Java：如何从资源复制文件夹并复制到临时目录？

Question

Project structure:

src
|
|--resource
    |
    |--PMD
        |-pmd-bin
            |-test.bat
        |-report
            |-report.xml
    |
    |--staticresource

Using maven-assembly plugin, I am including the resources in the jar file.

As PMD folder will be used by the applcaition, I would like to create a copy of the PMD folder in the temp directory, so that I can start reading the bat files and other files from that temp directory.

ISSUE

When the jar loads, it fails to read the PMD folder inside resource.

Tried:

        InputStream pmdFolder = classLoader.getResourceAsStream("PMD");
        InputStreamReader isr = new InputStreamReader(pmdFolder, StandardCharsets.UTF_8);
        BufferedReader br = new BufferedReader(isr);
        List<URL> collect = br.lines().map(l -> "PMD" + "/" + l)
                .map(r -> classLoader.getResource(r))
                .collect(toList());
        Path tempPMDFolder = null;
        Path pmd = Files.createTempDirectory("PMD");
        for (URL url : collect) {
            System.out.println(url.toString());
            createSameTempStructure(url, pmd);
        }

private static void createSameTempStructure(URL url, Path pmd) throws IOException {
    //tempPMDFolder.toFile().deleteOnExit();
    try(final InputStream is = url.openStream()) {
        File file = FileUtils.toFile(url);
        System.out.println("file -> "+file.getName());
        if(file.isDirectory()){
            Path tempPMDFolder = createTempPMDFolder(pmd, file.getName());
            System.out.println("tempPMDFolder -> "+tempPMDFolder.toString());
            FileUtils.copyDirectory(file, tempPMDFolder.toFile());
        } else {
            try (OutputStream outputStream = new FileOutputStream(file)) {
                IOUtils.copy(is, outputStream);
            } catch (IOException e) {
                System.out.println(e.getMessage());
            }
        }
    }
}

Here it just creates the PMD folder in temp directory and nothing, inner files and folders are not copied. Any way we can achieve this?

Answer 1

Here is what I came up with.

Converted the folder to zip and put that zipped file in resources. As inputstream can only read through a file.

InputStream pmdFolder = classLoader.getResourceAsStream("PMD.zip");
Path tempPMDDirectory = Files.createTempDirectory("PMD");

Then extracted the zip contents to the temp directory and then using that overall application.

if (pmdFolder != null) {
    try (ZipInputStream zipInputStream = new ZipInputStream(pmdFolder)) {
        // Extract the zip contents and keep in temp directory
        extract(zipInputStream, tempPMDDirectory.toFile());
    }
}
public static void extract(ZipInputStream zip, File target) throws IOException {
    try {
        ZipEntry entry;

        while ((entry = zip.getNextEntry()) != null) {
            File file = new File(target, entry.getName());

            if (!file.toPath().normalize().startsWith(target.toPath())) {
                throw new IOException("Bad zip entry");
            }

            if (entry.isDirectory()) {
                file.mkdirs();
                continue;
            }

            byte[] buffer = new byte[BUFFER_SIZE];
            file.getParentFile().mkdirs();
            BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(file));
            int count;

            while ((count = zip.read(buffer)) != -1) {
                out.write(buffer, 0, count);
            }

            out.close();
        }
    } finally {
        zip.close();
    }
}