I use Maven on daily basis in my work for more then 5 years. But I never tried to test the minimum dependencies project.
So I created a new directory on my disk and put inside a pom.xml file. It is the most simple pom file you can create. It contains only this:
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>info.jikra</groupId>
<artifactId>whatever</artifactId>
<version>0.1</version>
</project>
And that's it. There is nothing more. No other directories, not a single Java file, nothing.
Then I cleared my local repository and ran mvn clean install in the folder with my pom file.
Maven downloaded tons of dependencies I don't need. My project is empty, there is only one pom file. Yet, there are more then 7,6M of files in my local repository, now.
I'm not any kind of Maven master, so I wonder why all those dependencies are necessary. Does anyone know?
Your project has some predefined plugins declared as well as packaging (default is jar) which defines a list of additional plugins as well as their bindings. Those are getting downloaded along with their transitive dependencies.
You can run mvn help:effective-pom in order to see what's actually present in your project.
You could also see plugins and their dependencies with: mvn dependency:resolve-plugins
Related
I a maven rookie and am wondering how to get a binary jar file if it is not already in the repo. Specifically i'm in need of: jackson-dataformats-text-2.13.0.jar. Do I need to build it myself? I'm used to creating a project and marking a library as a dependency and seeing the jar downloaded into my .m2 cache but all i see in my cache is:
jchan#jchan-Z170N:~/.m2/repository/com/fasterxml/jackson/dataformat/jackson-dataformats-text/2.13.0$ ls
jackson-dataformats-text-2.13.0.jar.lastUpdated jackson-dataformats-text-2.13.0.pom.sha1
jackson-dataformats-text-2.13.0.pom _remote.repositories
Can someone advise how I am to get a built version of the jar from maven central?
We are still maintaining our ant build and I need the jar file for this. (i know i know, ancient stuff but team is not ready to port just yet).
parent pom don't contain jar file
This is the reason why no bundle link is present on the official public maven repository https://mvnrepository.com
The maven dependency is not a jar, is a parent. So the extension is: .pom which is just a plain pom.xml
Parent dependencies don't contain compiled class like .jar.
In your specific case, there are another dependencies who contains jars:
https://repo1.maven.org/maven2/com/fasterxml/jackson/dataformat/jackson-dataformat-yaml/2.13.0/
https://repo1.maven.org/maven2/com/fasterxml/jackson/dataformat/jackson-dataformat-xml/2.13.0/
advice
Check what classes do you need on your ant project and search if exist a jar (with the classes you need) on https://mvnrepository.com
Another option is to get all the dependencies from pom :
https://repo1.maven.org/maven2/com/fasterxml/jackson/dataformat/jackson-dataformats-text/2.9.0/jackson-dataformats-text-2.9.0.pom and download them into your ant project. In theory is the same of add the parent pom in a maven project
I have maven projet with this architecture:
++parent-project
+module-a
+module-b
module-b is a web application. it will be run on Jboss AS 7.1.1. I'm using netbeans IDE.
Now module-b depend on module-a. this is a porm section of module-b:
<dependency>
<groupId>groupid</groupId>
<artifactId>module-a</artifactId>
<scope>compile</scope>
</dependency>
When i build the war file of module-b, module-a is not present to lib folder ( in war file. i open it with archive explorer ). therefore JBoss return ClassNotFoundException.
I'm tried differends scope ( compile , provided , runtime , test ). But nothing.
Please how can i solve this.
First of all, I think you should try to see how does it work in "pure" maven, without the IDE at all (NetBeans). So my answer will be based only on maven knowledge:
A couple of facts:
Module b has to have the following in pom: <packaging>war</packaging> This will instruct maven that you really want to get a war from this module.
When packaging WAR is specified in some pom, maven will take all the dependencies defined in this pom and will put them into the WEB-INF/lib folder of the war. Automatically. Of course, you can customize the output, but its more advanced stuff (see Maven WAR plugin if required)
All the dependencies have to be defined with group id, artifact id, and version at least. So make sure that you have the dependency on module a with version. There is no need to fiddle with scopes in this case. The default scope (if you don't specify a scope at all) is 'compile' which is fine.
Go to the directory of module b and from within the directory type: mvn dependency:tree. Once its done, please carefully observe the output, especially make sure that module a is listed (with a correct version) in a tree.
Sometime to make sure that no stale artifacts reside in the local m2 repository you might want to delete all the jars of your project from there and then execute the mvn package command again. The war has to be created in module b/target - and this is the WAR you should check out.
Note, all these steps are done without any interaction with NetBeans at all.
I have a Java Maven project where I have some dependencies defined in the pom.xml file. Recently I decided to move from Junit to TestNG so I deleted the Junit dependency from my pom.xml and added the TestNG one.
I was expecting to see the Junit jar library disappear from the Maven Dependencies folder as a part of the process but that didn't happen. I can still see the jar file in the dependencies folder and it is still being used by my test cases.
I can see TestNG jar is there as well but it's not being used. I can change it manually of course but that wasn't my intention.
Am I doing something wrong are there any additional steps that I missed that will allow me to remove the old dependency?
The following applies for the global .m2 folder where maven dependencies can be downloaded and is common to your maven projects.
the .m2 folder will not clean by itself as those dependencies could be used in another project so its wrong assumption that replacing a dependency in a a pom file will automatically remove from your repo.
you can look at the depedency plugin and run the following
mvn dependency:purge-local-repository
or
mvn dependency:purge-local-repository -DreResolve=false
After being introduced to Maven in my most recent project, I've been experimenting with it for the past couple of weeks.
I currently have a multi-module project in my development environment. Project "A" and Project "B" are child modules of Project "root", with B having a dependency on A.
I am aware that I can build B independently by using mvn reactor:make... as outlined here. However, I'm curious as to why am I not allowed to build B from inside B's root folder.
To illustrate this, I first built A independently by running a clean install from within A's root directory. However, when I tried doing the same action from B's root directory, Maven reported an error as below -
Could not find artifact org.divesh.mavenrnd:root:pom:1.0 in central
It looks like Maven is not able to resolve the parent's POM file. Any thoughts on why this is happening? From my initial understanding of Maven multi-module projects, the main reason to split a project into sub modules is to share dependencies. This should not, however, prevent me from building a particular module independently from within its folder.
Thanks.
EDIT
Ran an mvn -N clean install to install only the root project's POM in the rep. After this, I was able to successfully build B after building and installing A. There is still one thing I'm not quite clear about -
Assuming I've installed the root project's POM in the repository, if I try to build A, does it refer to the parent root POM directly above it or the POM that is installed in the repository?
That's right. The error you mentioned tells you that maven cannot find parent's pom.
You have 2 options here:
First call mvn -N install in your root project directory to install parent pom to your local repository. Then you can go to B's directory and build the submodule.
Specify <relativePath> in your submodule pom. By default maven will look for parent pom only one level up the file system. If you have other directory structure in your project, you have to specify this option in order for maven to locate your parent pom.
Here's a sample:
<parent>
<groupId>...</groupId>
<artifactId>...</artifactId>
<version>...</version>
<relativePath>../../pom.xml</relativePath>
</parent>
You should use mvn -pl ProjectToBuild lifecycle like from the root of your tree:
mvn -pl module-b package
You shouldn't use mvn reactor:make anymore. Except you are using maven 2.0
If you wan't to be sure that everything is depending on module-b is build as well you should use:
mvn -amd -pl module -b package
The best is having a folder layout which represents the appropriate structure of your project and not using relativePath is necessary.
I am trying to move my MyEclipes projects to maven. But of course there are problems. After creating a web priject I get missing jar files - about 5
org.springframework.security jar files e.g. org.springframework.security.ldap-3.0.5.RELEASE
show as missing in the jar build path. They are not in the corresponding .m2 directory. I un-installed ME4S, and deleted .m2, which force .me to be rebuilt on re-install, but it has the same problem.
How do I fix this?
It would be very helpful to understand how the .m2 process works - where is this coming from and how is it controlled?
I am not sure about the MyEclipse part, but this seems to be a pure maven question.
Maven (2/3) uses the pom.xml. This file describe your project. In that file you should define a list of dependencies (which can have their own dependencies and so on).
Maven read the pom.xml and build the classpath accordingly using direct and transitive dependencies.
You can use the mvn dependency:tree command to see how your classpath is built.
More on the plugin page