Maybe at the beginning that question is stupid and i get minuses but..
please tell me which one plugin code should i use ?
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
</plugins>
or
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<!-- put your configurations here -->
</configuration>
</plugin>
</plugins>
The groupId is optional since org.apache.maven.plugins is the default
groupID, yet I would recommend keeping it around anyway
You should always use the version tag to pin down the plugin
version and avoid surprises regarding regressions introduced in newer
plugins.
If you are sure about the JDK you develop for, you should definitely
specify the source and target version
So use a combination of the above IMHO
You should use the second one, especially if you use maven 3.
It is a good practice to explicitly specify the groupId so that there is no confusion. Some plugins are available from org.codehaus.mojo, for instance. Maven does resolve the plugin as documented here.
version is relevant if you are using maven3, as described here.
You would still specify the source/target versions in either case, if you want it to be different from the jdk you are using.
Related
In our project, we have configured jetty inside build plugin in pom, i want to understand configuration settings in pom/ what and all we can configure in pom.
what is <build><plugin> section in pom, when to use.
difficult to understand from tutorials because lot of different examples which is making confuse.
Please can somebody explain for the above in detail?
Plugins defined in your buildsection plugins tag will be executed during the build of your project.
There are many plugins that do something with your build.
For example the maven-compiler-plugin which allows you to set the Java version for your project.
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.6.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
a list of maven build plugins supported by maven itself
I have a project with a pom.xml that has the following <build> declaration:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
When I run mvn install on this project, it compiles the project, runs unit tests and publishes it to my local repo. I am trying to learn a little more about Maven here, and am having a tough time finding documentation/explanations on the following:
How am I able to run mvn install, if the POM doesn't declare it under build/plugins? Does maven-compiler-plugin include maven-install-plugin, if so, how could I have figured that out?
Most importantly: the value of build/plugins/plugin/configuration/source and .../target are both set to 1.8. If my machine has Java 8 on it, and I run mvn install on this project without any errors, does that guarantee that the project builds with Java 8? I'm looking at the docs for the Compiler Plugin and don't see those source/target configs listed anywhere.
First you should learn what the build life cycle is and how it works and how the plugins are bound to the life cycle by default.
Furthermore you should understand that in Maven every project inherits from the super pom file which is part of the maven distribution (the package you have downloaded). The super pom defines the default folder layout and some versions of plugins.
The question to define the maven-compiler-plugin as you did is to be very accurate simply wrong. You should have defined it like the following:
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
This would overwrite the definition which is inherited by the super pom and changes it's configuration. In your case i would suggest to change the definition into this:
<project>
...
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
..
</project>
The encoding should be set globally cause there are other plugins which use this definition like the maven-resources-plugin. The usage of the above property simplifies this, cause every plugin which has an option for encoding will use the default as defined in the property.
To be sure using the correct version of Java (your JDK on your machine) you have to use the maven-enforcer-plugin.
Apart from that please take a look onto the plugins page which shows the most up-to-date releases of the plugins.
As a good documentation i can recomment the Books on Maven but be aware they are written with Maven 2 in mind. So if something is not clear ask on users mailing list of here on SO.
4th time typing this message up as this crappy machine I am to use crashes randomly throughout the day. Gotta love it.
My development environment JAVA_HOME is set to "c:jdk1.7.0_45"
and in the POM I have the following
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<verbose>true</verbose>
<fork>true</fork>
<executable>${JAVA_HOME}\jdk1.7.0_45\bin\javac</executable>
<compilerVersion>1.7</compilerVersion>
<configuration>
</plugin>
but have also tried
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
So Why do I get the error: multi-catch statement is not supported in -source 1.5?
I don't see anything that references 1.5.
Also, I am not clear on what the source and target are exactly am only assuming things, same for what maven-compiler-plugin is to stand for.
Any straight forward answers to these questions would be greatly appreciated as I'm new and not aware to go read up on the section I don't know about because what I'm working on I don't know what it's called nor what I am to be asking what I am to be looking up. Nobody in house has a clue either as to how to use Maven. Appreciate any guidance in this painful environment.
===========================
The following is how I had to have it in order for the default of 1.5 not to execute.
Changed the JAVA_HOME to the JDK 1.7 path.
<configuration>
<forceJavacCompilerUse>true</forceJavacCompilerUse>
<source>1.7</source>
<target>1.7</target>
</configuration>
However, other projects that require the 1.6 are now broken. What a horrible setup.
For maven compiler plugin, as explained here
the default source setting is 1.5 and the default target setting is
1.5
Also as mentioned in the link you can try the configuration "forceJavacCompilerUse"
try using
<properties>
<maven.compiler.target>1.7</maven.compiler.target>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.test.skip>true</maven.test.skip>
</properties>
I know Maven compiler plugin by DEFAULT is bind to :
compile
test compile
life cycles, in general without specifying addition configuration, we don't have to
explicitly define it in our POM, but I still seen experienced developer putting things like
this in their POM, e.g
<build>
<plugins>
<plugin>
<artifactId>maven-shade-plugin</artifactId>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
</plugin>
</plugins>
</build>
I wander what's the point? and why is he doing this?
For the shade plugin, he is probably using POM inheritance. Look in the parent POM hierarchy for a pluginManagement section, there is probably shade plugin configuration there that he is pulling into this module.
For the compiler plugin, I do not know. You are correct, for jar/war/ear/ejb projects Maven will pull in the compiler config automatically, even if he has defined specific configuration in a parent POM's pluginManagement section.
If they put such things in their pom's they don't understand Maven. You should define the version of the plugins your are using in your build. This is done by:
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin<artifactId>
<version>3.1</version>
<configuration>
<target>1.6</target>
<source>1.6</source>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin<artifactId>
<version>2.3</version>
</plugin>
</plugins>
</pluginManagement>
</build>
This should be usually located into a pom file known under Company POM which defines versions of plugins for projects within a company.
Furthermore based on the life-cycle definition in Maven the Maven Super POM which contains the default bindings there you could see that particular plugins versions are defined.This means if you upgrade your Maven version you start using different plugin versions which is fact not the best related to build reproducibility. So the best practice is to define all used plugins like here as an example.. Based on the definition you shouldn't need to mention anything in your build-tag area if you have a defined packaging type (This is one of those Convention Over Configuration paradigm hints).
While searching for maven-check-style plugin information online I found that it can be added both as a <dependency> tag like this:
<dependency>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-checkstyle-plugin</artifactId>
<version>2.5</version>
</dependency>
and also under <plugins> tag like this:
<reporting>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-checkstyle-plugin</artifactId>
<configuration>
<configLocation>config/sun_checks.xml</configLocation>
</configuration>
</plugin>
</plugins>
</reporting>
I would like to know the difference between each and which one to use when. Please guide.
As far as I know, plugins are also artifacts, so they can be added as a dependency to a project. However adding plugin artifact as a dependency, doesnt bind its execution to any phase of maven build, therefore it cannot be executed.
Here you can find some answers:
https://www.quora.com/In-Maven-what-is-the-difference-between-dependency-and-plugins
"A plugin is an extension to Maven, something used to produce your artifact (maven-jar-plugin for an example, is used to, you guess it, make a jar out of your compiled classes and resources).
A dependency is a library that is needed by the application you are building, at compile and/or test and/or runtime time."Olivier Demeijer