Main.java

package org.codehaus.mojo.animal_sniffer;

/*
 * The MIT License
 *
 * Copyright (c) 2008 Kohsuke Kawaguchi and codehaus.org.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

import java.io.DataInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * @author Kohsuke Kawaguchi
 */
public class Main
    extends ClassFileVisitor
{
    private boolean humanReadableName = false;

    private String maximumVersion = "00.0";

    public static void main( String[] args )
        throws IOException
    {
        if ( args.length == 0 )
        {
            System.err.println( "Usage: java -jar animal-sniffer.jar [JAR/CLASS FILES]" );
            System.err.println("  -h   : show a human readable Java version number");
            System.err.println("  -t N : return exit code 1 if any file has a class file version number > N");
            System.exit( -1 );
        }

        Main m = new Main();
        String threshold = null;

        List files = new ArrayList();
        for ( int i = 0; i < args.length; i++ )
        {
            if (args[i].equals("-h"))
            {
                m.humanReadableName = true;
                continue;
            }
            if (args[i].equals("-t"))
            {
                threshold = args[++i];
                for (Iterator j=HUMAN_READABLE_NAME.entrySet().iterator(); j.hasNext(); )
                {
                    Map.Entry v = ((Map.Entry)j.next());
                    if (v.getValue().equals(threshold))
                    {
                        threshold = (String)v.getKey();
                        break;
                    }
                }
                continue;
            }

            files.add(new File(args[i]));
        }

        for (int i = 0; i < files.size(); i++)
        {
            m.process((File) files.get(i));
        }

        if (threshold!=null && m.maximumVersion.compareTo(threshold)>0)
            System.exit(1);
    }

    protected void process( String name, InputStream image )
        throws IOException
    {
        DataInputStream dis = new DataInputStream( image );
        byte[] buf = new byte[8];
        dis.readFully( buf );

        String v = u2(buf[6], buf[7]) + "." + u2(buf[4], buf[5]);
        if (maximumVersion.compareTo(v)<0)
        {
            maximumVersion = v;
        }

        if (humanReadableName)
        {
            String hn = (String)HUMAN_READABLE_NAME.get(v);
            if (hn!=null)   v = hn;
        }

        System.out.println( v + " " + name );
    }

    private static int u2( byte u, byte d )
    {
        return ( (int) u ) * 256 + d;
    }

    private static final Map HUMAN_READABLE_NAME = new HashMap();

    static
    {
        HUMAN_READABLE_NAME.put("45.0","Java1");
        HUMAN_READABLE_NAME.put("46.0","Java2");
        HUMAN_READABLE_NAME.put("47.0","Java3");
        HUMAN_READABLE_NAME.put("48.0","Java4");
        HUMAN_READABLE_NAME.put("49.0","Java5");
        HUMAN_READABLE_NAME.put("50.0","Java6");
    }
}