最近在看maven项目，发现自己对maven想想有很多的不理解之处
我们知道，项目中我们使用的jar都是从maven远程仓库中进行下载的，maven仓库有两个一个是远程网上仓库，我们常见的有阿里云的仓库，和maven仓库都是网上的仓库。另外的一个是我们本地的仓库我们也就是.m2文件夹里存储的那些jar。在使用的时候会先从我们的本地的仓库进行检索如果找不到对应的jar就会从远程仓库中进行加载，当然你要在pom.xml中引用这个jar包，不然就会报错class not found
其实我们看仓库的地址是我们在maven的conf里面的setting文件进行配置的
首先我们来本地仓库地地址配置，其实也就是我们所说的m2文件:
<localRepository>E:\.m2\mydemo2</localRepository>
这个就是我们本地仓库的地址
那么网上的仓库地址我们怎么配置
最常用的是镜像:
<mirrors>
<mirror>
<id>Central</id>
<url>http://repo1.maven.org/maven2</url>
<mirrorOf>central</mirrorOf>
</mirror>
</mirrors>这个是一个地址，我们pom中所需要的jar也就是从http://repo1.maven.org/maven2这个网上的远程仓库获取到
当这切都配置好之后我运行maven工程，我希望用到的是tomcat插件，但是发现在上面这个仓库中并不能加载到tomcat插件
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.2</version>
<configuration>
<port>8080</port>
<path>/MyMavenProject</path>
<uriEncoding>UTF-8</uriEncoding>
</configuration>
</plugin>那么我们该怎么办，我知道有一个地方可以下载到这个插件，阿里云仓库里面有，我们可以在setting文件中添加私服，我认为私服的优先级要高于mirror仓库的优先级，在setting.xml文件中添加如下配置:
<profiles>
<profile>
<id>alwaysActiveProfile</id>
<pluginRepositories>
<pluginRepository>
<id>alwaysActiveProfile</id>
<name>alwaysPlugin</name>
<url>https://maven.aliyun.com/repository/central/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</profile>
</profiles>
<activeProfiles>
<activeProfile>alwaysActiveProfile</activeProfile>
</activeProfiles>添加私服并激活私服
这样我们上面的插件就可以从这个私服里面获取到
下面是我的settting文件的配置:
<?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>E:\.m2\mydemo2</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>org.apache.tomcat.maven</pluginGroup>
<pluginGroup>org.codehaus.mojo</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>
<id>optional</id>
<active>true</active>
<protocol>http</protocol>
<username>optional-proxyuser</username>
<password>optional-proxypass</password>
<host>proxy.host.net</host>
<port>80</port>
<nonProxyHosts>local.net|some.host.com</nonProxyHosts>
</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>
<id>Central</id>
<url>http://repo1.maven.org/maven2</url>
<mirrorOf>central</mirrorOf>
</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>
<id>alwaysActiveProfile</id>
<pluginRepositories>
<pluginRepository>
<id>alwaysActiveProfile</id>
<name>alwaysPlugin</name>
<url>https://maven.aliyun.com/repository/central/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</profile>
</profiles>
<activeProfiles>
<activeProfile>alwaysActiveProfile</activeProfile>
</activeProfiles>
</settings>
希望对你有所帮助