Jar files and class path
I have a small swing application which connects to an external database and queries something and creates a small report on the local machine. Running from the command line calling the == java MyClass works good. I would like to deploy this to two other machines. I dont want the use to run from the command line solution. I want to run it from a batch file using the jar file. But I am getting a a classpath issue ( ClassNotFoundException for the jdbc drivers ) . I signed my jar file using jarsigner too. I am not interesed in using the Web Start because there are no other security attached to this app. Only couple of people intends to use it. Running from the command line calling the app file explicitly works. In the batch file I added the setclass path too. Still it gives an exception. I added the jdbc driver jar file to the appication jar file too. Still the problem exists.
Any ideas ?
instead of including the JDBC driver inside your application's jar, have the two jars sit in a directory separatly and include both of them on your classpath. Or, you can even specify a manifest.mf Class-Path parameter for your application's jar file so that it automatically includes the driver's jar.
Similar Messages
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How to add jar file in class path ?
Hello,
how can I add jar file in system class path.
I am using Linux and installed java.
Now I am creating one java package and working programs.
I want to add commons-net-2.0.jar jar file into class path.
how can I add in linux systems.
Thank you.the same way you add anything else to the classpath.
-
Encryption/decryption through jar file and classes
Hi,
My application uses tomcat as web server.
I am doing encrytion and decyption.
i fetch encypted data from database and then decrypt it
If i use calsses in webapps -> WEB-INF -> classes folder, i place classes in that ,
In other case i use jar file and place that file in WEB-INF -> lib folder in the webapps directory.
There is huge performance difference.
While using classes performance is great while using jar file performance is very disappointed.
I am using a file for encryption /decryption also.Are you getting any error messages? Have you put debugging code in those classes to see what is happening?
-
Hi
1)When a jar file is run how can I access a file that is in the same directory that the jar is in ?
(I need access to another file that is not in the jar.)
2) If you read an ini file from the jar with getResource etc can you write back to that ini with new values ?
Thanks for your help.
Tim1) Use getResource to locate the jar url that contains the class. You will now have to extract the local filesystem path from the jar url.
2) No -
Problem: Multiple jar files in Class-Path [ IOException: line too long]
Hello Folks,
I am trying to create a jar file using the following command:
jar -cvfm mygrid.jar MANIFEST.MF -C grid-jar/ .
My MANIFEST.MF file is as following:
Manifest-Version: 1.0
Main-Class: com.gridftp.INSPgridFTP
Class-Path: lib/activation.jar lib/ant.jar lib/antlr.jar lib/axis.jar lib/castor-0.9.3.jar lib/cog-abstraction-common-2.0.jar lib/cog-abstraction-examples-2.1.jar lib/cog-certmanagement-1.0.jar lib/cog-certrequest-1.0.jar lib/cog-grapheditor-0.46.jar lib/cog-gridfaces-1.0.jar lib/cog-gridshell-1.0.jar lib/cog-jglobus-1.2-050621.jar lib/cog-karajan-0.31.jar lib/cog-provider-clref-gt3_0_2.jar lib/cog-provider-clref-gt3_2_0.jar lib/cog-provider-clref-gt3_2_1.jar lib/cog-provider-clref-gt4_0_0.jar lib/cog-provider-condor-2.0.jar lib/cog-provider-gt2-2.0.jar lib/cog-provider-gt2ft-1.0.jar lib/cog-provider-gt3_0_2-2.0.jar lib/cog-provider-gt3_2_0-2.0.jar lib/cog-provider-gt3_2_1-2.0.jar lib/cog-provider-gt4_0_0-2.2.jar lib/cog-provider-local-2.0.jar lib/cog-provider-ssh-2.0.jar lib/cog-provider-webdav-1.0.jar lib/cog-resources-1.0.jar lib/cog-setup-0.91.jar lib/cog-util-0.91.jar lib/commons-discovery.jar lib/commons-httpclient.jar lib/commons-logging.jar lib/concurrent.jar lib/cryptix32.jar lib/cryptix-asn1.jar lib/cryptix.jar lib/j2ssh-common-0.2.2.jar lib/j2ssh-core-0.2.2.jar lib/jaas.jar lib/jakarta-regexp-1.2.jar lib/jakarta-slide-webdavlib-2.0.jar lib/jaxrpc.jar lib/jce-jdk13-125.jar lib/jgss.jar lib/jug-1.0.1.jar lib/junit.jar lib/log4j-1.2.8.jar lib/mail.jar lib/puretls.jar lib/saaj.jar lib/wsdl4j.jar lib/xercesImpl.jar lib/xml4j.jar lib/xml-apis-1.1.jar lib/xmlsec.jar lib/xpp3-1.1.3.4d_b4_min.jar lib/xstream-1.1.1-patched.jar .
The grid-jar directory structure is:
| - com -- all classes are under this dir.
| - lib -- all the required jar files are in this dir.
There are 59 jar files in the lib directory. When I try to create the jar file, I get the following exception:
jar -cvfm mygrid.jar MANIFEST.MF -C grid-jar/ .
java.io.IOException: line too long
at java.util.jar.Attributes.read(Attributes.java:356)
at java.util.jar.Manifest.read(Manifest.java:167)
at java.util.jar.Manifest.<init>(Manifest.java:52)
at sun.tools.jar.Main.run(Main.java:124)
at sun.tools.jar.Main.main(Main.java:904)
Any idea, why do I get this exception? Is there any restriction as to how many jar files (or characters) can be there in the Class-Path value in the MANIFEST.MF file?
Please help.
Thanks,
Anause as the following way to resolve the problem:
(1) use separate lines, to avoid too long a line for java package name lists
(2) type a preceding space before each folloing lines, for example:
Class-Path: ...jar ...jar ...jar
...jar ..jar
...jar ...jar
...jar ...jar
Hello Folks,
I am trying to create a jar file using the following
command:
jar -cvfm mygrid.jar MANIFEST.MF -C grid-jar/ .
My MANIFEST.MF file is as following:
Manifest-Version: 1.0
Main-Class: com.gridftp.INSPgridFTP
Class-Path: lib/activation.jar lib/ant.jar
lib/antlr.jar lib/axis.jar lib/castor-0.9.3.jar
lib/cog-abstraction-common-2.0.jar
lib/cog-abstraction-examples-2.1.jar
lib/cog-certmanagement-1.0.jar
lib/cog-certrequest-1.0.jar
lib/cog-grapheditor-0.46.jar
lib/cog-gridfaces-1.0.jar lib/cog-gridshell-1.0.jar
lib/cog-jglobus-1.2-050621.jar
lib/cog-karajan-0.31.jar
lib/cog-provider-clref-gt3_0_2.jar
lib/cog-provider-clref-gt3_2_0.jar
lib/cog-provider-clref-gt3_2_1.jar
lib/cog-provider-clref-gt4_0_0.jar
lib/cog-provider-condor-2.0.jar
lib/cog-provider-gt2-2.0.jar
lib/cog-provider-gt2ft-1.0.jar
lib/cog-provider-gt3_0_2-2.0.jar
lib/cog-provider-gt3_2_0-2.0.jar
lib/cog-provider-gt3_2_1-2.0.jar
lib/cog-provider-gt4_0_0-2.2.jar
lib/cog-provider-local-2.0.jar
lib/cog-provider-ssh-2.0.jar
lib/cog-provider-webdav-1.0.jar
lib/cog-resources-1.0.jar lib/cog-setup-0.91.jar
lib/cog-util-0.91.jar lib/commons-discovery.jar
lib/commons-httpclient.jar lib/commons-logging.jar
lib/concurrent.jar lib/cryptix32.jar
lib/cryptix-asn1.jar lib/cryptix.jar
lib/j2ssh-common-0.2.2.jar lib/j2ssh-core-0.2.2.jar
lib/jaas.jar lib/jakarta-regexp-1.2.jar
lib/jakarta-slide-webdavlib-2.0.jar lib/jaxrpc.jar
lib/jce-jdk13-125.jar lib/jgss.jar lib/jug-1.0.1.jar
lib/junit.jar lib/log4j-1.2.8.jar lib/mail.jar
lib/puretls.jar lib/saaj.jar lib/wsdl4j.jar
lib/xercesImpl.jar lib/xml4j.jar lib/xml-apis-1.1.jar
lib/xmlsec.jar lib/xpp3-1.1.3.4d_b4_min.jar
lib/xstream-1.1.1-patched.jar .
The grid-jar directory structure is:
| - com -- all classes are under this dir.
| - lib -- all the required jar files are in
e in this dir.
There are 59 jar files in the lib directory. When I
try to create the jar file, I get the following
exception:
jar -cvfm mygrid.jar MANIFEST.MF -C grid-jar/ .
java.io.IOException: line too long
at
at
at
at
java.util.jar.Attributes.read(Attributes.java:356)
at
at
at java.util.jar.Manifest.read(Manifest.java:167)
at
at
at java.util.jar.Manifest.<init>(Manifest.java:52)
at sun.tools.jar.Main.run(Main.java:124)
at sun.tools.jar.Main.main(Main.java:904)
Any idea, why do I get this exception? Is there any
restriction as to how many jar files (or characters)
can be there in the Class-Path value in the
MANIFEST.MF file?
Please help.
Thanks,
Anajust -
Jar files and Main-Class attribute
Sorry, I know there are other topics regarding this argument but none of them helped me solving my problem.
I've tried a thousand time in every possible way, but I still can't run my application from a jar file. I've got a package called client, whose main class is called Client. The package contains a sub-package called Icons. I've put everything into a jar file and added this manifest:
Manifest version: 1.0
Name: client/
Sealed: True
Main-Class: client.Client
But it won't work. I've tried to erase the Sealed part, I've tried "Main-Class: Client" and also "client/Client", I've tried putting into the jar the client directory and I've tried omitting it, but the answer is always the same:
Failed to load main-class header etc.
Can anyone help me? Please, I'm almost desperate!
ThanksHere's the verbose-mode description of what I did.
jar -cfv client.jar clientaggiunto manifesto
aggiunta in corso di: client/(in = 0) (out= 0)(archiviato 0%)
aggiunta in corso di: client/.nbattrs(in = 767) (out= 310)(compresso 59%)
aggiunta in corso di: client/Client.class(in = 533) (out= 340)(compresso 36%)
aggiunta in corso di: client/Client.java(in = 288) (out= 140)(compresso 51%)
aggiunta in corso di: client/ClientForm$1.class(in = 691) (out= 383)(compresso 44%)
aggiunta in corso di: client/ClientForm$10.class(in = 678) (out= 380)(compresso 43%)
aggiunta in corso di: client/ClientForm$11.class(in = 689) (out= 385)(compresso 44%)
aggiunta in corso di: client/ClientForm$2.class(in = 686) (out= 379)(compresso 44%)
aggiunta in corso di: client/ClientForm$3.class(in = 686) (out= 381)(compresso 44%)
aggiunta in corso di: client/ClientForm$4.class(in = 686) (out= 380)(compresso 44%)
aggiunta in corso di: client/ClientForm$5.class(in = 686) (out= 383)(compresso 44%)
aggiunta in corso di: client/ClientForm$6.class(in = 718) (out= 399)(compresso 44%)
aggiunta in corso di: client/ClientForm$7.class(in = 718) (out= 400)(compresso 44%)
aggiunta in corso di: client/ClientForm$8.class(in = 718) (out= 399)(compresso 44%)
aggiunta in corso di: client/ClientForm$9.class(in = 718) (out= 398)(compresso 44%)
aggiunta in corso di: client/ClientForm.class(in = 33070) (out= 13510)(compresso 59%)
aggiunta in corso di: client/ClientForm.form(in = 131398) (out= 4521)(compresso96%)
aggiunta in corso di: client/ClientForm.java(in = 73435) (out= 6863)(compresso 90%)
aggiunta in corso di: client/Icons/(in = 0) (out= 0)(archiviato 0%)
aggiunta in corso di: client/Icons/brick.gif(in = 1044) (out= 1049)(compresso 0%)
aggiunta in corso di: client/Icons/corpo.gif(in = 4011) (out= 3400)(compresso 15%)
aggiunta in corso di: client/Icons/door.gif(in = 1092) (out= 1097)(compresso 0%)
aggiunta in corso di: client/Icons/floor.gif(in = 1102) (out= 1107)(compresso 0%)
aggiunta in corso di: client/Icons/mappa.gif(in = 20901) (out= 20575)(compresso 1%)
aggiunta in corso di: client/Icons/paesaggio.gif(in = 18962) (out= 18603)(compresso 1%)
aggiunta in corso di: client/Icons/sole.gif(in = 7063) (out= 6546)(compresso 7%)
aggiunta in corso di: client/Icons/trap.gif(in = 1062) (out= 1067)(compresso 0%)
aggiunta in corso di: client/Icons/void.gif(in = 842) (out= 847)(compresso 0%)
aggiunta in corso di: client/Listener.class(in = 1869) (out= 1136)(compresso 39%)
aggiunta in corso di: client/Listener.java(in = 2296) (out= 708)(compresso 69%)
aggiunta in corso di: client/manifesto.txt(in = 62) (out= 58)(compresso 6%)
aggiunta in corso di: client/ScorciatoieDialog$1.class(in = 740) (out= 391)(compresso 47%)
aggiunta in corso di: client/ScorciatoieDialog$PopupListener.class(in = 1579) (out= 773)(compresso 51%)
aggiunta in corso di: client/ScorciatoieDialog.class(in = 3524) (out= 1638)(compresso 53%)
aggiunta in corso di: client/ScorciatoieDialog.form(in = 8500) (out= 910)(compresso 89%)
aggiunta in corso di: client/ScorciatoieDialog.java(in = 5676) (out= 1222)(compresso 78%)
jar umf mainclass.txt client.jar[NOTE: mainclass.txt only contains the line "Main-Class: client.Client"]
java -jar client.jarFailed to load Main-Class manifest attribute from
client.jar
I've also tried to manually create a MANIFEST.MF file that only contained the following lines:
Manifest Version: 1.0
Main-Class: client.Client
guess what was the result?
java -jar client.jarException in thread "main" java.io.IOException: invalid manifest format
at java.util.jar.Manifest.read(Manifest.java:193)
at java.util.jar.Manifest.<init>(Manifest.java:52)
at java.util.jar.JarFile.getManifest(JarFile.java:158)
>
the same procedure with the addition of "Name: client/" before the main-class attribute generated the usual "Failed to load Main-Class manifest attribute" result. So now what?!? I'm getting crazy.... -
Jar file and classpath problem
I0m writing a program that use the kunststoff.jar Look&Feel.
Now I would like to put all I'm writing into a jar file but I always have a NoClassFoundException when I try to start my application.
here is a MANIFEST:ME I'm using:
Manifest-Version: 1.0
Created-By: 1.4.2-beta (Sun Microsystems Inc.)
Main-Class: JListaR.JListaR
Class-Path: kunststoff.jar img\ .why this don't work?Unfortunately you can't embed jars within a jar and
expect them to be referencable for the classpath from
outside the main jar. The "Class-Path" attribute in
the manifest is used to refer to other jar files
outside of your jar file.
The usual approach to solve this problem is to unpack
the jar files you want to embed and then rejar
everything together in one big jar file again. This
isn't always a great approach though, I know I'm
looking for an alternative. So far my only alternative
is dynamic class loading using a classloader, however
this isn't great if you need to refer to several
hundreds or even thousands of classes.thank you very mach...now I understand because it dosen't work correctly! -
Hi,
i am encountering a strange problem.
I am trying to run quartz (java application) on oc4j server.
When i have all the quartz classes in web-inf/classes folder, the application runs fine, but the moment i make a jar out of all classes and put the jar file in web-inf/lib folder, the application gives me a null pointer exception saying it is not able to set properties from an external properties file.This properties file is located in web-inf/classes folder.
Any help on sorting this out is welcome.
Regards
AshishThe are 2 possible ideas :
1. If processing your external properties file is not hardcoded in .jar, so point
classpath to the properties in META-INF/MANIFEST.MF file, example :
Class-Path: .
dot (.) point to the location WEB-INF/classes and you can test it easily with such code :
Properties config = new Properties() ;
InputStream is = getClass().getClassLoader().getResourceAsStream("config.properties") ;
if ( is == null ) {
System.err.println("Could not load config.properties") ;
} else {
config.load(is) ;
Manifest file could be easily generated using ant.
2. If it will not help, you should put your properties file inside .jar , but I suppose
first solution will rock. -
Verify a jar's manifest class-path
I want to verify a jar file's manifest class-path. By that I mean I want to verify that every import of every class in the jar file is reachable on the classpath specified in the jar file's manifest. I tried using a ClassLoader to load every class in the jar file and that does indeed catch a few errors (imported classes that are not on the classpath), but it does not catch them all -- I have situations where loading the class works fine, but when the code is executed, I get NoClassDefFoundError because an imported class is missing from the classpath. I have tried things like calling getDeclaredMethod() on the loaded class to sortof force all the imports to be resolved, but that apparently does not work.
So, can someone tell me how to sortof "force" a loaded class to reference/validate all its imports?
Thanks,
LeeWell yes, I know that executing the code would do it. But I'm not in a position to execute the code -- I'm doing this during a build and want to verify that I've built all the jars properly and have all the right classpaths. It's actually quite easy to use ANT to compile and create jar files that produce NoClassDefFoundError at runtime, due to leaving needed classes from the jar, or from bogus classpaths in the jar's manifest.
So, I was hoping there was some other way to do this. Perhaps I need to do something ugly like examining the bytecodes of each method...
Thanks,
Lee -
How to Add JAR files and Config files to CLASSPATH at runtime?
QUERY:
During runtime, I need to load the JAR files and relevant config files( .cfg files and .properties file) into CLASSPATH and run a specific java program from one of the JAR which is available in CLASSPATH.
Please advise me any relevant Java API details or a sample java program to implement the above use case.
Thanks in advance.During runtime, I need to load the JAR files and relevant config files( .cfg files and .properties file) into CLASSPATH and run a specific java program from one of the JAR which is available in CLASSPATH.
Please advise me any relevant Java API details or a sample java program to implement the above use case.
You don't add to YOUR classpath once your app is launched.
You create a NEW process for the app you want to run and provide the proper environment for it to run in - including any PATH or CLASSPATH environment variables.
The Java API for the ProcessBuilder class has a simple example that shows how to create the arguments and launch an external application.
ProcessBuilder (Java Platform SE 7 )
There are also PLENTY of other examples of using ProcessBuilder; just search the net. -
Setting path and class path help
I am a complete beginner who is currently starting a cd based tutorial!I have downloaded jdk1.1.6 which is the nearest developement kit to the one used in the tutorial.I use windows 98.When I try to set my path or class path as instructed in the docs, I cannot find any thing in the autoexec file at all.I have opened using notepad/Run and DOS edit but all three open an empty file.Where will I need to set up the path and class paths.My system must run these from somewhere else perhaps due to an update.
Hi,
Put the following statements in your autoexec.bat.
<homepath> = Path of your JDK folder on the drive. e.g. c:\jdk
SET CLASSPATH=;.;<homepath>\lib\tools.jar; .... continue with other jar files on the same line and seperate the entries by a semicolon.
SET PATH=C:\WINDOWS\;C:\<homepath>\BIN\;
This autoexec.bat must be on c:\. i.e. U can open it in notepad by giving c:\autoexec.bat in the File Open Dialog. It is possible for this file to be empty. Simply add the commands on the last line.
Regards ,
Karan -
Hello i have the following piece of code in class x.y.z.Tester:
String rootPath = this.getClass().getResource("/").getPath();
System.out.println(rootPath);which prints the path where the x.y.z.Tester class is located on my FS.
for example if my class is store at:
C/folder_1/bin/x/y/z/Tester.class
the returned path would be:
C:/folder_1/bin
Now, when I bundle this class (along with others) in a JAR file and set the x.y.z.Tester as the main class and run it, i get this error:
Exception in thread "main" java.lang.NullPointerException
at com.nortelnetworks.productsupportability.netrx.service.report.generator.Tester.<init>(Tester.java:9)
at com.nortelnetworks.productsupportability.netrx.service.report.generator.Tester.main(Tester.java:35)
On line 9 is the first line of code above.
On line 35 is the call to the method that has line 9.
However, the funny thing is that when I unzip (or extract) the contents of my JAR file, the it works fine and returns the path where the x.y.z.Tester is stored.
Now, I would like to have this work without having to unzip the JAR file. does anyone know if any issues or why the "getResource()" method returns a NullPointerException if it's JAR'ed.
thank you,Not sure what your goal is, but try this.
import java.net.URL;
import java.security.CodeSource;
import java.security.ProtectionDomain;
public class CodeSourceExample {
public static void main(String[] args) {
CodeSourceExample object = new CodeSourceExample();
Class cls = object.getClass();
ProtectionDomain domain = cls.getProtectionDomain();
CodeSource source = domain.getCodeSource();
URL location = source.getLocation();
System.out.println(location);
} -
Execution from JAR files and Classpaths -- Help
I am confused about how classes are resolved when running from within a JAR file, and why this is different than running a class that is not inside a JAR file.
I have an application that uses classes from a third party library stored in a JAR file (biojava.jar) . If I run the app from the class file it works as expected and is capable of finding the external classes when the path to the biojava.jar is on my classpath. It also works if biojava.jar is instead placed in the extensions folder jre/lib/ext folder without an explicit path entry in my classpath.
However when I package all my application classes up in a JAR file and try to execute the application from the JAR file it will ONLY work if I add a manifest entry to myApp.jar ... Class-Path: biojava.jar AND I place the file biojava.jar in the SAME directory as the Packaged JAR application. I would like to find a way to make this JAR file work for anyone who has biojava.jar in their classpath or ext directory. In other words I don't want my user community to have to copy the biojava.jar file when I email them myApp.jar. This community will already have biojava.jar on their CLASSPATH.
How can I make my app within a JAR recognize either the user's CLASSPATH or ext folder? I have tried reading the documentation and many experiments but the only way it works is as described above.
I am running Running Windows 2000.
java version "1.4.1_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_01-b01)
Java HotSpot(TM) Client VM (build 1.4.1_01-b01, mixed mode)
Here are the results of my experimentations:
The following Works:
Manifest: Main-Class: org/biojava/app/SequenceSpiral
Manifest: Class-Path: biojava.jar
Place biojava.jar in the same directory as SequenceSpiral.jar
java -jar SequenceSpiral.jar
This works perfectly
NONE of the following work
0) Placing biojava.jar in my jre/lib/ext directory instead of the same dir as SequenceSpiral.jar
Exception in thread "main" java.lang.NoClassDefFoundError: org/biojava/bio/seq/FeatureFilter
(this is the first class referenced from biojava.jar)
1) Just see if it will find the proper jar on my classpath
Manifest: Main-Class: org/biojava/app/SequenceSpiral
I have biojava.jar on my classpath but not in same directory as SequenceSprial.jar
java -jar SequenceSpiral.jar
Exception in thread "main" java.lang.NoClassDefFoundError: org/biojava/bio/seq/FeatureFilter
2) Specify the name if the jar in the Manifest Classpath and see if it will find the proper jar on my classpath
Manifest: Main-Class: org/biojava/app/SequenceSpiral
Manifest: Class-Path: biojava.jar
I have biojava.jar on my classpath but not in same directory as SequenceSprial.jar
java -jar SequenceSpiral.jar
Exception in thread "main" java.lang.NoClassDefFoundError: org/biojava/bio/seq/FeatureFilter
3) Specify the path of the jar in the Manifest Classpath
Manifest: Main-Class: org/biojava/app/SequenceSpiral
Manifest: Class-Path: d:/biojava/biojava.jar
I have biojava.jar on my classpath (D;\biojava\biojava.jar) but not in same directory as SequenceSprial.jar
java -jar SequenceSpiral.jar
Exception in thread "main" java.lang.NoClassDefFoundError: org/biojava/bio/seq/FeatureFilter
(note that in this case it is not fnding my main even though the Main-Class is specified)
4) Specify current directory and biojava.jar in the Manifest Class-Path
Manifest: Main-Class: org/biojava/app/SequenceSpiral
Manifest: Class-Path: .;biojava.jar
I have biojava.jar on my classpath (D;\biojava\biojava.jar) but not in same directory as SequenceSprial.jar
java -jar SequenceSpiral.jar
Exception in thread "main" java.lang.NoClassDefFoundError: org/biojava/bio/seq/FeatureFilter
5)Specify current directory and the URL of biojava.jar in the Manifest Class-Path
Manifest: Main-Class: org/biojava/app/SequenceSpiral
Manifest: Class-Path: . d:/biojava/biojava.jar
I have biojava.jar on my classpath (D;\biojava\biojava.jar) but not in same directory as SequenceSprial.jar
java -jar SequenceSpiral.jar
Exception in thread "main" java.lang.NoClassDefFoundError: org/biojava/bio/seq/FeatureFilter.
Thank you very much for any help or suggestions,
David MaynardI did some more testing and I think I now understand what is going on.
I don't like it, but at least I understand it.
The problem: I have an app packaged into a JAR file, myApp.jar. It has a dependancy upon an external JAR file extern.jar.
extern.jar is on my Classpath (and also in jre/lib/ext)
1) For some reason (bug?) java -jar myApp.jar does NOT use the classpath or the jre/lib/ext mechanisms to find .jar files needed to resolve references to external classes. This seems to be true even if you add an explicit -classpath argument on the command line!
thus
java -jar -cp c:\\absolutePathToMy\extern.jar myApp.jar
also fails as does
java -cp c:\\absolutePathToMy\extern.jar -jar myApp.jar
2) Inside the myApp Jar file you can specify a URL to an jar extension jar file but the URL IS RELATIVE TO THE PATH WHERE THE myApp.Jar is executed from! If I add the Manifest item Class-Path: ..\..\..\myexterndir\extern.jar then
java -jar myApp.jar
works correctly and resolves the external references.
This is why several people have reported that this class-path mechanism works ONLY when the extern.jar file is in the SAME DIRECTORY as the myApp.jar file when they had added a Class-Path: extern.jar to the Manifest.
However together these two items make it IMPOSSIBLE to distribute myApp.jar to others and have it work since the path names statically encoded inside the jar are relative to where the jar gets executed from. If I move myApp.jar to a different location on my hard drive it may also fail.
In my case I know all my customers already have extern.jar (5MB) installed on their classpaths and I would like to just send them the myApp.jar ( .5MB ).
However I don't see how to do this given the current specification of a JAR file, and the bug that makes all -jar file act like they have the Sealed=true property.
I tried explicity setting Sealed=false in the manifest but this didn't seem to have any effect.
I hope that this will save others the many hours of time it has taken be to determine that JARS are not well suited for deploying apps with dependenncies on external libs.
I also hope that someone can show me how execute a JAR and specify a classpath that doesn't get IGNORED my the classloader used in loading the jar classes.
This is using java version:
java version "1.4.1_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_01-b01)
Java HotSpot(TM) Client VM (build 1.4.1_01-b01, mixed mode)
Does any one know this bug is fixed in a later release?
David Maynard -
Executable jar files and manifest file
Hi,
I have the following files in a folder named: Test
a.jar
b.jar
c.jar
Driver.class
Driver.mf
Here, MainClass is the main executable class that uses a,band c.jar files. This is how my MainClass.mf file looks:
Manifest-Version: 1.0
Main-Class: Driver
Class-Path: a.jar b.jar c.jar
Now I use the following command to make one executable jar file:
jar cmf Driver.mf DriverMain.jar *
It creates an executable jar file named : DriverMain.jar
Now I copy the executable jar file (DriverMain.jar) into a different folder named: RunTest
and double click it, doesn't work.
my question is:
what am I doing wrong? Any special characters needed in my Driver.mf file (space/newline/etc)?
What I am trying to get is: One execuatble jar file so I can just double click to run it, and that single executable jar file will have all the necessary jars in it (i.e. a.jar, b.jar, c.jar in this case)
Anyone please help!
Thanks
-RonRony,
Sorry to disappoint, but you can not use embeded jar/zip files within an executable jar. The JDK sadly for some reason decided this was not a useful idea, so developers like me who want to distribute plugins with thier own dependencies have one of two choices. You either have to unzip the jar file that contains the embeded jars to a directory, then run your primary exectuable jar, OR you have to write a custom classloader that your "launcher" creates then loads the embeded jar files.
The best thing to do is either jar up a, b, c and driver into one jar, so that it works, if you can legally do this. A lot of 3rd party libraries may not allow this per their license. Otherwise, another choice is to use a free installer or buy an installer that allows you to distribute a single exectuable installer program that will properly create the dir structure you need.
As for the way it works, if you declare:
Class-Path: a.jar b.jar c.jar
the JAR loader code in the JDK looks in the root dir where your application was started for a/b/c jar files. They have to be on disk.
If you want to place them in /lib, for example, you would havd a jar file like:
Driver.class
Driver.mf
lib/a.jar
lib/b.jar
lib/c.jar
When unzipped, your "root" dir would look exactly like the above, and your manifest would have Class-Path using ./lib/a.jar ./lib/b.jar ./lib/c.jar
Anyway, there thus far isn't any way around this issue of embeding jar files in an executable jar file. You MIGHT be able to not specify any classpath, then in your Driver.class, create a new custom classloader that dervies from URLClassLoader, but in the findClass(), you get a ref to the .jar file that the classloader class is inside of, and from that use it to find the lib/*.jar files and add them to the classpath. For this to work, however, your Driver.class code should ALSO be contained in an embeded jar file that is loaded by this custom loader. The only thing Driver.class would contain (and I would rename it to something like Launcher) is the code to create the custom classloader.
It's fun stuff, but a little bit of work to make it work. You can infact make it work! I may yet one day take our plugin engine custom loader and create a way for this to work! -
Just starting a J2ME project.
An embarrassingly Noobie Question:
1) All the classes that are supposedly "built-in" to my device (phone)
do NOT need to be included in the deployed JAR file, right?
2) Anyone know how to do that in Netbeans 5.0?
Project -> Properties -> Build shows sources filtering
but that doesn't include anything from my "input"/library .JARS.
However, all the com.*, javax.* and java.* files are being included in
my output JAR file and it causes failures in preverify and loading
on the phone.
HELP!!hi,
any know this question
please send me the procedures about how load my J2ME
application(jad and jar file) into CDMA mobiles
like(Nokia 6255,6235,6235i etc..).
its very urgent for me,
please anybody known this answer reply very soon.
thanks a lot
laxmi.Hi
I am also having the same problem , any one has found solutions kindly inform. I want to install the spreadsheet viewer. Has any body developed solutions for the same - Please help
Thanks a lot
Ragupathi
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