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mvn spring-boot:run vs java -jar

I know it may sound silly question but I am unable to understand the difference between mvn spring-boot:run and java -jar (.jar file generated with mvn install)

mvn spring-boot:run

java -jar

I have a spring boot application with jsp pages in /src/main/resources/META-INF/resources/WEB-INF/. If I use mvn spring-boot:run these pages are served. But If I use java -jar these pages are not found by application.

/src/main/resources/META-INF/resources/WEB-INF/

mvn spring-boot:run

java -jar

The application that I am working on is at https://github.com/ArslanAnjum/angularSpringApi

UPDATE:
It works with spring boot 1.4.2.RELEASE while I intend to use the latest version i.e., 1.5.8.RELEASE.

UPDATE:
Well I solved the problem by putting jsps in src/main/webapp/WEB-INF/views/ and changing packaging type to war and then running this war using java -jar target/myapp.war and its working fine now.

2 Answers
2

Short answer: spring-boot:run is a java -jar command on steroïd running as part of your Maven build, ensuring all required parameters are passed to your app (such as resources). spring-boot:run will also ensure that your project is compiled by executing test-compile lifecycle goals prior to running your app.

spring-boot:run

java -jar

spring-boot:run

test-compile

Long answer:

When you run java -jar, you launch a new JVM instance with all the parameters you passed to this JVM. For example, using the Spring doc example

java -jar

java -Xdebug -Xrunjdwp:server=y,
transport=dt_socket, address=8000, suspend=
-jar target/myproject-0.0.1-SNAPSHOT.jar


You will launch a brand new JVM with the given parameters. You need to make sure to include everything needed, such as classpath elements, application parameters, JVM options, etc. on the command line.

When you run mvn spring-boot:run, you launch a Maven build that will:

mvn spring-boot:run

test-compile

resources:resources

compiler:compile

resources:testResources

compiler:testCompile

target/classes

fork

agent

As per:

I have a spring boot application with jsp pages in
/src/main/resources/META-INF/resources/WEB-INF/. If I use mvn
spring-boot:run these pages are served. But If I use java -jar these
pages are not found by application.

It's because the mvn spring:boot command will make sure your target/classes folder is present in the Classpath when your app is running. After compilation, this folder will contain target/classes/META-INF/resources/WEB-INF among other things. Your app will then be able to find META-INF/resources/WEB-INF and load them when asked. When you ran java -jar command, this folder was probably not on the classpath, your app was then not able to find your resources. (these resources were copied from the src/main/resources folder during the resources:resources goal)

mvn spring:boot

target/classes

target/classes/META-INF/resources/WEB-INF

META-INF/resources/WEB-INF

java -jar

src/main/resources

resources:resources

To have a similar result with your java -jar command, you must include your resources on the classpath such as javar -jar myapp.jar -cp $CLASSPATH;/path/to/my/project/target/classes/

java -jar

javar -jar myapp.jar -cp $CLASSPATH;/path/to/my/project/target/classes/

./target/classes

Have you tried creating a jar file using mvn package instead of mvn install when you are running jar file using java -jar? package will create a jar/war as per your POM file whereas install will install generated jar file to the local repository for other dependencies if present.

mvn package

mvn install

java -jar

package

install

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