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137 lines
5.1 KiB
137 lines
5.1 KiB
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN">
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<html>
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<head>
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<title>Java Optimize and Decompile Environment (JODE)</title>
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<meta name="description" content="The home page of jode, my Java decompiler.">
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<meta name="author" content="Jochen Hoenicke">
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<meta name="keywords" content="jode, java, decompile, decompiler,
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java-decompiler, reverse engineering, free, GPL">
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<meta name="robots" content="index">
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<meta name="robots" content="nofollow">
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<meta name="date" content="2000-01-24">
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</head>
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<body>
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<table cellpadding=4 cellspacing=1 width=100%>
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<tr>
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<td></td>
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<td> <img src="jode-logo.gif" alt="JODE" width=286 height=110></td>
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</tr>
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<tr>
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<td valign="top">
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<B><a href="http://www.informatik.uni-oldenburg.de/~delwi">Homepage</a></B>
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<br><br>
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<a
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href="http://www.informatik.uni-oldenburg.de/~delwi/jode/jode.html">
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<B>Jode (WWW)</B></a>
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<ul>
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<li><a href="applet.html">Test It Online</a></li>
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<li><a href="download.html">Download</a></li>
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<li><a href="usage.html">Usage</a></li>
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<li><a href="license.html">License</a></li>
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<li><a href="history.html">History</a></li>
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<li><a href="links.html">Links</a></li>
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<li><a href="bluesky.html">Blue Sky</a></li>
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</ul>
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</td>
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<td>
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<P><i>JODE</i> is a java package containing a decompiler and an
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optimizer (aka obfuscator ;-) for java. This package was totally
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written in my spare time and is available for free (see <a
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href="license.html">license</a>).<p>
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<P>The decompiler takes <tt>class</tt> files as input and produces
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something similar to the original <tt>java</tt> file. Of course this
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can't be perfect: There is no way to produce the comments or the names
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of local variables (except when compiled with debuging) and there are
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often more ways to write the same thing. But <i>JODE</i> does its job
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quite well, so you should give it a try: <a href="applet.html">start
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the applet</a>.</P>
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<P>The optimizer transforms <tt>class</tt> files in various ways with
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can be controlled by a script file. It supports the following
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operations:</p>
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<ul>
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<li>Renaming class, method, field and local names to shorter or unique
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names or according to a given translation table</li>
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<li>Removing debugging information</li>
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<li>Removing dead code (classes, fields, methods) and constant
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fields</li>
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<li>Optimizing local variable allocation</li>
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</ul>
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<h2>News</h2>
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<ul>
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<li>I can now decompile <b>inner and anonymous</b> classes.</li>
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<li>The optimizer (aka obfuscator) can now be customized via a small
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config file</li>
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<li>Jode is now <tt>autoconf</tt>igured.</li>
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<li>I use the <a href="http://www.urbanophile.com/arenn/hacking/download.html#getopt">getopt</a> package</li>
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</ul>
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<h3>Older News</h3>
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<ul>
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<li>There is a <a href="usage.html#swing">swing</a> interface</li>
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<li>Jode handles zip and jar archives as both input and output.</li>
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</ul>
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<h2>Known Bugs</h2>
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<p>Small bugs, that should be fixed in the next release:</p>
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<ul>
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<li>If there is more than one assignment to a final local variable
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(they can be conditionally, so that only one is actually excuted),
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jode refuses to mark it as final. This can make decompilation of
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method scoped classes wrong. </li>
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<li>There's probably a bug in LocalOptimizer (part of the obfuscator).
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It is triggered very seldom, and may produces incorrect code. If your
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application doesn't work after obfuscation, or is refused by the
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bytecode verifier, try again without the LocalOptimizer. If this was
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the reason send me your class file ;-)
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</li>
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</ul>
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<p>Now follows a list of oddities, that will probably never get
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completely fixed.</p>
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<p>If not all dependent classes can be found, the verifier (which is
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run before decompilation starts) may exit with a type error. You
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can decompile it with <tt>--verify=off</tt>, but take the warning
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serious, that the types may be incorrect. There's sometimes no way
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to guess the right type, if you don't have access the full class
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hierarchie.<br>
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This is not a bug in the verifier: java will complain the same way,
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if it is run with bytecode verification turned on. And if you don't
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have the dependent classes, you can't compile the code again.</p>
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<p>There may be situations, where the code doesn't understand complex
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expressions. In this case many ugly temporary variables are used, but
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the code should still be compileable. This does especially happen
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when you compile with <tt>`-O'</tt> flag and javac has inlined some
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methods. </p>
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<p>Sometimes this program may exit with an <code>Exception</code> or
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produce incorrect code. Most time the code can't be compiled, so that
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it can be easily spotted. If you have one of these problems (except
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those that occur on some of the <code>jode.test</code> files, I would
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be very interested in a bug report (including the <code>class</code>
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file, if possible).</p>
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<p>Sometimes <i>JODE</i> generates some GOTO expression and labels.
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This shouldn't happen any more with code produced by javac or jikes.
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But some flow obfuscator may provoke this. In that case you can run
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the Obfuscator first (to optimize away the flow obfuscation ;-).</p>
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</td>
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</table>
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<hr>
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<p><A HREF="mailto:Jochen.Hoenicke@Informatik.Uni-Oldenburg.DE">
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http://www.informatik.uni-oldenburg.de/~delwi/jode/jode.html</A>, last
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updated on <em>24-Jan-2000</em>.</p>
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</body>
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</html>
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