classmap.java

Javassist是一个开源的分析、编辑和创建Java字节码的类库。是由东京技术学院的数学和计算机科学系的 Shigeru Chiba 所创建的。它已加入了开放源代码JBoss 应用服务器项目,通过使

/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999-2006 Shigeru Chiba. All Rights Reserved.
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 */

package javassist;

import javassist.bytecode.Descriptor;

/**
 * A hash table associating class names with different names.
 *
 * <p>This hashtable is used for replacing class names in a class
 * definition or a method body.  Define a subclass of this class
 * if a more complex mapping algorithm is needed.  For example,
 *
 * <ul><pre>class MyClassMap extends ClassMap {
 *   public Object get(Object jvmClassName) {
 *     String name = toJavaName((String)jvmClassName);
 *     if (name.startsWith("java."))
 *         return toJvmName("java2." + name.substring(5));
 *     else
 *         return super.get(jvmClassName);
 *   }
 * }</pre></ul>
 *
 * <p>This subclass maps <code>java.lang.String</code> to
 * <code>java2.lang.String</code>.  Note that <code>get()</code>
 * receives and returns the internal representation of a class name.
 * For example, the internal representation of <code>java.lang.String</code>
 * is <code>java/lang/String</code>.
 *
 * @see #get(Object)
 * @see CtClass#replaceClassName(ClassMap)
 * @see CtNewMethod#copy(CtMethod,String,CtClass,ClassMap)
 */
public class ClassMap extends java.util.HashMap {
    private ClassMap parent;

    /**
     * Constructs a hash table.
     */
    public ClassMap() { parent = null; }

    ClassMap(ClassMap map) { parent = map; }

    /**
     * Maps a class name to another name in this hashtable.
     * The names are obtained with calling <code>Class.getName()</code>.
     * This method translates the given class names into the
     * internal form used in the JVM before putting it in
     * the hashtable.
     *
     * @param oldname   the original class name
     * @param newname   the substituted class name.
     */
    public void put(CtClass oldname, CtClass newname) {
        put(oldname.getName(), newname.getName());
    }

    /**
     * Maps a class name to another name in this hashtable.
     * If the hashtable contains another mapping from the same
     * class name, the old mapping is replaced. 
     * This method translates the given class names into the
     * internal form used in the JVM before putting it in
     * the hashtable.
     *
     * <p>If <code>oldname</code> is equivalent to
     * <code>newname</code>, then this method does not
     * perform anything; it does not record the mapping from
     * <code>oldname</code> to <code>newname</code>.  See
     * <code>fix</code> method.
     *
     * @param oldname   the original class name
     * @param newname   the substituted class name.
     * @see #fix(String)
     */
    public void put(String oldname, String newname) {
        if (oldname == newname)
            return;

        String oldname2 = toJvmName(oldname);
        String s = (String)get(oldname2);
        if (s == null || !s.equals(oldname2))
            super.put(oldname2, toJvmName(newname));
    }

    protected final void put0(Object oldname, Object newname) {
        super.put(oldname, newname);
    }

    /**
     * Returns the class name to wihch the given <code>jvmClassName</code>
     * is mapped.  A subclass of this class should override this method.
     *
     * <p>This method receives and returns the internal representation of
     * class name used in the JVM.
     *
     * @see #toJvmName(String)
     * @see #toJavaName(String)
     */
    public Object get(Object jvmClassName) {
        Object found = super.get(jvmClassName);
        if (found == null && parent != null)
            return parent.get(jvmClassName);
        else
            return found;
    }

    /**
     * Prevents a mapping from the specified class name to another name.
     */
    public void fix(CtClass clazz) {
        fix(clazz.getName());
    }

    /**
     * Prevents a mapping from the specified class name to another name.
     */
    public void fix(String name) {
        String name2 = toJvmName(name);
        super.put(name2, name2);
    }

    /**
     * Converts a class name into the internal representation used in
     * the JVM.
     */
    public static String toJvmName(String classname) {
        return Descriptor.toJvmName(classname);
    }

    /**
     * Converts a class name from the internal representation used in
     * the JVM to the normal one used in Java.
     */
    public static String toJavaName(String classname) {
        return Descriptor.toJavaName(classname);
    }
}