Can't run groovyc from Ant build.xml

Question

I am trying to run groovyc from inside an Ant build.xml file. Here's my project directory structure:

myapp/
    src/main/java
        <Some Java sources>
    src/main/groovy
        DemoController
    lib/main
        groovy-all-2.2.2.jar
        servlet-2.4.jar
    gen
        bin
        dist

Here's my compile target:

<?xml version="1.0"?>
<project name="myapp" default="compile" basedir=".">
    <path id="groovy-path">
        <fileset dir="lib/main" includes="groovy-all-2.2.2.jar" />
    </path>

    <taskdef name="groovyc"
        classname="org.codehaus.groovy.ant.Groovyc"
        classpathref="groovy-path" />

    <!-- Other targets omitted for brevity... -->

    <target name="compile" depends="init">
        <echo message="Compiling Java sources..." />
        <javac destdir="gen/bin" includeantruntime="false">
            <src path="src/main/java" />
            <src path="lib/main" />
        </javac>

        <echo message="Compiling Groovy sources..." />
        <groovyc destdir="gen/bin">
            <src path="src/main/java" />
            <src path="src/main/groovy" />
            <src path="lib/main" />
        </groovyc>
    </target>
</project>

In my code, under the src/main/groovy, I have a Groovy class called DemoController:

package com.ar.myapp.controllers

import javax.servlet.http.HttpServlet
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

class DemoController extends HttpServlet {
    @Override
    void doGet(HttpServletRequest request, HttpServletResponse response) {
        String resp = "Hello, Groovy!";
        response.getWriter().write(resp);
    }
}

From Eclipse (I installed the Groovy plugin and created a Groovy project for all this code) I don't see any compiler errors or red flags. But when I run the Ant compile target, I get the following exception:

compile:
    [echo] Compiling Java sources...
    [javac] Compiling 1 source file to /home/myuser/sandbox/eclipse/workspace/myapp/gen/bin
    [echo] Compiling Groovy sources...
    [groovyc] Compiling 1 source file to /home/myuser/sandbox/eclipse/workspace/myapp/gen/bin
    [groovyc] org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
    [groovyc] /home/myuser/sandbox/eclipse/workspace/myapp/src/main/groovy/com/myapp/controllers/DemoController.groovy: 3: unable to resolve class javax.servlet.http.HttpServlet
    [groovyc]  @ line 3, column 1.
    [groovyc]    import javax.servlet.http.HttpServlet
    [groovyc]    ^
    [groovyc] 
    [groovyc] /home/myuser/sandbox/eclipse/workspace/myapp/src/main/groovy/com/myapp/controllers/DemoController.groovy: 4: unable to resolve class javax.servlet.http.HttpServletRequest
    [groovyc]  @ line 4, column 1.
    [groovyc]    import javax.servlet.http.HttpServletRequest;
    [groovyc]    ^
    [groovyc] 
    [groovyc] /home/myuser/sandbox/eclipse/workspace/myapp/src/main/groovy/com/myapp/controllers/DemoController.groovy: 5: unable to resolve class javax.servlet.http.HttpServletResponse
    [groovyc]  @ line 5, column 1.
    [groovyc]    import javax.servlet.http.HttpServletResponse;
    [groovyc]    ^
    [groovyc] 
    [groovyc] 3 errors

When I open up lib/main/servlet-2.4.jar I do in fact see the Http* classes packaged where they ought to be (under javax.servlet.http). I would understand this error if I didn't have lib/main/servlet-2.4.jar added to groovyc's path, but this just doesn't make sense. What is going on here?

Answer 1

You need to add the classpath attribute to the groovyc task.

  <groovyc destdir="gen/bin">
    <src path="src/main/groovy" />
    <classpath>
      <path location="gen/bin"/>
      <fileset dir="lib/main">
          <include name="*.jar" />
      </fileset>
    </classpath>
  </groovyc>

Note the original build.xml includes the Java source in both the javac and groovyc tasks. You can either 1) add the javac target (i.e. gen/bin) to classpath of groovyc task rather than reference the source or 2) compile the java and groovy source together in groovyc task and remove the javac step entirely.

Option 2: Remove "javac" task and use combined groovy task with java + groovy source:

  <groovyc destdir="gen/bin">
    <src path="src/main/java" />
    <src path="src/main/groovy" />
    <classpath>
      <fileset dir="lib/main">
          <include name="*.jar" />
      </fileset>
    </classpath>
  </groovyc>