Including external jar-files in a new jar-file build with Ant

Question

I have just  inherited  a Java-project and not coming from a Java-background I am a little lost at times  Eclipse is used to debug and run the application during development  I have through Eclipse succeeded in creating a  jar-file that  includes  all the required external jars like Log4J  xmlrpc-server  etc  This big  jar can then be run successfully using   java -jar myjar jar   My next step is to automate builds using Ant  version 1 7 1  so I don t have to involve Eclipse to do builds and deployment  This has proven to be a challenge due to my lacking java-knowledge  The root of the project looks like this    - gt  jars  where external jars have been placed   - gt  java    - gt  bin  where the finished  class    jars are placed     - gt  src  Where code lives     - gt    files like build xml etc  - gt  sql  you guessed it  sql      My build xml contains the following    lt  xml version  1 0  encoding  UTF-8  standalone  no   gt   lt project basedir     default  build  name  Seraph  gt       lt property environment  env   gt       lt property name  debuglevel  value  source lines vars   gt       lt property name  target  value  1 6   gt       lt property name  source  value  1 6   gt        lt property name  build dir      value  bin   gt       lt property name  src dir        value  src   gt       lt property name  lib dir        value     jars   gt       lt property name  classes dir    value    build dir  classes   gt       lt property name  jar dir        value    build dir  jar   gt       lt property name  jar file       value    jar dir  seraph jar   gt       lt property name  manifest file  value    jar dir  MANIFEST MF   gt        lt property name  main class  value  no easyconnect seraph core SeraphCore   gt        lt path id  external jars  gt           lt fileset dir    lib dir   includes       jar   gt       lt  path gt        lt path id  project classpath  gt           lt pathelement location    src dir    gt           lt path refid  external jars    gt       lt  path gt        lt target name  init  gt           lt mkdir dir    build dir    gt           lt mkdir dir    classes dir    gt           lt mkdir dir    jar dir    gt           lt copy includeemptydirs  false  todir    build dir   gt               lt fileset dir    src dir   gt                   lt exclude name       launch   gt                   lt exclude name       java   gt               lt  fileset gt           lt  copy gt       lt  target gt        lt target name  clean  gt           lt delete dir    build dir    gt       lt  target gt        lt target name  cleanall  depends  clean   gt        lt target name  build  depends  init  gt           lt echo message    ant project name     ant file    gt           lt javac debug  true  debuglevel    debuglevel   destdir  bin  source    source   target    target   classpathref  project classpath  gt               lt src path    src dir    gt           lt  javac gt       lt  target gt        lt target name  build-jar  depends  build  gt           lt delete file    jar file     gt           lt delete file    manifest file     gt            lt manifest file    manifest file    gt               lt attribute name  built-by  value    user name     gt               lt attribute name  Main-Class  value    main class     gt           lt  manifest gt            lt jar destfile    jar file                basedir    build dir                manifest    manifest file   gt               lt fileset dir    classes dir   includes       class    gt               lt fileset dir    lib dir   includes       jar    gt           lt  jar gt       lt  target gt   lt  project gt    I then run      ant clean build-jar  and a file named seraph jar is placed in the java bin jar-directory  I then try to run this jar using the following command      java -jar bin jar seraph jar  The result is this output at the console   Exception in thread  main  java lang NoClassDefFoundError  org apache log4j Logger     at no easyconnect seraph core SeraphCore  lt clinit gt  SeraphCore java 23  Caused by  java lang ClassNotFoundException  org apache log4j Logger     at java net URLClassLoader 1 run URLClassLoader java 200      at java security AccessController doPrivileged Native Method      at java net URLClassLoader findClass URLClassLoader java 188      at java lang ClassLoader loadClass ClassLoader java 307      at sun misc Launcher AppClassLoader loadClass Launcher java 301      at java lang ClassLoader loadClass ClassLoader java 252      at java lang ClassLoader loadClassInternal ClassLoader java 320          1 more Could not find the main class  no easyconnect seraph core SeraphCore  Program will exit    I suspect that I have done something amazingly silly in the build xml-file and have spent the better part of two days trying variations on the configuration  to no avail  Any help on getting this working is greatly appreciated   Oh  and I m sorry if I left some crucial information out  This is my first time posting here at SO

User · Answer

As Cheesle said  you can unpack and your library Jars and re-jar them all with the following modification        lt jar destfile    jar file             basedir    build dir             manifest    manifest file   gt            lt fileset dir    classes dir   includes       class    gt            lt zipgroupfileset dir    lib dir   includes       jar    gt        lt  jar gt     Jar files are really just zip files with a manifest file embedded   You can extract and repackage the dependency Jars into your application s Jar file     http   ant apache org manual Tasks zip html  The Zip task also supports the merging of multiple zip files into the zip file  This is possible through either the src attribute of any nested filesets or by using the special nested fileset zipgroupfileset    Do pay attention to the licenses involved with your dependency libaries   Linking externally to a library and including the library in your application are very different things legally   EDIT 1  Darn my slow typing   Grodriguez beat me to it      EDIT 2  If you decide you can t include your dependencies into your application then you have to specify them in your Jar s classpath either at the command line at startup or via the Manifest file   There s a nice command in ANT to handle the special formatting of the classpath in a Manifest file for you    lt manifestclasspath property  manifest classpath  jarfile    jar file   gt       lt classpath location    lib dir     gt   lt  manifestclasspath gt     lt manifest file    manifest file    gt                 lt attribute name  built-by  value    user name     gt                 lt attribute name  Main-Class  value    main class     gt               lt attribute name  Class-Path  value    manifest classpath     gt    lt  manifest gt

User · Answer

Two options  either reference the new jars in your classpath or unpack all classes in the enclosing jars and re-jar the whole lot   As far as I know packaging jars within jars is not recommeneded and you ll forever have the class not found exception

User · Answer

This is a classpath issue when running an executable jar as follows   java -jar myfile jar   One way to fix the problem is to set the classpath on the java command line as follows  adding the missing log4j jar   java -cp myfile jar log4j jar otherjar jar com abc xyz MyMainClass   Of course the best solution is to add the classpath into the jar manifest so that the we can use the  -jar  java option    lt jar jarfile  myfile jar  gt                     lt manifest gt          lt attribute name  Main-Class  value  com abc xyz MyMainClass   gt          lt attribute name  Class-Path  value  log4j jar otherjar jar   gt       lt  manifest gt   lt  jar gt    The following answer demonstrates how you can use the manifestclasspath to automate the seeting of the classpath manifest entry  Cannot find Main Class in File Compiled With Ant

User · Answer

I m using NetBeans and needed a solution for this also  After googleling around and starting from Christopher s answer i managed to build a script that helps you easily do this in NetBeans  I m putting the instructions here in case someone else will need them   What you have to do is download one-jar  You can use the link from here  http   one-jar sourceforge net index php page getting-started amp file ant Extract the jar archive and look for one-jar dist folder that contains one-jar-ant-task- jar  one-jar-ant-task xml and one-jar-boot- jar  Extract them or copy them to a path that we will add to the script below  as the value of the property one-jar dist dir   Just copy the following script at the end of your build xml script  from your NetBeans project   just before  project tag  replace the value for one-jar dist dir with the correct path and run one-jar target   For those of you that are unfamiliar with running targets  this tutorial might help  http   www oracle com technetwork articles javase index-139904 html   It also shows you how to place sources into one jar  but they are exploded  not compressed into jars    lt property name  one-jar dist dir  value  path to one-jar-ant   gt   lt import file    one-jar dist dir  one-jar-ant-task xml  optional  true    gt    lt target name  one-jar  depends  jar  gt   lt property name  debuglevel  value  source lines vars   gt   lt property name  target  value  1 6   gt   lt property name  source  value  1 6   gt   lt property name  src dir           value  src   gt   lt property name  bin dir           value  bin   gt   lt property name  build dir         value  build   gt   lt property name  dist dir          value  dist   gt   lt property name  external lib dir  value    dist dir  lib   gt   lt property name  classes dir       value    build dir  classes   gt   lt property name  jar target dir    value    build dir  jars   gt   lt property name  final jar         value    dist dir    ant project name  jar   gt   lt property name  main class        value    main class    gt    lt path id  project classpath  gt       lt fileset dir    external lib dir   gt           lt include name    jar   gt       lt  fileset gt   lt  path gt    lt mkdir dir    bin dir    gt   lt  --  lt mkdir dir    build dir    gt  -- gt   lt  --  lt mkdir dir    classes dir    gt  -- gt   lt mkdir dir    jar target dir    gt   lt copy includeemptydirs  false  todir    classes dir   gt       lt fileset dir    src dir   gt           lt exclude name       launch   gt           lt exclude name       java   gt       lt  fileset gt   lt  copy gt    lt  --  lt echo message    ant project name     ant file    gt  -- gt   lt javac debug  true  debuglevel    debuglevel   destdir    classes dir   source    source   target    target   gt       lt src path    src dir    gt       lt classpath refid  project classpath   gt      lt  javac gt    lt delete file    final jar     gt   lt one-jar destfile    final jar   onejarmainclass    main class   gt       lt main gt           lt fileset dir    classes dir    gt       lt  main gt       lt lib gt           lt fileset dir    external lib dir     gt       lt  lib gt   lt  one-jar gt    lt delete dir    jar target dir    gt   lt delete dir    bin dir    gt   lt delete dir    external lib dir    gt    lt  target gt      Best of luck and don t forget to vote up if it helped you

User · Answer

From your ant buildfile  I assume that what you want is to create a single JAR archive that will contain not only your application classes  but also the contents of other JARs required by your application   However your build-jar file is just putting required JARs inside your own JAR  this will not work as explained here  see note    Try to modify this    lt jar destfile    jar file        basedir    build dir        manifest    manifest file   gt       lt fileset dir    classes dir   includes       class    gt       lt fileset dir    lib dir   includes       jar    gt   lt  jar gt    to this    lt jar destfile    jar file        basedir    build dir        manifest    manifest file   gt       lt fileset dir    classes dir   includes       class    gt       lt zipgroupfileset dir    lib dir   includes       jar    gt   lt  jar gt    More flexible and powerful solutions are the JarJar or One-Jar projects  Have a look into those if the above does not satisfy your requirements

User · Answer

You can use a bit of functionality that is already built in to the ant jar task    If you go to The documentation for the ant jar task and scroll down to the  merging archives  section there s a snippet for including the all the   class files from all the jars in you  lib main  directory    lt jar destfile  build main checksites jar  gt       lt fileset dir  build main classes   gt       lt restrict gt           lt name name       class   gt           lt archives gt               lt zips gt                   lt fileset dir  lib main  includes       jar   gt               lt  zips gt           lt  archives gt       lt  restrict gt       lt manifest gt         lt attribute name  Main-Class  value  com acme checksites Main   gt       lt  manifest gt   lt  jar gt    This Creates an executable jar file with a main class  com acme checksites Main   and embeds all the classes from all the jars in lib main   It won t do anything clever in case of namespace conflicts  duplicates and things like that  Also  it will include all class files  also the ones that you don t use  so the combined jar file will be full size   If you need more advanced things like that  take a look at like one-jar and jar jar links

User · Answer

Cheesle is right   There s no way for the classloader to find the embedded jars   If you put enough debug commands on the command line you should be able to see the  java  command failing to add the jars to a classpath  What you want to make is sometimes called an  uberjar    I found one-jar as a tool to help make them  but I haven t tried it  Sure there s many other approaches

User · Answer

With the helpful advice from people who have answered here I started digging into One-Jar  After some dead-ends  and some results that were exactly like my previous results I managed to get it working  For other peoples reference I m listing the build xml that worked for me    lt  xml version  1 0  encoding  UTF-8  standalone  no   gt   lt project basedir     default  build  name   lt INSERT PROJECT NAME HERE gt   gt       lt property environment  env   gt       lt property name  debuglevel  value  source lines vars   gt       lt property name  target  value  1 6   gt       lt property name  source  value  1 6   gt        lt property name  one-jar dist dir  value     onejar   gt       lt import file    one-jar dist dir  one-jar-ant-task xml  optional  true    gt        lt property name  src dir           value  src   gt       lt property name  bin dir           value  bin   gt       lt property name  build dir         value  build   gt       lt property name  classes dir       value    build dir  classes   gt       lt property name  jar target dir    value    build dir  jars   gt       lt property name  external lib dir  value     jars   gt       lt property name  final jar         value    bin dir   lt INSERT NAME OF FINAL JAR HERE gt    gt        lt property name  main class        value   lt INSERT MAIN CLASS HERE gt    gt        lt path id  project classpath  gt           lt fileset dir    external lib dir   gt               lt include name    jar   gt           lt  fileset gt       lt  path gt        lt target name  init  gt           lt mkdir dir    bin dir    gt           lt mkdir dir    build dir    gt           lt mkdir dir    classes dir    gt           lt mkdir dir    jar target dir    gt           lt copy includeemptydirs  false  todir    classes dir   gt               lt fileset dir    src dir   gt                   lt exclude name       launch   gt                   lt exclude name       java   gt               lt  fileset gt           lt  copy gt       lt  target gt        lt target name  clean  gt           lt delete dir    build dir    gt           lt delete dir    bin dir    gt       lt  target gt        lt target name  cleanall  depends  clean   gt        lt target name  build  depends  init  gt           lt echo message    ant project name     ant file    gt           lt javac debug  true  debuglevel    debuglevel   destdir    classes dir   source    source   target    target   gt               lt src path    src dir    gt               lt classpath refid  project classpath   gt              lt  javac gt       lt  target gt        lt target name  build-jar  depends  build  gt           lt delete file    final jar     gt           lt one-jar destfile    final jar   onejarmainclass    main class   gt               lt main gt                   lt fileset dir    classes dir    gt               lt  main gt               lt lib gt                   lt fileset dir    external lib dir     gt               lt  lib gt           lt  one-jar gt       lt  target gt   lt  project gt    I hope someone else can benefit from this

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