原文地址 http://www.cnblogs.com/DreamDrive/p/5571916.html
在Maven中提供了一个settings.xml文件来定义Maven的全局环境信息。这个文件会存在于Maven的安装目录的conf子目录下面，或者是用户家目录的.m2子目录下面。我们可以通过这个文件来定义本地仓库、远程仓库和联网使用的代理信息等。
其实相对于多用户的PC机而言，在Maven安装目录的conf子目录下面的settings.xml才是真正的全局的配置。而用户家目录的.m2子目录下面的settings.xml的配置只是针对当前用户的。当这两个文件同时存在的时候，那么对于相同的配置信息用户家目录下面的settings.xml中定义的会覆盖Maven安装目录下面的settings.xml中的定义。用户家目录下的settings.xml文件一般是不存在的，但是Maven允许我们在这里定义我们自己的settings.xml，如果需要在这里定义我们自己的settings.xml的时候就可以把Maven安装目录下面的settings.xml文件拷贝到用户家目录的.m2目录下，然后改成自己想要的样子。
先来看看一个基本的settings.xml文件中的内容:
<?xml version="1.0" encoding="UTF-8"?>
<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>D:\\develop\\mavenRepository</localRepository>
<interactiveMode>true</interactiveMode>
<offline>false</offline>
<pluginGroups>
</pluginGroups>
<proxies>
<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>
<server>
<id>deploymentRepo</id>
<username>repouser</username>
<password>repopwd</password>
</server>
</servers>
<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>
<profiles>
<profile>
<id>jdk-1.5</id>
<activation>
<jdk>1.5</jdk>
</activation>
<repositories>
<repository>
<id>jdk15</id>
<name>jdk1.5</name>
<url>http://www.myhost.com/maven/jdk15</url>
<layout>default</layout>
<snapshotPolicy>always</snapshotPolicy>
</repository>
</repositories>
</profile>
</profiles>
<activeProfiles>
<activeProfile>jdk-1.5</activeProfile>
</activeProfiles>
</settings>
如上是原作者的,如下是我本机的:
<?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>F:\Development\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>
-->
<!-- 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>
-->
</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>
-->
<!--
| 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>
我本机是使用的默认配置,可见默认配置很多都注释掉了,只有一个<localRepository>
settings.xml中主要包括以下元素：
localRepository：表示Maven用来在本地储存信息的本地仓库的目录。默认是用户家目录下面的.m2/repository目录。
interactiveMode：表示是否使用交互模式，默认是true；如果设为false，那么当Maven需要用户进行输入的时候，它会使用一个默认值。
offline：表示是否离线，默认是false。这个属性表示在Maven进行项目编译和部署等操作时是否允许Maven进行联网来下载所需要的信息。
pluginGroups：在pluginGroups元素下面可以定义一系列的pluginGroup元素。表示当通过plugin的前缀来解析plugin的时候到哪里寻找。pluginGroup元素指定的是plugin的groupId。默认情况下，Maven会自动把org.apache.maven.plugins和org.codehaus.mojo添加到pluginGroups下。
proxies：其下面可以定义一系列的proxy子元素，表示Maven在进行联网时需要使用到的代理。当设置了多个代理的时候第一个标记active为true的代理将会被使用。下面是一个使用代理的例子：
<proxies>
<proxy>
<id>xxx</id>
<active>true</active>
<protocol>http</protocol>
<username>用户名</username>
<password>密码</password>
<host>代理服务器地址</host>
<port>代理服务器的端口</port>
<nonProxyHosts>不使用代理的主机</nonProxyHosts>
</proxy>
</proxies>
servers：其下面可以定义一系列的server子元素，表示当需要连接到一个远程服务器的时候需要使用到的验证方式。这主要有username/password和privateKey/passphrase这两种方式。以下是一个使用servers的示例：
<servers>
<server>
<id>id</id>
<username>用户名</username>
<password>密码</password>
</server>
</servers>
mirrors：用于定义一系列的远程仓库的镜像。我们可以在pom中定义一个下载工件的时候所使用的远程仓库。但是有时候这个远程仓库会比较忙，所以这个时候人们就想着给它创建镜像以缓解远程仓库的压力，也就是说会把对远程仓库的请求转换到对其镜像地址的请求。每个远程仓库都会有一个id，这样我们就可以创建自己的mirror来关联到该仓库，那么以后需要从远程仓库下载工件的时候Maven就可以从我们定义好的mirror站点来下载，这可以很好的缓解我们远程仓库的压力。在我们定义的mirror中每个远程仓库都只能有一个mirror与它关联，也就是说你不能同时配置多个mirror的mirrorOf指向同一个repositoryId。
看以下是一个使用mirrors的例子：
<mirrors>
<mirror>
<id>mirrorId</id>
<mirrorOf>repositoryId</mirrorOf>
<name>定义一个容易看懂的名称 </name>
<url>http://my.repository.com/repo/path</url>
</mirror>
</mirrors>
id：是用来区别mirror的，所有的mirror不能有相同的id
mirrorOf：用来表示该mirror是关联的哪一个仓库，其值为其关联仓库的id。当要同时关联多个仓库时，这多个仓库之间可以用逗号隔开；当要关联所有的仓库时，可以使用“*”表示；当要关联除某一个仓库以外的其他所有仓库时，可以表示为“*,!repositoryId”；当要关联不是localhost或用file请求的仓库时，可以表示为“external:*”。
url：表示该镜像的url。当Maven在建立系统的时候就会使用这个url来连接到我们的远程仓库。
profiles：用于指定一系列的profile。profile元素由activation、repositories、pluginRepositories和properties四个元素组成。当一个profile在settings.xml中是处于活动状态并且在pom.xml中定义了一个相同id的profile时，settings.xml中的profile会覆盖pom.xml中的profile。
（1）activation：这是profile中最重要的元素。跟pom.xml中的profile一样，settings.xml中的profile也可以在特定环境下改变一些值，而这些环境是通过activation元素来指定的。
看下面一个例子：
<profiles>
<profile>
<id>test</id>
<activation>
<activeByDefault>false</activeByDefault>
<jdk>1.6</jdk>
<os>
<name>Windows 7</name>
<family>Windows</family>
<arch>x86</arch>
<version>5.1.2600</version>
</os>
<property>
<name>mavenVersion</name>
<value>2.0.3</value>
</property>
<file>
<exists>${basedir}/file2.properties</exists>
<missing>${basedir}/file1.properties</missing>
</file>
</activation>
...
</profile>
</profiles>
在上面这段代码中，当所有的约束条件都满足的时候就会激活这个profile。
jdk：表示当jdk的版本满足条件的时候激活，在这里是1.6。这里的版本还可以用一个范围来表示，如
<jdk>[1.4,1.7)</jdk>表示1.4、1.5和1.6满足；
<jdk>[1.4,1.7]</jdk>表示1.4、1.5、1.6和1.7满足；
os：表示当操作系统满足条件的时候激活。
property：property是键值对的形式，表示当Maven检测到了这样一个键值对的时候就激活该profile。
(1)下面的示例表示当存在属性hello的时候激活该profile。
<property>
<name>hello</name>
</property>
(2)下面的示例表示当属性hello的值为world的时候激活该profile。
<property>
<name>hello</name>
<value>world</value>
</property>
这个时候如果要激活该profile的话，可以在调用Maven指令的时候加上参数hello并指定其值为world，如：
mvn compile –Dhello=world
file：表示当文件存在或不存在的时候激活，exists表示存在，missing表示不存在。如下面的例子表示当文件hello/world不存在的时候激活该profile。
<profile>
<activation>
<file>
<missing>hello/world</missing>
</file>
</activation>
</profile>
activeByDefault：当其值为true的时候表示如果没有其他的profile处于激活状态的时候，该profile将自动被激活。
（2）properties：用于定义属性键值对的。当该profile是激活状态的时候，properties下面指定的属性都可以在pom.xml中使用。
（3）repositories：用于定义远程仓库的，当该profile是激活状态的时候，这里面定义的远程仓库将作为当前pom的远程仓库。
<repositories>
<repository>
<id>codehausSnapshots</id>
<name>Codehaus Snapshots</name>
<releases>
<enabled>false</enabled>
<updatePolicy>always</updatePolicy>
<checksumPolicy>warn</checksumPolicy>
</releases>
<snapshots>
<enabled>true</enabled>
<updatePolicy>never</updatePolicy>
<checksumPolicy>fail</checksumPolicy>
</snapshots>
<url>http://snapshots.maven.codehaus.org/maven2</url>
<layout>default</layout>
</repository>
</repositories>
releases、snapshots：这是对于工件的类型的限制。
enabled：表示这个仓库是否允许这种类型的工件
updatePolicy：表示多久尝试更新一次。可选值有always、daily、interval:minutes（表示每多久更新一次）和never。
checksumPolicy：当Maven在部署项目到仓库的时候会连同校验文件一起提交，checksumPolicy表示当这个校验文件缺失或不正确的时候该如何处理，可选项有ignore、fail和warn。
（4）pluginRepositories：在Maven中有两种类型的仓库，一种是存储工件的仓库，另一种就是存储plugin插件的仓库。pluginRepositories的定义和repositories的定义类似，它表示Maven在哪些地方可以找到所需要的插件。
activeProfiles：底包含一系列的activeProfile元素，表示对于所有的pom都处于活跃状态的profile。如：
<activeProfiles>
<activeProfile>alwaysActiveProfile</activeProfile>
<activeProfile>anotherAlwaysActiveProfile</activeProfile>
</activeProfiles>