Running MyBatis Generator With Maven

MyBatis Generator (MBG) includes a Maven plugin for integration into a maven build. In keeping with Maven's configuration by convention strategy, including MBG in a Maven build can be very simple. The minimum configuration is shown below:

   <project ...>
     ...
     <build>
       ...
       <plugins>
        ...
        <plugin>
      	  <groupId>org.mybatis.generator</groupId>
      	  <artifactId>mybatis-generator-maven-plugin</artifactId>
          <version>1.3.0</version>
        </plugin>
        ...
      </plugins>
      ...
    </build>
    ...
  </project>

Of course, things are never that easy!

Maven Goal and Execution

The MBG Maven plugin includes one goal:

  • mybatis-generator:generate

The goal is not automatically executed by Maven. It can be executed in two ways.

The goal can be executed from the command line with the command:

  • mvn mybatis-generator:generate

You can pass parameters to the goal with standard Maven command line properties. For example:

  • mvn -Dmybatis.generator.overwrite=true mybatis-generator:generate

This will run MBG and instruct it to overwrite any existing Java files it may find.

In a continuous build environment, you may want to automatically execute MBG as a part of a Maven build. This can be accomplished by configuring the goal to execute automatically. An example of this is shown below:

   <project ...>
     ...
     <build>
       ...
       <plugins>
        ...
        <plugin>
      	  <groupId>org.mybatis.generator</groupId>
      	  <artifactId>mybatis-generator-maven-plugin</artifactId>
          <version>1.3.0</version>
          <executions>
            <execution>
              <id>Generate MyBatis Artifacts</id>
              <goals>
                <goal>generate</goal>
              </goals>
            </execution>
          </executions>
        </plugin>
        ...
      </plugins>
      ...
    </build>
    ...
  </project>

The MBG plugin is bound to the generate-sources phase of a Maven build, so it will execute before the complie step. Also note that MBG generates both Java source files and XML resources. The MBG goal will bind both generated Java files and XML resources to the build and they will both be included in any JAR generated by the build.

MyBatis Generator Configuration Properties

Any property specified in the POM will be passed into the configuration file and may be used in the normal way. For example:

   <project ...>
     ...
     <properties>
       <dao.target.dir>src/main/java</dao.target.dir>
     </properties>
     ...
     <build>
       ...
       <plugins>
        ...
        <plugin>
      	  <groupId>org.mybatis.generator</groupId>
      	  <artifactId>mybatis-generator-maven-plugin</artifactId>
          <version>1.3.0</version>
          <executions>
            <execution>
              <id>Generate MyBatis Artifacts</id>
              <goals>
                <goal>generate</goal>
              </goals>
            </execution>
          </executions>
        </plugin>
        ...
      </plugins>
      ...
    </build>
    ...
  </project>

In this case, the property may be accessed in the configuration file with the syntax ${dao.target.dir}.

Parameter Reference

All parameters are optional and most have suitable defaults.

Parameter Expression Type Comments
configurationFile ${mybatis.generator.configurationFile} java.io.File The location of the XML configuration file.

Default value:

${basedir}/src/main/resources/generatorConfig.xml
contexts ${mybatis.generator.contexts} java.lang.String A comma delimited list of contexts to use in the current run. Any id specified in the list must exactly match the value of the id attribute of an <context> configuration element. Only ids specified in this list will be active for this run. If this parameter is not specified, then all contexts will be active.
jdbcDriver ${mybatis.generator.jdbcDriver} java.lang.String If you specify a sqlScript, then this is the fully qualified JDBC driver class name to use when connecting to the database.
jdbcPassword ${mybatis.generator.jdbcPassword} java.lang.String If you specify a sqlScript, then this is the password to use when connecting to the database.
jdbcURL ${mybatis.generator.jdbcURL} java.lang.String If you specify a sqlScript, then this is the JDBC URL to use when connecting to the database.
jdbcUserId ${mybatis.generator.jdbcUserId} java.lang.String If you specify a sqlScript, then this is the JDBC user ID to use when connecting to the database.
outputDirectory ${mybatis.generator.outputDirectory} java.io.File The directory where files generated by MBG will be placed. This directory is used whenever a targetProject in the configuration file is set to the special value "MAVEN" (case sensitive).

Default value:

${project.build.directory}/generated-sources/mybatis-generator
overwrite ${mybatis.generator.overwrite} boolean If true, then existing Java files will be overwritten if an existing Java file if found with the same name as a generated file. If not specified, and a Java file already exists with the same name as a generated file, then MBG will write the newly generated Java file to the proper directory with a unique name (e.g. MyClass.java.1, MyClass.java.2, etc.). Important: MBG will always merge and overwrite XML files.

Default value:

false
sqlScript ${mybatis.generator.sqlScript} java.lang.String Location of a SQL script file to run before generating code. If null, then no script will be run. If not null, then jdbcDriver, jdbcURL must be supplied also. In addition, jdbcUserId and jdbcPassword may be supplied if the database requires authentication.

Value can be specified as a location in the file system or, if prefixed with "classpath:" a location on the build classpath.
tableNames ${mybatis.generator.tableNames} java.lang.String If specified, then this is a comma delimited list of tables to use in the current run. Any table specified in the list must exactly match the fully qualified table name specified in a <table> configuration element. Only tables specified in this list will be active for this run. If this argument is not specified, then all tables will be active. Specify table names as:

table
schema.table
catalog..table
etc.
verbose ${mybatis.generator.verbose} boolean If true, then MBG will write progress messages to the build log.

Interpretation of targetProject

The targetProject attribute of the generator configurations is interpreted differently when running with Maven. If set to the special value "MAVEN" (case sensitive), then targetProject will be set to the plugin's output directory, and that directory will be created if it doesn't already exist. If not set to "MAVEN", then targetProject will be interpreted as normal by MBG - it must be set to a directory that already exists.