I am majorly confused about where the classpath is. I understand when we create a spring mvc, resources folder, or inside web-inf is considered classpath. And we can use "classpath:" inside xml files to declare the folder. However, where is this classpath exactly? How is it set ? I have been reading about it for a long time, i still couldnt manage to get a real clear image in my head how the classpath is initially determined etc.
For example when we create a war file, and deploy it on a tomcat server, all the resource files can still be read via given paths with "classpath:" in the xml files. How does this work?
Thanks.
Ok, if it's web application, the classpath begins in WEB-INF/classes. Also, jar files in WEB-INF/lib are also on the classpath.
The Classpath is where the JVM will look for class files and other resources. Since you are using Spring MVC, I assume you are deploying a Web application (ie WAR file). This means that the classpath is set by the container which is following the Servlet spec.
The classpath for a WAR file includes the WEB-INF/classes and WEB-INF/lib folders. The Java EE/Servlet container where the WAR file is deployed will also include other common folders in the classpath.
Here is how Tomcat works.
You might also want to try this StackOverflow article/answer
Related
I'm having trouble deploying a Java web app. It centers on our application config file (myapp.properties). In certain situations, having this file external to the WAR seems to work fine, but whenever I try to deploy it properly (Docker, proper JBoss deployment, etc.) the deployments inevitably fail due to being unable to find/read from myapp.properties.
I've seen a few references here and elsewhere to packaging these files inside the WAR archive, but I can't find any information on how to actually do that. So, my questions is:
What is the proper way to include an application config file in a WAR archive and/or deployment?
It depends in how you want to access the file.
If you want to load it via classloader resources, you need it to be in the class-path, so the best location is inside WEB-INF/classes.
That's by the way, where resources in src/main/resources will end up if you are using Maven
You can also put it anywhere inside your WAR, for example, WEB-INF/config and access it via ServletContext.getResourceAsStream("/WEB-INF/config/..... Beware but, that it's not inside the WEB-INF directory, you will have to explicitly forbid the access to the file in the web.xml deployement descriptor, otherwise it would be accessible to client requests.
In my application I have a directory that is in CLASS_PATH and where I store jar files. I use ATG so have to use my .class in properie file to have a way to init components (in this situation it's servlet). So I need my webapp.war in my CLASS_PATH direcory. I put this war file but it does'nt work. How can I put my compiled servlet classes to this directory?
Of course it's not good idea to put only this compiled classes from archive :)
I think what you are looking for is a custom class loader, adapted to handle WAR files. Such a class loader would unpack or peek into the WAR file, to extract the class files.
I have never heard of anyone loading from within WAR files, but it should not be that hard to implement.
Your classloader can not find the servlet classes in war because are in WEB-INF/classes.
Try to unzip and copy WEB-INF/classes to a classpath location
In ATG, Classpath setting start from the way in which you build the ear. Every module in ATG has a MANIFEST file, which specifies an attribute called "ATG Classpath". The value of this attribute is used to construuct the classpath at runtime. So, if you include the path to your class files as a value to this attribute, ATG automatically sets this in the classpath (runAssembler, to be more specific) when creating the ear. Jboss when deploying the ear will then pick it up.
How does WebLogic 11g load libraries in an EAR file? I have this problem with a web application, that when deployed as a WAR (with libraries it depends on in WEB-INF/lib), it works just fine. However, when it's inside an EAR file, WebLogic does not find those libraries unless I put them in APP-INF/lib. Does that mean that if I'm deploying as an EAR I'd have to pull out all JAR files from the WEB-INF/lib directory and place them in APP-INF/lib ? or is there a configuration that can be done in WebLogic to avoid this?
Thanks!
If you have JAR files that you need to share between multiple WAR files or between WAR files and EAR files then you will need to package them in the EAR.
If WAR#1 has a JAR in its WEB-INF/lib and is packaged in an EAR with WAR#2, then WAR#2 will not be able to see the JAR files in WAR#1/WEB-INF/lib.
Solving your problem will take some understanding of how Java EE classloading works in a container. You should look at this link to get an understanding, but the basic problem is that when you package your application as an EAR, you've introduced another classloader (the application classloader) into the class loading hierarchy. You can configure WebLogic to load from your webapp by using the prefer-web-inf-classes element.
I am deploying a web application in a Jetty container and I need to know how to add a classpath for Jetty to be able to load resources from a testing directory.
I think it's best to not modify the Jetty CLASSPATH; use what you know about the defaults for your web app.
All the JARs in WEB-INF/lib are your web app's CLASSPATH; so are all paths relative to WEB-INF/classes. If you put a directory /test-resources under WEB-INF/classes and load it as a resource stream from the context you'll be able to access those test files without having to alter the Jetty startup scripts.
I find it much easier to keep my test jars in a separate folder where they are built by a different process or IDE.
I extracted start.config from the Jetty jar and added my classpath to it as documented at
http://docs.codehaus.org/display/JETTY/A+look+at+the+start.jar+mechanism
My goal is pretty simple: to use ant to build an EAR which contains 1 EJB and 1 jar containing all of the dependencies. This jar, called common.jar for the sake of example has vendor jar files in it as well as other xml files that the EJB depends on and will need to be able to see during runtime....
So far I have everything packaged correctly as an EAR like this:
EARFILE.ear
-EJBFILE.jar
/META-INF
-MANIFEST.MF
-common.jar
/META-INF
-MANIFEST.MF
/lib
-(all vendor jars inside here)
-(All the xml config files are inside the root of the common.jar)
Inside the MANIFEST.MF for the EJBFILE.jar is...
Class-path: ../../common.jar
Inside the MANIFEST.MF for the common.jar is...
Class-path: ../lib/some_common.jar
When I deploy this the appserver (websphere) cannot find the JAR file when I try to start the server. I am getting the ClassDefNotFoundError because the classes inside the EJB cant find the vendor JAR files when I try to start the instance. However I know that common.jar is setup correctly though, else the EJB wouldn't have compiled since it needed to have those vendor jars on the classpath for javac.
So what I want to know is this:
How can I get the runtime to correctly see the Vendor jar files.
Will the EJB be able to see the xml files at run-time? I am concerned about this because these xml files are located outside of the EJB inside of a jar that is just in the EAR, it isn't even a module its just a jar inside the EAR.
Does it even matter when using websphere? From what I gather some containers don't even care what is in the Class-path of MANIFEST.MF.
There are several improvements I can suggest, based on running into similar problems.
First and most importantly, use the appxml attribute of the Ant ear task to specify your deployment descriptor (usually named application.xml); also include references to the vendor JAR files bundled as defined below
I would recommend you not put your vendor JAR files into another JAR - instead, just copy them into the EAR at the same level as EJBFILE.jar
The configuration XML files can go in a sub-directory of the EJBFILE.jar (such as config), and then you can reference them as /config/filename.xml.
The application.xml file will tell WebSphere where to find your JAR files. Classpath traversal in an application server is not the same as that of a compiler, which JBoss has taught me the hard way.
I am using all of the above patterns, and my in-container code (deployed in the EAR) can see all my XML files, as well as find all my dependencies.