How to compile a class from a Servlet using ant!!!

Question

Hi I have the following problem:
I have a Servlet that must compile a java class.
Here is the code that i use to compile:
File buildFile = new File(build.xml path);
String[] arg = { "-buildfile", buildFile.toString(), "compile" };
Properties userProps = null;
ClassLoader loader = ClassLoader.getSystemClassLoader();
Main.start(arg, userProps, loader);
The build.xml file was written correctly, infact if i lunch the command ant by dos it is correctly done.
When I put my application in tomcat/webapps and try to compile with code above I have the following error:
BUILD FAILED C:\......: Could not create task or type of type: property.
Ant could not find the task or a class this task relies upon.
This is common and has a number of causes; the usual
solutions are to read the manual pages then download and
install needed JAR files, or fix the build file:
- You have misspelt 'property'.
Fix: check your spelling.
- The task needs an external JAR file to execute
and this is not found at the right place in the classpath.
Fix: check the documentation for dependencies.
Fix: declare the task.
- The task is an Ant optional task and the JAR file and/or libraries implementing the functionality were not found at the time you yourself built your installation of Ant from the Ant sources.
Fix: Look in the ANT_HOME/lib for the 'ant-' JAR corresponding to the task and make sure it contains more than merely a META-INF/MANIFEST.MF.
If all it contains is the manifest, then rebuild Ant with the needed libraries present in ${ant.home}/lib/optional/ , or alternatively,
download a pre-built release version from apache.org
- The build file was written for a later version of Ant Fix: upgrade to at least the latest release version of Ant
- The task is not an Ant core or optional task and needs to be declared using <taskdef>.
- You are attempting to use a task defined using <presetdef> or <macrodef> but have spelt wrong or not defined it at the point of use
Remember that for JAR files to be visible to Ant tasks implemented in ANT_HOME/lib, the files must be in the same directory or on the classpath
Please neither file bug reports on this problem, nor email the Ant mailing lists, until all of these causes have been explored, as this is not an Ant bug.

Answer 1

Java code Snippet
import org.apache.tools.ant.*;// ant.jar
String SourceDir="c:\java";
     String DestinationDir="c:\classes";
     Project project = new Project();
     try
String baseDir = getServletContext().getRealPath( "/WEB-INF/build/");//Build.xml should be in this folder or else make use of the build folder here
     File buildFile = new File( baseDir, "build.xml");
     project.setUserProperty( "SourceDir", SourceDir);
     project.setUserProperty( "DestinationDir", DestinationDir);
     project.setUserProperty( "ant.file", buildFile.getAbsolutePath());
     project.setBaseDir( new File( baseDir));
     project.init();
     ProjectHelper.configureProject( project, buildFile);
     project.executeTarget(project.getDefaultTarget());
     catch (Exception e)
Build.xml
<?xml version="1.0"?>
<project name="Sample" default="compile" basedir=".">
     <property name="SrcDir" value="${SourceDir}"/>
     <property name="DestnDir" value="${DestinationDir}"/>
     <target name="compile">
          <javac srcdir="${SrcDir}" destdir="${DestnDir">
               <classpath > <!-- If any supporting jars required to compile the file add this-->
                    <fileset dir="${SrcDir}" includes="*.jar" />
               </classpath>
          </javac>
     </target>
</project>