How Maven knows what remote repositories to access and check? - maven

Let's say i'm adding Spring dependency to my Maven project:
http://mvnrepository.com/artifact/org.springframework/spring-core/4.2.1.RELEASE
To my pom.xml, the following will be added:
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>4.2.1.RELEASE</version>
</dependency>
How my Maven will know from where exactly the artifact will be fetched? I didn't setup anything in maven settings.xml besides our enterprise Artifactory repositories.

There are several official Central repositories and proxies. (See documentation) and Maven knows them by default.
Specifying something in your settings.xml will just add some to the list.
A convenient way to search through the Central repository is to go to: search.maven.org

Related

Dependency javax.mail:mail:1.4 not found

After I imported a maven project in IntelliJ IDEA, there are two errors in the pom.xml file:
"Failed to read artifact descriptor for javax.mail:mail:jar:1.4"
"Dependency javax.mail:mail:1.4 not found"
Does anyone know the reason behind these errors and how can I fix them?
Thank you and have a great day!
Due to license restrictions the older java mail classes are not in maven central or the java.net repository. usually companies host their own maven proxy and add these classes there.
Since around version 1.4.5 the dependencies are available in the java.net repository. Some later versions are also in maven central.
All other versions need to be downloaded from the oracle website and either added to a maven proxy or to your local maven repository - for example using the dependency plugin.
Change the pom.xml to include:
<dependencies>
<dependency>
<groupId>com.sun.mail</groupId>
<artifactId>jakarta.mail</artifactId>
<version>1.6.3</version>
</dependency>
</dependencies>
Or if you have a build.gradle file in the dependencies section add:
compile "com.sun.mail:jakarta.mail:1.6.3"

How to cache specific maven artifact into local repository?

Suppose I have some Maven coordinates, like
org.ow2.asm:asm:5.0.3
How would I cache these artifact into (existing) local maven repository?
I believe this truly answers your question: it shows how to download and cache locally a specific Maven artifact from specific Maven repository with all dependencies without having to create pom.xml or any other sort of dependency declaration.
In your pom.xml add under <dependencies> the following :
<dependency>
<groupId>org.ow2.asm</groupId>
<artifactId>asm</artifactId>
<version>5.0.3</version>
</dependency>
and use the command
mvn clean verify
at your project level to build the project and its dependencies to find the artifact in the corresponding .m2/repository folder.

Nexus sonatype does not get zip dependency

I have setup Sonatype Nexus with Maven and seems to be working. However, my project depends (transitively) on docbook-xsl-1.75.2 but instead of a jar there you find a zip file. Is this the reason why Nexus is not getting it, that it is a zip file? I haven't found any Nexus configuration page in the web console offering a possible filter.
I browse my Nexus repository and see it gets the pom file but nothing else.
That module has no main artifact, it's packaging type is set to "pom".
What it does have is two additional artifacts which can be retrieved using Maven module classifiers as follows:
<dependency>
<groupId>net.sf.docbook</groupId>
<artifactId>docbook-xsl</artifactId>
<version>1.75.2</version>
<classifier>resources</classifier>
<type>zip</type>
</dependency>
And
<dependency>
<groupId>net.sf.docbook</groupId>
<artifactId>docbook-xsl</artifactId>
<version>1.75.2</version>
<classifier>ns-resources</classifier>
<type>zip</type>
</dependency>
Sorry, I have no idea how you'd retrieve these as transitive dependencies.
The next day, and after restarting Nexus it pulled the dependency. I don't still understand the magic behind Nexus not seeing the dependencies while they are clearly available but at least this question is resolved.

can't find valid maven repository for hibernate-search-4.2.0.Final.jar

I use maven.
I want to use the last version of hibernate-search : 4.2.0.Final
I was under 3.3.0.Final
I can't a valid maven repository for this version.
Which maven repository I have to use to get this version of hibernate search ?
Because if you go there :
https://repository.jboss.org/nexus/index.html#nexus-search;gav~org.hibernate~hibernate-search~~~~kw,versionexpand
You'll find the version I need, but when I download hibernate-search-4.2.0.Final.jar and I unarchive it, I see there is only META-INF folder but no class in the jar : the jar is invalid !
Thanks for your help !
The hibernate-search project changed their artifact structure to use hibernate-search-orm instead of hibernate-search. Hibernate-search is now just a jar that declares a dependency on hibernate-search-orm which maven will resolve transitively and include in your project.
See the upgrade notes here - https://community.jboss.org/wiki/HibernateSearchMigrationGuide
More specifically this note - https://community.jboss.org/wiki/HibernateSearchMigrationGuide#New_jars_Maven_modules_reorganization
If you look in the pom for hibernate search you will see the dependency - this should all be resolved from central without any additional repository.
<dependency>
<groupId>${project.groupId}</groupId>
<artifactId>hibernate-search-orm</artifactId>
<version>${project.version}</version>
</dependency>
The best repository for JBoss artifacts is: https://repository.jboss.org/nexus/content/groups/public-jboss/
The available repositories are explained in their wiki: https://community.jboss.org/wiki/MavenRepository
The group public-jboss contains all releases and third-party artifacts required to by JBoss artifacts.
Isn't maven central good enough ?
http://search.maven.org/#search|ga|1|hibernate-search
Since this is a JBoss project, you can get newest builds from our Nexus repository. Here is how to configure it in your ~/.m2/settings.xml. Your pom.xml then should contain this dependecy.
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-search</artifactId>
<version>4.2.0.Final</version>
</dependency>

Can I download a jar file from maven central using maven?

I have a dependency problem with maven. I used to have saxon 8.7 that is located on maven central. Then, I had to upgrade to the latests saxon-b 9.1.0.0 which is only partially on maven central.
This is a snippet of my dependencies:
<dependency>
<groupId>net.sourceforge.saxon</groupId>
<artifactId>saxon</artifactId>
<version>9.1.0.8</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>net.sourceforge.saxon</groupId>
<artifactId>saxon-dom</artifactId>
<version>9.1.0.8</version>
<scope>runtime</scope>
</dependency>
The first artifact 'saxon' is available on maven central, but the secon 'saxon-dom'. Here is the artifact I want.
Can I tell maven to download the "jar" file or am I obliged to download the jar and publish it locally on my maven repo to use it as a dependency?
Did not expect to resolve this so easily :
<dependency>
<groupId>net.sourceforge.saxon</groupId>
<artifactId>saxon</artifactId>
<version>9.1.0.8</version>
<classifier>dom</classifier>
</dependency>
Basically, I can get the dependencies that are "attached" to the 'saxon' artifact using the classifier tag. Did not know about this and I found out that the tag existed when I searched for 'saxon' on Sonatype repository (which is quite good). It gave me the dependency snippet above.
Reference : http://maven.apache.org/pom.html
If the required version is not in the repo, then yes you need to do one of the following alternatives
Search for a public repo containing the required version of jar. And add the repo to your pom.xml file. OR
Download it manually, and install it locally on your machine, to help the project build completely.

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