How to unzip files stored in HDFS using Java, with

问题:

We are storing zip files, containing XML files, in HDFS. We need to be able to programmatically unzip the file and stream out the contained XML files, using Java. FileSystem.open returns a FSDataInputStream but ZipFile constructors only take File or String as parameters. I really don't want to have to use FileSystem.copyToLocalFile.

Is it possible to stream the contents of a zip file stored in HDFS without first copying the zip file to the local file system? If so how?

回答1:

Hi Please find the sample code,

public static Map<String, byte[]> loadZipFileData(String hdfsFilePath) {
            try {
                ZipInputStream zipInputStream = readZipFileFromHDFS(new Path(hdfsFilePath));
                ZipEntry zipEntry = null;
                byte[] buf = new byte[1024];
                Map<String, byte[]> listOfFiles = new LinkedHashMap<>();
                while ((zipEntry = zipInputStream.getNextEntry()) != null ) {
                    int bytesRead = 0;
                    String entryName = zipEntry.getName();
                    if (!zipEntry.isDirectory()) {
                        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
                        while ((bytesRead = zipInputStream.read(buf, 0, 1024)) > -1) {
                            outputStream.write(buf, 0, bytesRead);
                        }
                        listOfFiles.put(entryName, outputStream.toByteArray());
                        outputStream.close();
                    }
                    zipInputStream.closeEntry();
                }
                zipInputStream.close();
                return listOfFiles;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }



protected ZipInputStream readZipFileFromHDFS(FileSystem fileSystem, Path path) throws Exception {
    if (!fileSystem.exists(path)) {
        throw new IllegalArgumentException(path.getName() + " does not exist");
    }
    FSDataInputStream fsInputStream = fileSystem.open(path);
    ZipInputStream zipInputStream = new ZipInputStream(fsInputStream);
    return zipInputStream;
}