com.jiminger.util.LibraryLoader.java Source code

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Here is the source code for com.jiminger.util.LibraryLoader.java

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/***********************************************************************
Legacy Film to DVD Project
Copyright (C) 2005 James F. Carroll
    
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
    
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
    
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
****************************************************************************/

package com.jiminger.util;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;

public class LibraryLoader {
    static {
        InputStream is = null;

        try {
            // All we're going to do here is load the library from a jar file

            is = getInputStream("com.jiminger.lib.properties");

            if (is == null)
                throw new UnsatisfiedLinkError(
                        "Couldn't load the com.jiminger native library. Is the jar file containing the library on the classpath?");

            Properties libProps = new Properties();

            try {
                libProps.load(is);
            } catch (IOException e) {
                throw new UnsatisfiedLinkError(
                        "Couldn't load the com.jiminger native library. Couldn't load the properties out of the jar:"
                                + e.getLocalizedMessage());
            }

            IOUtils.closeQuietly(is);

            String libName = libProps.getProperty("library");
            String libSuffix = libProps.getProperty("suffix");
            is = getInputStream(libName);
            if (is == null)
                throw new UnsatisfiedLinkError(
                        "Couldn't load the library identified as the com.jiminger native library (" + libName
                                + ").");

            File tmpFile = null;
            try {
                tmpFile = File.createTempFile("com.jiminger", libSuffix);
            } catch (IOException e) {
                throw new UnsatisfiedLinkError(
                        "Couldn't load the com.jiminger native library. Couldn't copy the library out of the jar:"
                                + e.getLocalizedMessage());
            }

            try {
                FileUtils.copyInputStreamToFile(is, tmpFile);
            } catch (IOException e) {
                throw new UnsatisfiedLinkError(
                        "Couldn't load the com.jiminger native library. Couldn't copy the library out of the jar:"
                                + e.getLocalizedMessage());
            }

            System.out.println("Loading:" + tmpFile.getAbsolutePath());
            System.load(tmpFile.getAbsolutePath());
        } finally {
            if (is != null)
                IOUtils.closeQuietly(is);
        }
    }

    private static InputStream getInputStream(String resource) {
        // I need to find the library. Let's start with the "current" classloader.
        // see http://www.javaworld.com/javaworld/javaqa/2003-06/01-qa-0606-load.html
        // also see: http://www.javaworld.com/javaworld/javaqa/2003-03/01-qa-0314-forname.html
        InputStream is = getInputStreamFromClassLoader(LibraryLoader.class.getClassLoader(), resource);
        if (is == null) // ok, now try the context classloader
            is = getInputStreamFromClassLoader(Thread.currentThread().getContextClassLoader(), resource);
        if (is == null) // finally try the system classloader though if we're here we're probably screwed
            is = getInputStreamFromClassLoader(ClassLoader.getSystemClassLoader(), resource);

        return is;
    }

    private static InputStream getInputStreamFromClassLoader(ClassLoader loader, String resource) {
        InputStream is = loader.getResourceAsStream(resource);
        if (is == null)
            is = loader.getResourceAsStream("/" + resource);

        return is;
    }
}