org.eclipse.xtend.core.parser.JFlexLoader.java Source code

Introduction

Here is the source code for org.eclipse.xtend.core.parser.JFlexLoader.java

Source

/*******************************************************************************
 * Copyright (c) 2013 itemis AG (http://www.itemis.eu) and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *******************************************************************************/
package org.eclipse.xtend.core.parser;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

import org.apache.log4j.Logger;
import org.eclipse.emf.mwe2.runtime.workflow.IWorkflowComponent;
import org.eclipse.emf.mwe2.runtime.workflow.IWorkflowContext;

import com.google.common.io.ByteStreams;

/**
 * @author Sebastian Zarnekow - Initial contribution and API
 */
public class JFlexLoader implements IWorkflowComponent, JFlexMain {

    private final static Logger log = Logger.getLogger(JFlexLoader.class);

    private static final String DOWNLOAD_URL = "http://jflex.de/jflex-1.4.3.zip";

    private static final String MAIN_CLASS = "JFlex.Main";

    private ClassLoader loader = JFlexLoader.class.getClassLoader();

    private String downloadTo = "./.jflex.jar";

    private boolean askBeforeDownload = true;

    public ClassLoader getClassLoader() {
        return loader;
    }

    @Override
    public void runJFlex(String... args) {
        try {
            Class<?> main = loader.loadClass(MAIN_CLASS);
            Method mainMethod = main.getMethod("main", String[].class);
            mainMethod.invoke(null, new Object[] { args });
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public void setDownloadPath(String downloadTo) {
        this.downloadTo = downloadTo;
    }

    public void setAskBeforeDownload(boolean askBeforeDownload) {
        this.askBeforeDownload = askBeforeDownload;
    }

    public String getDownloadTo() {
        return downloadTo;
    }

    public File getJarFile() {
        return new File(downloadTo);
    }

    @Override
    public void preInvoke() {
        try {
            loader.loadClass(MAIN_CLASS);
        } catch (ClassNotFoundException e) {
            File jarFile = getJarFile();
            if (!jarFile.exists()) {
                try {
                    if (!download(jarFile))
                        return;
                } catch (IOException ioe) {
                    throw new RuntimeException(ioe);
                }
            }
            if (jarFile.exists()) {
                try {
                    URL url = jarFile.toURI().toURL();
                    loader = new URLClassLoader(new URL[] { url }, loader);
                    ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
                    try {
                        Thread.currentThread().setContextClassLoader(loader);
                        loader.loadClass(MAIN_CLASS);
                    } finally {
                        Thread.currentThread().setContextClassLoader(contextClassLoader);
                    }
                } catch (Exception e1) {
                    throw new RuntimeException(e);
                }
            }
        }
    }

    private boolean download(final File jarFile) throws IOException {
        final File tempFile = File.createTempFile("JFlex", "zip");
        tempFile.deleteOnExit();
        if (askBeforeDownload) {
            boolean ok = false;
            while (!ok) {
                System.err.print("Download JFlex 1.4.3? (type 'y' or 'n' and hit enter)");
                int read = System.in.read();
                if (read == 'n') {
                    return false;
                } else if (read == 'y') {
                    ok = true;
                }
            }
        }
        log.info("downloading JFlex 1.4.3 from '" + DOWNLOAD_URL + "' ...");
        copyIntoFileAndCloseStream(new URL(DOWNLOAD_URL).openStream(), tempFile);
        log.info("finished downloading. Now extracting to " + downloadTo);
        final ZipFile zipFile = new ZipFile(tempFile);
        try {
            final ZipEntry entry = zipFile.getEntry("jflex/lib/JFlex.jar");
            copyIntoFileAndCloseStream(zipFile.getInputStream(entry), jarFile);
        } finally {
            zipFile.close();
        }
        return true;
    }

    protected void copyIntoFileAndCloseStream(InputStream content, final File file)
            throws FileNotFoundException, IOException {
        BufferedInputStream inputStream = new BufferedInputStream(content);
        try {
            BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(file));
            try {
                ByteStreams.copy(inputStream, outputStream);
            } finally {
                outputStream.close();
            }
        } finally {
            inputStream.close();
        }
    }

    @Override
    public void invoke(IWorkflowContext ctx) {
    }

    @Override
    public void postInvoke() {
    }

}