eclipse背后的魔力生成了可执行的jar文件 [英] The magic behind the eclipse generated executable jar file

问题描述

我可以用Eclipse制作一个可执行的jar文件。假设它叫做 ast.jar ，而Main类是ASTExplorer。我可以验证这适用于 java -jar ast.jar 。

I can make a executable jar file with Eclipse. Let's say it is called ast.jar, and the Main class is ASTExplorer. I can verify that this works with java -jar ast.jar.

然后，我将jar文件解压缩到一个单独的目录中，并验证ASTExplorer是否位于astexplorer目录中。但是当我执行这个命令 java -cp时。 astexplorer.ASTExplorer 我收到此错误。

Then, I unzip the jar file in a separate directory and verify that the ASTExplorer is in astexplorer directory. But when I executed this command java -cp . astexplorer.ASTExplorer I get this error.

java -cp . astexplorer/ASTExplorer
Exception in thread "main" java.lang.NoClassDefFoundError: org/eclipse/swt/widgets/Composite
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)

问题是jar文件中没有org / eclipse / swt目录。

The thing is that there is no org/eclipse/swt directory in the jar file.

可执行jar文件背后的魔力是什么？解压缩时为什么不运行？

What's the magic behind the executable jar file? Why doesn't it run when unzipped?

推荐答案

当Eclipse打包一个可运行的jar时，它包含作为嵌套jar文件的依赖项，还包括一个特殊的类加载器，它可以理解如何在嵌套的jar中查找类。它仅适用于嵌套的jar，当你提取所有东西时，它阻止它工作。

When Eclipse packages a runnable jar, it includes the dependencies as nested jar files, and also includes a special classloader that understands how to find classes in nested jars. It works only with nested jars and when you extract everything you prevent it from working.

我看过Eclipse生产的可运行jar，这就是我认为你需要做的事情：

I've looked in an Eclipse-produced runnable jar, and here's what I think you'd need to do:

1. 将所有内容解压缩到目录。依赖关系jar在顶级目录中提取


2. 删除org / eclipse / jdt / internal目录



3. 从顶级目录运行你的主类

1. Extract everything to a directory. The dependency jars are extracted at the top level directory
2. Delete the org/eclipse/jdt/internal directory

3. Run your main class from the top level directory with

java -cp .; dep-jar; dep-jar; ...你的.main.class

我用可运行的罐子试过这个我碰巧躺着周围，​​它的工作原理。第2步并非绝对必要。

I tried this with a runnable jar I happen to have lying around and it works. Step 2 isn't strictly necessary.

这篇关于eclipse背后的魔力生成了可执行的jar文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！