如何找到编译类的目标Java版本？ [英] How can I find the target Java version for a compiled class?

问题描述

读取和显示Java .class版本的工具

一个编译的Java类，有没有办法从类文件告诉它的目标版本兼容性是什么？具体来说，我有一些类文件，编译为Java 6，它们运行在Java 5下，并给出无法识别的版本的错误。我想能够查看一个类文件，并找到它的目标版本兼容性是没有运行JVM。任何想法？

If I have a compiled Java class, is there a way to tell from just the class file what its target version compatibility is? Specifically, I have a number of class files, compiled to Java 6, which are running under Java 5 and giving the the "Unrecognized version" error. I want to be able to look at a class file and find what its target version compatibility is without running the JVM. Any ideas?

推荐答案

我在网上找到了这个网址，它的工作原理。

I've found this on the net and it works.

每个'.class'文件以
开头如下：

Every '.class' file starts off with the following:

• 魔术数字[4字节]


• 版本信息[4字节]

'.class'文件编译
与以下每个选项
显示：

A hexdump of a '.class' file compiled with each of the following options reveals:

javac -target 1.1 ==> CA FE BA BE 00 03 00 2D

javac -target 1.2 ==> CA FE BA BE 00 00 00 2E

javac -target 1.3 ==> CA FE BA BE 00 00 00 2F

javac -target 1.4 == > CA FE BA BE 00 00 00 30

javac -target 1.1 ==> CA FE BA BE 00 03 00 2D
javac -target 1.2 ==> CA FE BA BE 00 00 00 2E
javac -target 1.3 ==> CA FE BA BE 00 00 00 2F
javac -target 1.4 ==> CA FE BA BE 00 00 00 30

也许您可以使用这个资讯
自己的'.class'文件
版本检查实用程序，使用Java，
或者可能是脚本或shell
语言;）

Perhaps you could use this information to write your own '.class' file version checking utility, using Java, or perhaps a scripting or shell language ;) !

我希望这有助于。

Anthony Borla

Anthony Borla

From： http://bytes.com/groups/java/16603-how-determine -java-bytecode-version

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