JAXB XJC Possible to suppress comment creation in generated classes?

问题

Our project uses XJC to generate Java classes from an XSD. I'm using JAVA EE 6.

When all the XSDs we have are re-generated, the generated classes include this comment at the top of the file:

// Generated on: 2011.02.23 at 02:17:06 PM GMT

Is it possible to suppress this comment? The reason is that we use SVN for version control, and every time we regenerate our classes, every single file shows as being changed in SVN, even though the only thing that differs is this comment. So I'd like to remove the comment altogether if possible.

There is a -no-header directive, but I don't want to remove the entire header, so that future generations know that it's a file generated from a tool, and that modifications will be overwritten. I only want to remove the timestamp. (Or alternatively, I'd remove the inbuilt header and then insert my own header somehow.)

回答1:

If it's not possible using an option you can post-process the generated files yourself. For a very specific use-case we had to do it that way on our project... We use Maven and we execute a specific script after the Java classes have been generated and before we compile and package them to a distriuable JAR.

回答2:

I am using this mvn plugin which replaces the // Generated on: 2011.02.23 at 02:17:06 PM GMT line:

<plugin>
    <groupId>com.google.code.maven-replacer-plugin</groupId>
    <artifactId>maven-replacer-plugin</artifactId>
    <version>1.3.8</version>
    <executions>
        <execution> 
            <phase>prepare-package</phase>                          
            <goals>
                <goal>replace</goal>
            </goals>
        </execution>
    </executions>
    <configuration>                         
        <includes>                              
            <include>src/main/java/jaxb/*.java</include>            
        </includes>
        <token>^// Generated on.*$</token>
        <value>// Generated on: [TEXT REMOVED by maven-replacer-plugin]</value>                         
        <regexFlags>
            <regexFlag>MULTILINE</regexFlag>
        </regexFlags>
    </configuration>
</plugin>

回答3:

I'm late to the party, but since version 2.0 of the jaxb2-maven-plugin, there's a noGeneratedHeaderComments configuration option. (see the JAXB-2 Maven Plugin Docs)

You can use it like this:

...
<plugins>
    <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>jaxb2-maven-plugin</artifactId>
        <version>2.3.1</version>
        <executions>
            <execution>
                <id>xjc</id>
                <goals>
                    <goal>xjc</goal>
                </goals>
            </execution>
        </executions>
        <configuration>
            <target>2.1</target>
            <sources>
                <source>FirstXSD.xsd</source>
                <source>SecondXSD.xsd</source>
            </sources>
            <xjbSources>
                <xjbSource>OptionalBindings.xjb</xjbSource>
            </xjbSources>
            <noGeneratedHeaderComments>true</noGeneratedHeaderComments>
        </configuration>
        <dependencies>
            <dependency>
                <groupId>org.glassfish.jaxb</groupId>
                <artifactId>jaxb-xjc</artifactId>
                <version>${jaxb.version}</version>
            </dependency>
        </dependencies>
    </plugin>
</plugins>
...

So no need for another plugin or script to run.

If you want to keep a disclaimer, you can use one of the techniques already mentioned to inject it where wanted.

回答4:

If you use ant, the following snippet may be useful for replacing the comments:

<replaceregexp
        match="^// Generated on:.*$" 
        replace="// Generated on: [date removed]"
        byline="true">
    <fileset dir="src">
        <include name="**/*.java"/>
    </fileset>
</replaceregexp>

回答5:

I know this is 2 years after the fact, but because the classes are generated they aren't necessarily needed in SVN. What needs to be in SVN is the schema or whatever file you use for source to generate the classes. As long as you have the source and the tools to generate the classes, the classes in SVN are redundant and as you saw, problematic in SVN or any SCCS. So put the schema file in SVN and avoid the issue altogether.

回答6:

To build on cata's answer (upvoted) the maven-replacer-plugin is the way to go. I've come up with the following that strips out the entire comment (not just the timestamp) which you can replace with your file comment (license etc.).

<plugin>
    <groupId>com.google.code.maven-replacer-plugin</groupId>
    <artifactId>maven-replacer-plugin</artifactId>
    <executions>
      <execution>
        <phase>prepare-package</phase>
          <goals>
            <goal>replace</goal>
          </goals>                   
        </execution>
      </executions>
      <configuration>
        <!-- assumes your xjc is putting source code here -->
        <includes>
          <include>src/main/java/**/*.java</include>
        </includes>
        <regex>true</regex>
        <regexFlags>
          <regexFlag>MULTILINE</regexFlag>
        </regexFlags>
        <replacements>
          <replacement>
            <token>(^//.*\u000a|^\u000a)*^package</token>
            <value>// your new comment
package</value>
          </replacement>         
        </replacements>
      </configuration>
   </plugin>

The one gotcha to watch out for is that the <value> element treats the text literally. So if you want a line break in your replacement text you need to put a line break in your pom.xml file (as I've demonstrated above).

回答7:

What you should you :

Generate your classes in target :

${project.build.directory}/generated-sources

If you add target to ignore list (svn), that's all.

回答8:

I also want to have text header with warning about classes was auto-generated and should not be modified manually, but because I place such files into git I do not want there always changed date of generation.

That header generated in com.sun.tools.xjc.Options#getPrologComment method. So essentially it call:

return Messages.format(
            Messages.FILE_PROLOG_COMMENT,
dateFormat.format(new Date()));

Messages.FILE_PROLOG_COMMENT defined as Driver.FilePrologComment. With futher debugging I found it use standard Java localization bundles.

So, to change header format we just may provide our properties override for their values from MessageBundle.properties.

We can do it in two way:

Just copy that file (from repo by link, or just from jar of appropriate version what you are using) into src/main/resources/com/sun/tools/xjc/MessageBundle.properties in your project and change key Driver.FilePrologComment as you wish.
But first case have some drawbacks - first you copy-paste many code which you do not change, second you should update it when you update XJC dependency. So better I recommend place it as src/main/resources/com/sun/tools/xjc/MessageBundle_en.properties (note _en suffix in filename) file and place there only properties you really want to change. Something like:

# We want header, but do NOT willing there `Generated on: {0}` part because want commit them into git!
Driver.FilePrologComment = \
    This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, v2.4.0-b180830.0438 \n\
    See <a href="https://javaee.github.io/jaxb-v2/">https://javaee.github.io/jaxb-v2/</a> \n\
    Any modifications to this file will be lost upon recompilation of the source schema. \n

Ensure that file in compiler classpath, especially if you call it from some plugins.

That is common mechanism for translation. See related answer: JAXB english comments in generated file

来源：https://stackoverflow.com/questions/5093514/jaxb-xjc-possible-to-suppress-comment-creation-in-generated-classes

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