org.kawanfw.file.api.util.client.JarReader.java Source code

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Here is the source code for org.kawanfw.file.api.util.client.JarReader.java

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/*
 * This file is part of Awake FILE. 
 * Awake file: Easy file upload & download over HTTP with Java.                                    
 * Copyright (C) 2015,  KawanSoft SAS
 * (http://www.kawansoft.com). All rights reserved.                                
 *                                                                               
 * Awake FILE is free software; you can redistribute it and/or                 
 * modify it under the terms of the GNU Lesser General Public                    
 * License as published by the Free Software Foundation; either                  
 * version 2.1 of the License, or (at your option) any later version.            
 *                                                                               
 * Awake FILE 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             
 * Lesser General Public License for more details.                               
 *                                                                               
 * You should have received a copy of the GNU Lesser General Public              
 * License along with this library; if not, write to the Free Software           
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  
 * 02110-1301  USA
 *
 * Any modifications to this file must keep this entire header
 * intact.
 */
package org.kawanfw.file.api.util.client;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.kawanfw.commons.util.ClientLogger;
import org.kawanfw.commons.util.FrameworkDebug;

/**
 * 
 * Utilities to read content of .jar files and extracing bytecode from a .class in a jar.
 * 
 * @author Nicolas de Pomereu
 *
 */
public class JarReader {

    /** For debug info */
    private static boolean DEBUG = FrameworkDebug.isSet(JarReader.class);

    /**
     * Protected constructor
     */
    protected JarReader() {

    }

    /**
     * Extract all classnames from a jar.
     * 
     * @param in
     *            the input stream of the jar file
     * @return the class names
     * @throws IOException
     *             ir any I/O error
     */
    public static List<String> getClassnames(InputStream in) throws IOException {

        try {
            List<String> classNames = new ArrayList<String>();
            ZipInputStream zip = new ZipInputStream(in);
            for (ZipEntry entry = zip.getNextEntry(); entry != null; entry = zip.getNextEntry())
                if (entry.getName().endsWith(".class") && !entry.isDirectory()) {
                    // This ZipEntry represents a class. Now, what class does it
                    // represent?
                    StringBuilder className = new StringBuilder();
                    for (String part : entry.getName().split("/")) {
                        if (className.length() != 0)
                            className.append(".");
                        className.append(part);
                        if (part.endsWith(".class"))
                            className.setLength(className.length() - ".class".length());
                    }
                    classNames.add(className.toString());
                }
            return classNames;
        } finally {
            IOUtils.closeQuietly(in);
        }
    }

    /**
     * Extract bytecode of .class as byte array
     * 
     * @param in
     *            the ZipInputStream
     * @param classname
     *            the class name to search for
     * @return byte array contaning the .class bytecode
     * @throws IOException
     *             if I/O errrors
     * @throws FileNotFoundException
     *             if the .class file corresponding to the classname does not
     *             exists
     */
    public static byte[] extractClassFileBytecode(InputStream in, String classname)
            throws IOException, FileNotFoundException {

        if (in == null) {
            throw new IllegalArgumentException("in is null!");
        }

        if (classname == null) {
            throw new IllegalArgumentException("classname is null!");
        }

        String entryToFind = convertClassNameToEntry(classname);

        ZipInputStream zis = new ZipInputStream(in);

        byte[] byteArray = null;

        try {
            ZipEntry entry;
            while ((entry = zis.getNextEntry()) != null) {
                debug("Unzipping: " + entry.getName());

                int size;
                byteArray = new byte[2048];

                ByteArrayOutputStream bos = new ByteArrayOutputStream();

                while ((size = zis.read(byteArray, 0, byteArray.length)) != -1) {
                    bos.write(byteArray, 0, size);
                }
                bos.flush();
                bos.close();

                if (entry.getName().equals(entryToFind)) {
                    return bos.toByteArray();
                }

            }

            return null;

        } finally {
            zis.close();
        }

    }

    /**
     * Convert a class name to corresponding zip entry name
     * @param classname   the clas name to convert
     * @return the c entry name
     */
    public static String convertClassNameToEntry(String classname) {

        if (classname == null) {
            throw new IllegalArgumentException("classname is null!");
        }

        String entryToFind = classname;
        if (entryToFind.contains(".")) {
            entryToFind = entryToFind.replace(".", "/");
            entryToFind = entryToFind + ".class";
        }
        return entryToFind;
    }

    /**
     * debug tool
     */
    private static void debug(String s) {
        if (DEBUG) {
            ClientLogger.getLogger().log(Level.WARNING, s);
        }
    }

    /**
     * @param args
     */
    public static void main(String[] args) throws Exception {

        InputStream in = new FileInputStream("I:\\_dev_awake\\awake-file-3.0\\dist\\awake-file-3.0.jar");

        byte[] b = extractClassFileBytecode(in, "org.kawanfw.file.api.util.client.PathUtil");
        System.out.println("b.length: " + b.length);
        FileUtils.writeByteArrayToFile(new File("c:\\temp\\the.class"), b);

    }

}