如何将jar中的文件复制到jar中？

首先，我想说的是，之前发布的一些答案是完全正确的，但是我想告诉我，因为有时我们不能在GPL下使用开放源代码库，或者因为我们懒得下载jar XD或其他文件无论您的理由在哪里，都是独立的解决方案。

下面的函数将资源复制到Jar文件旁边：

  /**
     * Export a resource embedded into a Jar file to the local file path.
     *
     * @param resourceName ie.: "/SmartLibrary.dll"
     * @return The path to the exported resource
     * @throws Exception
     */
    static public String ExportResource(String resourceName) throws Exception {
        InputStream stream = null;
        OutputStream resStreamOut = null;
        String jarFolder;
        try {
            stream = ExecutingClass.class.getResourceAsStream(resourceName);//note that each / is a directory down in the "jar tree" been the jar the root of the tree
            if(stream == null) {
                throw new Exception("Cannot get resource \"" + resourceName + "\" from Jar file.");
            }

            int readBytes;
            byte[] buffer = new byte[4096];
            jarFolder = new File(ExecutingClass.class.getProtectionDomain().getCodeSource().getLocation().toURI().getPath()).getParentFile().getPath().replace('\\', '/');
            resStreamOut = new FileOutputStream(jarFolder + resourceName);
            while ((readBytes = stream.read(buffer)) > 0) {
                resStreamOut.write(buffer, 0, readBytes);
            }
        } catch (Exception ex) {
            throw ex;
        } finally {
            stream.close();
            resStreamOut.close();
        }

        return jarFolder + resourceName;
    }

只需将ExecutingClass更改为您的类的名称，然后像这样调用它：

String fullPath = ExportResource("/myresource.ext");

为Java 7+编辑（为了您的方便）

正如GOXR3PLUS回答并由Andy Thomas指出的那样，您可以使用以下方法实现此目标：

Files.copy( InputStream in, Path target, CopyOption... options)

有关更多详细信息，请参见GOXR3PLUS答案