/** * The repository maintains informations about class interdependencies, e.g., whether a class is a * sub-class of another. Delegates actual class loading to SyntheticRepository with current class * path by default. * * @see com.sun.org.apache.bcel.internal.util.Repository * @see com.sun.org.apache.bcel.internal.util.SyntheticRepository * @author <A HREF="mailto:[email protected]">M. Dahm</A> */ public abstract class Repository { private static com.sun.org.apache.bcel.internal.util.Repository _repository = SyntheticRepository.getInstance(); /** @return currently used repository instance */ public static com.sun.org.apache.bcel.internal.util.Repository getRepository() { return _repository; } /** Set repository instance to be used for class loading */ public static void setRepository(com.sun.org.apache.bcel.internal.util.Repository rep) { _repository = rep; } /** * Lookup class somewhere found on your CLASSPATH, or whereever the repository instance looks for * it. * * @return class object for given fully qualified class name, or null if the class could not be * found or parsed correctly */ public static JavaClass lookupClass(String class_name) { try { JavaClass clazz = _repository.findClass(class_name); if (clazz == null) { return _repository.loadClass(class_name); } else { return clazz; } } catch (ClassNotFoundException ex) { return null; } } /** * Try to find class source via getResourceAsStream(). * * @see Class * @return JavaClass object for given runtime class */ public static JavaClass lookupClass(Class clazz) { try { return _repository.loadClass(clazz); } catch (ClassNotFoundException ex) { return null; } } /** @return class file object for given Java class. */ public static ClassPath.ClassFile lookupClassFile(String class_name) { try { return ClassPath.SYSTEM_CLASS_PATH.getClassFile(class_name); } catch (IOException e) { return null; } } /** Clear the repository. */ public static void clearCache() { _repository.clear(); } /** * Add clazz to repository if there isn't an equally named class already in there. * * @return old entry in repository */ public static JavaClass addClass(JavaClass clazz) { JavaClass old = _repository.findClass(clazz.getClassName()); _repository.storeClass(clazz); return old; } /** Remove class with given (fully qualified) name from repository. */ public static void removeClass(String clazz) { _repository.removeClass(_repository.findClass(clazz)); } /** Remove given class from repository. */ public static void removeClass(JavaClass clazz) { _repository.removeClass(clazz); } /** * @return list of super classes of clazz in ascending order, i.e., Object is always the last * element */ public static JavaClass[] getSuperClasses(JavaClass clazz) { return clazz.getSuperClasses(); } /** * @return list of super classes of clazz in ascending order, i.e., Object is always the last * element. return "null", if class cannot be found. */ public static JavaClass[] getSuperClasses(String class_name) { JavaClass jc = lookupClass(class_name); return (jc == null ? null : getSuperClasses(jc)); } /** * @return all interfaces implemented by class and its super classes and the interfaces that those * interfaces extend, and so on. (Some people call this a transitive hull). */ public static JavaClass[] getInterfaces(JavaClass clazz) { return clazz.getAllInterfaces(); } /** * @return all interfaces implemented by class and its super classes and the interfaces that * extend those interfaces, and so on */ public static JavaClass[] getInterfaces(String class_name) { return getInterfaces(lookupClass(class_name)); } /** * Equivalent to runtime "instanceof" operator. * * @return true, if clazz is an instance of super_class */ public static boolean instanceOf(JavaClass clazz, JavaClass super_class) { return clazz.instanceOf(super_class); } /** @return true, if clazz is an instance of super_class */ public static boolean instanceOf(String clazz, String super_class) { return instanceOf(lookupClass(clazz), lookupClass(super_class)); } /** @return true, if clazz is an instance of super_class */ public static boolean instanceOf(JavaClass clazz, String super_class) { return instanceOf(clazz, lookupClass(super_class)); } /** @return true, if clazz is an instance of super_class */ public static boolean instanceOf(String clazz, JavaClass super_class) { return instanceOf(lookupClass(clazz), super_class); } /** @return true, if clazz is an implementation of interface inter */ public static boolean implementationOf(JavaClass clazz, JavaClass inter) { return clazz.implementationOf(inter); } /** @return true, if clazz is an implementation of interface inter */ public static boolean implementationOf(String clazz, String inter) { return implementationOf(lookupClass(clazz), lookupClass(inter)); } /** @return true, if clazz is an implementation of interface inter */ public static boolean implementationOf(JavaClass clazz, String inter) { return implementationOf(clazz, lookupClass(inter)); } /** @return true, if clazz is an implementation of interface inter */ public static boolean implementationOf(String clazz, JavaClass inter) { return implementationOf(lookupClass(clazz), inter); } }
/** * Drop in replacement for the standard class loader of the JVM. You can use it in conjunction with * the JavaWrapper to dynamically modify/create classes as they're requested. * * <p>This class loader recognizes special requests in a distinct format, i.e., when the name of the * requested class contains with "$$BCEL$$" it calls the createClass() method with that name * (everything bevor the $$BCEL$$ is considered to be the package name. You can subclass the class * loader and override that method. "Normal" classes class can be modified by overriding the * modifyClass() method which is called just before defineClass(). * * <p>There may be a number of packages where you have to use the default class loader (which may * also be faster). You can define the set of packages where to use the system class loader in the * constructor. The default value contains "java.", "sun.", "javax." * * @version $Id: ClassLoader.java,v 1.1.2.1 2005/07/31 23:47:03 jeffsuttor Exp $ * @author <A HREF="mailto:[email protected]">M. Dahm</A> * @see JavaWrapper * @see ClassPath */ public class ClassLoader extends java.lang.ClassLoader { private Hashtable classes = new Hashtable(); // Hashtable is synchronized thus thread-safe private String[] ignored_packages = {"java.", "javax.", "sun."}; private Repository repository = SyntheticRepository.getInstance(); private java.lang.ClassLoader deferTo = ClassLoader.getSystemClassLoader(); public ClassLoader() {} public ClassLoader(java.lang.ClassLoader deferTo) { this.deferTo = deferTo; this.repository = new ClassLoaderRepository(deferTo); } /** * @param ignored_packages classes contained in these packages will be loaded with the system * class loader */ public ClassLoader(String[] ignored_packages) { addIgnoredPkgs(ignored_packages); } public ClassLoader(java.lang.ClassLoader deferTo, String[] ignored_packages) { this.deferTo = deferTo; this.repository = new ClassLoaderRepository(deferTo); addIgnoredPkgs(ignored_packages); } private void addIgnoredPkgs(String[] ignored_packages) { String[] new_p = new String[ignored_packages.length + this.ignored_packages.length]; System.arraycopy(this.ignored_packages, 0, new_p, 0, this.ignored_packages.length); System.arraycopy( ignored_packages, 0, new_p, this.ignored_packages.length, ignored_packages.length); this.ignored_packages = new_p; } protected Class loadClass(String class_name, boolean resolve) throws ClassNotFoundException { Class cl = null; /* First try: lookup hash table. */ if ((cl = (Class) classes.get(class_name)) == null) { /* Second try: Load system class using system class loader. You better * don't mess around with them. */ for (int i = 0; i < ignored_packages.length; i++) { if (class_name.startsWith(ignored_packages[i])) { cl = deferTo.loadClass(class_name); break; } } if (cl == null) { JavaClass clazz = null; /* Third try: Special request? */ if (class_name.indexOf("$$BCEL$$") >= 0) clazz = createClass(class_name); else { // Fourth try: Load classes via repository if ((clazz = repository.loadClass(class_name)) != null) { clazz = modifyClass(clazz); } else throw new ClassNotFoundException(class_name); } if (clazz != null) { byte[] bytes = clazz.getBytes(); cl = defineClass(class_name, bytes, 0, bytes.length); } else // Fourth try: Use default class loader cl = Class.forName(class_name); } if (resolve) resolveClass(cl); } classes.put(class_name, cl); return cl; } /** * Override this method if you want to alter a class before it gets actually loaded. Does nothing * by default. */ protected JavaClass modifyClass(JavaClass clazz) { return clazz; } /** * Override this method to create you own classes on the fly. The name contains the special token * $$BCEL$$. Everything before that token is consddered to be a package name. You can encode you * own arguments into the subsequent string. You must regard however not to use any "illegal" * characters, i.e., characters that may not appear in a Java class name too<br> * The default implementation interprets the string as a encoded compressed Java class, unpacks * and decodes it with the Utility.decode() method, and parses the resulting byte array and * returns the resulting JavaClass object. * * @param class_name compressed byte code with "$$BCEL$$" in it */ protected JavaClass createClass(String class_name) { int index = class_name.indexOf("$$BCEL$$"); String real_name = class_name.substring(index + 8); JavaClass clazz = null; try { byte[] bytes = Utility.decode(real_name, true); ClassParser parser = new ClassParser(new ByteArrayInputStream(bytes), "foo"); clazz = parser.parse(); } catch (Throwable e) { e.printStackTrace(); return null; } // Adapt the class name to the passed value ConstantPool cp = clazz.getConstantPool(); ConstantClass cl = (ConstantClass) cp.getConstant(clazz.getClassNameIndex(), Constants.CONSTANT_Class); ConstantUtf8 name = (ConstantUtf8) cp.getConstant(cl.getNameIndex(), Constants.CONSTANT_Utf8); name.setBytes(class_name.replace('.', '/')); return clazz; } }
