I upgraded my spring boot app to 2.5.0, then is app.jar and app-plain.jar is created by gradle.
I would like to the difference between these jars.
thanks
app.jar is the archive produced by the bootJar task. This is a Spring Boot fat jar that contains all of the module's dependencies as well as its classes and resources. It can be run using java -jar.
app-plain.jar is the archive produced by the jar task. This is a plain or standard jar file that contains only the module's classes and resources.
You can learn a bit more about this in the documentation for Spring Boot's Gradle plugin.
Related
While creating a spring boot project I define property in pom.xml as <packaging>war</packaging> with which I can create a war and thereafter deploy the war into server maybe tomcat or WAS.
But I came across a plugin named spring-boot-maven-plugin whose documentation states that it's use is to package executable jar or war archives and run an application in-place.
My query is why do we need this at all ?
If my packaging can tell me what to create and then can deploy it to run, what is the used of this plugin.
I am trying to understand a new project so wanted to be sure that every line makes sense
The maven plugin will create an "executable" archive. In the case of the war packaging, you would be able to execute your app with java -jar my-app.war. If you intend to deploy your Spring Boot application in an existing Servlet container, then this plugin is, indeed, not necessary.
The maven plugin does more things like running your app from the shell or creating build information.
Check the documentation
The Spring Boot Maven Plugin provides Spring Boot support in Apache Maven, letting you package executable jar or war archives and run an application “in-place”.
Refer this - https://www.javaguides.net/2019/02/use-of-spring-boot-maven-plugin-with.html
We are using Gradle to build spring boot application.
Our application does not require commons-io. But one of the other dependencies requires commons-io. So we've not added commons-io as dependencies. gradle build worked fine.
But when we run the spring boot using "java -jar my-fat-jar.jar", it throws classNotFound Exception for a commons-io class.
My fat jar does not contain commons-io in its lib folder.
So we just added commons-io as dependencies, now everything works fine.
But we don't want to add each such dependencies. Instead is there any way to include the dependent jars of my dependencies in lib folder of my fat jar?
Please note that we are using spring boot gradle plugin.
Using spring boot maven plugin we are able to generate executable jars. And we can execute the jar using java -jar ...
In spring boot there is another option for installation . This generates the jar which can be added in init.d.
But is it possible to generate a sh|cmd file which can be used to start|stop|restart spring boot applications?
The executable true flag to create a 'fully executable’ jar actually pre-pends a shell script into the beginning of the jar.
It works outside init.d too. Try this:
./myapp.jar start
I've got a spring boot app and I'm building a myApp.jar using the spring-boot antlib. When I jar -tf myApp.jar I see that I have a jar called lib/foo.jar. Yet when I print out System.getProperty("java.class.path") I don't see that jar file on the classpath. I also get a ClassNotFound exception from URLClassLoader when the code attempts to use this class for the first time. I'm using the JarLauncher since that's what the antlib defaults to.
Any ideas why this jar file would not be on the classpath?
You won't see a bundled JAR in System.getProperty('java.class.path'). The class path specifies where the JVM will look in the filesystem for classes you attempt to load.
Spring Boot uses fat JARs, which are loaded in a completely different way. Refer to the Spring Boot documentation.
How to use spring boot maven plug in to create an application which will have a single executable jar with all direct and transitively dependent jar files packaged into it and can be a standalone runnable.
Use the spring-boot-starter-parent (or copy the spring-boot plugin config from there) and then "mvn package".