可以以编程方式更新Jar文件而无需重写整个文件吗？ [英] Can a Jar File be updated programmatically without rewriting the whole file?

问题描述

可以使用 jar 命令更新JAR文件中的单个文件，如下所示：

It is possible to update individual files in a JAR file using the jar command as follows:

jar uf TicTacToe.jar images/new.gif

是否有以编程方式执行此操作的方法？

Is there a way to do this programmatically?

如果我使用 JarOutputStream ，我必须重写整个jar文件，所以我是想知道是否有类似的随机访问方式来做到这一点。鉴于可以使用 jar 工具完成，我原本预计会有类似的方式以编程方式完成。

I have to rewrite the entire jar file if I use JarOutputStream, so I was wondering if there was a similar "random access" way to do this. Given that it can be done using the jar tool, I had expected there to be a similar way to do it programmatically.

推荐答案

可以使用 Zip文件系统提供程序：

import java.util.*;
import java.net.URI;
import java.nio.file.Path;
import java.nio.file.*;

public class ZipFSPUser {
    public static void main(String [] args) throws Throwable {
        Map<String, String> env = new HashMap<>(); 
        env.put("create", "true");
        // locate file system by using the syntax 
        // defined in java.net.JarURLConnection
        URI uri = URI.create("jar:file:/codeSamples/zipfs/zipfstest.zip");

       try (FileSystem zipfs = FileSystems.newFileSystem(uri, env)) {
            Path externalTxtFile = Paths.get("/codeSamples/zipfs/SomeTextFile.txt");
            Path pathInZipfile = zipfs.getPath("/SomeTextFile.txt");          
            // copy a file into the zip file
            Files.copy( externalTxtFile,pathInZipfile, 
                    StandardCopyOption.REPLACE_EXISTING ); 
        } 
    }
}

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