0. 先上结论

注意这里说的是“jenkins里的maven插件的settings.xml配置文件在哪里，如果你的jenkins用的不是maven插件，而是单独安装的maven，那就另说。搜一下也许可以搜到 find / -name settings.xml”

centos7中的maven插件的settings.xml配置文件在哪里？
/var/lib/jenkins/.m2

---

1.centOS7 版本

2、jenkins版本

见下图右下角版本号

3、maven插件版本号

4. 配置文件路径

其中settings.xml文件本是没有的，是我自己新建文件，并且输入内容的。

以下是当前我这个“纯天然”的settings.xml文件的内容
settings.xml

<?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.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: ${user.home}/.m2/repository
  <localRepository>/path/to/local/repo</localRepository>
  -->
  <localRepository>D:\myMvnLocal</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>
		
	</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>
     -->	 
	 <mirror> 
     			<id>alimaven</id> 
     			<name>aliyun maven</name> 
     			<url>http://maven.aliyun.com/nexus/content/groups/public/</url> 
     		<mirrorOf>central</mirrorOf>         
   </mirror> 
  </mirrors>
  <profiles>
    <profile>
            <id>XaNexus</id>
            <repositories>
                <repository>
                    <id>XaNexus</id>
                    <url>http://maven.aliyun.com/nexus/content/groups/public</url>
                    <releases>
                        <enabled>true</enabled>
                        <updatePolicy>daily</updatePolicy>
                        <checksumPolicy>warn</checksumPolicy>
                    </releases>
                    <snapshots>
                        <enabled>true</enabled>
                        <checksumPolicy>fail</checksumPolicy>
                    </snapshots>
                </repository>
            </repositories>
            <pluginRepositories>
                <pluginRepository>
                    <id>XaNexus</id>
                    <url>http://maven.aliyun.com/nexus/content/groups/public</url>
                    <releases>
                        <enabled>true</enabled>
                        <checksumPolicy>warn</checksumPolicy>
                    </releases>
                    <snapshots>
                        <enabled>true</enabled>
                        <checksumPolicy>fail</checksumPolicy>
                    </snapshots>
                </pluginRepository>
            </pluginRepositories>
        </profile>
		<profile>   
        <id>jdk1.8</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>

 
  <activeProfiles>
    <activeProfile>XaNexus</activeProfile>
  </activeProfiles>

</settings>

当然前提有个必要操作：
mkdir /home/myMvnLocal
chmod 777 /home/myMvnLocal （我直接赋予777权限，你看着办）

5. 证明配置文件确实生效了

如下图，明显可见是从aliun下载的包。
在此之前，是从官方中心仓库下载的 ，比较慢。
改了配置文件之后，将jenkins正在进行的构建停止，重新开始一次就可以了。

完毕。