背景

工作中使用到很多的Maven插件，雖然可以從網(wǎng)上拷貝別人的配置來用，但是想要深入了解一個插件一共有哪些可用的配置參數(shù)，就無從下手了。

當(dāng)然可以從插件的官方網(wǎng)站查看幫助手冊，也可以通過Maven的help命令查看插件幫助，包括插件的簡略和詳細(xì)的描述信息，也可以查看插件所有的目標(biāo)goal，以及插件的配置參數(shù)等。

幫助命令

在命令行下面，使用Maven的help:describe目標(biāo)查看插件信息：mvn help:describe -Dplugin=插件標(biāo)識

• 通過plugin參數(shù)指定要查看的插件，插件標(biāo)識可以是groupId:artifactId[:version]形式的，
• 其中version是可選的，
• 也可以是插件前綴，
• 它是插件的簡稱，
• 插件前綴和插件是一一對應(yīng)的，
• 這種對應(yīng)關(guān)系存儲在Maven倉庫元數(shù)據(jù)中：https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-metadata.xml
• 比如插件前綴help和插件maven-help-plugin是對應(yīng)的

<plugin>
  <name>Apache Maven Help Plugin</name>
  <prefix>help</prefix>
  <artifactId>maven-help-plugin</artifactId>
</plugin>

使用舉例

下面查看maven-help-plugin插件的信息，即查看幫助命令自己的信息，下面兩條命令是等價的：

mvn help:describe -Dplugin=org.apache.maven.plugins:maven-help-plugin
mvn help:describe -Dplugin=help

輸出查詢結(jié)果如下

[INFO] Scanning for projects...
[INFO]
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
[INFO]
[INFO] --- maven-help-plugin:3.2.0:describe (default-cli) @ standalone-pom ---
[INFO] org.apache.maven.plugins:maven-help-plugin:3.2.0
 
Name: Apache Maven Help Plugin
Description: The Maven Help plugin provides goals aimed at helping to make
  sense out of the build environment. It includes the ability to view the
  effective POM and settings files, after inheritance and active profiles have
  been applied, as well as a describe a particular plugin goal to give usage
  information.
Group Id: org.apache.maven.plugins
Artifact Id: maven-help-plugin
Version: 3.2.0
Goal Prefix: help
 
This plugin has 8 goals:
 
help:active-profiles
  Description: Displays a list of the profiles which are currently active for
    this build.
 
help:all-profiles
  Description: Displays a list of available profiles under the current
    project.
    Note: it will list all profiles for a project. If a profile comes up with a
    status inactive then there might be a need to set profile activation
    switches/property.
 
help:describe
  Description: Displays a list of the attributes for a Maven Plugin and/or
    goals (aka Mojo - Maven plain Old Java Object).
 
help:effective-pom
  Description: Displays the effective POM as an XML for this build, with the
    active profiles factored in, or a specified artifact. If verbose, a comment
    is added to each XML element describing the origin of the line.
 
help:effective-settings
  Description: Displays the calculated settings as XML for this project,
    given any profile enhancement and the inheritance of the global settings
    into the user-level settings.
 
help:evaluate
  Description: Evaluates Maven expressions given by the user in an
    interactive mode.
 
help:help
  Description: Display help information on maven-help-plugin.
    Call mvn help:help -Ddetail=true -Dgoal=<goal-name> to display parameter
    details.
 
help:system
  Description: Displays a list of the platform details like system properties
    and environment variables.
 
For more information, run 'mvn help:describe [...] -Ddetail'
 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.613 s
[INFO] Finished at: 2021-10-12T15:38:22+08:00
[INFO] ------------------------------------------------------------------------

可以看到maven-help-plugin對應(yīng)的插件前綴是help

Group Id: org.apache.maven.plugins
Artifact Id: maven-help-plugin
Version: 3.2.0
Goal Prefix: help

可以看到help:describe用來查看插件的屬性和目標(biāo)

help:describe
  Description: Displays a list of the attributes for a Maven Plugin and/or
    goals (aka Mojo - Maven plain Old Java Object).

• 可以看到help命令自帶的幫助: mvn help:help
• 輸出的結(jié)果基本和上面的相同
• 這里更推薦使用help:describe命令

查看詳細(xì)信息

通過在命令后追加-Ddetail參數(shù)，可以查看插件的詳細(xì)信息：

簡略信息：
mvn help:describe -Dplugin=help
詳細(xì)信息：
mvn help:describe -Dplugin=help -Ddetail

詳細(xì)信息輸出如下,這是可以看到每個goal的配置參數(shù)說明

[INFO] Scanning for projects...
[INFO]
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
[INFO]
[INFO] --- maven-help-plugin:3.2.0:describe (default-cli) @ standalone-pom ---
[INFO] org.apache.maven.plugins:maven-help-plugin:3.2.0
 
Name: Apache Maven Help Plugin
Description: The Maven Help plugin provides goals aimed at helping to make
  sense out of the build environment. It includes the ability to view the
  effective POM and settings files, after inheritance and active profiles have
  been applied, as well as a describe a particular plugin goal to give usage
  information.
Group Id: org.apache.maven.plugins
Artifact Id: maven-help-plugin
Version: 3.2.0
Goal Prefix: help
 
This plugin has 8 goals:
 
help:active-profiles
  Description: Displays a list of the profiles which are currently active for
    this build.
  Implementation: org.apache.maven.plugins.help.ActiveProfilesMojo
  Language: java
 
  Available parameters:
 
    output
      User property: output
      Optional parameter to write the output of this help in a given file,
      instead of writing to the console.
      Note: Could be a relative path.
 
help:all-profiles
  Description: Displays a list of available profiles under the current
    project.
    Note: it will list all profiles for a project. If a profile comes up with a
    status inactive then there might be a need to set profile activation
    switches/property.
  Implementation: org.apache.maven.plugins.help.AllProfilesMojo
  Language: java
 
  Available parameters:
 
    output
      User property: output
      Optional parameter to write the output of this help in a given file,
      instead of writing to the console.
      Note: Could be a relative path.
 
help:describe
  Description: Displays a list of the attributes for a Maven Plugin and/or
    goals (aka Mojo - Maven plain Old Java Object).
  Implementation: org.apache.maven.plugins.help.DescribeMojo
  Language: java
 
  Available parameters:
 
    artifactId
      User property: artifactId
      The Maven Plugin artifactId to describe.
      Note: Should be used with groupId parameter.
 
    cmd
      User property: cmd
      A Maven command like a single goal or a single phase following the Maven
      command line:
      mvn [options] [<goal(s)>] [<phase(s)>]
 
    detail (Default: false)
      User property: detail
      This flag specifies that a detailed (verbose) list of goal (Mojo)
      information should be given.
 
    goal
      User property: goal
      The goal name of a Mojo to describe within the specified Maven Plugin. If
      this parameter is specified, only the corresponding goal (Mojo) will be
      described, rather than the whole Plugin.
 
    groupId
      User property: groupId
      The Maven Plugin groupId to describe.
      Note: Should be used with artifactId parameter.
 
    minimal (Default: false)
      User property: minimal
      This flag specifies that a minimal list of goal (Mojo) information should
      be given.
 
    output
      User property: output
      Optional parameter to write the output of this help in a given file,
      instead of writing to the console.
      Note: Could be a relative path.
 
    plugin
      Alias: prefix
      User property: plugin
      The Maven Plugin to describe. This must be specified in one of three
      ways:
 
      1.  plugin-prefix, i.e. 'help'
      2.  groupId:artifactId, i.e. 'org.apache.maven.plugins:maven-help-plugin'
      3.  groupId:artifactId:version, i.e.
        'org.apache.maven.plugins:maven-help-plugin:2.0'
 
    version
      User property: version
      The Maven Plugin version to describe.
      Note: Should be used with groupId/artifactId parameters.
 
help:effective-pom
  Description: Displays the effective POM as an XML for this build, with the
    active profiles factored in, or a specified artifact. If verbose, a comment
    is added to each XML element describing the origin of the line.
  Implementation: org.apache.maven.plugins.help.EffectivePomMojo
  Language: java
 
  Available parameters:
 
    artifact
      User property: artifact
      The artifact for which to display the effective POM.
      Note: Should respect the Maven format, i.e. groupId:artifactId[:version].
      The latest version of the artifact will be used when no version is
      specified.
 
    output
      User property: output
      Optional parameter to write the output of this help in a given file,
      instead of writing to the console.
      Note: Could be a relative path.
 
    verbose (Default: false)
      User property: verbose
      Output POM input location as comments.
 
help:effective-settings
  Description: Displays the calculated settings as XML for this project,
    given any profile enhancement and the inheritance of the global settings
    into the user-level settings.
  Implementation: org.apache.maven.plugins.help.EffectiveSettingsMojo
  Language: java
 
  Available parameters:
 
    output
      User property: output
      Optional parameter to write the output of this help in a given file,
      instead of writing to the console.
      Note: Could be a relative path.
 
    showPasswords (Default: false)
      User property: showPasswords
      For security reasons, all passwords are hidden by default. Set this to
      true to show all passwords.
 
help:evaluate
  Description: Evaluates Maven expressions given by the user in an
    interactive mode.
  Implementation: org.apache.maven.plugins.help.EvaluateMojo
  Language: java
 
  Available parameters:
 
    artifact
      User property: artifact
      An artifact for evaluating Maven expressions.
      Note: Should respect the Maven format, i.e. groupId:artifactId[:version].
      The latest version of the artifact will be used when no version is
      specified.
 
    expression
      User property: expression
      An expression to evaluate instead of prompting. Note that this must not
      include the surrounding ${...}.
 
    forceStdout (Default: false)
      User property: forceStdout
      This options gives the option to output information in cases where the
      output has been suppressed by using -q (quiet option) in Maven. This is
      useful if you like to use maven-help-plugin:evaluate in a script call
      (for example in bash) like this:
      RESULT=$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout)
      echo $RESULT
      This will only printout the information which has been requested by
      expression to stdout.
 
    output
      User property: output
      Optional parameter to write the output of this help in a given file,
      instead of writing to the console. This parameter will be ignored if no
      expression is specified.
      Note: Could be a relative path.
 
help:help
  Description: Display help information on maven-help-plugin.
    Call mvn help:help -Ddetail=true -Dgoal=<goal-name> to display parameter
    details.
  Implementation: org.apache.maven.plugins.help.HelpMojo
  Language: java
 
  Available parameters:
 
    detail (Default: false)
      User property: detail
      If true, display all settable properties for each goal.
 
    goal
      User property: goal
      The name of the goal for which to show help. If unspecified, all goals
      will be displayed.
 
    indentSize (Default: 2)
      User property: indentSize
      The number of spaces per indentation level, should be positive.
 
    lineLength (Default: 80)
      User property: lineLength
      The maximum length of a display line, should be positive.
 
help:system
  Description: Displays a list of the platform details like system properties
    and environment variables.
  Implementation: org.apache.maven.plugins.help.SystemMojo
  Language: java
 
  Available parameters:
 
    output
      User property: output
      Optional parameter to write the output of this help in a given file,
      instead of writing to the console.
      Note: Could be a relative path.
 
 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.904 s
[INFO] Finished at: 2021-10-12T15:53:53+08:00
[INFO] ------------------------------------------------------------------------

查看指定目標(biāo)

可以通過-Dgoal參數(shù)，查看指定目標(biāo)的詳細(xì)信息：

簡略信息：
mvn help:describe -Dplugin=help -Dgoal=describe
詳細(xì)信息：
mvn help:describe -Dplugin=help -Dgoal=describe -Ddetail

簡略信息輸出如下

[INFO] Scanning for projects...
[INFO]
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
[INFO]
[INFO] --- maven-help-plugin:3.2.0:describe (default-cli) @ standalone-pom ---
[INFO] Mojo: 'help:describe'
help:describe
  Description: Displays a list of the attributes for a Maven Plugin and/or
    goals (aka Mojo - Maven plain Old Java Object).
 
For more information, run 'mvn help:describe [...] -Ddetail'
 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.031 s
[INFO] Finished at: 2021-10-12T15:56:50+08:00
[INFO] ------------------------------------------------------------------------

詳細(xì)信息輸出如下

[INFO] Scanning for projects...
[INFO]
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
[INFO]
[INFO] --- maven-help-plugin:3.2.0:describe (default-cli) @ standalone-pom ---
[INFO] Mojo: 'help:describe'
help:describe
  Description: Displays a list of the attributes for a Maven Plugin and/or
    goals (aka Mojo - Maven plain Old Java Object).
  Implementation: org.apache.maven.plugins.help.DescribeMojo
  Language: java
 
  Available parameters:
 
    artifactId
      User property: artifactId
      The Maven Plugin artifactId to describe.
      Note: Should be used with groupId parameter.
 
    cmd
      User property: cmd
      A Maven command like a single goal or a single phase following the Maven
      command line:
      mvn [options] [<goal(s)>] [<phase(s)>]
 
    detail (Default: false)
      User property: detail
      This flag specifies that a detailed (verbose) list of goal (Mojo)
      information should be given.
 
    goal
      User property: goal
      The goal name of a Mojo to describe within the specified Maven Plugin. If
      this parameter is specified, only the corresponding goal (Mojo) will be
      described, rather than the whole Plugin.
 
    groupId
      User property: groupId
      The Maven Plugin groupId to describe.
      Note: Should be used with artifactId parameter.
 
    minimal (Default: false)
      User property: minimal
      This flag specifies that a minimal list of goal (Mojo) information should
      be given.
 
    output
      User property: output
      Optional parameter to write the output of this help in a given file,
      instead of writing to the console.
      Note: Could be a relative path.
 
    plugin
      Alias: prefix
      User property: plugin
      The Maven Plugin to describe. This must be specified in one of three
      ways:
 
      1.  plugin-prefix, i.e. 'help'
      2.  groupId:artifactId, i.e. 'org.apache.maven.plugins:maven-help-plugin'
      3.  groupId:artifactId:version, i.e.
        'org.apache.maven.plugins:maven-help-plugin:2.0'
 
    version
      User property: version
      The Maven Plugin version to describe.
      Note: Should be used with groupId/artifactId parameters.
 
 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.162 s
[INFO] Finished at: 2021-10-12T15:57:13+08:00
[INFO] ------------------------------------------------------------------------

其他命令

該幫助插件還有很多有用的goal，下面僅列出幾個常用的，更多的請自行嘗試。文章來源地址http://www.zghlxwxcb.cn/news/detail-617417.html

• 查看當(dāng)前pom.xml具體生效的結(jié)果，并且輸出到文件: mvn help:effective-pom -Doutput=EffectivePom.xml
• 查看pom中生效的profile: mvn help:active-profiles -N
• 查看系統(tǒng)所有環(huán)境變量: mvn help:system

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