I'm new to Maven and m2e. It frustrates me that I have to ask this question, but the sparse m2e documentation and Google are failing me.
How do get m2e to build a JAR? I understand that this should happen during the maven package phase, but m2e doesn't seem to do this as part of the build process and I can't find a way to explicitly execute the package phase in Eclipse (nor any other phases that aren't part of the default build).
Thanks.
As long as you have your POM.xml file with the following parameters:
<modelVersion>[a model number eg 4.0.0]</modelVersion>
<groupId>[a group id eg com.myapp]</groupId>
<artifactId>[a unique artifact id within your packages eg myapp]</artifactId>
<version>[the version number eg 1.0-SNAPSHOT]</version>
<packaging>jar</packaging>
<name>[the name eg myapp]</name>
then you just need to run maven build with the goals clean install to create a jar file from your project. You can run maven build by right clinking on the project and going to run > maven build ...
The jar will be created in [project dir]/target
Although "Run As maven install" would do the trick, it can be good
to know that m2e will perform the equivalent of the package phase when doing "Export... Jar/War/EAR file". It seems to understand the plugin configurations too, at least a little bit, and at least for EARs...
As it will resolve artifacts using projects and the m2 repository,
it will also work for "unrelated" modules, as the dependency that resolves to a project is good enough for eclipse to package.
(That is, you don't have to install the unrelated dependency separately, it will be built automatically from the eclipse project.)
I'm not sure I would deploy anything it builds though :-)
Related
This feels like a really stupid question but I haven't been able to find an answer.
I'm working on a maven project but I do most of my development in eclipse. Is there any way for me to force maven to generate all of my dependencies under target even if there are errors in the code? I set my eclipse project's build path to use the jars under target/dependencies/jars, but calling mvn clean kills them and if there are any errors in my code causing it to not compile mvn package won't create the dependencies but will instead just crash saying BUILD FAILURE. This makes the problem even worse since instead of seeing the actual errors my eclipse will just bombard me with errors everywhere since all of its dependencies just died.
Or maybe the way I'm working with it is just stupid and there's a better way.
Are you using the m2e plugins for Eclipse to process maven projects, or simply importing the projects as general ones?
If the latter, you should use the m2 plugins (simply go to the Eclipse Marketplace and search for Maven), as they interrogate your POM and set up your dependences properly. You can then concentrate on any compile errors in your code.
You should not point to the jars in the target folder for dependent JAR's since this is where the products of building your project are stored. Performing a mvn clean removes this folder.
To use Maven with Eclipse install the m2e plugin in Eclipse. This makes Eclipse understand the structure of Maven projects.
Once installed you can import your Maven project into Eclipse. I use Import... | Existing Maven Projects for this. But you can also directly import form a versioning system.
During the import Eclipse will set up the Eclipse project to use the Maven dependencies to locate the required JAR's. These are taken from the repository as configured with the used Maven installation.
I'm hacking on a Maven-based project with a lot of dependencies; the project is normally meant to be developed in Eclipse but I need to work on it from the command line.
How to build+execute the project in a sane way? Something like mvn run, but of course Maven is not meant for running Java projects (for some reason).
The problem is specifying all the dependencies on java's commandline, I don't even know how to autogenerate that. I can currently deal with it using the assembly:single maven plugin (using the jar-with-dependencies descriptor) which will package the dependencies to a single .jar for me.
However, there really is a lot of dependencies and the assembly phase can take about two minutes, greatly disrupting my hack-test cycles so I'm looking for other ways to run the project with minimum build overhead - any recommendations, please?
Note: One possibility is running it in Eclipse once and capturing the java commandline. However, that's just a one-time hack, not a general solution in case I change pom.xml later or come to another project from the suite without Eclipse access anymore.
Have a look at the maven exec plugin
mvn exec:java -Dexec.mainClass="com.example.Main"
if you do this frequently, you can of course configure it via plugin configuration.
Regarding finding out project dependencies - you can use maven dependency plugin
http://maven.apache.org/plugins/maven-dependency-plugin/list-mojo.html
If you want to put them into file it'd be smth like
mvn dependency:list > dependencies.txt
See this question: How can I create an executable JAR with dependencies using Maven?. You can use the dependency-plugin to generate all dependencies in a separate directory before the package phase and then include that in the classpath of the manifest.
I see three solution to this:
onejar-maven-plugin - faster than assemlby with jar-with-dependencies descriptor
With onejar-maven-plugin, you'll (...) get a nice clean super jar with the dependency jars inside.
Spring Boot Maven Plugin - but this is dedicated to Spring projects
Maven Assembly Plugin with custom descriptor. This custom descriptor should grab all dependencies into lib folder, maven-jar-plugin should set Class-Path in Manifest.fm according to this new location. After this you can simply execute your program or zip your jar with lib folder as distribution.
After this is possible to run your program on your computer or any other with one command:
java -jar myjar.jar
If i want to convert an EAR project a maven project , do i need to add the module in the deployment assembly as maven dependency or just use the convert in m2eclipse without any further configuration.
Me personally I wouldn't attempt any kind of conversion of an existing project. I would add the poms, make sure that mvn clean install works on the command prompt and then create a new mavenized Eclipse project from the poms.
The main reason is that you current project settings are effectively wrong when you switch to Maven - the Maven poms are the truth and what feeds the Eclipse project setup, so you really do not want to make your life difficult and work against m2eclipse - let it do the project creation for you. Fresh.
You can install m2eclipse and then do the following as well.
Go to the project menu (right click on Package Explorer) > Configure > Convert to Maven Project
Open the pom.xml and right-click and choose Run As -> Maven Clean. Similarly Choose Run As -> Maven Install.
Note : Please ensure that your eclipse project settings are correct and classpath libraries are not absolute and you don't have any project specific environment variables defined in your workspace. Please take a backup of your project before you do this.This is to ensure we don't mess up the current stable project configurations. Once m2eclipse generates the pom.xml for your project, you can update and make changes to it to
fully obtain a mavenized ear build. hope this helps
You can also try creating new maven project with archetype selection of "jboss-javaee6-ear" and follow the similar structure for your project. Most probably you will need parent Pom and child poms per each module (ejb, war, jar etc). There are other few similar approach but almost all of them requires you to have mulitple POMs
maven-ear-plugin and JBoss AS 7
You can also go through all the examples for maven ear plugin to find settings suitable for you
http://maven.apache.org/plugins/maven-ear-plugin/
I ended up ditching ear for war :) single POM and even ditched the JBOss for tomcat/jetty :)
If you want to convert your existing eclipse dependencies into Maven dependencies, you can try the JBoss Tools (JBT) Maven integration feature, which contains an experimental conversion wizard, plugged into m2e's conversion process : http://docs.jboss.org/tools/whatsnew/maven/maven-news-4.0.0.Beta1.html.
So, all you have to do is, as Keerthi explained, right-click on your project and Configure > Convert to Maven...
If your dependencies already are maven artifacts, it should work easily. If not, you'll need to convert them to Maven (if they're workspace projects) or make them available in your maven enterprise repository, before converting the EAR project.
JBT (requires Eclipse JavaEE) can be installed from http://download.jboss.org/jbosstools/updates/stable/kepler/ or from the Eclipse Marketplace (See https://marketplace.eclipse.org/search/site/jboss%2520tools)
If I have 6 modules in my project is it possible to build only one out of six ? without commenting out others ?
EDIT
Submodule will not work itselft because or parent tags. I need to install the parent first to make it build. how can I do it without installing parent
is it possible to build only one out of six ? without commenting out others ?
My understanding is that you want to launch maven from the aggregating project (i.e. a reactor build) but only build one module. This is possible using the -pl, --projects project list option (see advanced reactor options):
mvn --projects my-submodule install
This is a very powerful option, especially when combined with --aslo-make (to also build the projects on which the listed modules depend) or the --also-make-dependents (to also build the projects that depends on the listed modules). On the basis of your update, you might want this actually:
mvn --projects my-submodule --also-make install
Launching Maven from the directory of the module you want to build is of course an option but this won't allow you to do the things mentioned above nor to build a subset of all modules. For such use cases, the advanced reactor options are the way to go.
Opening a command shell, navigating to the submodule directory and executing mvn install (or whatever your preferred lifecycle is) should do the trick.
You can simply build the module by going in this module directory and run the mvn clean install.
However, note that with this method, the dependencies with the others modules will be taken from your local repository (or the entreprise repository).
Let's take a simple example:
project
+ commons
+ business
Now, imagine that you build, on the root directory the whole project, using the mvn clean install command. Consider that all your modules are in version 1.0.
Now, you move to version 1.1. If you run the mvn clean install on the business project only, it will try to get the 1.1 of module commons. You will then have an error, as Maven will not find any version 1.1 in your local repository.
Within Eclipse, assuming you have m2eclipse installed: Right-click on the module in question and choose Run As -> Maven package.
Our software is written in Java and comprise many (7) projects.
These projects are Netbeans ant projects.
I'm considering to converting them to maven2.
Where can I find some hints for doing such thing?
Don't read that book. It will only make you confused. Read this book instead: "Maven - The definitive guide" http://www.sonatype.com/books/maven-book/reference/ .
Also, the maven site has a lot of information, but the structure is terrible so you'll need to use google to navigate in it.
Here is my suggestion:
Do this by hand, not with "automagic" "help" from the IDE. Maven integration doesn't work that good yet, not in any IDE.
Make sure you program project is divided into modules under a common umbrella module, so that each module produces a single binary artifact (jar, war,...) possibly accompanied by the javadoc of the source code behind that artifact, a zip with the source code etc. The basic principle is that each module produces a single artifact, containing all the non-test-code under that module. You can do this while the project is still built by ant.
Each module should conform to the standard maven directory layout. The build destination is under [module]/target/[output-type, e.g. "classes"]. The source code is under [module]/src/main/[src-type e.g. "java"] and [module]/test/[src-type]. The artifact consists of all the code under src/main, and none of the code under src/test, as it built to the target directories. You can do this while the is still built by ant.
Start by transforming the sub-module that has no dependencies on other modules in the project.
Now you can create the parent maven module pom.xml with artifact type "pom", consisting of one of the modules below. Make a child module for the first submodule (the one with only external dependencies), using the umbrella module as "parent". Remember that you need to specify version for the parent. Remember to add the child module as a "module" in the parent too. Always use ${project.version} as version in the child modules when you create multi-module projects like this. All modules under a parent must be released simultaneously in a single operation, and if you use this setting maven will make sure the version fields stay the same across all modules and gets updated everywhere during the release. This may make it difficult to re-use the existing numbering scheme, but that doesn't matter. You are never going to run out of version numbers anyway.
Add the necessary dependencies, and make sure you can build the parent and the child module together using the command "mvn clean install" from the parent module.
Proceed with the rest of the modules the same way. Dependencies to other modules under the same parent project should also use ${project.version} as the "version" they are depending on, meaning "the same version as this". NOTE THAT in order to build, the module you are depending on must be built using "mvn install", so that it gets deployed to you local (computer) repository. Otherwise the depending module will not be able to find the classes. There are NO source-code dependencies between modules in maven, only dependencies to built and packed versions installed in local and remote repositories. This can be very confusing if you come from ant-projects. Build from the root module until you get comfortable with this. It takes two days.
Don't use maven integration in IDEs. It is a bad idea. Use "mvn idea:idea" or "mvn eclipse:eclipse" to set up your workspace as a non-maven ordinary IDE project. The inter-module dependencies mechanisms in maven and the IDE aren't identical and will never be. Also, if you have several mavenized projects with dependencies in between, you want to have several of these in your workspace with dependencies set up between. You can do this with mvn idea:idea / eclipse:eclipse if you create a separate maven project file called "workspace.xml" (or whatever) in the same directory as parent module, set up as a multi-module project containing modules "." and "../otherproject" (only one-way reference here, no parent ref back). If you run "mvn idea:idea / eclipse:eclipse -f workspace.xml" you get a workspace with all these modules linked together. No IDE integration lets you do that. This sound like a lot of extra work, but the workspace.xml-file is really small. It doesn't have to contain all that dependency stuff and all that, only the reference to the modules you want to bind together in your IDE.
I did a succeful migration of NetBeans Ant project to Maven project using the instruccions by Joseph Mocker here: http://forums.netbeans.org/ptopic55953.html
I cite the important part:
close the project
rename the build.xml, nbproject files/folders to something so NB won't recognize them.
close and restart NB (so any memory cache knowledge of the project is gone)
copy in an empty pom from some other project.
open the project back up in NB (NB should now identify it as a maven project)
rearrange the files to follow the maven way (™)
This won't be an easy task since Maven2 expects the files to be organized in a specific way. Anyway Better Builds with Maven is a free book that should get you started. It will help you understand Maven and it also has a chapter on migration.
I discovered that the migration is not necessary. The real requirements that I need was automatic download of dependencies (libraries).
This is also achieved by Ivy which nonetheless uses maven repositories.
I solved converting project from ant to ant+ivy with IvyBeans.
I have built a script to migrate Ant builds to Maven. You can find more information here:
https://github.com/ewhauser/ant2maven
It won't help you with fixing your directory structure and or any additional Ant tasks, but it removes a lot of the tedious steps to get started.