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
Related
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.
I have spring boot jar. It contains boot-inf folder with that folder it contains classes and lib folder. I need to run the certain class which is having main method. But I don't know how to run it. For normal jar we can use the below format to run the class from the jar.
java -cp "sample.jar;dependecy.jar" com.sample.ClassName
But in spring boot jar what is the format to run the class. Because it contains boot-inf folder. I am using gradle script to build the project
It should be very easy, just:
java -jar sample.jar
where sample.jar is your spring boot jar.
See https://docs.spring.io/spring-boot/docs/current/reference/html/using-boot-running-your-application.html
You can try with the distribution to run the class in a jar. Build the project to create the dist. Then you can run the class as you mentioned in the question.
java -cp "sample.jar;dependecy.jar" com.sample.ClassName
So I created a spring boot application. And I simply like to run it as a program from a Main class. No need for web controller access.
It runs great in my Intellij.
But how do I ship it as a jar?
It depends on your project structure. If you use maven just run "maven install" and find your jar in your local repository.
When you have it, run "java -jar your.jar"
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
From the documentation of Spring Boot, I can see the directory of the executable jar will be the working directory when you start the Spring Boot application. I would like to understand, whether there are configurations/flags to explode/unpack the jar on deployment, so that I can find access the contents of the executable jar in the file system ?
There are not flags to explode the jar automatically but you can extract it yourself using the jar command. This reference may be helpful http://docs.spring.io/spring-boot/docs/current/reference/html/executable-jar.html in understanding the structure and what you can do.