Create GWT-compile rule for Ant build.xml

Question

I'm trying to make an Eclipse-compilable GWT project also compilable on the command line (via Ant).

Eclipse provides functionality to export a build.xml; this works fine for compiling the classes, but since GWT's special stuff is all provided via a plugin, these rules are not included.

Google provides a tool for creating build.xml files for new projects. I've incorporated the rules generated by this into the Eclipse-exported file.

Compiling (the part provided by Eclipse) is successful.

Here is the compile-things-to-javascript task:

  <target name="gwtc" depends="build" description="GWT compile to JavaScript (production mode)">
    <java failonerror="true" fork="true" classname="com.google.gwt.dev.Compiler">
      <classpath>
        <pathelement location="war/WEB-INF/classes"/>
        <pathelement location="src"/>
        <path refid="project.class.path"/>
        <pathelement location="/Applications/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.4.0.v201201120043-rel-r37/gwt-2.4.0/validation-api-1.0.0.GA.jar" />
        <pathelement location="/Applications/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.4.0.v201201120043-rel-r37/gwt-2.4.0/validation-api-1.0.0.GA-sources.jar" />
      </classpath>
      <!-- add jvmarg -Xss16M or similar if you see a StackOverflowError -->
      <jvmarg value="-Xmx256M"/>
      <!--<arg line="-style PRETTY"/>-->
      <arg line="-war"/>
      <arg value="war"/>
      <!-- Additional arguments like -style PRETTY or -logLevel DEBUG -->
      <arg line="${gwt.args}"/>
      <arg value="edu.calpoly.csc.scheduler"/>
    </java>
  </target>

The .gwt.xml file looks like so:

<?xml version="1.0" encoding="UTF-8"?>                                                 
<module rename-to='gwtview'>                                                           
  <!-- Inherit the core Web Toolkit stuff.                        -->                  
  <inherits name='com.google.gwt.user.User'/>                                          

  <!-- Inherit the default GWT style sheet.  You can change       -->
  <!-- the theme of your GWT application by uncommenting          -->                  
  <!-- any one of the following lines.                            -->                  
  <inherits name='com.google.gwt.user.theme.clean.Clean'/>                             
  <!-- <inherits name='com.google.gwt.user.theme.standard.Standard'/> -->              
  <!-- <inherits name='com.google.gwt.user.theme.chrome.Chrome'/> -->                  
  <!-- <inherits name='com.google.gwt.user.theme.dark.Dark'/>     -->                  

  <!-- Other module inherits                                      -->                  

  <!-- Specify the app entry point class.                         -->                  
  <entry-point class='edu.calpoly.csc.scheduler.view.client.GWTView'/>                                                                                                        
  <!-- Specify the paths for translatable code                    -->                  
  <source path='client'/>                                                              
  <source path='shared'/>
  <source path='view'/>                                                                

</module> 

When trying to run the task, I get this error:

gwtc:
     [java] Compiling module edu.calpoly.csc.scheduler
     [java]    Finding entry point classes
     [java]       [ERROR] Unable to find type 'edu.calpoly.csc.scheduler.view.client.GWTView'
     [java]          [ERROR] Hint: Previous compiler errors may have made this type unavailable
     [java]          [ERROR] Hint: Check the inheritance chain from your module; it may not be inheriting a required module or a module may not be adding its source path entries properly

Which seems strange to me, since the class is very much there:

[$]> ls war/WEB-INF/classes/edu/calpoly/csc/scheduler/view/client 
GWTView$1.class            GWTView$1MyHandler.class   GreetingService.class
GWTView$1MyHandler$1.class GWTView.class              GreetingServiceAsync.class

Halp?

Answer 1

Make sure that you have that library/jar and any other SOURCE needed available on the classpath you pass to the GWT Compiler, as it will need to be able to find the Java source inside GWT libs to be able to compile them, unlike the Javac compiler than can compile against libraries using just the provided .class files.

Here is my ant gwtc compile macro. (removed leading <to avoid formatting problems...)

macrodef name="gwtCompileApplication"  >
    <attribute name="app" />
    <attribute name="extraArgs" default="" />
    <attribute name="gwtcExtras" default="" />
    <sequential>
        <java classpathref="gwtCompile.classpath" classname="com.google.gwt.dev.Compiler" fork="true" failonerror="true">
            <jvmarg value="-Xmx512M" />

            <arg value="-strict" />

            <!-- Compile with -strict or with -logLevel set to TRACE or DEBUG to see all errors.
            <arg value="-logLevel" />
            <arg value="DEBUG" />
    -->

            <!-- request detailed, non-obfuscated JS output 
            <arg value="-style" />
            <arg value="DETAILED" />
    -->

            <arg value="-localWorkers" />
            <arg value="4" />

            <arg value="-war" />
            <arg value="${war.dir}" />

            <arg value="-deploy" />
            <arg value="deploy" />

            <!-- These two lines have been removed as otherwise it won't work on Mac OS X 
                    <arg value="@{extraArgs}" />
                    <arg value="@{gwtcExtras}" />
            -->

            <!-- This can be used to see more details about warnings, but they will be converted to errors and build will fail
            <arg value="-strict" />
            -->

            <arg value="-logLevel" />
            <arg value="INFO" />

            <arg value="@{app}" />
        </java>
    </sequential>
</macrodef>

This can be invoked from any target thus: A target to compile a specific module of mine called 'Admin" where the file Admin.gwt.xml file is inside .ta.Admin. I have a debug and production build type and a .gwt.xml different for each one to speed up compiling for debug (fewer user agents and languages = fewer permutations)

target name="gwtcAdmin" depends="compile, buildtype" description="GWT Compile Admin" >
    <gwtCompileApplication app="com.bcntouch.ta.Admin.${build_type}_Admin" extraArgs="${gwtcArgs}" gwtcExtras="${gwtcExtras}"/>
</target>

But the key part if the GWT compile class path I use. Here is the target where I setup my paths:

target name="gwtPath">
    <path id="gwt.classpath">
        <pathelement location="${gwt.sdk.dir}/gwt-user.jar" />
        <pathelement location="${gwt.sdk.dir}/gwt-servlet.jar" />
    </path>

    <!-- For GWT compile we need a path with source AND the GWT Compiler classes -->
    <path id="gwtCompile.classpath">
        <path refid="source.classpath" />
        <!-- This is put after source, so GWT Compiler it doesn't pick up out of date versions of old css and uibinder
             files in classes generated by Eclipse/GWT Plugin -->
        <path refid="classpath" /> 
        <path refid="tool.classpath" />
    </path>     
</target>

Answer 2

Are you sure you have sources of your GWT app on classpath? GWT is compiling java sources to js, not *.class files.