使用DigestInputStream计算来自同一InputStream的多个校验和 [英] Calculate multiple checksums from the same InputStream using DigestInputStream

问题描述

我试图找出如何使用 DigestInputStream InputStream 读取多个摘要（md5，sha1，gpg） C $ C>。根据我在文档中检查的内容，似乎可以通过克隆摘要来实现。有人可以说明一下吗？

I am trying to figure out how to read multiple digests (md5, sha1, gpg) based on the same InputStream using DigestInputStream. From what I've checked in the documentation, it seems to be possible by cloning the digest. Could somebody please illustrate this?

我不想重新读取流来计算校验和。

I don't want to be re-reading the stream in order to calculate the checksums.

推荐答案

您可以围绕 DigestInputStream 包装 DigestInputStream 所以递归：

You could wrap a DigestInputStream around a DigestInputStream and so on recursively:

DigestInputStream shaStream = new DigestInputStream(
    inStream, MessageDigest.getInstance("SHA-1"));
DigestInputStream md5Stream = new DigestInputStream(
    shaStream, MessageDigest.getInstance("MD5"));
// VERY IMPORTANT: read from final stream since it's FilterInputStream
byte[] shaDigest = shaStream.getMessageDigest().digest();
byte[] md5Digest = md5Stream.getMessageDigest().digest();

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