一直在使用Maven，用了各種各樣的外掛，但是有時候沒有的話，還是需要自己寫點。寫一個外掛並不難，會寫外掛的另一個好處就是了解了更多的Maven工作機制的內幕。對更好的使用Maven有幫助。

首先建立一個Maven專案，名叫plugin-example1。

這裡要理解一個術語:mojo，就是Maven Plain Old Java Object,也就是一個普通的Java類。我們需要mojo的api庫，所以在pom.xml中新增一個依賴：

  <dependencies>    <dependency>      <groupId>org.apache.maven</groupId
 
>      <artifactId>maven-plugin-api</artifactId>      <version>2.0</version>    </dependency>  </dependencies>

public class Example extends AbstractMojo{    public void execute() throws MojoExecutionException, MojoFailureException 
 
{        getLog().info("Hello world");    }    }

現在修改一下工程的描述資訊：

  <groupId>org.freebird</groupId>  <artifactId>plugin-example1</artifactId>  <version>1.0-SNAPSHOT</version>
 
  <packaging>maven-plugin</packaging>  <name>plugin-example1</name>  <url>http://maven.apache.org</url>  <properties>    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>  </properties>

現在編譯吧，很快就遇到錯誤：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-plugin-plugin:2.9:descriptor (default-descriptor) on project plugin-example1: Error extracting plugin descriptor: 'No mojo definitions were found for plugin: org.freebird:plugin-example1.' -> [Help 1]org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-plugin-plugin:2.9:descriptor (default-descriptor) on project plugin-example1: Error extracting plugin descriptor: 'No mojo definitions were found for plugin: org.freebird:plugin-example1.'

  <build>    <plugins>      <plugin>        <groupId>org.apache.maven.plugins</groupId>        <artifactId>maven-plugin-plugin</artifactId>        <version>3.0</version>        <executions>        </executions>        <configuration>          <!-- Needed for Java 5 annotation based configuration, for some reason. -->          <skipErrorNoDescriptorsFound>true</skipErrorNoDescriptorsFound>        </configuration>      </plugin>    </plugins>  </build>

這樣編譯就通過了。或者在類的注視上新增一個descriptor:

/** * * @goal sayhi */public class Example extends AbstractMojo{

為了將Maven部署在私服上，需要加上如下配置：

  <distributionManagement>    <snapshotRepository>      <id>snapshots</id>      <url>http://your_server:8080/nexus/content/repositories/snapshots</url>    </snapshotRepository>  </distributionManagement>

部署成功。