ClassLoadUtils.java

/*
 * Copyright (c) 2007, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package nsk.share.classload;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.FileInputStream;

import java.util.Arrays;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.Files;

public class ClassLoadUtils {
    private ClassLoadUtils() {
    }

    /**
     * Get filename of class file from classpath for given class name.
     *
     * @param className class name
     * @return filename or null if not found
     */
    public static String getClassPath(String className) {
        String fileName = className.replace(".", File.separator) + ".class";
        String[] classPath = System.getProperty("java.class.path").split(File.pathSeparator);
        File target = null;
        int i;
        for (i = 0; i < classPath.length; ++i) {
            target = new File(classPath[i] + File.separator + fileName);
            System.out.println("Try: " + target);
            if (target.exists()) {
                break;
            }
        }
        if (i != classPath.length) {
            return classPath[i];
        }
        return null;
    }

    /**
     * Get filename of class file from classpath for given class name.
     *
     * @param className class name
     * @return filename or null if not found
     */
    public static String getClassPathFileName(String className) {
        String fileName = className.replace(".", File.separator) + ".class";
        String[] classPath = System.getProperty("java.class.path").split(File.pathSeparator);
        File target = null;
        int i;
        for (i = 0; i < classPath.length; ++i) {
            target = new File(classPath[i] + File.separator + fileName);
            System.out.println("Try: " + target);
            if (target.exists()) {
                break;
            }
        }
        if (i != classPath.length) {
            try {
                return target.getCanonicalPath();
            } catch (IOException e) {
                return null;
            }
        }
        return null;
    }

    public static String getRedefineClassFileName(String dir, String className) {
        String fileName = className.replace(".", File.separator) + ".class";
        return Arrays.stream(System.getProperty("java.class.path").split(File.pathSeparator))
                     .map(Paths::get)
                     .map(p -> p.resolve(dir))
                     .map(p -> p.resolve(fileName))
                     .filter(p -> Files.exists(p))
                     .map(Path::toAbsolutePath)
                     .map(Path::toString)
                     .findAny()
                     .orElse(null);
    }

    /**
     * Get filename of class file which is to be redefined.
     */
    public static String getRedefineClassFileName(String className) {
            return getRedefineClassFileName("newclass", className);
    }
}