如何将新的java类添加到jar文件中的现有类

Question

I created new modules for software written in java. This software is run from jar file.My classes are extending the classes in this software. I want to write a plugin which adds new classes to the jar file. I know how to extract a jar file to the directory and add them to the jar file using java.util.jar package but as there are a lot of files to extract from the file, is it possible to add new classes without extracting the files to the folder, somehow directly.

Answer 1

您可以使用以下命令

jar uf foo.jar foo.class

Answer 2

Your question indicates that you want to do this programmatically, not using the command-line jar tool.

From the docs it appears that you'll at least need to get a JarInputStream from an existing JarFile , iterate over the entries using getNextJarEntry , and write to a JarOutputStream with the entries, also adding your own new files using new JarEntry objects for each new file.

Here's sample code for writing a jar from scratch programmatically, this should extend nicely to your case, the difference being that most of the JarEntry objects will be coming from a JarInputStream .

Answer 3

jar uf jar-file input-file(s)

将允许在jar中添加新文件/更新现有文件而不提取。