Properties Maven Plugin

Plugin limitations

Maven load project model (from pom.xml) for project and all submodules at startup time. During project reading all available properties are resolved from projects and settings properties.

This plugin (as all other) is executed in the later phase - when project model is already build in memory.

So properties read from external files by this plugin can not by used in project definitions in items like <goal>, <version> and so on.

Properties read by plugin in one module are not propagated to other modules or child projects.

Properties are only available for other plugins in runtime like for maven-resource-plugin for filtering resources.

In order to resolve such issue new features must by implement in Maven itself, like:

Plugin Overview

The Properties Maven Plugin is here to make life a little easier when dealing with properties. It provides goals to read properties from files and URLs and write properties to files, and also to set system properties.

It's main use-case is loading properties from files or URLs instead of declaring them in pom.xml, something that comes in handy when dealing with different environments.

If you have a properties file called teams.properties with this content:

  toronto=raptors
  miami=heat

and invoke the properties:read-project-properties goal, it would be similar (with described limitations) as declaring the following in your pom.xml:

  <properties>
    <toronto>raptors</toronto>
    <miami>heat</miami>
  </properties>

The properties loaded from files or URLs can be used to filter resources differently for different environments.

Optionally, the plugin can process default values within property placeholders.

Property name is separated from the default value with ':'.

For example, given these initial values

  host=example.com
  port=9090
  fallback=fallback value

the following replacements will happen:

Raw value	Replacement (`useDefaultValues` flag enabled)	Replacement (`useDefaultValues` flag disabled)
`${unknown:}`	`${unknown}`	`${unknown:}`
`${unknown:defaultValue}`	`defaultValue`	`${unknown:defaultValue}`
`http://${uhost:localhost}:${uport:8080}`	`http://localhost:8080`	`http://${uhost:localhost}:${uport:8080}`
`http://${host:localhost}:${port:8080}`	`http://example.com:9090`	`http://${host:localhost}:${port:8080}`
`${unknown:${fallback}}`	`fallback value`	`${unknown:${fallback}}`
`${unknown:${double.unknown}}`	`${double.unknown}`	`${unknown:${double.unknown}}`
`${unknown:with space}`	`with space`	`${unknown:with space}`
`${unknown:with extra :}`	`with extra :`	`${unknown:with extra :}`
`${malformed:defVal`	`${malformed:defVal`	`${malformed:defVal`
`${malformed:with space`	`${malformed:with space`	`${malformed:with space`
`${malformed:with extra :`	`${malformed:with extra :`	`${malformed:with extra :`
`${unknown::}`	`:`	`${unknown::}`
`${host}`	`example.com`	`example.com`

Goals Overview

properties:read-project-properties Reads property files or properties from URLs as Project properties.
properties:write-project-properties Writes project properties to a file.
properties:write-active-profile-properties Writes properties of all active profiles to a file.
properties:set-system-properties Sets system properties.

Usage

Instructions on how to use the Properties Maven Plugin can be found here.