classutil.java

ProGuard 是一个免费的 Java类文件的压缩

/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2007 Eric Lafortune ([e-mail])
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.util;

import proguard.classfile.*;

import java.util.*;

/**
 * Utility methods for converting between internal and external representations
 * of names and descriptions.
 *
 * @author Eric Lafortune
 */
public class ClassUtil
{
    private static final String EMPTY_STRING = "";

    private static final InternalTypeEnumeration internalTypeEnumeration = new InternalTypeEnumeration();
    private static final ExternalTypeEnumeration externalTypeEnumeration = new ExternalTypeEnumeration();


    /**
     * Checks whether the given class magic number is correct.
     * @param magicNumber the magic number.
     * @throws UnsupportedOperationException when the magic number is incorrect.
     */
    public static void checkMagicNumber(int magicNumber) throws UnsupportedOperationException
    {
        if (magicNumber != ClassConstants.MAGIC)
        {
            throw new UnsupportedOperationException("Invalid magic number ["+Integer.toHexString(magicNumber)+"] in class");
        }
    }


    /**
     * Returns the combined class version number.
     * @param majorVersion the major part of the class version number.
     * @param minorVersion the minor part of the class version number.
     * @return the combined class version number.
     */
    public static int internalClassVersion(int majorVersion, int minorVersion)
    {
        return (majorVersion << 16) | minorVersion;
    }


    /**
     * Returns the major part of the given class version number.
     * @param classVersion the combined class version number.
     * @return the major part of the class version number.
     */
    public static int internalMajorClassVersion(int classVersion)
    {
        return classVersion >>> 16;
    }


    /**
     * Returns the internal class version number.
     * @param classVersion the external class version number.
     * @return the internal class version number.
     */
    public static int internalMinorClassVersion(int classVersion)
    {
        return classVersion & 0xffff;
    }


    /**
     * Returns the internal class version number.
     * @param classVersion the external class version number.
     * @return the internal class version number.
     */
    public static int internalClassVersion(String classVersion)
    {
        return
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_0) ||
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_1) ? ClassConstants.INTERNAL_CLASS_VERSION_1_0 :
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_2) ? ClassConstants.INTERNAL_CLASS_VERSION_1_2 :
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_3) ? ClassConstants.INTERNAL_CLASS_VERSION_1_3 :
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_4) ? ClassConstants.INTERNAL_CLASS_VERSION_1_4 :
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_5_ALIAS) ||
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_5) ? ClassConstants.INTERNAL_CLASS_VERSION_1_5 :
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_6_ALIAS) ||
            classVersion.equals(ClassConstants.EXTERNAL_CLASS_VERSION_1_6) ? ClassConstants.INTERNAL_CLASS_VERSION_1_6 :
                                                                             0;
    }


    /**
     * Returns the minor part of the given class version number.
     * @param classVersion the combined class version number.
     * @return the minor part of the class version number.
     */
    public static String externalClassVersion(int classVersion)
    {
        switch (classVersion)
        {
            case ClassConstants.INTERNAL_CLASS_VERSION_1_0: return ClassConstants.EXTERNAL_CLASS_VERSION_1_0;
            case ClassConstants.INTERNAL_CLASS_VERSION_1_2: return ClassConstants.EXTERNAL_CLASS_VERSION_1_2;
            case ClassConstants.INTERNAL_CLASS_VERSION_1_3: return ClassConstants.EXTERNAL_CLASS_VERSION_1_3;
            case ClassConstants.INTERNAL_CLASS_VERSION_1_4: return ClassConstants.EXTERNAL_CLASS_VERSION_1_4;
            case ClassConstants.INTERNAL_CLASS_VERSION_1_5: return ClassConstants.EXTERNAL_CLASS_VERSION_1_5;
            case ClassConstants.INTERNAL_CLASS_VERSION_1_6: return ClassConstants.EXTERNAL_CLASS_VERSION_1_6;
            default:                                        return null;
        }
    }


    /**
     * Checks whether the given class version number is supported.
     * @param classVersion the combined class version number.
     * @throws UnsupportedOperationException when the version is not supported.
     */
    public static void checkVersionNumbers(int classVersion) throws UnsupportedOperationException
    {
        if (classVersion < ClassConstants.INTERNAL_CLASS_VERSION_1_0 ||
            classVersion > ClassConstants.INTERNAL_CLASS_VERSION_1_6)
        {
            throw new UnsupportedOperationException("Unsupported version number ["+
                                                    internalMajorClassVersion(classVersion)+"."+
                                                    internalMinorClassVersion(classVersion)+"] for class format");
        }
    }


    /**
     * Converts an external class name into an internal class name.
     * @param externalClassName the external class name,
     *                          e.g. "<code>java.lang.Object</code>"
     * @return the internal class name,
     *                          e.g. "<code>java/lang/Object</code>".
     */
    public static String internalClassName(String externalClassName)
    {
        return externalClassName.replace(ClassConstants.EXTERNAL_PACKAGE_SEPARATOR,
                                         ClassConstants.INTERNAL_PACKAGE_SEPARATOR);
    }


    /**
     * Converts an internal class description into an external class description.
     * @param accessFlags       the access flags of the class.
     * @param internalClassName the internal class name,
     *                          e.g. "<code>java/lang/Object</code>".
     * @return the external class description,
     *                          e.g. "<code>public java.lang.Object</code>".
     */
    public static String externalFullClassDescription(int    accessFlags,
                                                      String internalClassName)
    {
        return externalClassAccessFlags(accessFlags) +
               externalClassName(internalClassName);
    }


    /**
     * Converts an internal class name into an external class name.
     * @param internalClassName the internal class name,
     *                          e.g. "<code>java/lang/Object</code>".
     * @return the external class name,
     *                          e.g. "<code>java.lang.Object</code>".
     */
    public static String externalClassName(String internalClassName)
    {
        return //internalClassName.startsWith(ClassConstants.INTERNAL_PACKAGE_JAVA_LANG) &&
               //internalClassName.indexOf(ClassConstants.INTERNAL_PACKAGE_SEPARATOR, ClassConstants.INTERNAL_PACKAGE_JAVA_LANG.length() + 1) < 0 ?
               //internalClassName.substring(ClassConstants.INTERNAL_PACKAGE_JAVA_LANG.length()) :
               internalClassName.replace(ClassConstants.INTERNAL_PACKAGE_SEPARATOR,
                                         ClassConstants.EXTERNAL_PACKAGE_SEPARATOR);
    }


    /**
     * Converts an internal class name into an external short class name, without
     * package specification.
     * @param externalClassName the external class name,
     *                          e.g. "<code>java.lang.Object</code>"
     * @return the external short class name,
     *                          e.g. "<code>Object</code>".
     */
    public static String externalShortClassName(String externalClassName)
    {
        int index = externalClassName.lastIndexOf(ClassConstants.EXTERNAL_PACKAGE_SEPARATOR);
        return externalClassName.substring(index+1);
    }


    /**
     * Returns whether the given internal type is an array type.
     * @param internalType the internal type,
     *                     e.g. "<code>[[Ljava/lang/Object;</code>".
     * @return <code>true</code> if the given type is an array type,
     *         <code>false</code> otherwise.
     */
    public static boolean isInternalArrayType(String internalType)
    {
        return internalType.length() > 1 &&
               internalType.charAt(0) == ClassConstants.INTERNAL_TYPE_ARRAY;
    }


    /**
     * Returns the number of dimensions of the given internal type.
     * @param internalType the internal type,
     *                     e.g. "<code>[[Ljava/lang/Object;</code>".
     * @return the number of dimensions, e.g. 2.
     */
    public static int internalArrayTypeDimensionCount(String internalType)
    {
        int dimensions = 0;
        while (internalType.charAt(dimensions) == ClassConstants.INTERNAL_TYPE_ARRAY)
        {
            dimensions++;
        }

        return dimensions;
    }


    /**
     * Returns whether the given internal class name is one of the interfaces
     * that is implemented by all array types. These class names are
     * "<code>java/lang/Object</code>", "<code>java/lang/Cloneable</code>", and
     * "<code>java/io/Serializable</code>"
     * @param internalClassName the internal class name,
     *                          e.g. "<code>java/lang/Object</code>".
     * @return <code>true</code> if the given type is an array interface name,
     *         <code>false</code> otherwise.
     */
    public static boolean isInternalArrayInterfaceName(String internalClassName)
    {
        return ClassConstants.INTERNAL_NAME_JAVA_LANG_OBJECT.equals(internalClassName)    ||
               ClassConstants.INTERNAL_NAME_JAVA_LANG_CLONEABLE.equals(internalClassName) ||
               ClassConstants.INTERNAL_NAME_JAVA_IO_SERIALIZABLE.equals(internalClassName);
    }


    /**
     * Returns whether the given internal type is a plain primitive type
     * (not void).
     * @param internalType the internal type,
     *                     e.g. "<code>I</code>".
     * @return <code>true</code> if the given type is a class type,
     *         <code>false</code> otherwise.
     */
    public static boolean isInternalPrimitiveType(char internalType)
    {
        return internalType == ClassConstants.INTERNAL_TYPE_BOOLEAN ||
               internalType == ClassConstants.INTERNAL_TYPE_BYTE    ||
               internalType == ClassConstants.INTERNAL_TYPE_CHAR    ||
               internalType == ClassConstants.INTERNAL_TYPE_SHORT   ||
               internalType == ClassConstants.INTERNAL_TYPE_INT     ||
               internalType == ClassConstants.INTERNAL_TYPE_FLOAT   ||
               internalType == ClassConstants.INTERNAL_TYPE_LONG    ||
               internalType == ClassConstants.INTERNAL_TYPE_DOUBLE;