java - 如何根据GZIP的压缩字节数组得到原数组的长度？

Question

在解压GZIP压缩的数组之前，我想知道原始数组的长度，以便申请合适的缓冲区数组。例如下面代码中的“1024”。谢谢!

        byte[] buffer = new byte[1024];
        ByteArrayOutputStream out = new ByteArrayOutputStream(1024);
        try (ByteArrayInputStream bin = new ByteArrayInputStream(localByteBuf);
             GZIPInputStream gis = new GZIPInputStream(bin)) {
            int len;
            while ((len = gis.read(buffer)) > 0) {
                out.write(buffer, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

Answer 1

ByteArrayOutputStream 将负责内部 byte[] 数组的增长。根据类 javadoc:

This class implements an output stream in which the data is written into a byte array. The buffer automatically grows as data is written to it.

您很可能希望使用 InputStream.transferTo() 复制流使代码更具可读性:

ByteArrayOutputStream out = new ByteArrayOutputStream(); // default 32 size
GZIPInputStream in = new GZIPInputStream(
        new ByteArrayInputStream(localByteBuf)));
in.transferTo(out);