给定特定路径的jar文件的内容 [英] Read contents of jar file given specific path

问题描述

我有一个名为san.jar的jar文件，其中包含各种文件夹，如类，资源等，
比如说我有一个像资源/资产/图像这样的文件夹结构有各种各样的图像，我没有任何关于它们的信息，如图像的名称或文件夹下的图像数量，因为jar文件是私有的，我不允许解压缩jar。

I have a jar file named "san.jar" with various folders like "classes", "resources", etc., Say for e.g i have a folder structure like "resources/assets/images" under which there are various images which I do not have any information about them like name of the images or number of images under the folder as the jar file is private and I am not allowed to unzip the jar.

目标：我需要获取给定路径下的所有文件而不迭代整个jar文件。

OBJECTIVE: I need to get all the files under the given path without iterating over the whole jar file.

现在我正在做的是遍历每个条目，每当我遇到.jpg文件时，我都会执行一些操作。
这里只读资源/资产/图像，我正在遍历整个jar文件。

Right now what I am doing is iterating through each and every entry and whenever i come across .jpg file, I perform some operation. Here for reading just the "resources/assets/images", I am iterating through the whole jarfile.

JarFile jarFile = new JarFile("san.jar");  
for(Enumeration em = jarFile.entries(); em.hasMoreElements();) {  
                String s= em.nextElement().toString();  
                if(s.contains("jpg")){  
                   //do something  
                }  
 }  

现在我正在做的是遍历每个条目，每当我遇到.jpg文件时，我都会执行一些操作。
这里只读资源/资产/图像，我正在遍历整个jar文件。

Right now what I am doing is iterating through each and every entry and whenever i come across .jpg file, I perform some operation. Here for reading just the "resources/assets/images", I am iterating through the whole jarfile.

推荐答案

使用Java 8和文件系统现在非常简单，

With Java 8 and filesystems it is pretty easy now,

Path myjar;
try (FileSystem jarfs = FileSystems.newFileSystem(myjar, null)) {
   Files.find(jarfs.getPath("resources", "assets", "images"), 
              1, 
              (path, attr) -> path.endsWith(".jpg"),
              FileVisitOption.FOLLOW_LINKS).forEach(path -> {
            //do something with the image.
    });
}

Files.find只会搜索提供的路径，达到所需的深度。

Files.find will only search the provided path up the the desired depth.

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