Mojo开发：访问javadoc com.sun.tools.javadoc.Main类

Question

Problem : I want to access com.sun.tools.javadoc.Main from code in a Mojo plugin.

I have two parts to this question.

Part 1:

When creating a mojo plugin, is it best to use annotations or parameters inside the @Mojo For example you can set 'requiresDependencyResolution' in both.

 /*
 * @goal install
 * @phase process-classes
 * @configurator include-project-dependencies
 * @requiresDependencyResolution compile+runtime
 */
@Mojo(name = "document", requiresDependencyResolution = ResolutionScope.COMPILE_PLUS_RUNTIME)
public class CreatorMavenPlugin extends AbstractMojo

Part 2: (Main question)

I want to execute the following code in my plugin, I want to hook into the Javadoc generation.

 com.sun.tools.javadoc.Main.execute(new String[]
    {
        "-private",
        "-doclet",
        "com.test.tools.APIDocGenDoclet",
        javaFilePathAndName
    });

    return APIDocGenDoclet.getCurrentClassDocs();

The problem is that eclipse recognises com.sun.tools.javadoc.Main from the JDK it has.

Maven when it runs can't find the class and gives the error....

Number of foreign imports: 1
import: Entry[import  from realm ClassRealm[maven.api, parent: null]]

-----------------------------------------------------

        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:125)
        ... 20 more
Caused by: java.lang.NoClassDefFoundError: com/sun/tools/javadoc/Main

I've tried adding tools directly to start with as a dependency...

    <dependency>
        <groupId>com.sun</groupId>
        <artifactId>tools</artifactId>
        <version>1.6.0</version>
        <scope>system</scope>
        <systemPath>${java.home}/../lib/tools.jar</systemPath>
    </dependency>

But this doesn't work. (Same error)

I've tried adding it as a dependency of the profile my plugin runs under...

    <profile>
        <id>auto-doc</id>
        <dependencies>
            <dependency>
                <groupId>com.sun</groupId>
                <artifactId>tools</artifactId>
                <version>1.6.0</version>
                <scope>system</scope>
                <systemPath>${java.home}/../lib/tools.jar</systemPath>
            </dependency>
        </dependencies>
        <build>
            <plugins>
                <plugin>
                    <groupId>com.test</groupId>
                    <artifactId>updater</artifactId>
                    <version>1.0.0-SNAPSHOT</version>
                    <executions>
                        <execution>
                            <phase>install</phase>
                            <goals>
                                <goal>document</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
            </plugins>
        </build>
    </profile>

But not change, same error.

I feel this is something to do with the classpath setup defined for the Mojo Plugin, but I've tried many different combinations, but I'm stumped.

Can anyone help please? Note: I'm using Maven 3.0.4 & JDK 1.6.0_43 32 bit on Windows.

Answer 1

Part 1: if you don't need backward compatibility with ancient Maven versions, go with the annotations. It's the new and better way of specifying Mojo configuration, and your IDE will give you autocomplete and hovers.

Part 2:

Taking a look at what the existing Maven Javadoc plugin does :

It seems it uses the Toolchain API to locate the appropriate Javadoc tool to run. The Maven Compiler Plugin also does this to get javac.

Summarizing from the toolchain documentation:

add

@Component
private ToolchainManager toolchainManager;

@Component
private MavenSession session;

to your Mojo. Then in your code

Toolchain tc = toolchainManager.getToolchainFromBuildContext( "jdk", session );
String javadocExecutable = tc.findTool( "javadoc" );

and then you can execute it. Read the toolchain documentation in the link for more detailed information.

If you were using Java 8 or later, you could use ToolProvider.getSystemDocumentationTool() .

Answer 2

I was putting the Profile section in the project that was being built, not in the project that contains the Mojo Plugin.

This is what I've got in Mojo Plugin Project

<profiles>
    <profile>
        <id>default-tools.jar</id>
        <activation>
            <property>
                <name>java.vendor</name>
                <value>Sun Microsystems Inc.</value>
            </property>
        </activation>
        <dependencies>
            <dependency>
                <groupId>com.sun</groupId>
                <artifactId>tools</artifactId>
                <version>1.6.0</version>
                <scope>system</scope>
                <systemPath>${java.home}/../lib/tools.jar</systemPath>
            </dependency>
        </dependencies>
    </profile>
</profiles>

The Mojo plugin is defined as this...

/**
 * @goal install
 * @phase process-classes
 * @configurator include-project-dependencies
 * @requiresDependencyResolution compile+runtime
 */
@Mojo(name = "document", requiresDependencyResolution= ResolutionScope.COMPILE_PLUS_RUNTIME)
public class DocumationUpdatorMavenPlugin extends AbstractMojo 

My project that uses the plugin, has this in its POM...

<profile>
            <id>auto-doc</id>
            <build>
                <plugins>
                    <plugin>
                        <groupId>com.test</groupId>
                        <artifactId>updater</artifactId>
                        <version>1.0.0-SNAPSHOT</version>
                        <executions>
                            <execution>
                                <phase>install</phase>
                                <goals>
                                    <goal>document</goal>
                                </goals>
                            </execution>
                        </executions>
                    </plugin>
                </plugins>
            </build>
        </profile>  

Then my command "mvn install -Pauto-doc" kicks off my AutoDoc plugin.