如何找到已编译类的目标 Java 版本?
读取和显示 Java .class 版本的工具
如果我有一个已编译的 Java 类，有没有办法仅从类文件中判断它的目标版本兼容性是什么?具体来说，我有许多类文件，编译为 Java 6，它们在 Java 5 下运行并给出无法识别的版本".错误.我希望能够在不运行 JVM 的情况下查看类文件并找到其目标版本兼容性.有什么想法吗?
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，它可以工作.
I've found this on the net and it works.
每个.class"文件都以以下:
Every '.class' file starts off with the following:
- 幻数 [4 字节]
- 版本信息 [4 字节]
已编译的.class"文件的十六进制转储使用以下每个选项揭示:
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 2Djavac -target 1.2 ==> CA FE BA BE 00 00 00 2Ejavac -target 1.3 ==> CA FE BA BE 00 00 00 2Fjavac -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
也许您可以使用此信息编写自己的.class"文件版本检查实用程序，使用 Java，或者可能是脚本或外壳语言 ;) ！
Perhaps you could use this information to write your own '.class' file version checking utility, using Java, or perhaps a scripting or shell language ;) !
我希望这会有所帮助.
安东尼·博拉
来自:http://bytes.com/groups/java/16603-how-determine-java-bytecode-version
相关文章