Question

I have the following directory hierarchy:

generated 

   |    
   | -->java

Java directory has the following package: com.model

that contains java models that I copy/paste from somewhere before I compile the application.

The issue that I use Protocol buffer and I tell maven to output the generated files on same previous directory BUT over a new package:

Result : Protocol buffer generates the new package and deletes the old package.
I have no idea why does it do that although the package names are different?

Here is that part of pom I use to generate java from protocol buffer:

        <plugin>
            <groupId>com.google.protobuf.tools</groupId>
            <artifactId>maven-protoc-plugin</artifactId>
            <configuration>
                <protocExecutable>C:\protoc.exe</protocExecutable>
                <protoSourceRoot>./src/proto</protoSourceRoot>
                <outputDirectory>./src/generated/java</outputDirectory>

            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>compile</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

Answer 1

if you look at the code for the plugin you’ll see that the code has been hardcoded to clean the directory:

https://github.com/dtrott/maven-protoc-plugin/blob/master/src/main/java/com/google/protobuf/maven/AbstractProtocMojo.java#L154

// Quick fix to fix issues with two mvn installs in a row (ie no clean)
cleanDirectory(outputDirectory);

There’s 2 ways to solve this..either set the output directory to a temp directory and then use the maven copy plugin or the maven build plugin to copy the files into the directory of your choice, or modify the maven plugin to remove that line (or better yet make it configurable).

Tommy