除了通过访问在线文档了解某个插件的详细信息外，还可以借助 maven-help-plugin 插件来获取插件的详细信息。比如，在 CMD 命令行窗口中运行如下命令。
Mvn help:describe -Dplugin=org.apache.maven.plugins:maven-site-plugin:3.4 -Ddetail
就可以查看到 maven-site-plugin 插件 3.4 版本的详细信息，内容很多，如下列出的是开始的几个基本信息。
Name: Apache Maven Site Plugin
Description: The Maven Site Plugin is a plugin that generates a site for the
current project.
Group Id: org.apache.maven.plugins
Artifact Id: maven-site-plugin
Version: 3.4
Goal Prefix: site
This plugin has 9 goals:
site:attach-descriptor
Description: Adds the site descriptor (site.xml) to the list of files to be
installed/deployed.
For Maven-2.x this is enabled by default only when the project has pom
packaging since it will be used by modules inheriting, but this can be
enabled for other projects packaging if needed.
This default execution has been removed from the built-in lifecycle of
Maven 3.x for pom-projects. Users that actually use those projects to
provide a common site descriptor for sub modules will need to explicitly
define this goal execution to restore the intended behavior.
Implementation: org.apache.maven.plugins.site.SiteDescriptorAttachMojo
Language: java
Bound to phase: package
Name: Apache Maven Site Plugin
Description: The Maven Site Plugin is a plugin that generates a site for the
current project.
Group Id: org.apache.maven.plugins
Artifact Id: maven-site-plugin
Version: 3.4
Goal Prefix: site
This plugin has 9 goals:
site:attach-descriptor
Description: Adds the site descriptor (site.xml) to the list of files to be
installed/deployed.
For Maven-2.x this is enabled by default only when the project has pom
packaging since it will be used by modules inheriting, but this can be
enabled for other projects packaging if needed.
This default execution has been removed from the built-in lifecycle of
Maven 3.x for pom-projects. Users that actually use those projects to
provide a common site descriptor for sub modules will need to explicitly
define this goal execution to restore the intended behavior.
Implementation: org.apache.maven.plugins.site.SiteDescriptorAttachMojo
Language: java
Bound to phase: package
当然，如果不想查看太多，只是想具体了解插件的某个目标，可以用 -Dgoal=目标的方式查看指定目标的信息，比如运行如下命令，可以查看 site 插件的 site 目标信息。
Mvn help:describe -Dplugin=site -Dgoal=site -Ddetail
输出信息：
[INFO] Mojo: 'site:site'
site:site
Description: Generates the site for a single project.
Note that links between module sites in a multi module build will not work,
since local build directory structure doesn't match deployed site.
Implementation: org.apache.maven.plugins.site.render.SiteMojo
Language: java
Available parameters:
attributes
Additional template properties for rendering the site. See Doxia Site
Renderer.
generatedSiteDirectory (Default: ${project.build.directory}/generated-site)
Directory containing generated documentation. This is used to pick up
other source docs that might have been generated at build time.
generateProjectInfo (Default: true)
User property: generateProjectInfo
Whether to generate the summary page for project reports:
project-info.html.
generateReports (Default: true)
User property: generateReports
Convenience parameter that allows you to disable report generation.
generateSitemap (Default: false)
User property: generateSitemap
Generate a sitemap. The result will be a 'sitemap.html' file at the site
root.
inputEncoding (Default: ${project.build.sourceEncoding})
User property: encoding
Specifies the input encoding.
locales (Default: en)
User property: locales
A comma separated list of locales to render. The first valid token will
be the default Locale for this site.
moduleExcludes
Module type exclusion mappings ex: fml -> **/*-m1.fml (excludes fml files
ending in '-m1.fml' recursively)
The configuration looks like this:
filename1.ext,**/*sample.ext
changes.xml,navigation.xml
outputDirectory (Default: ${project.reporting.outputDirectory})
User property: siteOutputDirectory
Directory where the project sites and report distributions will be
generated.
outputEncoding (Default: ${project.reporting.outputEncoding})
User property: outputEncoding
Specifies the output encoding.
relativizeDecorationLinks (Default: true)
User property: relativizeDecorationLinks
Make links in the site descriptor relative to the project URL. By
default, any absolute links that appear in the site descriptor, e.g.
banner hrefs, breadcrumbs, menu links, etc., will be made relative to
project.url.
Links will not be changed if this is set to false, or if the project has
no URL defined.
saveProcessedContent
Whether to save Velocity processed Doxia content (*..vm) to
${generatedSiteDirectory}/processed.
siteDirectory (Default: ${basedir}/src/site)
Directory containing the site.xml file and the source for hand written
docs (one directory per Doxia-source-supported markup types): see Doxia
Markup Languages References).
skip (Default: false)
User property: maven.site.skip
Set this to 'true' to skip site generation and staging.
templateFile
User property: templateFile
The location of a Velocity template file to use. When used, skins and the
default templates, CSS and images are disabled. It is highly recommended
that you package this as a skin instead.
validate (Default: false)
User property: validate
Whether to validate xml input documents. If set to true, all input
documents in xml format (in particular xdoc and fml) will be validated
and any error will lead to a build failure.
xdocDirectory (Default: ${basedir}/xdocs)
Alternative directory for xdoc source, useful for m1 to m2 migration
Deprecated. use the standard m2 directory layout
命令中的 -Dplugin=site 通过插件的前缀来指定要查看的插件名称，与写成 -Dplugin=org.apache.maven.plugins:maven-site-plugin:3.6 是一样的意思。
-Dgoal=site，指定要查看的目标，名称是 site。
-Ddetail，表示要查看详细信息。