org.ebayopensource.turmeric.tools.codegen.util.JavaToolsClassLoader.java Source code

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Here is the source code for org.ebayopensource.turmeric.tools.codegen.util.JavaToolsClassLoader.java

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/*******************************************************************************
 * Copyright (c) 2006-2010 eBay Inc. All Rights Reserved.
 * 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
 *******************************************************************************/
package org.ebayopensource.turmeric.tools.codegen.util;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;

import org.apache.commons.io.FilenameUtils;
import org.ebayopensource.turmeric.tools.codegen.exception.CodeGenFailedException;

/**
 * Work in Progress.
 * Potential replacement for {@link CodeGenClassLoader}
 */
public class JavaToolsClassLoader extends URLClassLoader {
    public static ClassLoader createIfNeeded() throws CodeGenFailedException {
        ClassLoader parent = Thread.currentThread().getContextClassLoader();

        if (!needToolsJar(parent)) {
            return parent;
        }

        File toolsJar = findToolsJar();

        try {
            // Convert the tools.jar location to a URL and use it!
            URL urls[] = { toolsJar.toURI().toURL() };
            return new JavaToolsClassLoader(urls, parent);
        } catch (MalformedURLException e) {
            throw new CodeGenFailedException(
                    "MalformedURLException from the tools.jar location: " + toolsJar.getAbsolutePath(), e);
        }
    }

    public static boolean needToolsJar(ClassLoader classloader) {

        // @formatter:off
        String expectedClasses[] = { "com.sun.tools.javac.Main", "com.sun.tools.apt.Main", "com.sun.javadoc.Doclet",
                "com.sun.javadoc.Type" };
        // @formatter:on

        // If all of the expected classes are present already
        // then just return the active classloader.
        boolean foundExpected = true;

        for (String expectedClass : expectedClasses) {
            try {
                classloader.loadClass(expectedClass);
            } catch (ClassNotFoundException e) {
                foundExpected = false;
                break;
            }
        }

        return !foundExpected;
    }

    public static File findToolsJar() throws CodeGenFailedException {
        // Attempt to find the tools.jar near the java.home

        // The search paths for the tools.jar
        // @formatter:off
        String searchPaths[] = { "tools.jar", "lib/tools.jar", "../lib/tools.jar", "../Classes/classes.jar" };
        // @formatter:on

        // The search process
        File jdkHome = new File(System.getProperty("java.home"));
        File toolsJar = null;
        for (String searchPath : searchPaths) {
            File possible = new File(jdkHome, FilenameUtils.separatorsToSystem(searchPath));
            if (possible.exists()) {
                toolsJar = possible;
                break;
            }
        }

        // Not found. can't codegen!
        if (toolsJar == null) {
            StringBuilder msg = new StringBuilder();
            msg.append("Failed(2) to load tools.jar: Are you running with a JDK?");
            msg.append("\nSystem.ENV(JAVA_HOME)=").append(System.getenv("JAVA_HOME"));
            msg.append("\nSystem.ENV(JDK_HOME)=").append(System.getenv("JDK_HOME"));
            msg.append("\nSystem.property(java.home)=").append(System.getProperty("java.home"));
            throw new CodeGenFailedException(msg.toString());
        }

        return toolsJar;
    }

    public JavaToolsClassLoader(URL[] urls, ClassLoader parent) {
        super(urls, parent);
    }
}