Maven学习笔记(2) ---- 安装与运行Maven

　　上次我们初探了下Maven，现在来看下如何安装与运行Maven，以及如何使用Maven Help插件来获得更多信息。

 

　　1.　确认JDK的安装

　　Maven支持JDK1.4及以上版本，但建议使用Java 5.0或6.0。

 

　　2. 下载Maven分发包

　　Maven的下载地址为：http://maven.apache.org/download.html，请下载最新的分发包，目前Maven最新版本为2.1.0

 

　　3. 安装Maven

　　将下载的Maven分发包解压到本地目录，并且设置环境变量M2_HOME及PATH.

 

 

　　4. 验证Maven安装

　　在Windows命令窗口中输入 mvn -version，如果显示如下图所示，则表明Maven已经安装成功。

如果你看不到，而且你的操作系统找不到 mvn 命令，那么确认一下PATH和M2_HOME环境变量是否已经正确设置了。

 

　　5. Maven安装目录及文件介绍

• bin/目录包含了运行Maven的mvn脚本。
• boot/ 目录包含了一个负责创建Maven运行所需要的类装载器的JAR文件(classwords-1.1.jar)。
• conf/ 目录包含了一个全局的settings.xml文件，该文件用来自定义你机器上Maven的一些行为。如果你需要自定义Maven，更通常的做法是覆写 .m2目录下的settings.xml文件，每个用户都有对应的这个目录。
• lib/ 目录有了一个包含Maven核心的JAR文件(maven-2.1.0-uber.jar)
• LICENSE.txt 包含了Apache Maven的软件许可证。
• NOTICE.txt 包含了一些Maven依赖的类库所需要的通告及权限。
• README.txt包含了一些安装指令。

　　6. Maven本地仓库

　　从Apache下载的Maven是所谓的Maven核心包，不包含任何的插件，在上次介绍过，当第一次使用Maven时，它会从中央Maven仓库下载一些核心的Maven插件，而这些下载的插件将被安装到本地仓库，在Microsoft Windows XP系统中，Maven本地仓库被默认安装在C:/Documents and Settings/YU Zhipeng/.m2下；而Microsoft Windows Vista系统中，本地仓库位于C:/Users/YU Zhipeng/.m2，其中YU Zhipeng为当前用户名。

　　在.m2路径下，可以包含名为settings.xml的配置文件，该文件包含了用户相关的认证，仓库和其它信息的配置，用来自定义Maven的行为。

　　repository目录是你本地的仓库。当你从远程Maven仓库下载依赖的时候，Maven在你本地仓库存储了这个依赖的一个副本。如下图：

 

 

　　7. 使用Maven Help插件

　　Maven Help插件能让你列出活动的Maven Profile，显示一个实际POM（effective POM），打印实际settings（effective settings），或者列出Maven插件的属性。

　　Maven Help 插件有四个目标。前三个目标描述一个特定的项目，它们必须在项目的目录下运行。最后一个目标describe比较复杂，用于展示某个插件或者插件目标的相关信息。

• help:active-profiles

列出当前构建中活动的Profile（项目的，用户的，全局的）。

• help:effective-pom

显示当前构建的实际POM，包含活动的Profile。

• help:effective-settings

打印出项目的实际settings, 包括从全局的settings和用户级别settings继承的配置。

• help:describe
   
  描述插件的属性。它不需要在项目目录下运行。但是你必须提供你想要描述插件的 groupId 和 artifactId.

　　通常使用help:describe目标来获取Maven插件如何工作？配置参数是什么？目标是什么？ 等这些信息。它通过plugin参数指定你想要研究哪个插件，你可以传入插件的前缀，或者可以是坐标值groupId:artifactId:[version]，这里 version 是可选的。

　　例如，下面的命令使用 help 插件的describe目标来输出 Maven Help 插件的信息：

 

C:/>mvn help:describe -Dplugin=help[INFO] Scanning for projects...[INFO] Searching repository for plugin with prefix: 'help'.[INFO] ------------------------------------------------------------------------[INFO] Building Maven Default Project[INFO] task-segment: [help:describe] (aggregator-style)[INFO] ------------------------------------------------------------------------[INFO] [help:describe][INFO] org.apache.maven.plugins:maven-help-plugin:2.1Name: Maven Help PluginDescription: 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.pluginsArtifact Id: maven-help-pluginVersion: 2.1Goal Prefix: helpThis plugin has 9 goals:help:active-profiles Description: Displays a list of the profiles which are currently active for this build. Deprecated. No reason givenhelp: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. Deprecated. No reason givenhelp:describe Description: Displays a list of the attributes for a Maven Plugin and/or goals (aka Mojo - Maven plain Old Java Object). Deprecated. No reason givenhelp:effective-pom Description: Displays the effective POM as an XML for this build, with the active profiles factored in. Deprecated. No reason givenhelp: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. Deprecated. No reason givenhelp:evaluate Description: Evaluates Maven expressions given by the user in an interactive mode. Deprecated. No reason givenhelp:expressions Description: Displays the supported Plugin expressions used by Maven. Deprecated. No reason givenhelp:help Description: Display help information on maven-help-plugin. Call mvn help:help -Ddetail=true -Dgoal=<goal-name> to display parameter details. Deprecated. No reason givenhelp:system Description: Displays a list of the platform details like system properties and environment variables. Deprecated. No reason givenFor more information, run 'mvn help:describe [...] -Ddetail'[INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESSFUL[INFO] ------------------------------------------------------------------------[INFO] Total time: 2 seconds[INFO] Finished at: Mon Apr 20 14:02:21 CST 2009[INFO] Final Memory: 5M/10M[INFO] ------------------------------------------------------------------------

 

如果还想得到更详细的信息，可以使用full参数，即：

 C:/>mvn help:describe -Dplugin=help -Dfull[INFO] Scanning for projects...[INFO] Searching repository for plugin with prefix: 'help'.[INFO] ------------------------------------------------------------------------[INFO] Building Maven Default Project[INFO] task-segment: [help:describe] (aggregator-style)[INFO] ------------------------------------------------------------------------[INFO] [help:describe][INFO] org.apache.maven.plugins:maven-help-plugin:2.1Name: Maven Help PluginDescription: 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.pluginsArtifact Id: maven-help-pluginVersion: 2.1Goal Prefix: helpThis plugin has 9 goals:help:active-profiles Description: Displays a list of the profiles which are currently active for this build. Deprecated. No reason given Implementation: org.apache.maven.plugins.help.ActiveProfilesMojo Language: java Available parameters: 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. Deprecated. No reason givenhelp: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. Deprecated. No reason given Implementation: org.apache.maven.plugins.help.AllProfilesMojo Language: java Available parameters: 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. Deprecated. No reason givenhelp:describe Description: Displays a list of the attributes for a Maven Plugin and/or goals (aka Mojo - Maven plain Old Java Object). Deprecated. No reason given Implementation: org.apache.maven.plugins.help.DescribeMojo Language: java Available parameters: artifactId The Maven Plugin artifactId to describe. Note: Should be used with groupId parameter. Deprecated. No reason given cmd A Maven command like a single goal or a single phase following the Maven command line: mvn [options] [<goal(s)>] [<phase(s)>] Deprecated. No reason given detail (Default: false) This flag specifies that a detailed (verbose) list of goal (Mojo) information should be given. Deprecated. No reason given 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. Deprecated. No reason given groupId The Maven Plugin groupId to describe. Note: Should be used with artifactId parameter. Deprecated. No reason given medium (Default: true) This flag specifies that a medium list of goal (Mojo) information should be given. Deprecated. No reason given minimal (Default: false) This flag specifies that a minimal list of goal (Mojo) information should be given. Deprecated. No reason given 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. Deprecated. No reason given 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' Deprecated. No reason given version The Maven Plugin version to describe. Note: Should be used with groupId/artifactId parameters. Deprecated. No reason givenhelp:effective-pom Description: Displays the effective POM as an XML for this build, with the active profiles factored in. Deprecated. No reason given Implementation: org.apache.maven.plugins.help.EffectivePomMojo Language: java Available parameters: 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. Deprecated. No reason givenhelp: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. Deprecated. No reason given Implementation: org.apache.maven.plugins.help.EffectiveSettingsMojo Language: java Available parameters: 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. Deprecated. No reason given showPasswords (Default: false) For security reasons, all passwords are hidden by default. Set this to true to show all passwords. Deprecated. No reason givenhelp:evaluate Description: Evaluates Maven expressions given by the user in an interactive mode. Deprecated. No reason given Implementation: org.apache.maven.plugins.help.EvaluateMojo Language: java Available parameters: artifact An artifact for evaluating Maven expressions. Note: Should respect the Maven format, i.e. groupId:artifactId[:version][:classifier]. Deprecated. No reason givenhelp:expressions Description: Displays the supported Plugin expressions used by Maven. Deprecated. No reason given Implementation: org.apache.maven.plugins.help.ExpressionsMojo Language: java Available parameters: 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. Deprecated. No reason givenhelp:help Description: Display help information on maven-help-plugin. Call mvn help:help -Ddetail=true -Dgoal=<goal-name> to display parameter details. Deprecated. No reason given Implementation: org.apache.maven.plugins.help.HelpMojo Language: java Available parameters: detail (Default: false) If true, display all settable properties for each goal. Deprecated. No reason given goal The name of the goal for which to show help. If unspecified, all goals will be displayed. Deprecated. No reason given indentSize (Default: 2) The number of spaces per indentation level, should be positive. Deprecated. No reason given lineLength (Default: 80) The maximum length of a display line, should be positive. Deprecated. No reason givenhelp:system Description: Displays a list of the platform details like system properties and environment variables. Deprecated. No reason given Implementation: org.apache.maven.plugins.help.SystemMojo Language: java Available parameters: 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. Deprecated. No reason given[INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESSFUL[INFO] ------------------------------------------------------------------------[INFO] Total time: 2 seconds[INFO] Finished at: Mon Apr 20 14:04:13 CST 2009[INFO] Final Memory: 5M/10M[INFO] ------------------------------------------------------------------------

 　　

该选项能让你查看插件所有的目标及相关参数。但是有时候这些信息显得太多了。这时候你可以获取单个目标的信息，设置mojo参数和plugin参数。下面的命令列出了Compiler 插件的testCompile目标的所有信息:

mvn help:describe -Dplugin=compiler -Dmojo=testCompile -Dfull

C:/>mvn help:describe -Dplugin=compiler -Dmojo=testCompile -Dfull[INFO] Scanning for projects...[INFO] Searching repository for plugin with prefix: 'help'.[INFO] ------------------------------------------------------------------------[INFO] Building Maven Default Project[INFO] task-segment: [help:describe] (aggregator-style)[INFO] ------------------------------------------------------------------------[INFO] [help:describe][INFO] Mojo: 'compiler:testCompile'compiler:testCompile Description: Compiles application test sources Deprecated. No reason given Implementation: org.apache.maven.plugin.TestCompilerMojo Language: java Bound to phase: test-compile Available parameters: compilerArgument Sets the unformatted argument string to be passed to the compiler if fork is set to true. This is because the list of valid arguments passed to a Java compiler varies based on the compiler version. Deprecated. No reason given compilerArguments Sets the arguments to be passed to the compiler (prepending a dash) if fork is set to true. This is because the list of valid arguments passed to a Java compiler varies based on the compiler version. Deprecated. No reason given compilerId (Default: javac) The compiler id of the compiler to use. See this guide for more information. Deprecated. No reason given compilerVersion Version of the compiler to use, ex. '1.3', '1.5', if fork is set to true. Deprecated. No reason given debug (Default: true) Set to true to include debugging information in the compiled class files. Deprecated. No reason given encoding The -encoding argument for the Java compiler. Deprecated. No reason given executable Sets the executable of the compiler to use when fork is true. Deprecated. No reason given failOnError (Default: true) Indicates whether the build will continue even if there are compilation errors; defaults to true. Deprecated. No reason given fork (Default: false) Allows running the compiler in a separate process. If 'false' it uses the built in compiler, while if 'true' it will use an executable. Deprecated. No reason given maxmem Sets the maximum size, in megabytes, of the memory allocation pool, ex. '128', '128m' if fork is set to true. Deprecated. No reason given meminitial Initial size, in megabytes, of the memory allocation pool, ex. '64', '64m' if fork is set to true. Deprecated. No reason given optimize (Default: false) Set to true to optimize the compiled code using the compiler's optimization methods. Deprecated. No reason given outputFileName Sets the name of the output file when compiling a set of sources to a single file. Deprecated. No reason given showDeprecation (Default: false) Sets whether to show source locations where deprecated APIs are used. Deprecated. No reason given showWarnings (Default: false) Set to true to show compilation warnings. Deprecated. No reason given skip Set this to 'true' to bypass unit tests entirely. Its use is NOT RECOMMENDED, but quite convenient on occasion. Deprecated. No reason given source The -source argument for the Java compiler. Deprecated. No reason given staleMillis (Default: 0) Sets the granularity in milliseconds of the last modification date for testing whether a source needs recompilation. Deprecated. No reason given target The -target argument for the Java compiler. Deprecated. No reason given testExcludes A list of exclusion filters for the compiler. Deprecated. No reason given testIncludes A list of inclusion filters for the compiler. Deprecated. No reason given verbose (Default: false) Set to true to show messages about what the compiler is doing. Deprecated. No reason given[INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESSFUL[INFO] ------------------------------------------------------------------------[INFO] Total time: 2 seconds[INFO] Finished at: Mon Apr 20 14:10:06 CST 2009[INFO] Final Memory: 5M/10M[INFO] ------------------------------------------------------------------------