Ant example source code file (jlink.java)

This example Ant source code file (jlink.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

crc32, enumeration, file, file, fileinputstream, inputstream, io, ioexception, ioexception, string, string, util, vector, zip, zipentry, zipentry, zipfile

The jlink.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
/**
 * jlink.java links together multiple .jar files Original code by Patrick
 * Beard. Modifications to work with ANT by Matthew Kuperus Heun.
 *
 */
package org.apache.tools.ant.taskdefs.optional.jlink;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.Vector;
import java.util.zip.CRC32;
import java.util.zip.Deflater;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;

// CheckStyle:TypeNameCheck OFF - bc
/**
 * jlink links together multiple .jar files.
 */
public class jlink {


    private String outfile = null;

    private Vector mergefiles = new Vector(10);

    private Vector addfiles = new Vector(10);

    private boolean compression = false;

    // CheckStyle:VisibilityModifier OFF - bc

    byte[] buffer = new byte[8192];

    // CheckStyle:VisibilityModifier OFF - bc

    /** The file that will be created by this instance of jlink.
     * @param outfile the file to create.
     */
    public void setOutfile(String outfile) {
        if (outfile == null) {
            return;
        }
        this.outfile = outfile;
    }


    /**
     * Adds a file to be merged into the output.
     * @param fileToMerge the file to merge into the output.
     */
    public void addMergeFile(String fileToMerge) {
        if (fileToMerge == null) {
            return;
        }
        mergefiles.addElement(fileToMerge);
    }


    /** Adds a file to be added into the output.
     * @param fileToAdd the file to add to the output.
     */
    public void addAddFile(String fileToAdd) {
        if (fileToAdd == null) {
            return;
        }
        addfiles.addElement(fileToAdd);
    }


    /**
     * Adds several files to be merged into the output.
     * @param filesToMerge an array of files to merge into the output.
     */
    public void addMergeFiles(String[] filesToMerge) {
        if (filesToMerge == null) {
            return;
        }
        for (int i = 0; i < filesToMerge.length; i++) {
            addMergeFile(filesToMerge[i]);
        }
    }


    /**
     * Adds several file to be added into the output.
     * @param filesToAdd an array of files to add to the output.
     */
    public void addAddFiles(String[] filesToAdd) {
        if (filesToAdd == null) {
            return;
        }
        for (int i = 0; i < filesToAdd.length; i++) {
            addAddFile(filesToAdd[i]);
        }
    }


    /**
     * Determines whether output will be compressed.
     * @param compress if true use compression.
     */
    public void setCompression(boolean compress) {
        this.compression = compress;
    }


    /**
     * Performs the linking of files. Addfiles are added to the output as-is.
     * For example, a jar file is added to the output as a jar file. However,
     * mergefiles are first examined for their type. If it is a jar or zip
     * file, the contents will be extracted from the mergefile and entered
     * into the output. If a zip or jar file is encountered in a subdirectory
     * it will be added, not merged. If a directory is encountered, it becomes
     * the root entry of all the files below it. Thus, you can provide
     * multiple, disjoint directories, as addfiles: they will all be added in
     * a rational manner to outfile.
     * @throws Exception on error.
     */
    public void link() throws Exception {
        ZipOutputStream output = new ZipOutputStream(new FileOutputStream(outfile));

        if (compression) {
            output.setMethod(ZipOutputStream.DEFLATED);
            output.setLevel(Deflater.DEFAULT_COMPRESSION);
        } else {
            output.setMethod(ZipOutputStream.STORED);
        }

        Enumeration merges = mergefiles.elements();

        while (merges.hasMoreElements()) {
            String path = (String) merges.nextElement();
            File f = new File(path);

            if (f.getName().endsWith(".jar") || f.getName().endsWith(".zip")) {
                //Do the merge
                mergeZipJarContents(output, f);
            } else {
                //Add this file to the addfiles Vector and add it
                //later at the top level of the output file.
                addAddFile(path);
            }
        }

        Enumeration adds = addfiles.elements();

        while (adds.hasMoreElements()) {
            String name = (String) adds.nextElement();
            File f = new File(name);

            if (f.isDirectory()) {
                //System.out.println("in jlink: adding directory contents of " + f.getPath());
                addDirContents(output, f, f.getName() + '/', compression);
            } else {
                addFile(output, f, "", compression);
            }
        }
        if (output != null) {
            try {
                output.close();
            } catch (IOException ioe) {
                //do nothing
            }
        }
    }


    /**
     * The command line entry point for jlink.
     * @param args an array of arguments
     */
    public static void main(String[] args) {
        // jlink output input1 ... inputN
        if (args.length < 2) {
            System.out.println("usage: jlink output input1 ... inputN");
            System.exit(1);
        }
        jlink linker = new jlink();

        linker.setOutfile(args[0]);
        // To maintain compatibility with the command-line version,
        // we will only add files to be merged.
        for (int i = 1; i < args.length; i++) {
            linker.addMergeFile(args[i]);
        }
        try {
            linker.link();
        } catch (Exception ex) {
            System.err.print(ex.getMessage());
        }
    }


    /*
     * Actually performs the merging of f into the output.
     * f should be a zip or jar file.
     */
    private void mergeZipJarContents(ZipOutputStream output, File f) throws IOException {
        //Check to see that the file with name "name" exists.
        if (!f.exists()) {
            return;
        }
        ZipFile zipf = new ZipFile(f);
        Enumeration entries = zipf.entries();

        while (entries.hasMoreElements()) {
            ZipEntry inputEntry = (ZipEntry) entries.nextElement();
            //Ignore manifest entries.  They're bound to cause conflicts between
            //files that are being merged.  User should supply their own
            //manifest file when doing the merge.
            String inputEntryName = inputEntry.getName();
            int index = inputEntryName.indexOf("META-INF");

            if (index < 0) {
                //META-INF not found in the name of the entry. Go ahead and process it.
                try {
                    output.putNextEntry(processEntry(zipf, inputEntry));
                } catch (ZipException ex) {
                    //If we get here, it could be because we are trying to put a
                    //directory entry that already exists.
                    //For example, we're trying to write "com", but a previous
                    //entry from another mergefile was called "com".
                    //In that case, just ignore the error and go on to the
                    //next entry.
                    String mess = ex.getMessage();

                    if (mess.indexOf("duplicate") >= 0) {
                        //It was the duplicate entry.
                        continue;
                    } else {
                        // I hate to admit it, but we don't know what happened
                        // here.  Throw the Exception.
                        throw ex;
                    }
                }

                InputStream in = zipf.getInputStream(inputEntry);
                int len = buffer.length;
                int count = -1;

                while ((count = in.read(buffer, 0, len)) > 0) {
                    output.write(buffer, 0, count);
                }
                in.close();
                output.closeEntry();
            }
        }
        zipf.close();
    }


    /*
     * Adds contents of a directory to the output.
     */
    private void addDirContents(ZipOutputStream output, File dir, String prefix,
                                boolean compress) throws IOException {
        String[] contents = dir.list();

        for (int i = 0; i < contents.length; ++i) {
            String name = contents[i];
            File file = new File(dir, name);

            if (file.isDirectory()) {
                addDirContents(output, file, prefix + name + '/', compress);
            } else {
                addFile(output, file, prefix, compress);
            }
        }
    }


    /*
     * Gets the name of an entry in the file.  This is the real name
     * which for a class is the name of the package with the class
     * name appended.
     */
    private String getEntryName(File file, String prefix) {
        String name = file.getName();

        if (!name.endsWith(".class")) {
            // see if the file is in fact a .class file, and determine its actual name.
            InputStream input = null;
            try {
                input = new FileInputStream(file);
                String className = ClassNameReader.getClassName(input);

                if (className != null) {
                    return className.replace('.', '/') + ".class";
                }
            } catch (IOException ioe) {
                //do nothing
            } finally {
                if (input != null) {
                    try {
                        input.close();
                    } catch (IOException e) {
                        //do nothing
                    }
                }
            }
        }
        System.out.println("From " + file.getPath() + " and prefix " + prefix
                           + ", creating entry " + prefix + name);
        return (prefix + name);
    }


    /*
     * Adds a file to the output stream.
     */
    private void addFile(ZipOutputStream output, File file, String prefix,
                         boolean compress) throws IOException {
        //Make sure file exists
        if (!file.exists()) {
            return;
        }
        ZipEntry entry = new ZipEntry(getEntryName(file, prefix));

        entry.setTime(file.lastModified());
        entry.setSize(file.length());
        if (!compress) {
            entry.setCrc(calcChecksum(file));
        }
        FileInputStream input = new FileInputStream(file);

        addToOutputStream(output, input, entry);
    }


    /*
     * A convenience method that several other methods might call.
     */
    private void addToOutputStream(ZipOutputStream output, InputStream input,
                                   ZipEntry ze) throws IOException {
        try {
            output.putNextEntry(ze);
        } catch (ZipException zipEx) {
            //This entry already exists. So, go with the first one.
            input.close();
            return;
        }

        int numBytes = -1;

        while ((numBytes = input.read(buffer)) > 0) {
            output.write(buffer, 0, numBytes);
        }
        output.closeEntry();
        input.close();
    }


    /*
     * A method that does the work on a given entry in a mergefile.
     * The big deal is to set the right parameters in the ZipEntry
     * on the output stream.
     */
    private ZipEntry processEntry(ZipFile zip, ZipEntry inputEntry) {
        /*
          First, some notes.
          On MRJ 2.2.2, getting the size, compressed size, and CRC32 from the
          ZipInputStream does not work for compressed (deflated) files.  Those calls return -1.
          For uncompressed (stored) files, those calls do work.
          However, using ZipFile.getEntries() works for both compressed and
          uncompressed files.

          Now, from some simple testing I did, it seems that the value of CRC-32 is
          independent of the compression setting. So, it should be easy to pass this
          information on to the output entry.
        */
        String name = inputEntry.getName();

        if (!(inputEntry.isDirectory() || name.endsWith(".class"))) {
            try {
                InputStream input = zip.getInputStream(zip.getEntry(name));
                String className = ClassNameReader.getClassName(input);

                input.close();
                if (className != null) {
                    name = className.replace('.', '/') + ".class";
                }
            } catch (IOException ioe) {
                //do nothing
            }
        }
        ZipEntry outputEntry = new ZipEntry(name);

        outputEntry.setTime(inputEntry.getTime());
        outputEntry.setExtra(inputEntry.getExtra());
        outputEntry.setComment(inputEntry.getComment());
        outputEntry.setTime(inputEntry.getTime());
        if (compression) {
            outputEntry.setMethod(ZipEntry.DEFLATED);
            //Note, don't need to specify size or crc for compressed files.
        } else {
            outputEntry.setMethod(ZipEntry.STORED);
            outputEntry.setCrc(inputEntry.getCrc());
            outputEntry.setSize(inputEntry.getSize());
        }
        return outputEntry;
    }


    /*
     * Necessary in the case where you add a entry that
     * is not compressed.
     */
    private long calcChecksum(File f) throws IOException {
        BufferedInputStream in = new BufferedInputStream(new FileInputStream(f));

        return calcChecksum(in);
    }


    /*
     * Necessary in the case where you add a entry that
     * is not compressed.
     */
    private long calcChecksum(InputStream in) throws IOException {
        CRC32 crc = new CRC32();
        int len = buffer.length;
        int count = -1;
        int haveRead = 0;

        while ((count = in.read(buffer, 0, len)) > 0) {
            haveRead += count;
            crc.update(buffer, 0, count);
        }
        in.close();
        return crc.getValue();
    }


}