半兽人 发表于: 2016-01-13   最后更新时间: 2016-01-21  


This guide is intended to assist users in developing Java plugins for Maven 2.0.

本指南旨在帮助用户在 Maven 2.0 开发 Java 插件。

Important Notice: Plugin Naming Convention and Apache Maven Trademark

You will typically name your plugin <yourplugin>-maven-plugin.

通常这样命名你的插件  <yourplugin>-maven-plugin.

Calling it maven-<yourplugin>-plugin (note "Maven" is at the beginning of the plugin name) is strongly discouraged since it's a reserved naming pattern for official Apache Maven plugins maintained by the Apache Maven team with groupId org.apache.maven.plugins. Using this naming pattern is an infringement of the Apache Maven Trademark.
命名为 maven-<yourplugin>-plugin (注意“Maven”是插件名称的开头)是强烈反对的,因为它是由Apache Maven团队与groupld org.apache.maven.plugins保持的官方的Apache Maven Plugin保留的命名模式。使用这个命名模式Apache Maven商标的侵权。


In this section we will build a simple plugin which takes no parameters and simply displays a message on the screen when run. Along the way, we will cover the basics of setting up a project to create a plugin, the minimal contents of a Java mojo, and a couple ways to execute the mojo.
在本节中,我们将在本节中,我们将构建一个简单的插件,它不带任何参数,只是在运行时在屏幕上显示一条消息。接下来,我们将讨论建立一个项目,创建一个插件,内容最少的Java mojo和如何执行。


At its simplest, a Java mojo consists simply of a single class. There is no requirement for multiple classes like EJBs, although a plugin which contains a number of similar mojos is likely to use an abstract superclass for the mojos to consolidate code common to all mojos.
简单来说,Java mojo只是个独立的类。尽管插件包含大量类似的mojos,可使用抽象的超类mojos来定义共用的mojos代码。

When processing the source tree to find mojos, plugin-tools looks for classes with either @Mojo Java 5 annotation or "goal" javadoc annotation. Any class with this annotation are included in the plugin configuration file.
通过源码树去找到mojos,插件工具查找类的方式有2种,”@Mojo” Java 5的注解或”@goal“ javadoc的注解,任何有这个注解的类都包含在插件配置文件中。


Listed below is a simple mojo class which has no parameters. This is about as simple as a mojo can be. After the listing is a description of the various parts of the source.


package sample.plugin;
import org.apache.maven.plugin.AbstractMojo;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugins.annotations.Mojo;
 * Says "Hi" to the user.
@Mojo( name = "sayhi")
public class GreetingMojo extends AbstractMojo
    public void execute() throws MojoExecutionException
        getLog().info( "Hello, world." );
  • The class org.apache.maven.plugin.AbstractMojo provides most of the infrastructure required to implement a mojo except for the execute method.
  • The annotation "@Mojo" is required and control how and when the mojo is executed.
  • The execute method can throw two exceptions:
    • org.apache.maven.plugin.MojoExecutionException if an unexpected problem occurs. Throwing this exception causes a "BUILD ERROR" message to be displayed.
      如果发生错误是org.apache.maven.plugin.MojoExecutionException,引发此异常后会显示“BUILD ERROR”信息。
    • org.apache.maven.plugin.MojoFailureException if an expected problem (such as a compilation failure) occurs. Throwing this exception causes a "BUILD FAILURE" message to be displayed.
      如果错误是org.apache.maven.plugin.MojoFailureException(例如编译失败),会抛出”BUILD FAILURE”信息。
  • The getLog method (defined in AbstractMojo) returns a log4j-like logger object which allows plugins to create messages at levels of "debug", "info", "warn", and "error". This logger is the accepted means to display information to the user. Please have a look at the section Retrieving the Mojo Logger for a hint on its proper usage.
    getLog方法(AbstractMojo中定义)返回一个类似log4j的记录器对象,它允许在"debug", "info", "warn", 和 "error”级别来创建消息。这个记录器是通过公用的方法去显示信息给用户,

All Mojo annotations are described by the Mojo API Specification.

所有的Mojo注解的描述,点击Mojo API说明查看。

项目定义 Project Definition

Once the mojos have been written for the plugin, it is time to build the plugin. To do this properly, the project's descriptor needs to have a number of settings set properly:

groupId This is the group ID for the plugin, and should match the common prefix to the packages used by the mojos
artifactId This is the name of the plugin
version This is the version of the plugin
packaging This should be set to "maven-plugin"
dependencies A dependency must be declared to the Maven Plugin Tools API to resolve "AbstractMojo" and related classes

Listed below is an illustration of the sample mojo project's pom with the parameters set as described in the above table:


  <name>Sample Parameter-less Maven Plugin</name>
    <!-- dependencies to annotations -->


There are few goals which are defined with the maven-plugin packaging as part of a standard build lifecycle:

compile Compiles the Java code for the plugin and builds the plugin descriptor
test Runs the plugin's unit tests
package Builds the plugin jar
install Installs the plugin jar in the local repository
deploy Deploys the plugin jar to the remote repository


The most direct means of executing your new plugin is to specify the plugin goal directly on the command line. To do this, you need to configure the hello-maven-plugin plugin in you project:
And, you need to specify a fully-qualified goal in the form of:


mvn groupId:artifactId:version:goal
For example, to run the simple mojo in the sample plugin, you would enter "mvn sample.plugin:hello-maven-plugin:1.0-SNAPSHOT:sayhi" on the command line.
例如刚才我们上面的例子,你可以在命令行上运行 ”mvn sample.plugin:hello-maven-plugin:1.0-SNAPSHOT:sayhi“来执行。

Tips: version is not required to run a standalone goal.



There are several ways to reduce the amount of required typing:


  • If you need to run the latest version of a plugin installed in your local repository, you can omit its version number. So just use "mvn sample.plugin:hello-maven-plugin:sayhi" to run your plugin.
    如果你需要在本地库运行最新的版本插件,可以省略版本号,只需要"mvn sample.plugin:hello-maven-plugin:sayhi"就可以了。
  • You can assign a shortened prefix to your plugin, such as mvn hello:sayhi. This is done automatically if you follow the convention of using ${prefix}-maven-plugin (or maven-${prefix}-plugin if the plugin is part of the Apache Maven project). You may also assign one through additional configuration - for more information see Introduction to Plugin Prefix Mapping.
    你可以给你的插件设置一个短的前缀,如”mvn hello:sayhi“,后面不翻译了,太啰嗦了。意思大概是命名规范要按照上面讲的,更多插件前缀信息,点击查看。
  • Finally, you can also add your plugin's groupId to the list of groupIds searched by default. To do this, you need to add the following to your ${user.home}/.m2/settings.xml file:

At this point, you can run the mojo with "mvn hello:sayhi".

这样,你就可以用"mvn hello:sayhi"来运行了。


You can also configure your plugin to attach specific goals to a particular phase of the build lifecycle. Here is an example:



This causes the simple mojo to be executed whenever Java code is compiled. For more information on binding a mojo to phases in the lifecycle, please refer to the Build Lifecycle document.

Mojo archetype

To create a new plugin project, you could using the Mojo archetype with the following command line:
通过命令行,使用Mojo archetype创建一个插件项目。
mvn archetype:generate \
  -DgroupId=sample.plugin \
  -DartifactId=hello-maven-plugin \
  -DarchetypeGroupId=org.apache.maven.archetypes \


It is unlikely that a mojo will be very useful without parameters. Parameters provide a few very important functions:
  • It provides hooks to allow the user to adjust the operation of the plugin to suit their needs.
  • 允许根据自己的需要调整插件。
  • It provides a means to easily extract the value of elements from the POM without the need to navigate the objects.
  • 方便的提取POM元素的值。


Defining a parameter is as simple as creating an instance variable in the mojo and adding the proper annotations. Listed below is an example of a parameter for the simple mojo:
     * The greeting to display.
    @Parameter( property = "sayhi.greeting", defaultValue = "Hello World!" )
    private String greeting;

The portion before the annotations is the description of the parameter. The parameter annotation identifies the variable as a mojo parameter. The defaultValue parameter of the annotation defines the default value for the variable. This value can include expressions which reference the project, such as "${project.version}" (more can be found in the "Parameter Expressions" document). The property parameter can be used to allow configuration of the mojo parameter from the command line by referencing a system property that the user sets via the -D option.



Configuring the parameter values for a plugin is done in a Maven 2 project within the pom.xml file as part of defining the plugin in the project. An example of configuring a plugin:
In the configuration section, the element name ("greeting") is the parameter name and the contents of the element ("Welcome") is the value to be assigned to the parameter.


Note: More details can be found in the Guide to Configuring Plugins.


Listed below are the various types of simple variables which can be used as parameters in your mojos, along with any rules on how the values in the POM are interpreted.



This includes variables typed boolean and Boolean. When reading the configuration, the text "true" causes the parameter to be set to true and all other text causes the parameter to be set to false. Example:

     * My boolean.
    private boolean myBoolean;
Fixed-Point Numbers

This includes variables typed byte, Byte, int, Integer, long, Long, short, and Short. When reading the configuration, the text in the XML file is converted to an integer value using either Integer.parseInt() or the valueOf() method of the appropriate class. This means that the strings must be valid decimal integer values, consisting only of the digits 0 to 9 with an optional - in front for a negative value. Example:

     * My Integer.
    private Integer myInteger;
Floating-Point Numbers

This includes variables typed double, Double, float, and Float. When reading the configuration, the text in the XML file is converted to binary form using the valueOf() method for the appropriate class. This means that the strings can take on any format specified in section 3.10.2 of the Java Language Specification. Some samples of valid values are 1.0 and 6.02E+23.

     * My Double.
    private Double myDouble;

This includes variables typed Date. When reading the configuration, the text in the XML file is converted using one of the following date formats: "yyyy-MM-dd HH:mm:ss.S a" (a sample date is "2005-10-06 2:22:55.1 PM") or "yyyy-MM-dd HH:mm:ssa" (a sample date is "2005-10-06 2:22:55PM"). Note that parsing is done using DateFormat.parse() which allows some leniency in formatting. If the method can parse a date and time out of what is specified it will do so even if it doesn't exactly match the patterns above. Example:

     * My Date.
    private Date myDate;
<myDate>2005-10-06 2:22:55.1 PM</myDate>
Files and Directories

This includes variables typed File. When reading the configuration, the text in the XML file is used as the path to the desired file or directory. If the path is relative (does not start with / or a drive letter like C:), the path is relative to the directory containing the POM. Example:

     * My File.
    private File myFile;

This includes variables typed URL. When reading the configuration, the text in the XML file is used as the URL. The format must follow the RFC 2396 guidelines, and looks like any web browser URL (scheme://host:port/path/to/file). No restrictions are placed on the content of any of the parts of the URL while converting the URL.

     * My URL.
    private URL myURL;
Plain Text

This includes variables typed char, Character, StringBuffer, and String. When reading the configuration, the text in the XML file is used as the value to be assigned to the parameter. For char and Character parameters, only the first character of the text is used.


Enumeration type parameters can also be used. First you need to define your enumeration type and afterwards you can use the enumeration type in the parameter definition:

public enum Color {
     * My Enum
    private Color myColor;
You can also use elements from the enumeration type as defaultValues like the following:

 public enum Color {
     * My Enum
    @Parameter(defaultValue = "GREEN")
    private Color myColor;

Parameter Types With Multiple Values

Listed below are the various types of composite objects which can be used as parameters in your mojos, along with any rules on how the values in the POM are interpreted. In general, the class of the object created to hold the parameter value (as well as the class for each element within the parameter value) is determined as follows (the first step which yields a valid class is used):

  1. If the XML element contains an implementation hint attribute, that is used
  2. If the XML tag contains a ., try that as a fully qualified class name
  3. Try the XML tag (with capitalized first letter) as a class in the same package as the mojo/object being configured
  4. For arrays, use the component type of the array (for example, use String for a String[] parameter); for collections and maps, use the class specified in the mojo configuration for the collection or map; use String for entries in a collection and values in a map

Once the type for the element is defined, the text in the XML file is converted to the appropriate type of object


Array type parameters are configured by specifying the parameter multiple times. Example:

     * My Array.
    private String[] myArray;

This category covers any class which implements java.util.Collection such as ArrayList or HashSet. These parameters are configured by specifying the parameter multiple times just like an array. Example:

     * My List.
    private List myList;

For details on the mapping of the individual collection elements, see Mapping Lists.


This category covers any class which implements java.util.Map such as HashMap but does not implement java.util.Properties. These parameters are configured by including XML tags in the form <key>value</key> in the parameter configuration. Example:

     * My Map.
    private Map myMap;

This category covers any map which implements java.util.Properties. These parameters are configured by including XML tags in the form <property><name>myName</name> <value>myValue</value> </property> in the parameter configuration. Example:

     * My Properties.
    private Properties myProperties;
Other Object Classes

This category covers any class which does not implement java.util.Map, java.util.Collection, or java.util.Dictionary. Example:

     * My Object.
    private MyObject myObject;
Please see Mapping Complex Objects for details on the strategy used to configure those kind of parameters.

Using Setters

You are not restricted to using private field mapping which is good if you are trying to make you Mojos resuable outside the context of Maven. Using the example above we could name our private fields using the underscore convention and provide setters that the configuration mapping mechanism can use. So our Mojo would look like the following:

public class MyQueryMojo
    extends AbstractMojo
    private String _url;
    private int _timeout;
    private String[] _options;
    public void setUrl( String url )
        _url = url;
    public void setTimeout( int timeout )
        _timeout = timeout;
    public void setOptions( String[] options )
        _options = options;
    public void execute()
        throws MojoExecutionException
Note the specification of the property name for each parameter which tells Maven what setter and getter to use when the field's name does not match the intended name of the parameter in the plugin configuration.


  1. Mojo文档: Mojo API, Mojo注解
  2. Maven插件测试工具: 对你Mojos的测试架构.
  3. Plexus: 使用 Maven 的 IoC 容器.
  4. Plexus常见实用工具: Mojo开发实用工具类集.
  5. Commons IO:一整套file/path处理的实用工具类。.
  6. 常见的Bug和误区: 总结编码模式的问题.

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