在Java中获取文件的MD5校验和

有一个输入流装饰器, java.security.DigestInputStream

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();

使用 DigestUtils 从…起 Apache Commons Codec 图书馆:

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

这里有一个例子 Real's Java-How-to MessageDigest 班

检查该页面,查看使用CRC32和SHA-1的示例。

import java.io.*;
import java.security.MessageDigest;

public class MD5Checksum {

   public static byte[] createChecksum(String filename) throws Exception {
       InputStream fis =  new FileInputStream(filename);

       byte[] buffer = new byte[1024];
       MessageDigest complete = MessageDigest.getInstance("MD5");
       int numRead;

       do {
           numRead = fis.read(buffer);
           if (numRead > 0) {
               complete.update(buffer, 0, numRead);
           }
       } while (numRead != -1);

       fis.close();
       return complete.digest();
   }

   // see this How-to for a faster way to convert
   // a byte array to a HEX string
   public static String getMD5Checksum(String filename) throws Exception {
       byte[] b = createChecksum(filename);
       String result = "";

       for (int i=0; i < b.length; i++) {
           result += Integer.toString( ( b[i] & 0xff ) + 0x100, 16).substring( 1 );
       }
       return result;
   }

   public static void main(String args[]) {
       try {
           System.out.println(getMD5Checksum("apache-tomcat-5.5.17.exe"));
           // output :
           //  0bb2827c5eacf570b6064e24e0e6653b
           // ref :
           //  http://www.apache.org/dist/
           //          tomcat/tomcat-5/v5.5.17/bin
           //              /apache-tomcat-5.5.17.exe.MD5
           //  0bb2827c5eacf570b6064e24e0e6653b *apache-tomcat-5.5.17.exe
       }
       catch (Exception e) {
           e.printStackTrace();
       }
   }
}

com.google.common.hash API提供:

• 用于所有哈希函数的统一用户友好API
• 3的可种子32位和128位实现
• md5()、sha1()、sha256()、sha512()适配器,仅更改一行代码以在这些适配器之间切换,并发出杂音。
• goodFastHash(int位),用于不关心使用什么算法的情况
• HashCode实例的通用实用程序,如combineOrdered/CombineNordered

阅读用户指南( IO Explained , Hashing Explained ).

对于您的用例 Files.hash() 计算并返回文件的摘要值。

sha-1 摘要计算(将SHA-1更改为MD5以获得MD5摘要)

HashCode hc = Files.asByteSource(file).hash(Hashing.sha1());
"SHA-1: " + hc.toString();

注意 crc32 md5 ,所以使用 crc32 md5 不应用于存储密码等,因为它很容易暴力使用密码 bcrypt , scrypt 或 sha-256

Merkle signature scheme 欧洲委员会赞助的后量子密码研究小组建议使用这种密码技术对量子计算机进行长期保护( ref ).

注意 crc32 具有比其他类型更高的碰撞率。

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

要将结果与预期校验和进行比较,请执行以下操作:

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

Guava 现在提供了一个新的、一致的哈希API,它比JDK中提供的各种哈希API更加友好。看见 Hashing Explained

HashCode md5 = Files.hash(file, Hashing.md5());
byte[] md5Bytes = md5.asBytes();
String md5Hex = md5.toString();

HashCode crc32 = Files.hash(file, Hashing.crc32());
int crc32Int = crc32.asInt();

// the Checksum API returns a long, but it's padded with 0s for 32-bit CRC
// this is the value you would get if using that API directly
long checksumResult = crc32.padToLong();

好啊我必须补充一点。针对已经拥有Spring和Apache Commons依赖项或计划添加依赖项的用户的一行实现:

DigestUtils.md5DigestAsHex(FileUtils.readFileToByteArray(file))

仅适用于和Apache commons选项(credit@duleshi):

DigestUtils.md5Hex(FileUtils.readFileToByteArray(file))

希望这对别人有帮助。

一种不使用Java7的第三方库的简单方法

String path = "your complete file path";
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(Files.readAllBytes(Paths.get(path)));
byte[] digest = md.digest();

System.out.println(Arrays.toString(digest));

如果您需要此摘要中的十六进制字符串。使用方法如下

String digestInHex = DatatypeConverter.printHexBinary(digest).toUpperCase();
System.out.println(digestInHex);

我最近不得不为一个动态字符串这样做, MessageDigest 可以用多种方式表示散列。获得文件的签名,就像使用 md5sum 命令我必须这样做:

try {
   String s = "TEST STRING";
   MessageDigest md5 = MessageDigest.getInstance("MD5");
   md5.update(s.getBytes(),0,s.length());
   String signature = new BigInteger(1,md5.digest()).toString(16);
   System.out.println("Signature: "+signature);

} catch (final NoSuchAlgorithmException e) {
   e.printStackTrace();
}

public static void main(String[] args) throws Exception {
    MessageDigest md = MessageDigest.getInstance("MD5");
    FileInputStream fis = new FileInputStream("c:\\apache\\cxf.jar");

    byte[] dataBytes = new byte[1024];

    int nread = 0;
    while ((nread = fis.read(dataBytes)) != -1) {
        md.update(dataBytes, 0, nread);
    };
    byte[] mdbytes = md.digest();
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < mdbytes.length; i++) {
        sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
    }
    System.out.println("Digest(in hex format):: " + sb.toString());
}

或者你可以得到更多的信息 http://www.asjava.com/core-java/java-md5-example/

public static String MD5Hash(String toHash) throws RuntimeException {
   try{
       return String.format("%032x", // produces lower case 32 char wide hexa left-padded with 0
      new BigInteger(1, // handles large POSITIVE numbers 
           MessageDigest.getInstance("MD5").digest(toHash.getBytes())));
   }
   catch (NoSuchAlgorithmException e) {
      // do whatever seems relevant
   }
}

(如果需要,只需将MD5替换为SHA-1、SHA-256、SHA-384或SHA-512即可)

public String calcMD5() throws Exception{
        byte[] buffer = new byte[8192];
        MessageDigest md = MessageDigest.getInstance("MD5");

        DigestInputStream dis = new DigestInputStream(new FileInputStream(new File("Path to file")), md);
        try {
            while (dis.read(buffer) != -1);
        }finally{
            dis.close();
        }

        byte[] bytes = md.digest();

        // bytesToHex-method
        char[] hexChars = new char[bytes.length * 2];
        for ( int j = 0; j < bytes.length; j++ ) {
            int v = bytes[j] & 0xFF;
            hexChars[j * 2] = hexArray[v >>> 4];
            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
        }

        return new String(hexChars);
}

...
String signature = new BigInteger(1,md5.digest()).toString(16);
...

但是,请注意使用 BigInteger.toString() (例如,请尝试 s = "27" ,校验和应为 "02e74f10e0327ad868d138f2b4fdd6f0"

我支持使用ApacheCommons编解码器的建议,我用它替换了我们自己的代码。

String checksum = DigestUtils.md5Hex(new FileInputStream(filePath));

Fast MD5 Implementation in Java

String hash = MD5.asHex(MD5.getHash(new File(filename)));

Standard Java Runtime Environment way :

public String checksum(File file) {
  try {
    InputStream fin = new FileInputStream(file);
    java.security.MessageDigest md5er =
        MessageDigest.getInstance("MD5");
    byte[] buffer = new byte[1024];
    int read;
    do {
      read = fin.read(buffer);
      if (read > 0)
        md5er.update(buffer, 0, read);
    } while (read != -1);
    fin.close();
    byte[] digest = md5er.digest();
    if (digest == null)
      return null;
    String strDigest = "0x";
    for (int i = 0; i < digest.length; i++) {
      strDigest += Integer.toString((digest[i] & 0xff) 
                + 0x100, 16).substring(1).toUpperCase();
    }
    return strDigest;
  } catch (Exception e) {
    return null;
  }
}

结果与linux md5sum实用程序相同。

下面是一个简单的函数,它将Sunil的代码包装起来,以便将文件作为参数。该函数不需要任何外部库,但需要Java 7。

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import javax.xml.bind.DatatypeConverter;

public class Checksum {

    /**
     * Generates an MD5 checksum as a String.
     * @param file The file that is being checksummed.
     * @return Hex string of the checksum value.
     * @throws NoSuchAlgorithmException
     * @throws IOException
     */
    public static String generate(File file) throws NoSuchAlgorithmException,IOException {

        MessageDigest messageDigest = MessageDigest.getInstance("MD5");
        messageDigest.update(Files.readAllBytes(file.toPath()));
        byte[] hash = messageDigest.digest();

        return DatatypeConverter.printHexBinary(hash).toUpperCase();
    }

    public static void main(String argv[]) throws NoSuchAlgorithmException, IOException {
        File file = new File("/Users/foo.bar/Documents/file.jar");          
        String hex = Checksum.generate(file);
        System.out.printf("hex=%s\n", hex);            
    }


}

hex=B117DD0C3CBBD009AC4EF65B6D75C97B

这里有一个方便的变体,它利用了 InputStream.transferTo() 来自Java9,以及 OutputStream.nullOutputStream() 来自Java11。它不需要外部库,也不需要将整个文件加载到内存中。

public static String hashFile(String algorithm, File f) throws IOException, NoSuchAlgorithmException {
    MessageDigest md = MessageDigest.getInstance(algorithm);

    try(BufferedInputStream in = new BufferedInputStream((new FileInputStream(f)));
        DigestOutputStream out = new DigestOutputStream(OutputStream.nullOutputStream(), md)) {
        in.transferTo(out);
    }

    String fx = "%0" + (md.getDigestLength()*2) + "x";
    return String.format(fx, new BigInteger(1, md.digest()));
}

hashFile("SHA-512", Path.of("src", "test", "resources", "some.txt").toFile());

返回

"e30fa2784ba15be37833d569280e2163c6f106506dfb9b07dde67a24bfb90da65c661110cf2c5c6f71185754ee5ae3fd83a5465c92f72abd888b03187229da29"

<checksum file="${jarFile}" todir="${toDir}"/>

More info here.

谷歌番石榴提供了一个新的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();
}