Maven安装及环境变量配置

1、关于Maven

Maven项目对象模型（POM），是可以通过一小段描述信息来管理项目的构建、报告和文档的软件项目管理工具。
Maven也是一个用于Java web开发的容器，在这个容器中提供了很多Java web开发的所需的框架包和其他组件。

2、Maven下载

Maven可以从Apache网站上下载，下载地址：http://maven.apache.org/，进入后点击左侧的Download，然后在下面的下载表格中下载“apache-maven-*.*.*-bin.zip”。

3、Maven安装

3.1、安装

将以上下载好的maven解压后移动到自定的路径中。

3.2、环境变量配置

①右键桌面上的计算机，选择属性；
②点击高级系统设置（在属性页的左上侧）；
③弹出的窗口中点击右下侧的环境变量按钮；
④在系统变量区点击新建按钮，填写变量名为MAVEN_HOME，变量值为自定义的Maven的目录的环境变量，如下图所示；



⑤在系统变量中找到Path环境变量，新增“;%MAVEN_HOME%\bin;”的配置；

3.3、验证安装是否成功

①按下Windows+R键运行，输入cmd，按下回车键；
②在命令行窗口中输入“mvn -v”命令，若出现如下信息，则代表配置成功。

4、其他

除了以上配置之外，需要在内部修改的配置还有以下几点（都需要进入maven的conf目录中打开settings.xml）：

4.1、maven的本地仓库配置

在以下配置信息的下方配置：

<!-- localRepository
| The path to the local repository maven will use to store artifacts.
|
| Default: ${user.home}/.m2/repository
<localRepository>/path/to/local/repo</localRepository>
-->

需要在以上配置信息的下方添加如下代码的配置信息，其中两个尖括号<localRepository></localRepository>之间配置自定义的本地仓库的路径。

<localRepository>/../..</localRepository>

4.2、maven网络镜像优化配置

为什么要进行网络镜像优化配置呢？原因在于maven这个家伙是外国人开发的，但是并没有在中国设置服务器，在国内用大天朝的网络，如果用它自己默认配置的服务器的话下载jar包和镜像就要花费大半天的时间来下载jar包，时间就这么被浪费了，所以我们要解决网络问题。
还好马云爸爸给力啊，阿里给提供了阿里自己的镜像库，可以从阿里的镜像库进行下载，时间节省了，得不偿失呢！
先找到如下配置：

<mirrors>
<!-- mirror
| Specifies a repository mirror site to use instead of a given repository. The repository that
| this mirror serves has an ID that matches the mirrorOf element of this mirror. IDs are used
| for inheritance and direct lookup purposes, and must be unique across the set of mirrors.
|
<mirror>
<id>mirrorId</id>
<mirrorOf>repositoryId</mirrorOf>
<name>Human Readable Name for this Mirror.</name>
<url>http://my.repository.com/repo/path</url>
</mirror>
-->
</mirrors>

在以上配置中添加如下配置：

<mirror>
<id>alimaven</id>
<name>aliyun maven</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<mirrorOf>central</mirrorOf>
</mirror>

以下是配置完成后的效果：

<mirrors>
<!-- mirror
| Specifies a repository mirror site to use instead of a given repository. The repository that
| this mirror serves has an ID that matches the mirrorOf element of this mirror. IDs are used
| for inheritance and direct lookup purposes, and must be unique across the set of mirrors.
|
<mirror>
<id>mirrorId</id>
<mirrorOf>repositoryId</mirrorOf>
<name>Human Readable Name for this Mirror.</name>
<url>http://my.repository.com/repo/path</url>
</mirror>
-->

<mirror>
<id>alimaven</id>
<name>aliyun maven</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<mirrorOf>central</mirrorOf>
</mirror>

</mirrors>

以上阿里镜像中心，亲测，速度快得飞起。

4.3、JDK适配配置

由于maven对JDK 8不是很友好，在配置maven项目的时候会产生警告或者错误，需要进行动态适配。
解决方案：
找到如下配置：

<profiles>
<!-- profile
| Specifies a set of introductions to the build process, to be activated using one or more of the
| mechanisms described above. For inheritance purposes, and to activate profiles via <activatedProfiles/>
| or the command line, profiles have to have an ID that is unique.
|
| An encouraged best practice for profile identification is to use a consistent naming convention
| for profiles, such as 'env-dev', 'env-test', 'env-production', 'user-jdcasey', 'user-brett', etc.
| This will make it more intuitive to understand what the set of introduced profiles is attempting
| to accomplish, particularly when you only have a list of profile id's for debug.
|
| This profile example uses the JDK version to trigger activation, and provides a JDK-specific repo.
<profile>
<id>jdk-1.4</id>

<activation>
<jdk>1.4</jdk>
</activation>

<repositories>
<repository>
<id>jdk14</id>
<name>Repository for
b8aa
JDK 1.4 builds</name>
<url>http://www.myhost.com/maven/jdk14</url>
<layout>default</layout>
<snapshotPolicy>always</snapshotPolicy>
</repository>
</repositories>
</profile>
-->

<!--
| Here is another profile, activated by the system property 'target-env' with a value of 'dev',
| which provides a specific path to the Tomcat instance. To use this, your plugin configuration
| might hypothetically look like:
|
| ...
| <plugin>
|   <groupId>org.myco.myplugins</groupId>
|   <artifactId>myplugin</artifactId>
|
|   <configuration>
|     <tomcatLocation>${tomcatPath}</tomcatLocation>
|   </configuration>
| </plugin>
| ...
|
| NOTE: If you just wanted to inject this configuration whenever someone set 'target-env' to
|       anything, you could just leave off the <value/> inside the activation-property.
|
<profile>
<id>env-dev</id>

<activation>
<property>
<name>target-env</name>
<value>dev</value>
</property>
</activation>

<properties>
<tomcatPath>/path/to/tomcat/instance</tomcatPath>
</properties>
</profile>
-->
</profiles>

在其中添加如下配置：

<profile>
<id>jdk-1.8</id>
<activation>
<activeByDefault>true</activeByDefault>
<jdk>1.8</jdk>
</activation>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
</properties>
</profile>

以下是配置好之后的效果：

<profiles>
<!-- profile
| Specifies a set of introductions to the build process, to be activated using one or more of the
| mechanisms described above. For inheritance purposes, and to activate profiles via <activatedProfiles/>
| or the command line, profiles have to have an ID that is unique.
|
| An encouraged best practice for profile identification is to use a consistent naming convention
| for profiles, such as 'env-dev', 'env-test', 'env-production', 'user-jdcasey', 'user-brett', etc.
| This will make it more intuitive to understand what the set of introduced profiles is attempting
| to accomplish, particularly when you only have a list of profile id's for debug.
|
| This profile example uses the JDK version to trigger activation, and provides a JDK-specific repo.
<profile>
<id>jdk-1.4</id>

<activation>
<jdk>1.4</jdk>
</activation>

<repositories>
<repository>
<id>jdk14</id>
<name>Repository for JDK 1.4 builds</name>
<url>http://www.myhost.com/maven/jdk14</url>
<layout>default</layout>
<snapshotPolicy>always</snapshotPolicy>
</repository>
</repositories>
</profile>
-->

<!--
| Here is another profile, activated by the system property 'target-env' with a value of 'dev',
| which provides a specific path to the Tomcat instance. To use this, your plugin configuration
| might hypothetically look like:
|
| ...
| <plugin>
|   <groupId>org.myco.myplugins</groupId>
|   <artifactId>myplugin</artifactId>
|
|   <configuration>
|     <tomcatLocation>${tomcatPath}</tomcatLocation>
|   </configuration>
| </plugin>
| ...
|
| NOTE: If you just wanted to inject this configuration whenever someone set 'target-env' to
|       anything, you could just leave off the <value/> inside the activation-property.
|
<profile>
<id>env-dev</id>

<activation>
<property>
<name>target-env</name>
<value>dev</value>
</property>
</activation>

<properties>
<tomcatPath>/path/to/tomcat/instance</tomcatPath>
</properties>
</profile>
-->

<profile>
<id>jdk-1.8</id>
<activation>
<activeByDefault>true</activeByDefault>
<jdk>1.8</jdk>
</activation>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
</properties>
</profile>

</profiles>

5、关于macOS上的maven

在下载的时候下载”apache-maven-*.*.*-bin.tar.gz“的安装包，解压类似，环境变量无需配置，在内容配置的时候需要进行和第4点中相类似的配置。
到此，maven的安装和环境变量的配置的方法介绍完了，希望采纳。