Ant example source code file (AptCompilerAdapter.java)

This example Ant source code file (AptCompilerAdapter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

apt, apt, apt_compiler_success, aptcompileradapter, buildexception, buildexception, class, commandline, io, object, object, reflection, string, string, stringbuffer, util, vector

The AptCompilerAdapter.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

package org.apache.tools.ant.taskdefs.compilers;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.taskdefs.Apt;
import org.apache.tools.ant.types.Commandline;
import org.apache.tools.ant.types.Path;

import java.io.File;
import java.lang.reflect.Method;
import java.util.Enumeration;
import java.util.Vector;


/**
 * The implementation of the apt compiler for JDK 1.5
 * <p/>
 * As usual, the low level entry points for Java tools are neither documented or
 * stable; this entry point may change from that of 1.5.0_01-b08 without any
 * warning at all. The IDE decompile of the tool entry points is as follows:
 * <pre>
 * public class Main {
 * public Main() ;
 * <p/>
 * public static transient void main(String... strings) ;
 * <p/>
 * public static transient int process(String... strings);
 * <p/>
 * public static transient int process(PrintWriter printWriter,
 *      String... strings) ;
 * public static transient int process(
 *      AnnotationProcessorFactory annotationProcessorFactory,
 *      String... strings) ;
 * <p/>
 * public static transient int process(
 *      AnnotationProcessorFactory annotationProcessorFactory,
 *      PrintWriter printWriter,
 *      String... strings);
 * private static transient int processing(
 *      AnnotationProcessorFactory annotationProcessorFactory,
 *      PrintWriter printWriter,
 *      String... strings) ;
 * }
 * </pre>
 *
 * This Adapter is designed to run Apt in-JVM, an option that is not actually
 * exposed to end-users, because it was too brittle during beta testing; classpath
 * problems being the core issue.
 *
 *
 *
 * @since Ant 1.7
 */
public class AptCompilerAdapter extends DefaultCompilerAdapter {

    /**
     * Integer returned by the Apt compiler to indicate success.
     */
    private static final int APT_COMPILER_SUCCESS = 0;
    /**
     * class in tools.jar that implements APT
     */
    public static final String APT_ENTRY_POINT = "com.sun.tools.apt.Main";

    /**
     * method used to compile.
     */
    public static final String APT_METHOD_NAME = "process";

    /**
     * Get the facade task that fronts this adapter
     *
     * @return task instance
     * @see DefaultCompilerAdapter#getJavac()
     */
    protected Apt getApt() {
        return (Apt) getJavac();
    }

    /**
     * Using the front end arguments, set up the command line to run Apt
     *
     * @param apt task
     * @param cmd command that is set up with the various switches from the task
     *            options
     */
    static void setAptCommandlineSwitches(Apt apt, Commandline cmd) {

        if (!apt.isCompile()) {
            cmd.createArgument().setValue("-nocompile");
        }

        // Process the factory class
        String factory = apt.getFactory();
        if (factory != null) {
            cmd.createArgument().setValue("-factory");
            cmd.createArgument().setValue(factory);
        }

        // Process the factory path
        Path factoryPath = apt.getFactoryPath();
        if (factoryPath != null) {
            cmd.createArgument().setValue("-factorypath");
            cmd.createArgument().setPath(factoryPath);
        }

        File preprocessDir = apt.getPreprocessDir();
        if (preprocessDir != null) {
            cmd.createArgument().setValue("-s");
            cmd.createArgument().setFile(preprocessDir);
        }

        // Process the processor options
        Vector options = apt.getOptions();
        Enumeration elements = options.elements();
        Apt.Option opt;
        StringBuffer arg = null;
        while (elements.hasMoreElements()) {
            opt = (Apt.Option) elements.nextElement();
            arg = new StringBuffer();
            arg.append("-A").append(opt.getName());
            if (opt.getValue() != null) {
                arg.append("=").append(opt.getValue());
            }
            cmd.createArgument().setValue(arg.toString());
        }
    }

    /**
     * using our front end task, set up the command line switches
     *
     * @param cmd command line to set up
     */
    protected void setAptCommandlineSwitches(Commandline cmd) {
        Apt apt = getApt();
        setAptCommandlineSwitches(apt, cmd);
    }

    /**
     * Run the compilation.
     * @return true on success.
     * @throws BuildException if the compilation has problems.
     */
    public boolean execute() throws BuildException {
        attributes.log("Using apt compiler", Project.MSG_VERBOSE);
        //set up the javac options
        Commandline cmd = setupModernJavacCommand();
        //then add the Apt options
        setAptCommandlineSwitches(cmd);

        //finally invoke APT
        // Use reflection to be able to build on all JDKs:
        try {
            Class c = Class.forName(APT_ENTRY_POINT);
            Object compiler = c.newInstance();
            Method compile = c.getMethod(APT_METHOD_NAME,
                    new Class[]{(new String[]{}).getClass()});
            int result = ((Integer) compile.invoke
                    (compiler, new Object[]{cmd.getArguments()}))
                    .intValue();
            return (result == APT_COMPILER_SUCCESS);
        } catch (BuildException be) {
            //rethrow build exceptions
            throw be;
        } catch (Exception ex) {
            //cast everything else to a build exception
            throw new BuildException("Error starting apt compiler",
                    ex, location);
        }
    }
}