from a DEX file.
*/
private Class<?> findClassDalvik(String name)
throws ClassNotFoundException {
if (mDexFile == null) {
synchronized (FancyLoader.class) {
Constructor ctor;
/*
* Construct a DexFile object through reflection.
*/
try {
ctor = mDexClass.getConstructor(new Class[] {String.class});
} catch (NoSuchMethodException nsme) {
throw new ClassNotFoundException("getConstructor failed",
nsme);
}
try {
mDexFile = ctor.newInstance(DEX_FILE);
} catch (InstantiationException ie) {
throw new ClassNotFoundException("newInstance failed", ie);
} catch (IllegalAccessException iae) {
throw new ClassNotFoundException("newInstance failed", iae);
} catch (InvocationTargetException ite) {
throw new ClassNotFoundException("newInstance failed", ite);
}
}
}
/*
* Call DexFile.loadClass(String, ClassLoader).
*/
Method meth;
try {
meth = mDexClass.getMethod("loadClass",
new Class[] { String.class, ClassLoader.class });
} catch (NoSuchMethodException nsme) {
throw new ClassNotFoundException("getMethod failed", nsme);
}
try {
meth.invoke(mDexFile, name, this);
} catch (IllegalAccessException iae) {
throw new ClassNotFoundException("loadClass failed", iae);
} catch (InvocationTargetException ite) {
throw new ClassNotFoundException("loadClass failed",
ite.getCause());
}
return null;
}
/**
* Finds the class with the specified binary name, from .class files.
*/
private Class<?> findClassNonDalvik(String name)
throws ClassNotFoundException {
String pathName = CLASS_PATH + name + ".class";
//System.out.println("--- Fancy: looking for " + pathName);
File path = new File(pathName);
RandomAccessFile raf;
try {
raf = new RandomAccessFile(path, "r");
} catch (FileNotFoundException fnfe) {
throw new ClassNotFoundException("Not found: " + pathName);
}
/* read the entire file in */
byte[] fileData;
try {
fileData = new byte[(int) raf.length()];
raf.readFully(fileData);
} catch (IOException ioe) {
throw new ClassNotFoundException("Read error: " + pathName);
} finally {
try {
raf.close();
} catch (IOException ioe) {
// drop
}
}
/* create the class */
//System.out.println("--- Fancy: defining " + name);
try {
return defineClass(name, fileData, 0, fileData.length);
} catch (Throwable th) {
throw new ClassNotFoundException("defineClass failed", th);
}
}
/**
* Load a class.
*
* Normally a class loader wouldn't override this, but we want our
* version of the class to take precedence over an already-loaded
* version.
*
* We still want the system classes (e.g. java.lang.Object) from the
* bootstrap class loader.
*/
protected Class<?> loadClass(String name, boolean resolve)
throws ClassNotFoundException
{
Class res;
/*
* 1. Invoke findLoadedClass(String) to check if the class has
* already been loaded.
*
* This doesn't change.
*/
res = findLoadedClass(name);
if (res != null) {
System.out.println("FancyLoader.loadClass: "
+ name + " already loaded");
if (resolve)
resolveClass(res);
return res;
}
/*
* 3. Invoke the findClass(String) method to find the class.
*/
try {
res = findClass(name);
if (resolve)
resolveClass(res);
}
catch (ClassNotFoundException e) {
// we couldn't find it, so eat the exception and keep going
}
/*
* 2. Invoke the loadClass method on the parent class loader. If
* the parent loader is null the class loader built-in to the
* virtual machine is used, instead.
*
* (Since we're not in java.lang, we can't actually invoke the
* parent's loadClass() method, but we passed our parent to the
* super-class which can take care of it for us.)
*/
res = super.loadClass(name, resolve); // returns class or throws
return res;
}
}