在 Java 中获取文件的 MD5 校验和 [英] Getting a File's MD5 Checksum in Java

问题描述

我希望使用 Java 来获取文件的 MD5 校验和.我真的很惊讶，但我找不到任何显示如何获取文件的 MD5 校验和的内容.

I am looking to use Java to get the MD5 checksum of a file. I was really surprised but I haven't been able to find anything that shows how to get the MD5 checksum of a file.

是怎么做的?

推荐答案

有一个输入流装饰器，java.security.DigestInputStream，这样你就可以在使用输入流的同时计算摘要通常会，而不必对数据进行额外的传递.

There's an input stream decorator, java.security.DigestInputStream, so that you can compute the digest while using the input stream as you normally would, instead of having to make an extra pass over the data.

MessageDigest md = MessageDigest.getInstance("MD5");
try (InputStream is = Files.newInputStream(Paths.get("file.txt"));
     DigestInputStream dis = new DigestInputStream(is, md)) 
{
  /* Read decorated stream (dis) to EOF as normal... */
}
byte[] digest = md.digest();

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