I'm looking for some kind of "best practice" informations about Spring jar configuration. I have a web project (war) and I need connect some jar libraries - my jars which contains additional functions. These jars contains Spring services. But when I connect jar, the service class did not work, because Spring don't know about that. So I need to tell Spring about this by “package auto scan” configuration inside my jar.
The final solution must be war project (main functions) and some additional jars which contains other functions. When I add jar into war project, I don't want to change configuration in applicationContext.xml (in war). I want minimal dependency to war project. I was thinking, when if I place applicationContext.xml to META-INF folder in jar it will be auto loaded by Spring, but it is not.
Do you know how can i solve this? May be some kind of “after startup dynamic configuration” :-). thanx
If you are trying to load annotated beans from the jars into your war's Spring context, you can set up a component scan in the war's context xml file to scan the packages in the jars.
If you are trying to load beans defined in XML files from the jars, you can include them using something like this in your war's Spring context xml file:
<import resource="classpath:path/to/config/in/jar/beans-from-jar.xml"/>
You shouldn't need to have your jar know anything about your war this way. You just scan the annotated beans and/or import the config from the jar.
Related
I know that spring boot packages an executable jar with spring-boot-loader and loads other jars from BOOT-INF/lib as described in this post, using a class named JarLauncher.
After reading this post, I was thinking that Class-Path in manifest can do this, too.
So why does spring boot do so many works to load jars from a customed BOOT-INF/lib, rather than just write simply in META-INF/MANIFEST.MF:
Class-Path: BOOT-INF/lib
The Class-Path manifest approach does not support loading classes from jar files nested within a jar. From the Oracle documentation that you've linked to in your question:
The Class-Path header points to classes or JAR files on the local network, not JAR files within the JAR file or classes accessible over Internet protocols. To load classes in JAR files within a JAR file into the class path, you must write custom code to load those classes. For example, if MyJar.jar contains another JAR file called MyUtils.jar, you cannot use the Class-Path header in MyJar.jar's manifest to load classes in MyUtils.jar into the class path.
Spring Boot's JarLauncher and the other classes in spring-boot-loader are the custom code that allow classes to be loaded from jars nested within a jar.
We are trying to migrate our existing Spring MVC applications to Spring Boot application. Our existing applications are using 3.2.9, so tons of XML configurations. All the beans are defined in the XML files. What we have done is first we have upgraded our existing applications to Spring 4.2.5 version since Spring Boot will work only with Spring 4 versions.
Our requirement is to have both FAT JARs and WAR files from the build. Most of our existing customers would prefer Application Server deployment, so we have to create WAR file for them. Also for our internal testing and new deployments, we are planning to use FAT JARs.
How can we achieve them in the Maven file, we are able to provide separately as below. Is there any maven plug-in to generate both in single build?
<packaging>jar</packaging>
or
<packaging>war</packaging>
We are publishing our artifacts into Nexus repository. So, we want to have the separate repository location for JAR files and WAR files. Can we do that using the single pom.xml file?
Also another question, we have all the XML configurations under WEB-INF folder. When we are moving to the Spring Boot application, it has to be under the resources folder. How can we handle them easily. When we build FAT jars, the resources are not looked under WEB-INF because it simply ignores the webapp project.
I am looking forward for some guidance to complete the migration. Infact, we have already done that changes and it is working fine, but we are confused on this WAR / JAR generations.
Update:
I have got another question in mind, if we are converting our existing applications to spring boot, do we still have to maintain WEB-INF folder in the web-app or can move everything to the resources folder?. While building the WAR file, whether spring boot takes care of moving the resources to WEB-INF? How spring boot would manage to create the WAR file if you are putting all the resources under the resources folder.
Building WAR and FAT JAR is very easy with Gradle.
With Maven, I would try multi module setup, where one sub-module will build fat JAR and second will build WAR file.
Application logic can be as third sub-module and thus being standalone JAR with Spring configuration and beans. This application logic JAR would be as dependency for fat JAR and WAR module.
WAR specific configuration can be placed in Maven WAR sub-module.
I didn't have such requirement before, so don't know what challenges may occur. For sure I wouldn't try to integrate maven-assembly-plugin or other packaging plugins with spring-boot-maven-plugin.
Concerning location of config files, just place them into src/main/resources or it's sub-folders according Spring Boot conventions. Spring Boot is opinionated framework and will be most friendly to you if you don't try to resist defaults.
Maven does not handle this gracefully, but its far from difficult to solve. You can do this with 3 pom files. One parent pom that contains the majority of the configuration, and one each for the packaging portion of the work. This would neatly separate the concerns of the two different assembly patterns too.
To clarify -- I'm not recommending a multi-module configuration here, just multiple poms with names like war-pom.xml and fat-jar-pom.xml, along with parent-pom.xml.
Working with GlassFish, trying to be tidy, I would like to put all of my business logic into a single EJB JAR. I then have 2 WAR files.
app-frontend-war
app-backend-war
app-logic-ejb
Each of the WAR files need to use the EJBs that are within the app-logic-ejb JAR. This EJB JAR holds the main persistence unit. But I am finding that #Inject of any app-logic-ejb EJB's from any Java within the WAR files are not working.
Also, I am trying to avoid using an EAR.
With the help of the Java EE 7 tutorial I have finally worked it out.
Even though the beans in app-logic-ejb are on the same GlassFish they need to be annotated as remote beans. The WAR files then use #EJB injection (instead of #Inject) into the correct interface within the WAR file.
#EJB
TestBeanInterface t;
To share the interface between the EJB JAR and the War files a Java Library is needed.
So to make it work it turns out I need:
app-library
app-logic-ejb
app-frontend-war
app-backend-war
I am trying to use to versions of spring in the same application: the first one is a webapp with spring 2.6 and the second it a jar client, with spring 4.0.2. The client communicates with another application and will be a dependency for the webapp. The problem is that the classloader will just load one time the common classes from spring and it will certainly fail.
I tried to use ElasticSearch aproach of using shaded dependencies(maven shade plugin) and relocate spring from the client to a different package (from org.springframework to my.springframework) and the uber jar seems to be constructed fine.
The issue is that Spring is based on spring.schemas and spring.handlers for validating xml config files and loads this files from classpath (META-INF folder and this paths are hardcoded in Spring code - e.q. PluggableSchemaResolver). I modified this files to point from org.srpingframework to my.springframework.
At runtime it seems that the classloader reads these files from the webapp, which has this files but with the real spring path and the exception is something like
org.realsearch.springframework.beans.FatalBeanException: Class [org.springframework.context.config.ContextNamespaceHandler] for namespace [http://www.springframework.org/schema/context] does not implement the [my.springframework.beans.factory.xml.NamespaceHandler] interface.
To me it seems that is impossible to achieve what I am trying (use tho spring versions in the same application with one of them relocated). Any ideas here? Am I wright?:d
I have a class in a war...
SomeClass.java
This class is embedded into a war which is embedded in an ear. Also, embedded in the ear is an EJB class which references a class in the war (not my design). This class clearly exists and I can see it in the deployed WS app. The ear file looks as follows...
ear file
META-INF
war file <Where the .class is found>
ejb jar file
But I still get a ClassNotFound Exception on SomeClass can anyone think of what I am missing? This is pretty old versions so do I have to set the classpath in the META-INF in the ejb jar even if the jar is in the exploded war?
Thanks
OMG this is REALLY messy. Glad it's not your design. As you know EJB classes should NEVER depends on libs or classes from war files. That said if you need that your class "SomeClass.java" to be available to both, the war and ejb.jar package, than you should build a third standard.jar file with the class in it and place it under ear/lib folder of your package. This should make the class available to both packages, the .war and .jar(ejb) files.
Since you are using WebSphere, you may want to try setting the WAR class loader policy to "Application", as described in the following document:
http://pic.dhe.ibm.com/infocenter/wasinfo/v7r0/topic/com.ibm.websphere.express.doc/info/exp/ae/crun_classload.html
This would create a single class loader for the entire application, i.e. the EJBs and the classes in the WAR would be loaded by the same class loader. This should solve your problem.
Create a lib folder under the EAR file structure and copy all the jar fiels which you want to use as common for both WAR and EJB in it. This should solve the problem.