Maven下载依赖的顺序及配置文件小结

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<!--
 | 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
   本地仓库地址
  -->
  <localRepository>D:\Program Files\localMavenRepoistory</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).
     | 
     在 Maven 中，<server> 元素用于配置认证信息，主要是用于在构建过程中访问需要认证的远程仓库或资源
     当使用 Maven 构建项目时，有些远程仓库可能需要进行身份验证（例如私有仓库），这时候就需要提供访问该仓库的用户名和密码。
    为了不将用户名和密码明文写在 pom.xml 文件中，可以将认证信息放在 Maven的 settings.xml 文件中的 <servers> 元素中
     | 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>
    在上述示例中，配置了一个 <server> 元素，它的 <id> 是 "deploymentRepo"，表示该认证信息用于访问 ID 为 "deploymentRepo" 的远程仓库。
    然后，通过 <username> 和 <password> 元素分别提供用户名和密码，这些信息将用于在访问远程仓库时进行身份验证。
当 Maven 需要访问远程仓库或资源时，会检查 settings.xml 文件中的 <servers> 元素，如果有匹配的 <server> 元素（根据 <id> 属性匹配），
就会使用该认证信息进行访问。这样，就可以安全地在 settings.xml 文件中管理认证信息，而不需要在 pom.xml 文件中明文暴露用户名和密码。
    -->
    <!-- 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>
    -->
     <server>
            <id>releases</id>
            <username>zs</username>
            <password>pp</password>
        </server>
        <server>
            <id>snapshots</id>
            <username>zs</username>
            <password>pp</password>
        </server>
        <server>
            <id>docker.r.io</id>
            <username>zs</username>
            <password>pp</password>
        </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
       <mirror>
            <id>public</id>
            <name>Nexus Public Mirror</name>
            <url>http://repo.thunisoft.com/maven2/content/groups/public-repo/</url>
            <mirrorOf>central</mirrorOf>
        </mirror>
        <mirror>
            <id>nexus</id>
            <mirrorOf>public-snapshots</mirrorOf>
            <url>http://repo.thunisoft.com/maven2/content/groups/public-snapshots/</url>
        </mirror>
        -->
        <!--镜像仓库（Mirror Repository）是一种用于加速依赖项下载的机制。在 Maven 中，当你构建项目时，通常需要从远程仓库下载各种依赖项（JAR 文件、插件等）。这些远程仓库可能分布在全球各地，
        下载速度可能受到网络延迟和带宽限制的影响，导致构建过程较慢。
为了解决这个问题，Maven 允许配置一个镜像仓库，它是一个位于本地网络或高速服务器上的代理仓库。当你配置了镜像仓库后，Maven 将优先尝试从镜像仓库下载依赖项，而不是直接从远程仓库下载。
如果镜像仓库中已经存在所需的依赖项，下载速度将大大加快，因为镜像仓库通常位于本地网络或高速服务器上，与开发者的构建环境更近，网络延迟较小。
镜像仓库不保存所有的依赖项，它只会缓存从远程仓库下载的依赖项。当 Maven 需要下载依赖项时，首先尝试从镜像仓库获取。
如果在镜像仓库中找不到所需的依赖项，Maven 会继续从配置的其他远程仓库下载。-->
        <mirror>
            <id>rep</id>
            <!-- 用于指定该镜像仓库代理的目标仓库。它的作用是告诉 Maven 该镜像仓库要替代哪个远程仓库的下载请求。 
            当前配置表示这个镜像仓库将代理所有远程仓库的请求，但会排除掉 ID 分别为 "private1"、"private2" 和 "private3" 的远程仓库，这些仓库的请求将不会由这个镜像仓库来处理。
            这样的配置是有用的，例如，当你有多个私有仓库，并且想要一个镜像仓库来加速下载公共仓库的依赖项，同时不影响私有仓库的下载请求。通过排除私有仓库的 ID，确保私有仓库的请求不会被这个镜像仓库所代理，避免了可能出现的下载问题-->
            <mirrorOf>*,!private1,!private2,!private3</mirrorOf>
            <url>http://maven.r.io/</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.
   |
   Profile是一种用于在不同环境或需求下为项目定义不同配置选项的机制。
   通过使用 Profile，你可以根据不同的情况激活或禁用特定配置，从而实现项目的定制化构建
   |-->
  <profiles>
   <profile>
            <id>env1</id>
            <!-- 在 Maven 的 Profile 中，你可以通过 <repositories> 元素来定义特定的仓库配置。
            这允许你在不同的环境或需求下为项目指定不同的远程仓库，从而实现定制化的依赖管理 -->
            <repositories>
                <repository>
                    <id>releases</id>
                    <url>http://xxxxxx</url>
                    <releases>
                        <enabled>true</enabled>
                    </releases>
                    <snapshots>
                        <enabled>true</enabled>
                    </snapshots>
                </repository>
            </repositories>
            <pluginRepositories>
                <pluginRepository>
                    <id>rep-plugin</id>
                    <url>http://xxxxxxxx</url>
                    <releases>
                        <enabled>true</enabled>
                    </releases>
                    <snapshots>
                        <enabled>true</enabled>
                    </snapshots>
                </pluginRepository>
            </pluginRepositories>
        </profile>
    <!-- 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.
   |
   激活指定的环境
  <activeProfiles>
    <activeProfile>alwaysActiveProfile</activeProfile>
    <activeProfile>anotherAlwaysActiveProfile</activeProfile>
  </activeProfiles>
  -->
    <activeProfiles>
        <activeProfile>env1</activeProfile>
    </activeProfiles>
</settings>