Develop Reference

Must I unpack a war file to run a single class? [duplicate]

I have a Java class which has a main and I used to run as a standalone app from the command line e.g.
java -jar myjar.jar params
I needed to repackage the code to run under apache and all my code, including the entry point class from the old jar, has ended up in a WAR file for easy deplyment into the web server.
However, I still want to be able to run it from the command line and the code has not changed and is all in there, I just can't figure out how to get it to run.
Here's what I tried...
I presumed the WAR was just like a jar, so
java -jar mywar.war params
That failed saying there was no main class defined in the manifest.
I manually added a manifest to the war and tried again, with the same effect.
I noticed that in my war I had a folder called META-INF containing a manifest.mf, so I added a line to that declaring my main class as I would to a normal manifest...
Manifest-Version: 1.0
Main-Class: mypackage.MyEntryPointClass
This gave a noClassDefFoundError mypackage.MyEntryPointClass, which is progress of a sort. That led me to believe that it was just a path issue, so I tried
Manifest-Version: 1.0
Main-Class: WEB-INF.classes.mypackage.MyEntryPointClass
I now get the same error, but with a stack trace...
Exception in thread "main" java.lang.NoClassDefFoundError: WEB-INF/classes/mypackage/MyEntryPointClass (wrong name: mypackage/MyEntryPointClass)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
I've googled for a bit but can't find anything which answers my question, and I read a couple of other questions here which are slightly different, so I thought I would post.
Java 1.5, not that I think that should make any difference.

Similar to what Richard Detsch but with a bit easier to follow (works with packages as well)
Step 1: Unwrap the War file.
jar -xvf MyWar.war
Step 2: move into the directory
cd WEB-INF
Step 3: Run your main with all dependendecies
java -classpath "lib/*:classes/." my.packages.destination.FileToRun

You can do what Hudson (continuous integration project) does.
you download a war which can be deployed in tomcat or to execute using
java -jar hudson.war
(Because it has an embedded Jetty engine, running it from command line cause a server to be launched.) Anyway by looking at hudson's manifest I understand that they put a Main class in the root for the archive. In your case your war layout should be look like:
under root:
mypackage/MyEntryPointClass.class
WEB-INF/lib
WEB-INF/classes
META-INF/MANIFEST.MF
while the manifest should include the following line:
Main-Class: mypackage.MyEntryPointClass
please notice that the mypackage/MyEntryPointClass.class is accessable from the command line only, and the classes under WEB-INF/classes are accessable from the application server only.
HTH

A war is a webapp. If you want to have a console/standalone application reusing the same classes as you webapp, consider packaging your shared classes in a jar, which you can put in WEB-INF/lib. Then use that jar from the command line.
Thus you get both your console application, and you can use the same classes in your servlets, without making two different packages.
This, of course, is true when the war is exploded.

If you're using Maven, just follow the maven-war-plugin documentation about "How do I create a JAR containing the classes in my webapp?": add <attachClasses>true</attachClasses> to the <configuration> of the plugin:
<project>
...
<artifactId>mywebapp</artifactId>
<version>1.0-SNAPSHOT</version>
...
<build>
<plugins>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>2.6</version>
<configuration>
<attachClasses>true</attachClasses>
</configuration>
</plugin>
</plugins>
</build>
...
</project>
The you will have 2 products in the target/ folder:
The project.war itself
The project-classes.jar which contains all the compiled classes in a jar
Then you will be able to execute a main class using classic method: java -cp target/project-classes.jar 'com.mycompany.MainClass' param1 param2

To execute SomeClass.main(String [] args) from a deployed war file do:
Write class SomeClass.java that has a main method method i.e. (public static void main(String[] args) {...})
Deploy your WAR
cd /usr/local/<yourprojectsname>/tomcat/webapps/projectName/WEB-INF
java -cp "lib/jar1.jar:lib/jar2.jar: ... :lib/jarn.jar" com.mypackage.SomeClass arg1 arg2 ... arg3
Note1: to see if the class SomeOtherClass.class is in /usr/tomcat/webapps/<projectName>/WEB-INF/lib run:
cd /usr/tomcat/webapps/projectName/WEB-INF/lib &&
find . -name '*.jar' | while read jarfile; do if jar tf "$jarfile" | grep SomeOtherClass.class; then echo "$jarfile"; fi; done
Note2: Write to standard out so you can see if your main actually works via print statements to the console. This is called a back door.
Note3: The comment above by Bozhidar Bozhanov seems correct

The rules of locating classes in an archive file is that the location of the file's package declaration and the location of the file within the archive have to match. Since your class is located in WEB-INF/classes, it thinks the class is not valid to run in the current context.
The only way you can do what you're asking is to repackage the war so the .class file resides in the mypackage directory in the root of the archive rather than the WEB-INF/classes directory. However, if you do that you won't be able to access the file from any of your web classes anymore.
If you want to reuse this class in both the war and outside from the java command line, consider building an executable jar you can run from the command line, then putting that jar in the war file's WEB-INF/lib directory.

In Maven project, You can build jar automatically using Maven War plugin by setting archiveClasses to true. Example below.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<configuration>
<archiveClasses>true</archiveClasses>
</configuration>
</plugin>

the best way if you use Spring Boot is :
1/ Create a ServletInitializer extends SpringBootServletInitializer Class
. With method configure which run your Application Class
2/ Generate always a maven install WAR file
3/ With this artefact you can even :
. start application from war file with java -jar file.war
. put your war file in your favorite Web App server (like tomcat, ...)

Well, according to Wikipedia, with a WAR file, the classes that get loaded into the classpath are in the "/WEB-INF/classes" and "/WEB-INF/lib" directory.
You could try simply putting a copy of the classes on the root file system of the zip file (which is what a war/jar is). I'm not sure if that would work though.
You can always just create two separate files.

As an alternative option, include into the war file, the rest service to trigger the application logic via url. Deploy the war file onto any web/application server you want.
Then you can start your application via any command-line based HTTP client like curl on Linux.
The disadvantage: usually these HTTP clients are different on different OSs. Which is not critical for a lot of cases. Also you can install curl on Windows.

It's not possible to run a java class from a WAR file. WAR files have a different structure to Jar files.
To find the related java classes, export (preferred way to use ant) them as Jar put it in your web app lib.
Then you can use the jar file as normal to run java program. The same jar was also referred in web app (if you put this jar in web app lib)

How to include all dependent Jars within a single non-executable jar?

I am stuck in a very common problem.
I am plugging my jar (which has many dependencies on third party vendor) into an application server lib directory. If I just copy my jar along with its dependencies into server lib then server classpath becomes to long and hence server is not able to work. Therefore I want to package this Jar with all its dependencies in a single jar so that server's classpath doesn't become too long. I found on various forums that there is a utility to do this i.e. OneJar. But this utility works on executable jar. In my case, my final jar will not be executable.
Also I tried ZIPFileSetGroup utility provided by ANT but that is causing security issues with Manifest file.
Can you please help me in resolving this issue?
Thanks!

If you use Maven to build, you can use the maven dependency plugin and use the copy-dependency task. It will copy all dependencies into your jar file when it creates it.
If you manually add the jars to your jar file, then you need to make sure your jar file has a Manifest.mf file in it and specify the main class and classpath inside of that.
Manifest-Version: 1.0
Main-Class: com.mypackage.MainClass
Class-Path: my.jar log4j.jar
Another option may be to build an .ear file, that is usually how you see enterprise apps or a .war file for web apps when they package specific jar files with them. It sounds like you are using a server, so one of those formats may be a better fit for you.

Using zipgroupfileset in the jar task in ANT is the easiest approach.
<jar destfile="MyApplication.jar" filesetmanifest="mergewithoutmain">
<zipgroupfileset dir="lib" includes="*.jar" />
<!-- other options -->
<manifest>
<attribute name="Main-Class" value="Main.MainClass" />
</manifest>
</jar>
Note the filesetmanifest flag set to mergewithoutmain merges everything but the Main section of the manifests.
Signed jars are causing the SecurityException which need to be handled manually. If any classes associated with signed jars verify the signature on the jar as a whole then those will fail at runtime. Digest signatures against a particular file will be added to the manifest without a problem. Since problem is your classpath getting too large you may not be able to bundle all the jars into a single jar but merge most of them making the CLASSPATH manageable.
There is also : http://code.google.com/p/jarjar/
Create target directory with all dependent jars. Next move 10 jars into a temp directory and keep moving the jars in batches of 10 and each time try to create the single jar from that group. When you get the security exception you can isolate which one is causing the problem. Try divide-and-conquer approach. If you have 300 jars then only have to do this 30 times.

When you say
child process picks up classpath from server/lib directory
is this a process that is under your control? If the parent process were to specify the classpath just as
server/lib/*
(i.e. a literal *) then the target java process will enumerate the jar files in the lib directory itself - they do not all need to be named on the classpath.
But if the parent process is explicitly enumerating server/lib/*.jar to build the -cp value then you could take advantage of the fact that the Class-Path in a JAR manifest takes effect even if a JAR is not "executable". You could use a stanza like this to create a manifest-only JAR file
<!-- location of your 300 dependency JAR files, file1.jar ... file300.jar -->
<property name="lib.dir" location="lib" />
<fileset id="dependencies" dir="${lib.dir}" includes="*.jar" />
<pathconvert property="manifest.classpath" dirsep="/" pathsep=" "
refid="dependencies">
<map from="${lib.dir}" to="myapp" />
</pathconvert>
<jar destfile="myapp-manifest.jar">
<manifest>
<attribute name="Class-Path" value="${manifest.classpath}" />
</manifest>
</jar>
This will produce a JAR file named myapp-manifest.jar whose manifest contains
Class-Path: myapp/file1.jar myapp/file2.jar ... myapp/file300.jar
You put this file into server/lib and the 300 dependencies into a new directory server/lib/myapp. Now the generated -cp will include just one file (myapp-manifest.jar) but the resulting java process will have all the 300 myapp JAR files available to it.

create jar with custom manifest with multiple libraries in classpath

I'm trying to create a jar from my eclipse and in order to be able to use the external .jars, I'm using this manifest with multiple .jars in the classpath:
Manifest-Version: 1.0
Sealed: true
Main-Class: src.BatchTester
Class-Path: . P:/Tools/xstream/1.4.2/lib/kxml2-2.3.0.jar P:/Tools/xstream/1.4.2/lib/xstream-1.4.2.jar P:/Tools/StringTemplate/4.0.5/lib/antlr-3.3-complete.jar P:/Tools/StringTemplate/4.0.5/lib/ST-4.0.5.jar P:/Tools/Jdbc/lib/sqljdbc4.jar
Obviously if I don't put the libraries in the classpath the following error appears:
java.lang.NoClassDefFoundError: com/thoughtworks/xstream/XStream
But when I put them in the classpath the error changes to:
java.lang.NoClassDefFoundError: src/BatchTester
So it seemps that it can't found my main class. I've tryed with several possibilities in the classpath, like adding or removing . to the classpath, but can't make it work.
Any idea of how can I solve this???
Thanks for your time and effort,
PS: After creating the .jar the classpath in the manifest inside looks like:
Class-Path: . P:/Tools/xstream/1.4.2/lib/kxml2-2.3.0.jar P:/Tools/xstr
eam/1.4.2/lib/xstream-1.4.2.jar P:/Tools/StringTemplate/4.0.5/lib/ant
lr-3.3-complete.jar P:/Tools/StringTemplate/4.0.5/lib/ST-4.0.5.jar P:
/Tools/Jdbc/lib/sqljdbc4.jar
with new lines and spaces, but even after changing it to the "right" format, I got the same problems.
PS2: I know that with some plugins like Fat-Jar you can make it work, but I don't want to insert more data than needed in my .jar

Finally I've copied all the libs into the /lib folder and add them into the .jar with an ant target since seems to be OK with the IT guys (because it is a small application).
Here is the ant(in case is useful for someone):
<?xml version="1.0" encoding="UTF-8"?>
<project name="BatchTester" default="compile" basedir=".">
<property name="external" value="lib/external-libs.jar"/>
<target name="compile">
<javac srcdir="jav"
source="1.6"
/>
<echo>Creating jar File</echo>
<!--create a new .jar with all the external jars in /lib-->
<jar jarfile="${external}">
<zipgroupfileset dir="lib/">
<include name="**/*.jar"/>
</zipgroupfileset>
</jar>
<!--<sleep seconds="1"/>-->
<!--create .jar file-->
<jar jarfile="BatchTester.jar" index="true" filesetmanifest="mergewithoutmain">
<fileset dir=".">
<include name="**/jav/**/*.class"/>
<exclude name="**/jav/**/*.java"/>
</fileset>
<zipfileset src="${external}">
<exclude name="META-INF/*.SF"/>
</zipfileset>
<manifest>
<attribute name="Main-Class" value="jav.BatchTester"/>
</manifest>
</jar>
<!--delete previously created extern .jar-->
<delete file="${external}"/>
</target>
</project>

Sorry If my questions sounds obvious for you.
*Launch Command *
In order to exclude any doubt, didn't you tried to launch your jar with this kind of command ?
java -jar myJar.jar -cp ./lib
If you use classpath option, you probably didn't ;). Option --classpath (or -cp) and -jar can't be uses together.
Prefer the use of relative path too, like ./lib instead of P:/Tools/... But, anyway, that won't solve your problem.
*Package Location *
As brimborium said, what is you real package ? src sounds very strange. We suspect an error around this.
In your BatchTester class, what have you written for package directive ? Nothing (i.e default package which isnot recommanded ?)?
Does you class begin with (get rid off comments)
public class BatchTester {
In that case, for sure, src should not be mentionned.
Here an example of manifest which work for me.
Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven
Built-By: jrRevy
Build-Jdk: 1.6.0_31
Main-Class: com.sopragroup.training.dojo1.MainSwingApp
Class-Path: dojo1-0.5.0-SNAPSHOT-lib/spring-core-3.1.1.RELEASE.jar doj
o1-0.5.0-SNAPSHOT-lib/spring-asm-3.1.1.RELEASE.jar [blablabla]
with the following execution structure
/
|
+ --dojo1-0.5.0-SNAPSHOT.jar
|
+ --dojo1-0.5.0-SNAPSHOT-lib/
|
+ --spring-core-3.1.1.RELEASE.jar
Obviously, I'm using maven for build my app, but the main idea is in.

The manifest doesn't allow absolute paths in the Class-Path: tag. You have two alternatives:
Use relative paths as you already mention in your own answer
Use absolute paths via file protocol. This has been answered elsewhere too and it works absolute versus relative path names in jar manifest
Class-Path: file:///P:/Tools/xstream/1.4.2/lib/kxml2-2.3.0.jar
In addition, you should not edit the manifest.mf manually without being aware of several limitations:
line maximum length must not exceed 72 characters, and after breaking one line you must insert an space in the first column.
There must be a carriage return after the last line otherwise, the file can't be parsed correctly

Executable JAR ignores its own Class-Path attribute

I used the instructions found at Maven - how can I add an arbitrary classpath entry to a jar to add an arbitrary entry to the Class-Path attribute. Here is my MANIFEST.MF file:
Manifest-Version: 1.0
Class-Path: jace-runtime.jar
Main-Class: org.jace.examples.Test
I defined org.jace.examples.Test as follows:
public class Test
{
public static void main(String[] args)
{
System.out.println("classpath: " + System.getProperty("java.class.path"));
System.out.println("PeerExample: " + Class.forName("org.jace.util.ShutdownHook"));
}
}
where org.jace.util.ShutdownHook is defined in jace-runtime.jar. When I invoke java -jar peer_example1.jar I get the following output:
classpath: peer_example1.jar
Exception in thread "main" java.lang.ClassNotFoundException: org.jace.util.ShutdownHook
In other words, Java is adding the executable JAR file to the classpath but ignoring Class-Path. If I invoke java -cp jace-runtime.jar;peer_example1.jar org.jace.examples.Test I get the expected output:
classpath: jace-runtime.jar;peer_example1.jar
Any ideas?

Answering my own question:
Adding arbitrary entries to Class-Path is fine on its own. The problem arises when you enable JAR indexing using:
<configuration>
<archive>
<index>true</index>
</archive>
</configuration>
Maven will omit your entries from META-INF/INDEX.LIST.
When you use the JAR at runtime, Java will look at INDEX.LIST for finding classes, not MANIFEST.MF.
Because your entries are missing from INDEX.LIST, they will not be found by the classloader, no matter what the manifest says.
A simple workaround is to disable JAR indexing. I'm not sure how to inject an arbitrary Class-Path with indexing enabled.

For those that may otherwise be unaware, the executable archive mechanism takes the manifest classpath and uses it to load classes external to the archive.
So if you are expecting a WAR with a manifest classpath of WEB-INF/classes to find classes in the WEB-INF/classes entry inside the archive then you will be disappointed.

Per the tooldocs page for the jar option - Link to docs
When you use this option, the JAR file is the source of all user classes, and other user class path settings are ignored.

Ant build jar from multiple packages

I am attempting to create a JAR based on two separate Java packages. I can compile and run within Eclipse, but cannot get the code to function from the command line. I have Ant and the JDK correctly configured for usage, as I have an almost working Ant build script. The only problem is that the resulting JAR throws a ClassNotFoundException when I attempt to execute it.
The archive contains all the .class files from both packages in the correct directory hierarchy. Regardless, the JAR will throw the above mentioned exception.
The idea is to run this script from the top level directory that contains both packages.
Here are the relevant lines from my build script:
<manifest file="MANIFEST.MF">
<attribute name="Built-By" value="XBigTK13X"/>
<attribute name="Main-Class" value="com.main.MainClass"/>
<attribute name="Class-Path" value="./com/main/ ./secondpackage/shapes/" />
</manifest>
<jar destfile="App.jar"
basedir="./bin"
includes="**/*.class"
manifest="MANIFEST.MF"
excludes="App.jar"
/>

The JAR was correct the whole time. This error was thrown because I was attempting to run the JAR with the following command after creating a JAR:
java MainClass
I now realize that I need to explicitly target the JAR by using the following command:
java -jar MainClass.jar

Look in the resulting JAR file to make sure that the two packages have the correct path from the root. Your Class-Path statement in the manifest may not match the structure of folders containing the .class files.
Verify it by opening the JAR with a zip util.