Maven， 是基于项目对象模型（Project Object Model， POM），通过一小段描述信息来管理项目的构建，报告，文档的软件项目管理工具。

目前，绝大多数开发人员都把 Ant 当作 Java 编程项目的标准构建工具。但是，Ant 的项目管理工具（作为 make的替代工具）不能满足绝大多数开发人员的需要。通过检查 Ant 构建文件，很难发现项目的相关性信息和其它元信息（如开发人员/拥有者、版本或站点主页）。

Maven 除了以程序构建能力为特色之外，还提供 Ant 所缺少的高级项目管理工具。由于 Maven 的缺省构建规则有较高的可重用性，所以常常用两三行 Maven 构建脚本就可以构建简单的项目，而使用 Ant 则需要十几行。事实上，由于 Maven 的面向项目的方法，许多 Apache Jakarta 项目现在使用 Maven，而且公司项目采用 Maven 的比例在持续增长。

Maven这个单词来自于意第绪语，意为知识的积累，最早在Jakata Turbine项目中它开始被用来试图简化构建过程。当时有很多项目，它们的Ant build文件仅有细微的差别，而JAR文件都由CVS来维护。于是Maven创始者开始了Maven这个项目，该项目的清晰定义包括，一种很方便的发布项目信息的方式，以及一种在多个项目中共享JAR的方式。

Maven 和 Ant 有什么不同呢？

Ant 为 Java 技术开发项目提供跨平台构建任务

Maven 本身描述项目的高级方面，它从 Ant 借用了绝大多数构建任务

​	Maven	Ant
标准构建文件	project.xml 和 maven.xml	build.xml
特性处理顺序	${maven.home}/bin/driver.properties ${project.home}/project.properties ${project.home}/build.properties ${user.home}/build.properties 通过 -D 命令行选项定义的系统特性，最后一个定义起决定作用。	通过 -D 命令行选项定义的系统特性 由 <property> 任务装入的特性 第一个定义最先被处理。
构建规则	构建规则更为动态（类似于编程语言）；它们是基于 Jelly 的可执行 XML。	构建规则或多或少是静态的，除非使用 <script> 任务。
扩展语言	插件是用 Jelly（XML）编写的。	插件是用 Java 语言编写的。
构建规则可扩展性	通过定义 <preGoal> 和 <postGoal> 使构建 goal 可扩展。	构建规则不易扩展；可通过使用 <script> 任务模拟 <preGoal> 和 <postGoal> 所起的作用。

由上比较可知，Maven 和 Ant 代表两个差异很大的工具

1， 下载

官方下载地址：  maven_download， 最新版 apache-maven-3.0.5-bin.tar.gz

官方地址：  maven

2， 解压

tar   zxvf   apache-maven-3.0.5-bin.tar.gz       （例如安装目录为： /home/homer/Apache-maven/apache-maven-3.0.5）

3， 安装

1） 编辑 /etc/profile

sudo   vi   /etc/profile

2） 配置

配置maven安装目录： 

export MAVEN_HOME=/home/homer/Apache-maven/apache-maven-3.0.5                  // 安装目录      

export PATH=${MAVEN_HOME}/bin:${PATH}

如下图：

3） 生效

source   /etc/profile                // 使上面配置生效

4， 验证

命令行输入：  mvn  -v

如上图， 显示maven版本信息，表示安装成功！

5、setting.xml 配置文件

setting.xml 配置文件，在安装目录（/opt/maven-3.0.5/conf/settings.xml）和本地目录（/home/homer/.m2/settings.xml）都有，区别：

1） 安装目录（conf/settings.xml），是对本机器上所有用户有效（同一台机器可以有多个用户，均有效），全局设置

2） 当前目录（.m2/settings.xml），仅对当前用户有效，局部设置

maven还有一个配置文件pom.xml，是在java项目的根目录下，仅对当前项目有效，局部设置

setting.xml 配置文件示例：

<?xml version="1.0" encoding="UTF-8"?>

<!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
-->

<!--
 | This is the configuration file for Maven. It can be specified at two levels:
 |
 |  1. User Level. This settings.xml file provides configuration for a single user, 
 |                 and is normally provided in ${user.home}/.m2/settings.xml.
 |
 |                 NOTE: This location can be overridden with the CLI option:
 |
 |                 -s /path/to/user/settings.xml
 |
 |  2. Global Level. This settings.xml file provides configuration for all Maven
 |                 users on a machine (assuming they're all using the same Maven
 |                 installation). It's normally provided in 
 |                 ${maven.home}/conf/settings.xml.
 |
 |                 NOTE: This location can be overridden with the CLI option:
 |
 |                 -gs /path/to/global/settings.xml
 |
 | The sections in this sample file are intended to give you a running start at
 | getting the most out of your Maven installation. Where appropriate, the default
 | values (values used when the setting is not specified) are provided.
 |
 |-->
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
    <!-- localRepository
   | The path to the local repository maven will use to store artifacts.
   |
   | Default: ~/.m2/repository
  <localRepository>/path/to/local/repo</localRepository>
  -->
  <localRepository>~/.m2/repository</localRepository>

  <!-- interactiveMode
   | This will determine whether maven prompts you when it needs input. If set to false,
   | maven will use a sensible default value, perhaps based on some other setting, for
   | the parameter in question.
   |
   | Default: true
  <interactiveMode>true</interactiveMode>
  -->

  <!-- offline
   | Determines whether maven should attempt to connect to the network when executing a build.
   | This will have an effect on artifact downloads, artifact deployment, and others.
   |
   | Default: false
  <offline>false</offline>
  -->

  <!-- pluginGroups
   | This is a list of additional group identifiers that will be searched when resolving plugins by their prefix, i.e.
   | when invoking a command line like "mvn prefix:goal". Maven will automatically add the group identifiers
   | "org.apache.maven.plugins" and "org.codehaus.mojo" if these are not already contained in the list.
   |-->
  <pluginGroups>
      <!-- pluginGroup
     | Specifies a further group identifier to use for plugin lookup.
    <pluginGroup>com.your.plugins</pluginGroup>
    -->
  </pluginGroups>

  <!-- proxies
   | This is a list of proxies which can be used on this machine to connect to the network.
   | Unless otherwise specified (by system property or command-line switch), the first proxy
   | specification in this list marked as active will be used.
   |-->
  <proxies>
      <!-- proxy
     | Specification for one proxy, to be used in connecting to the network.
     |
    <proxy>
      <id>optional</id>
      <active>true</active>
      <protocol>http</protocol>
      <username>proxyuser</username>
      <password>proxypass</password>
      <host>proxy.host.net</host>
      <port>80</port>
      <nonProxyHosts>local.net|some.host.com</nonProxyHosts>
    </proxy>
    -->
  </proxies>

  <!-- servers
   | This is a list of authentication profiles, keyed by the server-id used within the system.
   | Authentication profiles can be used whenever maven must make a connection to a remote server.
   |-->
  <servers>
      <!-- server
     | Specifies the authentication information to use when connecting to a particular server, identified by
     | a unique name within the system (referred to by the 'id' attribute below).
     | 
     | NOTE: You should either specify username/password OR privateKey/passphrase, since these pairings are 
     |       used together.
     |
    <server>
      <id>deploymentRepo</id>
      <username>repouser</username>
      <password>repopwd</password>
    </server>
    -->


    <server>
        <id>nexus-server</id>
        <username>deployment</username>
        <password>12345678</password>
    </server>

    <server>
        <id>nexus-maven-server</id>
        <username>deployer</username>
        <password>123456</password>
    </server>

    <server>
        <id>releases</id>
        <username>deployer</username>
        <password>123456</password>
    </server>

    <server>
        <id>snapshots</id>
        <username>deployer</username>
        <password>123456</password>
    </server>

    <server>
        <id>public</id>
        <username>deployer</username>
        <password>123456</password>
    </server>

    <server>
        <id>thirdpary</id>
        <username>admin</username>
        <password>admin123</password>
    </server>

    <server>
      <id>myserver</id>
      <username>yanggang</username>
      <password>123456</password>
    </server>


    <!-- Another sample, using keys to authenticate.
    <server>
      <id>siteServer</id>
      <privateKey>/path/to/private/key</privateKey>
      <passphrase>optional; leave empty if not used.</passphrase>
    </server>
    -->
  </servers>

  <!-- mirrors
   | This is a list of mirrors to be used in downloading artifacts from remote repositories.
   | 
   | It works like this: a POM may declare a repository to use in resolving certain artifacts.
   | However, this repository may have problems with heavy traffic at times, so people have mirrored
   | it to several places.
   |
   | That repository definition will have a unique id, so we can create a mirror reference for that
   | repository, to be used as an alternate download site. The mirror site will be the preferred 
   | server for that repository.
   |-->
  <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>
     -->

    <!-- This sends everything else to /public -->
    <!--
    <mirror>
        <id>nexus</id>
        <mirrorOf>central</mirrorOf>
        <url>http://192.168.120.247:8081/nexus/content/repositories/public</url>
      </mirror>
    -->
    </mirrors>

         <!-- profiles
   | This is a list of profiles which can be activated in a variety of ways, and which can modify
   | the build process. Profiles provided in the settings.xml are intended to provide local machine-
   | specific paths and repository locations which allow the build to work in the local environment.
   |
   | For example, if you have an integration testing plugin - like cactus - that needs to know where
   | your Tomcat instance is installed, you can provide a variable here such that the variable is 
   | dereferenced during the build process to configure the cactus plugin.
   |
   | As noted above, profiles can be activated in a variety of ways. One way - the activeProfiles
   | section of this document (settings.xml) - will be discussed later. Another way essentially
   | relies on the detection of a system property, either matching a particular value for the property,
   | or merely testing its existence. Profiles can also be activated by JDK version prefix, where a 
   | value of '1.4' might activate a profile when the build is executed on a JDK version of '1.4.2_07'.
   | Finally, the list of active profiles can be specified directly from the command line.
   |
   | NOTE: For profiles defined in the settings.xml, you are restricted to specifying only artifact
   |       repositories, plugin repositories, and free-form properties to be used as configuration
   |       variables for plugins in the POM.
   |
   |-->
  <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>
    -->

    <profile>
        <id>nexus</id>

        <repositories>
            <repository>
                <id>public</id>
                <url>http://192.127.10.23:8081/nexus/content/groups/public </url>
                <snapshots>
                    <enabled>true</enabled>
                </snapshots>
                <releases>
                    <enabled>true</enabled>
                </releases>
            </repository>
            <repository>
                <id>thirdparty</id>
                <url>http://192.127.10.23:8081/nexus/content/repositories/thirdparty/ </url>
                <snapshots>
                    <enabled>true</enabled>
                </snapshots>
                <releases>
                    <enabled>true</enabled>
                </releases>
            </repository>
            <repository>
                <id>snapshots</id>
                <url>http://192.127.10.23:8081/nexus/content/repositories/snapshots/ </url>
                <snapshots>
                    <enabled>true</enabled>
                </snapshots>
                <releases>
                    <enabled>true</enabled>
                </releases>
            </repository>
            <repository>
                <id>releases</id>
                <url>http://192.127.10.23:8081/nexus/content/repositories/releases/ </url>
                <snapshots>
                    <enabled>true</enabled>
                </snapshots>
                <releases>
                    <enabled>true</enabled>
                </releases>
            </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>

  <!-- activeProfiles
   | List of profiles that are active for all builds.
   |
  <activeProfiles>
    <activeProfile>alwaysActiveProfile</activeProfile>
    <activeProfile>anotherAlwaysActiveProfile</activeProfile>
  </activeProfiles>
  -->
</settings>

注：

eclipse更新maven的时候，不小心手一抖，点上了Disable Maven Nature，然后工程右键菜单中的Maven栏就不见了！

其实这是把maven工程转换成了一般工程，再转回来就好了。

maven工程转为一般工程： 工程右键--->Maven--->Disable Maven Nature转为一般工程。

一般工程转为maven工程： 工程右键--->Configure--->Convert to Maven Project转为maven工程。

参考推荐：

maven（官方）

ant（官方）

maven常用命令介绍

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