Toolchain Description

The toolchain type id for JDK is "jdk".

Predefined <provides> identification tokens, for requirement matching in plugin configuration, are:

• "version" marks the version of the JDK in toolchains.xml. In plugin's selection, this can be either a single version or a version range.
• Other tokens are accepted, but only exact matches are supported.

In toolchains.xml, there is only one <configuration> element named "jdkHome". It designates the root directory of a JDK installation.

Sample ~/.m2/toolchains.xml setup

<toolchains> <toolchain> <type>jdk</type> <provides> <version>11</version> <vendor>temurin</vendor> <purpose>for_mevenide</purpose> </provides> <configuration> <jdkHome>/Library/Java/JavaVirtualMachines/temurin-11.jdk/Contents/Home</jdkHome> </configuration> </toolchain> [...] </toolchains>

This defines a toolchain with version 11, vendor "temurin", and purpose "for_mevenide".

A project can request this toolchain by specifying the type "jdk" and the version "11". It can also use a version range that includes 11 like [8, 17]. It can also ask for the vendor temurin, with or without version, or the purpose "for_mevenide".

Toolchains Plugin Configuration

A project specifies a toolchain in the configuration of the maven-toolchains-plugin like so:

<project> [...] <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-toolchains-plugin</artifactId> <version>3.2.0</version> <executions> <execution> <goals> <goal>toolchain</goal> </goals> </execution> </executions> <configuration> <toolchains> <jdk> <version>[1.8,)</version> </jdk> </toolchains> </configuration> </plugin> </plugins> </build> [...] </project>

In this example, the project is requesting any toolchain with type jdk that has a version of 1.8 or greater. "version" accepts any version range definitions. If you want exactly JDK 1.8 from the vendor temurin, the plugin would be configured like this:

 <configuration> <toolchains> <jdk> <version>1.8</version> <vendor>temurin</vendor> </jdk> </toolchains> </configuration>

Aside from version, the definitions are opaque strings. Maven looks in toolchains.xml for a toolchain that provides version=="1.8" and vendor=="temurin". It does not know or care what these strings mean. It does not, for instance, concern itself with whether the jdkHome configured by the toolchain that satisfies version=="1.8" and vendor=="temurin" is JDK 8 from the Temurin project, or JDK 21 from Oracle. JDK toolchain only checks that directory exists.

All conditions need to be satisfied to find a toolchain.