最近準備使用Jenkins+gitlab+nexus做CI，終於要用到之前就想搭建卻耽擱了許久的Nexus，今天上午終於成功的deploy上了一個測試的jar，今天記錄一下過程。（Windows上進行的安裝，版本為3.9）

Nexus是一個maven私服工具，它提供了便捷的管理界面，功能強大。

1、 下載、安裝、執行Nexus

　　Windows免安裝版：連結: https://pan.baidu.com/s/11Ya6rvNG7x8U1ypGjL-xBA 提取碼: 56jm。直接解壓，然後把nexus中bin的路徑配置成環境變數，cmd中執行nexus.exe /run，即可執行。

網站地址為http://localhost:8081，登入名：admin，密碼：admin123。

2、 配置倉庫

　　Nexus上會有幾個型別的倉庫，分別是：Hosted，proxy，group。hosted代表本地倉庫，即私服自己的倉庫（這也是私服和遠端倉庫的區別，私服可以在本地儲存構件和jar）；proxy是遠端倉庫的代理；group是組的概念，它可以把幾個倉庫繫結到一起，maven的settings.xml配置只需要新增這一個組就能引用組內的所有倉庫。

Nexus上會有預設的幾個倉庫，release、snapshots、central、group，這幾個就是對應的上面的倉庫型別，不同的release和snapshots兩個倉庫都是hosted型別的，區別是release是穩定版本，snapshots是快照版本。這個在原生代碼進行deploy時會很明顯的發現區別。

Nexus已經為我們配置好了這些倉庫，只需要修改一下maven-central的remote storage，改成一個國內的maven映象（這邊使用的aliyun）。

3、 settings.xml配置

　　配置如下：

<?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: ${user.home}/.m2/repository
    -->
  <localRepository>D:\java\maven-local\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>
    -->      
	<pluginGroup>org.apache.maven.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>release</id>
      <username>admin</username>
      <password>admin123</password>
    </server>
    
    <server>
      <id>snapshots</id>
      <username>admin</username>
      <password>admin123</password>
    </server>
    
    

    <!-- Another sample, using keys to authenticate.
    <server>
      <id>release</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>
     -->
	<mirror>
      <id>local-mirror</id>
      <mirrorOf>*</mirrorOf>
      <name>local-mirror</name>
      <url>http://127.0.0.1:8081/repository/maven-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>
    -->

    <!--
     | 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>

    </profile>
    -->
    
     <profile>
      <id>default_profile</id>
      <repositories>
        <!--包含需要連線到遠端倉庫的資訊 -->
        <repository>
          <!--遠端倉庫唯一標識 -->
          <id>localRepository</id>
          <!--遠端倉庫名稱 -->
          <name>localRepository</name>
          <!--如何處理遠端倉庫裡釋出版本的下載 -->
          <releases>
            <!--true或者false表示該倉庫是否為下載某種型別構件（釋出版，快照版）開啟。 -->
            <enabled>true</enabled>
            <!--該元素指定更新發生的頻率。Maven會比較本地POM和遠端POM的時間戳。這裡的選項是：always（一直），daily（預設，每日），interval：X（這裡X是以分鐘為單位的時間間隔），或者never（從不）。 -->
            <updatePolicy>never</updatePolicy>
            <!--當Maven驗證構件校驗檔案失敗時該怎麼做-ignore（忽略），fail（失敗），或者warn（警告）。 -->
            <checksumPolicy>warn</checksumPolicy>
          </releases>
          <!--如何處理遠端倉庫裡快照版本的下載。有了releases和snapshots這兩組配置，POM就可以在每個單獨的倉庫中，為每種型別的構件採取不同的策略。例如，可能有人會決定只為開發目的開啟對快照版本下載的支援。參見repositories/repository/releases元素 -->
          <snapshots>
            <!--true或者false表示該倉庫是否為下載某種型別構件（釋出版，快照版）開啟。 -->
            <enabled>true</enabled>
            <!--該元素指定更新發生的頻率。Maven會比較本地POM和遠端POM的時間戳。這裡的選項是：always（一直），daily（預設，每日），interval：X（這裡X是以分鐘為單位的時間間隔），或者never（從不）。 -->
            <updatePolicy>always</updatePolicy>
            <!--當Maven驗證構件校驗檔案失敗時該怎麼做-ignore（忽略），fail（失敗），或者warn（警告）。 -->
            <checksumPolicy>warn</checksumPolicy>
          </snapshots>
          <!--遠端倉庫URL，按protocol://hostname/path形式 -->
          <url>http://127.0.0.1:8081/repository/maven-public/</url>
          <!--用於定位和排序構件的倉庫佈局型別-可以是default（預設）或者legacy（遺留）。Maven 2為其倉庫提供了一個預設的佈局；然而，Maven 1.x有一種不同的佈局。我們可以使用該元素指定佈局是default（預設）還是legacy（遺留）。 -->
          <layout>default</layout>
        </repository>
      </repositories>
      
      <pluginRepositories>  
        <pluginRepository>  
          <id>maven-net-cn</id>  
          <name>maven-en</name>  
          <url>http://127.0.0.1:8081/repository/maven-public/</url>  
          <releases>  
            <enabled>true</enabled>  
          </releases>  
          <snapshots>  
            <enabled>true</enabled>  
          </snapshots>      
        </pluginRepository>  
      </pluginRepositories> 
  
    </profile>
  </profiles>

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

</settings>

4、 專案配置

　　新建maven專案，配置本地的maven地址，配置maven和settings.xml（步驟省略），然後就可以開始愉快的開發了。

5、 專案deploy

　　如果需要deploy安裝jar包的話，還需要在專案pom.xml檔案中加入

<distributionManagement>
        <repository>
            <id>release</id>
            <name>release</name>
            <url>http://127.0.0.1:8081/repository/maven-releases/</url>
        </repository>
        <snapshotRepository>
            <id>snapshots</id>
            <name>snapshots</name>
            <url>http://127.0.0.1:8081/repository/maven-snapshots/</url>
        </snapshotRepository>
    </distributionManagement>

　　注意：url是倉庫的url，id需要和settings.xml中<severs>配置的使用者密碼對應的id相同。

6、 其他：

　　1） 無法下載plugins相關的jar包：需要在settings.xml的<pluginGroups>標籤中加入<pluginGroup>org.apache.maven.plugins</pluginGroup>，然後把.lastUpload的檔案都刪除掉，重新reimport。

　　2） deploy報錯：首先檢查配置是否有問題，都沒問題還是失敗的話，可以敲命令列：mvn deploy -s d://java//maven//settings.xml（-s後面跟上settings.xml的檔案路徑）。