[java] Get source JARs from Maven repository

Does anyone have any idea if you can find source JARs on Maven repositories?

In IntelliJ IDEA you can download artifact sources automatically while importing by switching on Automatically download Sources option:

Settings ? Build, Execution, Deployment ? Build Tools ? Maven ? Importing

you can find info in this related question: Get source jar files attached to Eclipse for Maven-managed dependencies
if you use the eclipse maven plugin then use 'mvn eclipse:eclipse -DdownloadSources=true'

If a project creates a jar of the project sources and deploys it to a maven repository, then you'll find it :)

Just FYI, sources artifacts are generally created by the maven-source-plugin. This plugin can bundle the main or test sources of a project into a jar archive and, as explained in Configuring Source Plugin:

(...) The generated jar file will be named by the value of the finalName plus "-sources" if it is the main sources. Otherwise, it would be finalName plus "-test-sources" if it is the test sources.

The additional text was given to describe an artifact ("-sources" or "-test-sources" here) is called a classifier.

To declare a dependency on an artifact that uses a classifier, simply add the <classifier> element. For example:

<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate</artifactId>
  <version>3.2.7.ga</version>
  <classifier>sources</classifier>
</dependency>

Note that you generally don't do this, most IDEs provide support to download sources (and/or JavaDoc) from the main artifact without declaring explicitly a dependency on them.

Finally, also note that some repository search engines allow searching for artifacts using the classifier (at least Nexus does with the advanced search). See this search for example.

I have also used the eclipse plugin to get the project into the eclipse workspace. Since I've worked on a different project I saw that it is possible to work with eclipse but without the maven-eclipse-plugin. That makes it easier to use with different environments and enables the easy use of maven over eclipse. And that without changing the pom.xml-file.

So, I recommend the approach of Gabriel Ramirez.

In eclipse - click on the project then:

.

In Eclipse

1. Right click on the pom.xml
2. Select Run As -> Maven generate-sources
   it will generate the source by default in .m2 folder

Pre-Requisite:

Maven should be configured with Eclipse.

Maven repositories do provide simple way to download sources jar.

I will explain it using a demonstration for "spring-boot-actuator-autoconfigure".

1. Go to maven repository - https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-actuator-autoconfigure
2. The page lists various versions. Click-on to desired one, let's say, 2.1.6.RELEASE - https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-actuator-autoconfigure/2.1.6.RELEASE
3. The page have link "View All" next to "Files". Click it - https://repo1.maven.org/maven2/org/springframework/boot/spring-boot-actuator-autoconfigure/2.1.6.RELEASE/
4. The page lists various files including the one for sources - https://repo1.maven.org/maven2/org/springframework/boot/spring-boot-actuator-autoconfigure/2.1.6.RELEASE/spring-boot-actuator-autoconfigure-2.1.6.RELEASE-sources.jar

Otherwise, you can always "git clone" the repo from github, if its there and get the specific code.

As explained by others, you can use "mvn dependency:sources" command the get and generate sources jar for the dependency you are using.

Note: Some dependencies will not have sources.jar, as those contains no source code but a pom file. e.g. spring-boot-starter-actuator. As in this case:

Starter POMs are a set of convenient dependency descriptors that you can include in your application. You get a one-stop-shop for all the Spring and related technology that you need, without having to hunt through sample code and copy paste loads of dependency descriptors.

Reference: Intro to Spring Boot Starters

Based on watching the Maven console in Eclipse (Kepler), sources will be automatically downloaded for a Maven dependency if you attempt to open a class from said Maven dependency in the editor for which you do not have the sources downloaded already. This is handy when you don't want to grab source for all of your dependencies, but you don't know which ones you want ahead of time (and you're using Eclipse).

I ended up using @GabrielRamierez's approach, but will employ @PascalThivent's approach going forward.

Configuring and running the maven-eclipse plugin, (for example from the command line mvn eclipse:eclipse )

   <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-eclipse-plugin</artifactId>
                <configuration>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>true</downloadJavadocs>
                </configuration>
            </plugin>
        </plugins>
    </build>

if you're using eclipse you could also open Preferences > Maven and select Download Artifact Sources, this would let the pom.xml intact and keep your sources or java docs (if selected) just for development right at your machine location ~/.m2

NetBeans, Context-Click

In NetBeans 8 with a Maven-driven project, merely context-click on the jar file list item of the dependency in which you are interested. Choose Download Sources. Wait a moment and NetBeans will automatically download and install the source code, if available.

Similarly you can choose Download Javadoc to get the doc locally installed. Then you can context-click some code in the editor and choose to see the JavaDoc.

To download some specific source or javadoc we need to include the GroupIds - Its a comma separated value as shown below

mvn dependency:sources -DincludeGroupIds=com.jcraft,org.testng -Dclassifier=sources

Note that the classifier are not comma separated, to download the javadoc we need to run the above command one more time with the classifier as javadoc

mvn dependency:sources -DincludeGroupIds=com.jcraft,org.testng -Dclassifier=javadoc

You can, if they are uploaded. Generally they are called "frameworkname-version-source(s)"

For debugging you can also use a "Java Decompiler" such as: JAD and decompile source on the fly (although the generated source is never the same as the original). Then install JAD as a plugin in Eclipse or your favorite IDE.

To download any artifact use

mvn dependency:get -Dartifact=groupId:artifactId:version:packaging:classifier

For Groovy sources this would be

mvn dependency:get -Dartifact=org.codehaus.groovy:groovy-all:2.4.6:jar:sources

For Groovy's javadoc you would use

mvn dependency:get -Dartifact=org.codehaus.groovy:groovy-all:2.4.6:jar:javadoc

This puts the given artifact into your local Maven repository, i.e. usually $HOME/.m2/repository.

dependency:sources just downloads the project dependencies' sources, not the plugins sources nor the sources of dependencies defined inside plugins.

If you want find the source jar file for any of the artifact manually, go to maven repository location for the particular artifact and in Files click on 'view All'. You can find source jar file.

If you know the groupId and aritifactId,you can generate download url like this.

    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.2.3</version>
    </dependency>

http://central.maven.org/maven2/ch/qos/logback/logback-classic/

and you will get a page like this, chose the version you need,just enjoy it!

The maven idea plugin for IntelliJ Idea allows you to specify whether or not sources and java doc should be resolved and downloaded

mvn idea:idea -DdownloadSources=true -DdownloadJavadocs=true