jar文件到底包含什么？ [英] What exactly does a jar file contain?

问题描述

作为实习生，我在我的项目中使用公司代码，他们通常会向我发送 jar 文件。我将它添加到 Eclipse 中的构建路径，通常一切都很好，花花公子。

然而，我很想知道每个类包含什么，当我尝试打开 jar 文件中的一个类时，它告诉我我需要一个源文件。

这是什么意思？我来自 C / C ++ 背景，所以 jar 类似于已编译的 .o 文件，我能看到的只是 .h 的东西？或者我使用的 jar 文件中是否存在加密的实际代码，因此我无法读取它？

<感谢所有答案！

编辑：
谢谢，伙计们，我知道这有点像档案但我很困惑为什么当我试图打开 .class 文件时，我得到了一堆随机字符。当我尝试在C中打开 .o 文件时，输出类似，所以我只是想确定。

谢谢！

解决方案

JAR文件实际上只是一个ZIP文件。它可以包含任何东西 - 通常它包含已编译的Java代码（* .class），但有时也包含Java源代码（* .java）。

但是，Java可以被反编译 - 如果开发人员混淆了他的代码，你将无法获得任何有用的类/函数/变量名称。

As an intern, I use company code in my projects and they usually send me a jar file to work with. I add it to the build path in Eclipse and usually all is fine and dandy.

However, I got curious to know, what each class contained and when I try to open one of the classes in the jar file, it tells me that I need a source file.

What does this mean? I come from a C/C++ background so is a jar similar to an already compiled .o file and all I can see is the .h stuff? Or is there actual code in the jar file that I'm using that's encrypted so I can't read it?

Thanks for all the answers!

Edit:
Thanks, guys, I knew it was a sort of like an archive but I was confused to why when I tried to open the .class files, I got a bunch of random characters. The output was similar when I tried to open a .o file in C so I just wanted to make sure.
Thanks!

解决方案

A JAR file is actually just a ZIP file. It can contain anything - usually it contains compiled Java code (*.class), but sometimes also Java sourcecode (*.java).

However, Java can be decompiled - in case the developer obfuscated his code you won't get any useful class/function/variable names though.

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