I'm trying to package some external libraries into my java project, but failing miserably. I've got a .jar-file, with external libraries packaged into ./lib/jars. If I have the manifest pointing the Class-Path: at lib/jars/theJar.jar, I get a NoClassDefFoundError. If I have the Class-Path pointing at C:\Users\Owner\workspace\theProject\lib\jars\theJar.jar, the jar file is found - but I suppose that will only work on my computer.
How do I make the program go looking for the jars inside of the jar?
You don't, unless you use a custom classloader like JarClassLoader.
Alternatives include things like jarjar and One-JAR.
Edit It appears I misunderstood your problem, based on your question title--they're not really "internal", they're external, as your question correctly states. The last sentence is again misleading: are you trying to reference external jars, or jars inside of the jar?
Related
I've currently finished my project, but can't get it to work when it is exported. I use JAXB to read and write XML Files and also have dependencies on other external Folders, which are needed to use a POS-Printer.
I've managed to link my external XML Save-Files with absolute paths, but not with relative paths. So that worked, although not the way i wanted. Yet, using the external class folder for the printer didn't work at all.
This means, that in my Eclipse Project Build Path i've added a class folder, which contains all of these needed files (which are not only jars, so adding them one by one wouldnt work). So exporting my project to a jar either includes all the files into the jar itself, or doesnt include them at all.
Everything works perfectly in Eclipse, but not when i export it.
My folder structure looks like this:
src
/model
/view
/control
data
/articles.xml
/...
JavaPOS <--- needed folder with all its files
/jpos.xml
/xerxers.jar
/swt-..-.dll
I've tried:
InputStreams is = getClass().getResourceAsStream(url);
absolute paths
manipulating the manifest file and/or jar structure
runnable and non runnable jars with nearly every combination of options
putting the files inside the library "by hand"
changing the build path of the project
My Question is:
How do i get my jar-file to know where these files are?
EDIT:
Do you think Maven or an Ant file could solve my problems? I don't have any experience with those.
The Problem was, that i had more than one JRE installed and that the one eclipse was using, had all the dll files, but the other ones didnt have it. So i had to add them manually, because reinstalling the drivers of the printer didnt change anything. Gotta fix that somehow, but right now it works and that is all i wanted.
Turns out i didn't even need that Folder, just needed one file out of it and the missing dlls.
I've developed a utility library that will be used in many of our enterprise Java applications. This library has numerous additional dependencies that also need to be on the classpath. I'd like to avoid forcing our developers to add a zillion entries to their MANIFEST.MF files, and let them instead just include my library. Is there any way that my library's MANIFEST.MF file can reference its dependencies and have them picked up by the enterprise applications that will be using my library?
I've tried referencing them in my library's MANIFEST.MF file using the full path to the dependencies on the filesystem. That didn't work. I end up with ClassNotFoundException errors for all of my dependencies. Is there something else I should be trying?
When you create a web application, you'd normally put it in a WAR file. The idea is that you bundle the required dependencies in that WAR file, by adding the jars to the /WEB-INF/lib folder inside the WAR. Web containers (like in a Java EE application server) know of this structure and will include those jars on the classpath.
If your library has additional dependencies, just tell the users about it and either redistribute them with your library if the license allows it, or tell them where to obtain them. When using a decent tool for creating a web app like an IDE, Ant with Ivy, or Maven (or a combination of these), then handling and bundling dependencies should be no problem.
Alternatively, this works so long as you stick to the format very carefully, i.e. stick to exactly two spaces before each "file:" etc:
Manifest-Version: 1.0
Main-Class: package.TestClass
Class-Path: file:/D:/WebServer/Tomcat/shared/lib/BlueCove.jar
file:/D:/WebServer/Tomcat/shared/lib/classes12.jar
file:/D:/WebServer/Tomcat/shared/lib/comm.jar
file:/D:/WebServer/Tomcat/shared/lib/FTP.jar
file:/D:/WebServer/Tomcat/shared/lib/FTP2.jar
file:/D:/WebServer/Tomcat/shared/lib/iText.jar
file:/D:/WebServer/Tomcat/shared/lib/j2ee.jar
file:/D:/WebServer/Tomcat/shared/lib/jmxremote.jar
file:/D:/WebServer/Tomcat/shared/lib/jmxri.jar
file:/D:/WebServer/Tomcat/shared/lib/jmxtools.jar
file:/D:/WebServer/Tomcat/shared/lib/jpos15.jar
file:/D:/WebServer/Tomcat/shared/lib/js.jar
file:/D:/WebServer/Tomcat/shared/lib/mail.jar
...
file:/C:/WebServer/Tomcat/shared/lib/soap.jar
file:/C:/WebServer/Tomcat/shared/lib/sqljdbc.jar
file:/C:/WebServer/Tomcat/shared/lib/tools.jar
I've done this with a number of tools. It is a truly horrible hack but seems to work reliably.
Give them a special manifest to use. Something like:
Manifest-Version: 1.0
Main-Class: com.xxx.yyy.zzz.YourSpecialClassThatHacksTheClassPath
Real-Main-Class: com.ppp.qqq.TheirMainClass
In your special class, screw around with the classpath (not easy), read the manifest "Real-Main-Class" entry (a bit easier) and launch their main from that (not really difficult at all).
Obviously this will not work with a .war file.
Even I had the same problem. As mentioned above, the solution was to have exact two space after file:/ and one space after .jar file and at the end, press enter key.
I know this is not a neat solution, but it works. enjoy.
this will sound silly but i am executing my code from command prompt and have to use a jar in my class.
I have placed my jar in lib folder of JDK..
but i am still getting error of file not found
any explanation??
EDITED : guys tried all but still not working
EDIT 2 :i am trying to work as was told by this link i am using js-1.6R5.jar
Edit 3 : i undestand all the things you ppl have told but nothing working for me.. pls give me a link to upload my example that i can share with you all.
Edit 4 : i am fed up by setting classpaths but its not working... i have SDK installed in my system, do i need an extra JDK to run my programs from command prompt??
You need to add the jar to the class path by doing the following...
java -classpath D:\myprogram;D:\myprogram\lib\supportLib.jar org.mypackage.HelloWorld
Please see Wikipedia - Classpath_(Java)
You can place it anywhere, as long is you include it in your classpath. See Setting the Class Path for how to include jars in the classpath.
Have in mind that adding something in the JDK lib is almost never a good idea.
You can make a lib folder in your application's directory and put jar files there, then make your application find them by adding lib to your application's classpath.
And, don't put your jar files in JDK's lib folder. It's not good practise.
You need to let Java know that you want to include the jar in your classpath (the list of folders and jars it checks for classes). One way to do this is with the -cp command line argument, something like
java -cp ".;pathToMyJar\myJar.jar" MyClass
Another is to edit the CLASSPATH environment variable in your OS to include your jar.
A simple solution will be to place the jar fiel inside the windows folder if you are doing it in a Windows machine.
Unfortunately your question contains a lot of question signs and few information.
If you are using java.io.File to open jar as a regular file this jar should not be in lib directory. You just have to provide correct path in file system.
If however you are just trying to use jar as a part of your application it should be in classpath. Use either command line java -cp myjar.jar MyMainClassor put full path to this jar to global environment variableCLASSPATH`.
we have downloaded jar files for lambdaj and its dependencies which are again jar files.
we do not know how to go about it. we have copied these files in the
C:\Program Files\Java\jre6\lib\ext
have set the class path in environment variales as:
variable: classpath
path: C:\Program Files\Java\jre6\lib\ext
but we do not know how to go further. we want to run some lambdaj programs.
can anyone suggest how to run lambdaj programs?
You would run a Java program that requires lambdaj in exactly the same way you'd run any other java program with an external dependency, i.e. by invoking the java executable passing in the fully-qualified name of the Main class, or the JAR with an appropriate manifest, or by deploying it in a servlet container, etc. Additionally you should be putting the LambdaJ JAR on the classpath for this invocation, not in the lib folder for your entire JVM.
What have you tried so far and why/how is it not working? Your question at the moment is a bit analogous to "I want to use Microsoft Word to view some Word documents, how do I do this?".
Update for comment 1: You said "it's not working". That doesn't help anyone address your problem as it gives no clue what you expected to happen and what you observed, only that they were different. As for where JAR files can be stored - you can put them in any directory, so long as that directory is on the classpath (or you add it to the classpath) of the Java application that runs. The canonical place to put external dependencies is in a folder called lib below the root of your project, but the important thing is that you choose somewhere consistent and sensible.
It sounds like you don't quite grok Java and classpaths yet. If you have followed some tutorials and are still stuck, ask for help to let you understand. Adding more detail to your question, including the layout of your files, the commands you issued, and the response that came back would be useful too.
If you are using Netbeans create a project and right click on the Libraries folder within the desired project. Click Add JAR/Folder...
Basically let me first explain what I am aiming to do. I have a dynamic ETL transformer app written in JAVA. Due to the dynamic nature of this app I have to be able to add plugins jars to the app in a location outside of the apps jar file.
Basically would like to have the following directory structure:
AppFolder
|- plugins/
|- configs/
|- mainApp.jar
If possible I would like to be able to use wildcards in my manifest to dynamically add jars located in the plugins folder.
Unfortunately all I have tried so far has failed. I have tried to use both relative paths and absolute paths neither have worked (with or without wildcard).
If I however include the plugins folder in the main app's jar file itself it works fine given that I don't use wildcards.
So my question is, is it actually possible to have dependencies outside of a jar or do they always have to be contained within.
The other question is regarding the usage of wildcards. i have looked at [the java documentation] (http://java.sun.com/javase/6/docs/technotes/tools/windows/classpath.html) to no prevail unfortunately.
some examples of what I have tried so far:
../plugins/*
../plugins/plugin.jar
/abolute/path/to/plugins/*
/abolute/path/to/plugins/plugin.jar
and unfortunately none of them have done the trick so any help would be very much appreciated...
Yes you can have dependencies outside the jar. But wildcards are not supported for specify dependant jars.
The jars need to be explicitly specified in your manifest, and the location needs to be relative to where the application is run from
A better option for you may be to use the Extension Mechanism
java -Djava.ext.dirs=/abolute/path/to/plugins/ ......
If you have control of the code you could always add a JarClassLoader and load the jars dynamically.
http://java.sun.com/docs/books/tutorial/deployment/jar/jarclassloader.html