Appending files to a zip file with Java

Question

I am currently extracting the contents of a war file and then adding some new files to the directory structure and then creating a new war file.

This is all done programatically from Java - but I am wondering if it wouldn't be more efficient to copy the war file and then just append the files - then I wouldn't have to wait so long as the war expands and then has to be compressed again.

I can't seem to find a way to do this in the documentation though or any online examples.

Anyone can give some tips or pointers?

UPDATE:

TrueZip as mentioned in one of the answers seems to be a very good java library to append to a zip file (despite other answers that say it is not possible to do this).

Anyone have experience or feedback on TrueZip or can recommend other similar libaries?

Answer 1

You could use this bit of code I wrote

public static void addFilesToZip(File source, File[] files)
{
    try
    {

        File tmpZip = File.createTempFile(source.getName(), null);
        tmpZip.delete();
        if(!source.renameTo(tmpZip))
        {
            throw new Exception("Could not make temp file (" + source.getName() + ")");
        }
        byte[] buffer = new byte[1024];
        ZipInputStream zin = new ZipInputStream(new FileInputStream(tmpZip));
        ZipOutputStream out = new ZipOutputStream(new FileOutputStream(source));

        for(int i = 0; i < files.length; i++)
        {
            InputStream in = new FileInputStream(files[i]);
            out.putNextEntry(new ZipEntry(files[i].getName()));
            for(int read = in.read(buffer); read > -1; read = in.read(buffer))
            {
                out.write(buffer, 0, read);
            }
            out.closeEntry();
            in.close();
        }

        for(ZipEntry ze = zin.getNextEntry(); ze != null; ze = zin.getNextEntry())
        {
            out.putNextEntry(ze);
            for(int read = zin.read(buffer); read > -1; read = zin.read(buffer))
            {
                out.write(buffer, 0, read);
            }
            out.closeEntry();
        }

        out.close();
        tmpZip.delete();
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }
}

Answer 2

this works 100% , if you dont want to use extra libs .. 1) first, the class that append files to the zip ..

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class AddZip {

    public void AddZip() {
    }

    public void addToZipFile(ZipOutputStream zos, String nombreFileAnadir, String nombreDentroZip) {
        FileInputStream fis = null;
        try {
            if (!new File(nombreFileAnadir).exists()) {//NO EXISTE 
                System.out.println(" No existe el archivo :  " + nombreFileAnadir);return;
            }
            File file = new File(nombreFileAnadir);
            System.out.println(" Generando el archivo '" + nombreFileAnadir + "' al ZIP ");
            fis = new FileInputStream(file);
            ZipEntry zipEntry = new ZipEntry(nombreDentroZip);
            zos.putNextEntry(zipEntry);
            byte[] bytes = new byte[1024];
            int length;
            while ((length = fis.read(bytes)) >= 0) {zos.write(bytes, 0, length);}
            zos.closeEntry();
            fis.close();

        } catch (FileNotFoundException ex ) {
            Logger.getLogger(AddZip.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(AddZip.class.getName()).log(Level.SEVERE, null, ex);
        } 
    }

}

2) you can call it in your controller ..

//in the top
try {
fos = new FileOutputStream(rutaZip);
zos =   new ZipOutputStream(fos);
} catch (FileNotFoundException ex) {
Logger.getLogger(UtilZip.class.getName()).log(Level.SEVERE, null, ex);
}

...
//inside your method
addZip.addToZipFile(zos, pathFolderFileSystemHD() + itemFoto.getNombre(), "foto/" + itemFoto.getNombre());

Answer 3

Here are examples how easily files can be appended to existing zip using TrueVFS:

// append a file to archive under different name
TFile.cp(new File("existingFile.txt"), new TFile("archive.zip", "entry.txt"));

// recusively append a dir to the root of archive
TFile src = new TFile("dirPath", "dirName");
src.cp_r(new TFile("archive.zip", src.getName()));

TrueVFS, the successor of TrueZIP, uses Java 7 NIO 2 features under the hood when appropriate but offers much more features like thread-safe async parallel compression.

Beware also that Java 7 ZipFileSystem by default is vulnerable to OutOfMemoryError on huge inputs.

Answer 4

this a simple code to get a response with using servlet and send a response

myZipPath = bla bla...
    byte[] buf = new byte[8192];
    String zipName = "myZip.zip";
    String zipPath = myzippath+ File.separator+"pdf" + File.separator+ zipName;
    File pdfFile = new File("myPdf.pdf");
    ZipOutputStream out = new ZipOutputStream(new FileOutputStream(zipPath));
    ZipEntry zipEntry = new ZipEntry(pdfFile.getName());
    out.putNextEntry(zipEntry);
    InputStream in = new FileInputStream(pdfFile);
    int len;
    while ((len = in.read(buf)) > 0) {
         out.write(buf, 0, len);
     }
    out.closeEntry();
    in.close();
     out.close();
                FileInputStream fis = new FileInputStream(zipPath);
                response.setContentType("application/zip");
                response.addHeader("content-disposition", "attachment;filename=" + zipName);
    OutputStream os = response.getOutputStream();
            int length = is.read(buffer);
            while (length != -1)
            {
                os.write(buffer, 0, length);
                length = is.read(buffer);
            }

Answer 5

Yet Another Solution: You may find code below useful in other situations as well. I have used ant this way to compile Java directories, generating jar files, updating zip files,...

    public static void antUpdateZip(String zipFilePath, String libsToAddDir) {
    Project p = new Project();
    p.init();

    Target target = new Target();
    target.setName("zip");
    Zip task = new Zip();
    task.init();
    task.setDestFile(new File(zipFilePath));
    ZipFileSet zipFileSet = new ZipFileSet();
    zipFileSet.setPrefix("WEB-INF/lib");
    zipFileSet.setDir(new File(libsToAddDir));
    task.addFileset(zipFileSet);
    task.setUpdate(true);

    task.setProject(p);
    task.init();
    target.addTask(task);
    target.setProject(p);
    p.addTarget(target);

    DefaultLogger consoleLogger = new DefaultLogger();
    consoleLogger.setErrorPrintStream(System.err);
    consoleLogger.setOutputPrintStream(System.out);
    consoleLogger.setMessageOutputLevel(Project.MSG_DEBUG);
    p.addBuildListener(consoleLogger);

    try {
        // p.fireBuildStarted();

        // ProjectHelper helper = ProjectHelper.getProjectHelper();
        // p.addReference("ant.projectHelper", helper);
        // helper.parse(p, buildFile);
        p.executeTarget(target.getName());
        // p.fireBuildFinished(null);
    } catch (BuildException e) {
        p.fireBuildFinished(e);
        throw new AssertionError(e);
    }
}

Answer 6

I had a similar requirement sometime back - but it was for reading and writing zip archives (.war format should be similar). I tried doing it with the existing Java Zip streams but found the writing part cumbersome - especially when directories where involved.

I'll recommend you to try out the TrueZIP (open source - apache style licensed) library that exposes any archive as a virtual file system into which you can read and write like a normal filesystem. It worked like a charm for me and greatly simplified my development.