Groovy example source code file (JavacJavaCompiler.java)

This example Groovy source code file (JavacJavaCompiler.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 - Groovy tags/keywords

class, class, classloader, classnotfoundexception, classnotfoundexception, compilationunit, exceptionmessage, file, file, groovyclassloader, io, net, network, object, reflection, string, string, stringwriter, util

The Groovy JavacJavaCompiler.java source code

/*
 * Copyright 2003-2009 the original author or authors.
 *
 * Licensed 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.codehaus.groovy.tools.javac;

import groovy.lang.GroovyClassLoader;

import java.io.File;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.util.*;
import java.net.URLClassLoader;
import java.net.URL;
import java.net.URISyntaxException;

import org.codehaus.groovy.control.CompilationUnit;
import org.codehaus.groovy.control.CompilerConfiguration;
import org.codehaus.groovy.control.messages.ExceptionMessage;
import org.codehaus.groovy.control.messages.SimpleMessage;
import org.codehaus.groovy.runtime.DefaultGroovyMethods;

public class JavacJavaCompiler implements JavaCompiler {
    private CompilerConfiguration config;

    public JavacJavaCompiler(CompilerConfiguration config) {
        this.config = config;
    }

    public void compile(List<String> files, CompilationUnit cu) {
        String[] javacParameters = makeParameters(files, cu.getClassLoader());
        StringWriter javacOutput = null;
        int javacReturnValue = 0;
        try {
            Class javac = findJavac(cu);
            Method method = null;
            try {
                method = javac.getMethod("compile", new Class[]{String[].class, PrintWriter.class});
                javacOutput = new StringWriter();
                PrintWriter writer = new PrintWriter(javacOutput);
                Object ret = method.invoke(null, javacParameters, writer);
                javacReturnValue = (Integer) ret;
            } catch (NoSuchMethodException e) { }
            if (method == null) {
                method = javac.getMethod("compile", new Class[]{String[].class});
                Object ret = method.invoke(null, new Object[]{javacParameters});
                javacReturnValue = (Integer) ret;
            }
            cu.getConfiguration().getOutput();
        } catch (InvocationTargetException ite) {
            cu.getErrorCollector().addFatalError(new ExceptionMessage((Exception) ite.getCause(), true, cu));
        } catch (Exception e) {
            cu.getErrorCollector().addFatalError(new ExceptionMessage(e, true, cu));
        }
        if (javacReturnValue != 0) {
            switch (javacReturnValue) {
                case 1: addJavacError("Compile error during compilation with javac.", cu, javacOutput); break;
                case 2: addJavacError("Invalid commandline usage for javac.", cu, javacOutput); break;
                case 3: addJavacError("System error during compilation with javac.", cu, javacOutput); break;
                case 4: addJavacError("Abnormal termination of javac.", cu, javacOutput); break;
                default: addJavacError("unexpected return value by javac.", cu, javacOutput); break;
            }
        } else {
            // print warnings if any
            System.out.print(javacOutput);
        }
    }

    private void addJavacError(String header, CompilationUnit cu, StringWriter msg) {
        if (msg != null) {
            header = header + "\n" + msg.getBuffer().toString();
        } else {
            header = header +
                    "\nThis javac version does not support compile(String[],PrintWriter), " +
                    "so no further details of the error are available. The message error text " +
                    "should be found on System.err.\n";
        }
        cu.getErrorCollector().addFatalError(new SimpleMessage(header, cu));
    }

    private String[] makeParameters(List<String> files, GroovyClassLoader parentClassLoader) {
        Map options = config.getJointCompilationOptions();
        LinkedList<String> paras = new LinkedList();

        File target = config.getTargetDirectory();
        if (target == null) target = new File(".");

        // defaults
        paras.add("-d");
        paras.add(target.getAbsolutePath());
        paras.add("-sourcepath");
        paras.add(((File) options.get("stubDir")).getAbsolutePath());

        // add flags
        String[] flags = (String[]) options.get("flags");
        if (flags != null) {
            for (String flag : flags) {
                paras.add('-' + flag);
            }
        }

        boolean hadClasspath = false;
        // add namedValues
        String[] namedValues = (String[]) options.get("namedValues");
        if (namedValues != null) {
            for (int i = 0; i < namedValues.length; i += 2) {
                String name = namedValues[i];
                if (name.equals("classpath")) hadClasspath = true;
                paras.add('-' + name);
                paras.add(namedValues[i + 1]);
            }
        }

        // append classpath if not already defined
        if (!hadClasspath) {
            // add all classpaths that compilation unit sees
            StringBuffer resultPath = new StringBuffer(DefaultGroovyMethods.join(config.getClasspath(), File.pathSeparator));
            ClassLoader cl = parentClassLoader;
            while (cl != null) {
                if (cl instanceof URLClassLoader) {
                    for (URL u : ((URLClassLoader) cl).getURLs()) {
                        try {
                            resultPath.append(File.pathSeparator);
                            resultPath.append(new File(u.toURI()).getPath());
                        } catch (URISyntaxException e) {
                            // ignore it
                        }
                    }
                }
                cl = cl.getParent();
            }

            paras.add("-classpath");
            paras.add(resultPath.toString());
        }

        // files to compile
        paras.addAll(files);

        return paras.toArray(new String[paras.size()]);
    }

    private Class findJavac(CompilationUnit cu) throws ClassNotFoundException {
        String main = "com.sun.tools.javac.Main";
        try {
            return Class.forName(main);
        } catch (ClassNotFoundException e) {}

        try {
            ClassLoader cl = this.getClass().getClassLoader();
            return cl.loadClass(main);
        } catch (ClassNotFoundException e) {}

        try {
            return ClassLoader.getSystemClassLoader().loadClass(main);
        } catch (ClassNotFoundException e) {}

        try {
            return cu.getClassLoader().getParent().loadClass(main);
        } catch (ClassNotFoundException e3) {}


        // couldn't find compiler - try to find tools.jar
        // based on java.home setting
        String javaHome = System.getProperty("java.home");
        if (javaHome.toLowerCase(Locale.US).endsWith("jre")) {
            javaHome = javaHome.substring(0, javaHome.length() - 4);
        }
        File toolsJar = new File((javaHome + "/lib/tools.jar"));
        if (toolsJar.exists()) {
            GroovyClassLoader loader = cu.getClassLoader();
            loader.addClasspath(toolsJar.getAbsolutePath());
            return loader.loadClass(main);
        }

        throw new ClassNotFoundException("unable to locate the java compiler com.sun.tools.javac.Main, please change your classloader settings");
    }
}