Maven archetype 脚手架

一、背景

　　maven是一个很好的代码构建工具，采用“约定优先于配置”的原则进行项目管理，相信很多的java开发者应该都了解maven并可能在工作当中都是通过maven来管理项目的，在创建的项目的时候，我们往往会使用maven内置的项目骨架也就是archetype来快速生成项目结构。但是在一个团队做开发的过程中，可能仅仅依靠maven预先提供的archetyp可能是不够的，团队之间协作有自己的定义方式，每个人的结构定义风格也不尽相同，在这样的背景下我们有必要去定义一个统一的代码骨架供团队使用，这样做的好处是当团队需要开始一个新项目的时候，可以利用自定义的maven骨架一键生成项目。

简单来说maven archetype插件就是创建项目的脚手架，你可以通过命令行或者IDE集成简化项目创建的工作。例如：

• org.apache.maven.archetypes:maven-archetype-quickstart
• org.apache.maven.archetypes:maven-archetype-site
• org.apache.maven.archetypes:maven-archetype-webapp
• 以及spring或者第三方提供了一些archetype plugin。

二、archetype 项目

　　archetype脚手架项目的结构：

　　

　　概念说明：

• • “__rootArtifactId__”占位符会被parent项目的artifactId替换
  • ${rootArtifactId}也会被parent项目的artifactId替换
  • src/main/resources/archetype-resources里必须要有一个顶级pom文件（如果是单工程就是工程pom文件），同时子文件夹代表了模块定义

　　上图中的各个文件详解：

• • 根目录mcraft下的pom.xml和一般的maven项目一样主要定义archetype项目的坐标等信息。
  • 所有的项目骨架内容都集中在src/main/resources/archetype-resources文件夹下。
  • archetype-resources中的pom.xml定义了待生成项目的pom文件的内容，其他模板中分别定义了待生成项目中相应目录下的内容
  • /src/main/resources/META-INF/maven/archetype-metadata.xml中定义相关的元数据描述(其中该文件的位置固定为resources/META-INF/maven文件夹下,且名称固定为archetype-metadata.xml)。

　　2.1 mcraft/pom.xml内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.xxx</groupId>
    <artifactId>mcraft-archetype</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>mcraft-archetype</name>

    <distributionManagement>
        <repository>
            <id>local</id>
            <url>http://xxx.com/nexus/content/repositories/local/</url>
        </repository>

        <snapshotRepository>
            <id>local_snapshots</id>
            <url>http://xxx.com/nexus/content/repositories/local_snapshots/</url>
        </snapshotRepository>

    </distributionManagement>

    <repositories>
        <repository>
            <id>xxx-repos</id>
            <url>http://xxx.com/nexus/content/groups/public/</url>
            <releases>
                <enabled>true</enabled>
            </releases>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
    </repositories>

    <pluginRepositories>
        <pluginRepository>
            <id>snapshots</id>
            <url>http://xxx.com/nexus/content/repositories/snapshots</url>
            <releases>
                <enabled>true</enabled>
            </releases>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </pluginRepository>
    </pluginRepositories>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-source-plugin</artifactId>
                <version>3.0.1</version>
                <executions>
                    <execution>
                        <id>attach-sources</id>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
        <extensions>
            <extension>
                <groupId>org.apache.maven.archetype</groupId>
                <artifactId>archetype-packaging</artifactId>
                <version>3.0.1</version>
            </extension>
        </extensions>

        <pluginManagement>
            <plugins>
                <plugin>
                    <artifactId>maven-archetype-plugin</artifactId>
                    <version>3.0.1</version>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

　　2.2 src/main/resources/META-INF/maven/archetype-metadata.xml内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<archetype-descriptor
        xsi:schemaLocation="http://maven.apache.org/plugins/maven-archetype-plugin/archetype-descriptor/1.0.0 http://maven.apache.org/xsd/archetype-descriptor-1.0.0.xsd"
        name="demo-parent"
        xmlns="http://maven.apache.org/plugins/maven-archetype-plugin/archetype-descriptor/1.0.0"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

    <requiredProperties>
        <requiredProperty key="groupId">
            <defaultValue>com.xxx</defaultValue>
        </requiredProperty>
    </requiredProperties>

    <modules>
        <module id="${rootArtifactId}-common" dir="__rootArtifactId__-common" name="${rootArtifactId}-common">
            <fileSets>
                <fileSet filtered="true" packaged="true" encoding="UTF-8">
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.java</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory>src/main/resources</directory>
                </fileSet>
            </fileSets>
        </module>

        <module id="${rootArtifactId}-dal" dir="__rootArtifactId__-dal" name="${rootArtifactId}-dal">
            <fileSets>
                <fileSet filtered="true" packaged="true" encoding="UTF-8">
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.java</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.xml</include>
                        <include>**/*.properties</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory></directory>
                    <includes>
                        <include>generatorConfig.xml</include>
                    </includes>
                </fileSet>
            </fileSets>
        </module>

        <module id="${rootArtifactId}-biz" dir="__rootArtifactId__-biz" name="${rootArtifactId}-biz">
            <fileSets>
                <fileSet filtered="true" packaged="true" encoding="UTF-8">
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.java</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory>src/main/resources</directory>
                </fileSet>
            </fileSets>
        </module>

        <module id="${rootArtifactId}-service-api" dir="__rootArtifactId__-service-api"
                name="${rootArtifactId}-service-api">
            <fileSets>
                <fileSet filtered="true" packaged="true" encoding="UTF-8">
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.java</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.xml</include>
                        <include>**/*.properties</include>
                    </includes>
                </fileSet>
            </fileSets>
        </module>
        <module id="${rootArtifactId}-service-impl" dir="__rootArtifactId__-service-impl"
                name="${rootArtifactId}-service-impl">
            <fileSets>
                <fileSet filtered="true" packaged="true" encoding="UTF-8">
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.java</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.xml</include>
                        <include>**/*.properties</include>
                    </includes>
                </fileSet>
            </fileSets>
        </module>

        <module id="${rootArtifactId}-web" dir="__rootArtifactId__-web" name="${rootArtifactId}-web">
            <fileSets>
                <fileSet filtered="true" packaged="true" encoding="UTF-8">
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.java</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.xml</include>
                        <include>**/*.properties</include>
                    </includes>
                </fileSet>
            </fileSets>
        </module>

        <module id="${rootArtifactId}-job" dir="__rootArtifactId__-job" name="${rootArtifactId}-service-impl">
            <fileSets>
                <fileSet filtered="true" packaged="true" encoding="UTF-8">
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.java</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.xml</include>
                        <include>**/*.properties</include>
                    </includes>
                </fileSet>
            </fileSets>
        </module>

        <module id="${rootArtifactId}-runner" dir="__rootArtifactId__-runner" name="${rootArtifactId}-runner">
            <fileSets>
                <fileSet filtered="true" packaged="true" encoding="UTF-8">
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.java</include>
                    </includes>
                </fileSet>
                <fileSet filtered="true" encoding="UTF-8">
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.xml</include>
                        <include>**/*.properties</include>
                    </includes>
                </fileSet>
            </fileSets>
        </module>
    </modules>
</archetype-descriptor>

说明：

• • packaged="true"标识src/main/resources/archetype-resources/src/main/java中对应的内容是否要放入到package中,比如package为com.xxx,那么如果该属性为true,则对应的java文件会放到com/xxx文件夹下，也就是包路径下。
  • filtered="true"标识下面提到的${}是否要进行替换

属性变量定义:

<requiredProperties>
        <requiredProperty key="groupId">
            <defaultValue>com.xxx</defaultValue>
        </requiredProperty>
    </requiredProperties>

　　这些属性可以在资源元文件里的任意一个文件里通过${var}来引用，所以的元文件最终都可以选择通过velocity引擎来执行替换后生成。
　　默认的属性有：groupId，artifactId，packeage，version等

　　项目子模块定义:　　

    <modules >
        <module id="${rootArtifactId}-common" dir="__rootArtifactId__-common" name="${rootArtifactId}-common">
            ...
        </module>
        ...
    </modules>

module有三个属性，解释如下：
id     ：定义子模块工程的artifactId.
dir    ：子模块工程源文件在archetype-resources里对应的directory.
name   ：子模块的名字.

　　2.3 通过mvn clean install 命令把该jar包安装到本地仓库，然后通过本地仓库中的该jar包来生成一个项目看看效果，使用如下命令：

mvn org.apache.maven.plugins:maven-archetype-plugin:2.4::generate -DartifactId=demo -DarchetypeArtifactId=mcraft-archetype -DarchetypeVersion=1.0-SNAPSHOT -DarchetypeGroupId=com.xxx -DarchetypeCatalog=local