Java：无法解压 gzip 压缩文件？

Question

我正在尝试解压缩已作为字符串读入内存的 gzip 文件内容。

    /**
     * Read file content into a String
     */
    private static String readUsingFileInputStream(String fileName) {
        FileInputStream fis = null;
        byte[] buffer = new byte[10];
        StringBuilder sb = new StringBuilder();
        try {
            fis = new FileInputStream(fileName);


            while (fis.read(buffer) != -1) {
                sb.append(new String(buffer));
                buffer = new byte[10];
            }
            fis.close();

        } catch (IOException e) {
            //...
        return sb.toString();
    }

    /**
     * Unzip file content
     */
    public static String unzip(final byte[] compressed) {
        try (final GZIPInputStream gzipInput = new GZIPInputStream(new ByteArrayInputStream(compressed));
            final StringWriter stringWriter = new StringWriter()) {
            IOUtils.copy(gzipInput, stringWriter, UTF_8);
            return stringWriter.toString();
        } catch (IOException e) {
            throw new UncheckedIOException("Error while decompression!", e);
        }
    }

然后在我的

main

方法中，我正在做：

String compressedData = readUsingFileInputStream("/path/to/my/compressed_file_json.gz");
System.out.println(unzip(compressedData.getBytes(UTF_8)));

但是我收到以下错误：

java.util.zip.ZipException: Not in GZIP format
    at java.base/java.util.zip.GZIPInputStream.readHeader(GZIPInputStream.java:166)
    at java.base/java.util.zip.GZIPInputStream.<init>(GZIPInputStream.java:80)
    at java.base/java.util.zip.GZIPInputStream.<init>(GZIPInputStream.java:92)

我做错了什么？我已经验证该文件实际上是 GZIP 格式并且没有损坏。

注意：我知道我可以直接在 GZIPInputStream 中输入 FileInputStream，但出于实际问题的目的，我无法访问 FileInputStream，只是生成字符串。

Answer 1

“...我做错了什么？我已经验证该文件实际上是 GZIP 格式并且没有损坏。...”

从 readUsingFileInputStream 返回一个 字节数组，并使用 String 构造函数 创建一个 UTF-8 值。

/**
 * Read file content into a String
 */
private static byte[] readUsingFileInputStream(String fileName) throws IOException {
    try (FileInputStream fis = new FileInputStream(fileName)) {
        return fis.readAllBytes();
    }
}

/**
 * Unzip file content
 */
public static String unzip(final byte[] compressed) throws IOException {
    try (final GZIPInputStream gzipInput = new GZIPInputStream(new ByteArrayInputStream(compressed))) {
        return new String(gzipInput.readAllBytes(), StandardCharsets.UTF_8);
    }
}

示例

byte[] compressedData = readUsingFileInputStream("/path/to/my/compressed_file_json.gz");
System.out.println(unzip(compressedData));