使用nio2 (Java 7+)，不使用外部库:

byte[] b = Files.readAllBytes(Paths.get("/path/to/file"));
byte[] hash = MessageDigest.getInstance("MD5").digest(b);

将结果与期望的校验和进行比较:

String expected = "2252290BC44BEAD16AA1BF89948472E8";
String actual = DatatypeConverter.printHexBinary(hash);
System.out.println(expected.equalsIgnoreCase(actual) ? "MATCH" : "NO MATCH");

好的。对于那些已经有Spring和Apache Commons依赖关系或计划添加它的人，我必须添加。

DigestUtils.md5DigestAsHex(FileUtils.readFileToByteArray(file))

对于和Apache共享的唯一选项(credit @duleshi):

DigestUtils.md5Hex(FileUtils.readFileToByteArray(file))

希望这能帮助到一些人。

使用Apache Commons Codec库中的DigestUtils:

try (InputStream is = Files.newInputStream(Paths.get("file.zip"))) {
    String md5 = org.apache.commons.codec.digest.DigestUtils.md5Hex(is);
}

谷歌guava提供了一个新的API。找到下面的一个:

public static HashCode hash(File file,
            HashFunction hashFunction)
                     throws IOException

Computes the hash code of the file using hashFunction.

Parameters:
    file - the file to read
    hashFunction - the hash function to use to hash the data
Returns:
    the HashCode of all of the bytes in the file
Throws:
    IOException - if an I/O error occurs
Since:
    12.0

public static String getMd5OfFile(String filePath)
{
    String returnVal = "";
    try 
    {
        InputStream   input   = new FileInputStream(filePath); 
        byte[]        buffer  = new byte[1024];
        MessageDigest md5Hash = MessageDigest.getInstance("MD5");
        int           numRead = 0;
        while (numRead != -1)
        {
            numRead = input.read(buffer);
            if (numRead > 0)
            {
                md5Hash.update(buffer, 0, numRead);
            }
        }
        input.close();

        byte [] md5Bytes = md5Hash.digest();
        for (int i=0; i < md5Bytes.length; i++)
        {
            returnVal += Integer.toString( ( md5Bytes[i] & 0xff ) + 0x100, 16).substring( 1 );
        }
    } 
    catch(Throwable t) {t.printStackTrace();}
    return returnVal.toUpperCase();
}

有一个输入流装饰器，java。security。DigestInputStream，这样您就可以像往常一样在使用输入流时计算摘要，而不必对数据进行额外的传递。

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();