Maven, 是基于项目对象模型(Project Object Model, POM),通过一小段描述信息来管理项目的构建,报告,文档的软件项目管理工具。
目前,绝大多数开发人员都把 Ant 当作 Java 编程项目的标准构建工具。但是,Ant 的项目管理工具(作为 make的替代工具)不能满足绝大多数开发人员的需要。通过检查 Ant 构建文件,很难发现项目的相关性信息和其它元信息(如开发人员/拥有者、版本或站点主页)。
Maven 除了以程序构建能力为特色之外,还提供 Ant 所缺少的高级项目管理工具。由于 Maven 的缺省构建规则有较高的可重用性,所以常常用两三行 Maven 构建脚本就可以构建简单的项目,而使用 Ant 则需要十几行。事实上,由于 Maven 的面向项目的方法,许多 Apache Jakarta 项目现在使用 Maven,而且公司项目采用 Maven 的比例在持续增长。
Maven这个单词来自于意第绪语,意为知识的积累,最早在Jakata Turbine项目中它开始被用来试图简化构建过程。当时有很多项目,它们的Ant build文件仅有细微的差别,而JAR文件都由CVS来维护。于是Maven创始者开始了Maven这个项目,该项目的清晰定义包括,一种很方便的发布项目信息的方式,以及一种在多个项目中共享JAR的方式。
Maven 和 Ant 有什么不同呢?
Ant 为 Java 技术开发项目提供跨平台构建任务
Maven 本身描述项目的高级方面,它从 Ant 借用了绝大多数构建任务
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Maven
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Ant
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标准构建文件
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project.xml 和 maven.xml
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build.xml
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特性处理顺序
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${maven.home}/bin/driver.properties
${project.home}/project.properties
${project.home}/build.properties
${user.home}/build.properties
通过 -D 命令行选项定义的系统特性,最后一个定义起决定作用。
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通过 -D 命令行选项定义的系统特性
由 <property> 任务装入的特性
第一个定义最先被处理。
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构建规则
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构建规则更为动态(类似于编程语言);它们是基于 Jelly 的可执行 XML。
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构建规则或多或少是静态的,除非使用 <script> 任务。
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扩展语言
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插件是用 Jelly(XML)编写的。
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插件是用 Java 语言编写的。
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构建规则可扩展性
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通过定义 <preGoal> 和 <postGoal> 使构建 goal 可扩展。
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构建规则不易扩展;可通过使用 <script> 任务模拟 <preGoal> 和 <postGoal> 所起的作用。
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由上比较可知,Maven 和 Ant 代表两个差异很大的工具
1, 下载
官方下载地址: maven_download, 最新版 apache-maven-3.0.5-bin.tar.gz
官方地址: maven
2, 解压
tar zxvf apache-maven-3.0.5-bin.tar.gz (例如安装目录为: /home/homer/Apache-maven/apache-maven-3.0.5)
3, 安装
1) 编辑 /etc/profile
sudo vi /etc/profile
2) 配置
配置maven安装目录:
export MAVEN_HOME=/home/homer/Apache-maven/apache-maven-3.0.5 // 安装目录
export PATH=${MAVEN_HOME}/bin:${PATH}
如下图:
3) 生效
source /etc/profile // 使上面配置生效
4, 验证
命令行输入: mvn -v
如上图, 显示maven版本信息,表示安装成功!
5、setting.xml 配置文件
setting.xml 配置文件,在安装目录(/opt/maven-3.0.5/conf/settings.xml)和本地目录(/home/homer/.m2/settings.xml)都有,区别:
1) 安装目录(conf/settings.xml),是对本机器上所有用户有效(同一台机器可以有多个用户,均有效),全局设置
2) 当前目录(.m2/settings.xml),仅对当前用户有效,局部设置
maven还有一个配置文件pom.xml,是在java项目的根目录下,仅对当前项目有效,局部设置
setting.xml 配置文件示例:
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<?xml version="1.0" encoding="UTF-8"?>
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<!--
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Licensed to the Apache Software Foundation (ASF) under one
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or more contributor license agreements. See the NOTICE file
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distributed with this work for additional information
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regarding copyright ownership. The ASF licenses this file
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to you under the Apache License, Version 2.0 (the
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"License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing,
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software distributed under the License is distributed on an
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"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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KIND, either express or implied. See the License for the
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specific language governing permissions and limitations
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under the License.
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-->
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<!--
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| This is the configuration file for Maven. It can be specified at two levels:
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| 1. User Level. This settings.xml file provides configuration for a single user,
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| and is normally provided in ${user.home}/.m2/settings.xml.
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| NOTE: This location can be overridden with the CLI option:
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| -s /path/to/user/settings.xml
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|
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| 2. Global Level. This settings.xml file provides configuration for all Maven
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| users on a machine (assuming they're all using the same Maven
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| installation). It's normally provided in
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| ${maven.home}/conf/settings.xml.
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| NOTE: This location can be overridden with the CLI option:
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| -gs /path/to/global/settings.xml
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| The sections in this sample file are intended to give you a running start at
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| getting the most out of your Maven installation. Where appropriate, the default
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| values (values used when the setting is not specified) are provided.
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|
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|-->
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<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
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<!-- localRepository
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| The path to the local repository maven will use to store artifacts.
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| Default: ~/.m2/repository
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<localRepository>/path/to/local/repo</localRepository>
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-->
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<localRepository>~/.m2/repository</localRepository>
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<!-- interactiveMode
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| This will determine whether maven prompts you when it needs input. If set to false,
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| maven will use a sensible default value, perhaps based on some other setting, for
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| the parameter in question.
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| Default: true
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<interactiveMode>true</interactiveMode>
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-->
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<!-- offline
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| Determines whether maven should attempt to connect to the network when executing a build.
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| This will have an effect on artifact downloads, artifact deployment, and others.
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| Default: false
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<offline>false</offline>
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-->
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<!-- pluginGroups
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| This is a list of additional group identifiers that will be searched when resolving plugins by their prefix, i.e.
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| when invoking a command line like "mvn prefix:goal". Maven will automatically add the group identifiers
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| "org.apache.maven.plugins" and "org.codehaus.mojo" if these are not already contained in the list.
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|-->
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<pluginGroups>
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<!-- pluginGroup
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| Specifies a further group identifier to use for plugin lookup.
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<pluginGroup>com.your.plugins</pluginGroup>
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-->
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</pluginGroups>
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<!-- proxies
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| This is a list of proxies which can be used on this machine to connect to the network.
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| Unless otherwise specified (by system property or command-line switch), the first proxy
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| specification in this list marked as active will be used.
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|-->
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<proxies>
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<!-- proxy
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| Specification for one proxy, to be used in connecting to the network.
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<proxy>
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<id>optional</id>
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<active>true</active>
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<protocol>http</protocol>
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<username>proxyuser</username>
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<password>proxypass</password>
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<host>proxy.host.net</host>
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<port>80</port>
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<nonProxyHosts>local.net|some.host.com</nonProxyHosts>
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</proxy>
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-->
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</proxies>
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<!-- servers
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| This is a list of authentication profiles, keyed by the server-id used within the system.
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| Authentication profiles can be used whenever maven must make a connection to a remote server.
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|-->
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<servers>
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<!-- server
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| Specifies the authentication information to use when connecting to a particular server, identified by
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| a unique name within the system (referred to by the 'id' attribute below).
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| NOTE: You should either specify username/password OR privateKey/passphrase, since these pairings are
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| used together.
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<server>
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<id>deploymentRepo</id>
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<username>repouser</username>
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<password>repopwd</password>
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</server>
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-->
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<server>
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<id>nexus-server</id>
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<username>deployment</username>
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<password>12345678</password>
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</server>
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<server>
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<id>nexus-maven-server</id>
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<username>deployer</username>
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<password>123456</password>
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</server>
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<server>
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<id>releases</id>
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<username>deployer</username>
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<password>123456</password>
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</server>
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<server>
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<id>snapshots</id>
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<username>deployer</username>
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<password>123456</password>
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</server>
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<server>
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<id>public</id>
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<username>deployer</username>
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<password>123456</password>
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</server>
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<server>
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<id>thirdpary</id>
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<username>admin</username>
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<password>admin123</password>
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</server>
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<server>
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<id>myserver</id>
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<username>yanggang</username>
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<password>123456</password>
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</server>
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<!-- Another sample, using keys to authenticate.
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<server>
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<id>siteServer</id>
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<privateKey>/path/to/private/key</privateKey>
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<passphrase>optional; leave empty if not used.</passphrase>
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</server>
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-->
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</servers>
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<!-- mirrors
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| This is a list of mirrors to be used in downloading artifacts from remote repositories.
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| It works like this: a POM may declare a repository to use in resolving certain artifacts.
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| However, this repository may have problems with heavy traffic at times, so people have mirrored
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| it to several places.
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|
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| That repository definition will have a unique id, so we can create a mirror reference for that
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| repository, to be used as an alternate download site. The mirror site will be the preferred
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| server for that repository.
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|-->
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<mirrors>
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<!-- mirror
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| Specifies a repository mirror site to use instead of a given repository. The repository that
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| this mirror serves has an ID that matches the mirrorOf element of this mirror. IDs are used
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| for inheritance and direct lookup purposes, and must be unique across the set of mirrors.
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<mirror>
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<id>mirrorId</id>
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<mirrorOf>repositoryId</mirrorOf>
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<name>Human Readable Name for this Mirror.</name>
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<url>http://my.repository.com/repo/path</url>
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</mirror>
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-->
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<!--
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<mirror>
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<id>nexus</id>
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<mirrorOf>central</mirrorOf>
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<url>http://192.168.120.247:8081/nexus/content/repositories/public</url>
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</mirror>
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-->
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</mirrors>
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<!-- profiles
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| This is a list of profiles which can be activated in a variety of ways, and which can modify
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| the build process. Profiles provided in the settings.xml are intended to provide local machine-
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| specific paths and repository locations which allow the build to work in the local environment.
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|
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| For example, if you have an integration testing plugin - like cactus - that needs to know where
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| your Tomcat instance is installed, you can provide a variable here such that the variable is
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| dereferenced during the build process to configure the cactus plugin.
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| As noted above, profiles can be activated in a variety of ways. One way - the activeProfiles
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| section of this document (settings.xml) - will be discussed later. Another way essentially
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| relies on the detection of a system property, either matching a particular value for the property,
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| or merely testing its existence. Profiles can also be activated by JDK version prefix, where a
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| value of '1.4' might activate a profile when the build is executed on a JDK version of '1.4.2_07'.
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| Finally, the list of active profiles can be specified directly from the command line.
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|
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| NOTE: For profiles defined in the settings.xml, you are restricted to specifying only artifact
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| repositories, plugin repositories, and free-form properties to be used as configuration
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| variables for plugins in the POM.
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<profiles>
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<!-- profile
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| Specifies a set of introductions to the build process, to be activated using one or more of the
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| mechanisms described above. For inheritance purposes, and to activate profiles via <activatedProfiles/>
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| or the command line, profiles have to have an ID that is unique.
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| An encouraged best practice for profile identification is to use a consistent naming convention
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| for profiles, such as 'env-dev', 'env-test', 'env-production', 'user-jdcasey', 'user-brett', etc.
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| This will make it more intuitive to understand what the set of introduced profiles is attempting
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| to accomplish, particularly when you only have a list of profile id's for debug.
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| This profile example uses the JDK version to trigger activation, and provides a JDK-specific repo.
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<profile>
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<id>jdk-1.4</id>
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<activation>
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<jdk>1.4</jdk>
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</activation>
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<repositories>
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<repository>
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<id>jdk14</id>
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<name>Repository for JDK 1.4 builds</name>
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<url>http://www.myhost.com/maven/jdk14</url>
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<layout>default</layout>
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<snapshotPolicy>always</snapshotPolicy>
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</repository>
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</repositories>
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</profile>
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-->
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<profile>
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<id>nexus</id>
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<repositories>
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<repository>
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<id>public</id>
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<url>http://192.127.10.23:8081/nexus/content/groups/public </url>
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<snapshots>
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<enabled>true</enabled>
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</snapshots>
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<releases>
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<enabled>true</enabled>
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</releases>
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</repository>
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<repository>
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<id>thirdparty</id>
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<url>http://192.127.10.23:8081/nexus/content/repositories/thirdparty/ </url>
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<snapshots>
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<enabled>true</enabled>
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</snapshots>
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<releases>
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<enabled>true</enabled>
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</releases>
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</repository>
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<repository>
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<id>snapshots</id>
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<url>http://192.127.10.23:8081/nexus/content/repositories/snapshots/ </url>
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<snapshots>
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<enabled>true</enabled>
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</snapshots>
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<releases>
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<enabled>true</enabled>
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</releases>
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</repository>
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<repository>
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<id>releases</id>
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<url>http://192.127.10.23:8081/nexus/content/repositories/releases/ </url>
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<snapshots>
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<enabled>true</enabled>
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</snapshots>
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<releases>
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<enabled>true</enabled>
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</releases>
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</repository>
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</repositories>
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</profile>
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<!--
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| Here is another profile, activated by the system property 'target-env' with a value of 'dev',
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| which provides a specific path to the Tomcat instance. To use this, your plugin configuration
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| might hypothetically look like:
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|
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| ...
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| <plugin>
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| <groupId>org.myco.myplugins</groupId>
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| <artifactId>myplugin</artifactId>
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|
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| <configuration>
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| <tomcatLocation>${tomcatPath}</tomcatLocation>
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| </configuration>
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| </plugin>
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| ...
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|
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| NOTE: If you just wanted to inject this configuration whenever someone set 'target-env' to
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| anything, you could just leave off the <value/> inside the activation-property.
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|
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<profile>
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<id>env-dev</id>
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<activation>
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<property>
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<name>target-env</name>
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<value>dev</value>
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</property>
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</activation>
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<properties>
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<tomcatPath>/path/to/tomcat/instance</tomcatPath>
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</properties>
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</profile>
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-->
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</profiles>
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<!-- activeProfiles
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| List of profiles that are active for all builds.
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|
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<activeProfiles>
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<activeProfile>alwaysActiveProfile</activeProfile>
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<activeProfile>anotherAlwaysActiveProfile</activeProfile>
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</activeProfiles>
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-->
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</settings>
注:
eclipse更新maven的时候,不小心手一抖,点上了Disable Maven Nature,然后工程右键菜单中的Maven栏就不见了!
其实这是把maven工程转换成了一般工程,再转回来就好了。
maven工程转为一般工程: 工程右键--->Maven--->Disable Maven Nature转为一般工程。
一般工程转为maven工程: 工程右键--->Configure--->Convert to Maven Project转为maven工程。
参考推荐:
maven(官方)
ant(官方)
maven常用命令介绍
很全的mvn介绍
Maven Getting Started Guide(官方命令)
(责任编辑:IT) |