How do I run a class in a WAR from the command line

Question

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

User · Answer

To execute SomeClass main String    args  from a deployed war file do  Step 1   Write class SomeClass java that has a main method method i e   public static void main String   args         Step 2  Deploy your WAR Step 3  cd  usr local yourprojectsname tomcat webapps projectName WEB-INF   Step 4  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  amp  amp   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

User · Answer

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

User · Answer

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  lt attachClasses gt true lt  attachClasses gt  to the  lt configuration gt  of the plugin    lt project gt           lt artifactId gt mywebapp lt  artifactId gt     lt version gt 1 0-SNAPSHOT lt  version gt           lt build gt       lt plugins gt         lt plugin gt       lt artifactId gt maven-war-plugin lt  artifactId gt       lt version gt 2 6 lt  version gt       lt configuration gt         lt attachClasses gt true lt  attachClasses gt       lt  configuration gt         lt  plugin gt       lt  plugins gt     lt  build gt         lt  project gt    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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

In Maven project  You can build jar automatically using Maven War plugin by setting archiveClasses to true  Example below    lt plugin gt          lt groupId gt org apache maven plugins lt  groupId gt          lt artifactId gt maven-war-plugin lt  artifactId gt          lt configuration gt           lt archiveClasses gt true lt  archiveClasses gt          lt  configuration gt   lt  plugin gt

User · Answer

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

User · Answer

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

[java] How do I run a class in a WAR from the command line?

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