Java GzipInputStream转换为DataInputStream

Question

我在JavaGZip有一个问题。目前我处理的文件是gzip压缩的。一个gzip存档中的一个文件。如果我手动解压它们，然后解析它们，一切都可以工作。但我想用Java和GZipInputStream自动执行此操作，但它不起作用。我需要在最后有DataInputStream。我的代码是：

    byte[] bytesArray = Files.readAllBytes(baseFile.toPath());

    try {
        reader = new DataInputStream(new GZIPInputStream(new ByteArrayInputStream(bytesArray)));
        System.out.println("gzip");
    } catch (ZipException notZip) {
        reader = new DataInputStream(new ByteArrayInputStream(bytesArray));
        System.out.println("no gzip");
    }

我还尝试了新的GZIPInputStream（新的FileInputStream（baseFile））；结果是一样的。由于输出，我看到Gzip流无一例外地创建，但后来我从DataInputStream获得了无效数据。请帮助：）

Answer 1

我的最终解决方案：

    try {
        byte[] gzipBytes = new byte[getUncompressedFileSize()];
        new DataInputStream(new GZIPInputStream(new FileInputStream(baseFile))).readFully(gzipBytes);
        reader = new DataInputStream(new ByteArrayInputStream(gzipBytes));
    } catch (ZipException notZip) {
        byte[] bytesArray = Files.readAllBytes(baseFile.toPath());
        reader = new DataInputStream(new ByteArrayInputStream(bytesArray));
    }

private int getUncompressedFileSize() throws IOException {
    //last 4 bytes of file is size of original file if it is less than 2GB
    RandomAccessFile raf = new RandomAccessFile(baseFile, "r");
    raf.seek(raf.length() - 4);
    int b4 = raf.read();
    int b3 = raf.read();
    int b2 = raf.read();
    int b1 = raf.read();
    int val = (b1 << 24) | (b2 << 16) + (b3 << 8) + b4;
    raf.close();
    return val;
}

Answer 2

我毫无问题地运行了以下代码

public static void main(String[] args) throws IOException {
    byte[] originalBytesArray = Files.readAllBytes(new File("OrdLog.BR-1.17.2016-09-12.bin").toPath());
    byte[] bytesArray = Files.readAllBytes(new File("OrdLog.BR-1.17.2016-09-12.bin.gz").toPath());
    DataInputStream reader = null;
    try {
        reader = new DataInputStream(new GZIPInputStream(new ByteArrayInputStream(bytesArray)));
        System.out.println("gzip");
    } catch (ZipException notZip) {
        reader = new DataInputStream(new ByteArrayInputStream(bytesArray));
        System.out.println("no gzip");
    }
    byte[] uncompressedBytesArray = new byte[originalBytesArray.length];
    reader.readFully(uncompressedBytesArray);
    reader.close();
    boolean filesDiffer = false;
    for (int i = 0; i < uncompressedBytesArray.length; i++) {
        if (originalBytesArray[i] != uncompressedBytesArray[i]) {
            filesDiffer = true;
        }
    }
    System.out.println("Files differ: " + filesDiffer);
}

它读取gzip文件和未压缩文件并比较内容。它打印文件不同：false。如果它不适用于您的文件，则文件不相同。