Maven pom.xml for MATLAB compiler project - matlab

Question

I have a Tomcat servlet project that requires a MATLAB jar generated by mcc. I have implemented a mojo plugin (mcc-maven-plugin) that generates the jar. It simply takes the specifications from a pom and creates a MATLAB command of the form:
cd '/home/jeffemandel/webpropofolmm/matlab/src/main/matlab';mcc -W 'java:webpropofol_java,loadServlet' -d '/home/jeffemandel/webpropofolmm/matlab/target' class{loadServlet:loadServlet.m} class{locServlet:locServlet.m} class{testStruct:testStruct.m}
This generates the file /home/jeffemandel/webpropofolmm/matlab/target/webpropofol_java.jar
Note that target must exist for mcc to work.
I need this file in my main project, but it is resource-intensive to generate the jar every time I make a minor tweak to the UI (which has a small amount of Java and a lot of HTML, css, and javascript). My confusion point is how to generate a jar that doesn't depend on any Java code. Here is my pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.jeffmandel.webpropofol</groupId>
<artifactId>optimaltiva</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>javabuilder</groupId>
<artifactId>javabuilder</artifactId>
<version>9.8</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.4</version>
<executions>
<execution>
<phase>compile</phase>
<configuration>
<tasks>
<mkdir dir="${project.build.directory}"/>
</tasks>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.jeffmandel</groupId>
<artifactId>mcc-maven-plugin</artifactId>
<version>0.0.1-SNAPSHOT</version>
<executions>
<execution>
<goals>
<goal>mcc</goal>
</goals>
<phase>compile</phase>
</execution>
</executions>
<configuration>
<packageName>webpropofol_java</packageName>
<className>loadServlet</className>
<classes>
<loadServlet>loadServlet.m</loadServlet>
<locServlet>locServlet.m</locServlet>
<testStruct>testStruct.m</testStruct>
</classes>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.1</version>
<configuration>
<groupId>org.jeffmandel.webpropofol</groupId>
<artifactId>optimaltiva</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<file>${project.build.directory}/webpropofol_java.jar</file>
<generatePom>true</generatePom>
</configuration>
<executions>
<execution>
<id>install-jar-lib</id>
<goals>
<goal>install-file</goal>
</goals>
<phase>install</phase>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
When I run mvn compile, this is what I get:
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------< org.jeffmandel.webpropofol:optimaltiva >---------------
[INFO] Building optimaltiva 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) # optimaltiva ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /home/jeffemandel/webpropofolmm/matlab/src/main/resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) # optimaltiva ---
[INFO] No sources to compile
[INFO]
[INFO] --- maven-antrun-plugin:1.4:run (default) # optimaltiva ---
project.artifactId
[INFO] Executing tasks
[INFO] Executed tasks
[INFO]
[INFO] --- mcc-maven-plugin:0.0.1-SNAPSHOT:mcc (default) # optimaltiva ---
[INFO] cd '/home/jeffemandel/webpropofolmm/matlab/src/main/matlab';mcc -W 'java:webpropofol_java,loadServlet' -d '/home/jeffemandel/webpropofolmm/matlab/target' class{loadServlet:loadServlet.m} class{locServlet:locServlet.m} class{testStruct:testStruct.m}
[INFO] Loading source files for package webpropofol_java...
Constructing Javadoc information...
Standard Doclet version 1.8.0_221
Building tree for all the packages and classes...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/loadServlet.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/loadServletRemote.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/locServlet.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/locServletRemote.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/testStruct.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/testStructRemote.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/Webpropofol_javaMCRFactory.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/package-frame.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/package-summary.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/webpropofol_java/package-tree.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/constant-values.html...
Building index for all the packages and classes...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/overview-tree.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/index-all.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/deprecated-list.html...
Building index for all classes...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/allclasses-frame.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/allclasses-noframe.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/index.html...
Generating /home/jeffemandel/webpropofolmm/matlab/target/doc/html/help-doc.html...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 36.215 s
[INFO] Finished at: 2020-12-12T22:26:54-05:00
[INFO] -----
The problem is that every time I run mvn compile it generates the jar, rather than seeing that the source files haven't changed so don't regenerate the jar. My ultimate goal is to have one project that contains the matlab and servlet.

Answer 1

I did some more reading and figured out that it was the responsibility of the mojo plugin to figure out whether recompilation was needed. MATLAB needs to rebuild the entire jar even if only a single file changes, so I added the following code to my mojo plugin:
import org.apache.commons.io.filefilter.AgeFileFilter;
import java.io.FileFilter;
File myJar = new File(outputDirectory + File.separator + packageName + ".jar");
AgeFileFilter myFilter = new AgeFileFilter(myJar, false);
File source = new File(sourceDirectory);
File[] files = source.listFiles((FileFilter) myFilter);
if (files.length==0) {
getLog().info("Project up to date");
} else {
...
}
This does the trick.