如果你想知道Java编译器是如何做某些事情的，你不想要反编译，你想要的是反汇编。反编译涉及到将字节码转换为Java源代码，这意味着会丢失大量低级信息，如果您想了解编译器优化，那么这可能正是您感兴趣的信息。

不管怎样，我碰巧写了一个开源Java反汇编程序。与Javap不同的是，这甚至适用于高度病态的类，因此您可以看到混淆工具对您的类做了什么。它还可以进行反编译，尽管我不推荐这样做。

我使用JAD反编译器。

它有一个Eclipse插件jadeclipse。它很漂亮。

我尝试了几种，Procyon似乎最适合我。它正在积极开发中，支持最新版本Java的许多特性。

以下是我尝试过的其他方法:

CFR Promising, but often failed method decompilation. I'll be keeping my eye on this one. Also actively developed with support for the latest Java features. Krakatau Takes a different approach in that it tries to output equivalent Java code instead of trying to reconstruct the original source, which has the potential of making it better for obfuscated code. From my testing it was roughly on par with Procyon, but still nice to have something different. I did have to use the -skip command-line flag so it wouldn't stop on errors. Actively developed, and interestingly enough it's written in Python. JD-GUI Worked, but Procyon's output was much better. Here's a page comparing Procyon output to the original and JD-GUI. JD-GUI is also available as an Eclipse plugin, which didn't work for me at all. Doesn't seem to be open source and development seems sporadic. JAD Worked, but only supports Java 1.4 and below. Also available as an Eclipse plugin. No longer under development.

大多数Java反编译器都是基于JAD的。这是一个很棒的工具，但不幸的是，它已经有一段时间没有更新了，并且不能很好地处理Java 1.5+类。我还没有看到任何能够正确处理1.5+类的工具。

看看卡瓦伊。

使用AndroChef Java反编译器，您可以反编译apk, dex, jar和Java类文件。这很简单。AndroChef JD基于FernFlower。你可以在10次免费使用中评估它。

AndroChef支持Java语言特性，如泛型、枚举和注释。根据一些研究，AndroChef Java Decompiler能够反编译98.04%的由传统Java编译器生成的Java应用程序——一个非常高的回收率。它是一个简单但功能强大的工具，允许您将Java和Dalvik字节码(DEX, APK)反编译为可读的Java源代码。