另一个实现:

import javax.xml.bind.DatatypeConverter;

String hash = DatatypeConverter.printHexBinary( 
           MessageDigest.getInstance("MD5").digest("SOMESTRING".getBytes("UTF-8")));

您可能还想看看apache公用编解码器项目的DigestUtils类，它提供了非常方便的方法来创建MD5或SHA摘要。

发现了这个:

public String MD5(String md5) {
   try {
        java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
        byte[] array = md.digest(md5.getBytes());
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < array.length; ++i) {
          sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1,3));
       }
        return sb.toString();
    } catch (java.security.NoSuchAlgorithmException e) {
    }
    return null;
}

在下面的网站上，我没有功劳，但这是一个有效的解决方案! 对我来说，很多其他的代码都没有正常工作，我最终在哈希中丢失了0。 这一点似乎与PHP相同。 资料来源:http://m2tec.be/blog/2010/02/03/java - md5 -十六进制- 0093年

如果你不需要最好的安全性，MD5是完全可以的，如果你正在做一些像检查文件完整性这样的事情，那么安全性就不是一个考虑因素。在这种情况下，您可能希望考虑一些更简单和更快的方法，例如Adler32, Java库也支持它。

不像PHP，你可以通过调用MD5函数ie MD5 ($text)来对文本进行MD5哈希，在Java中它有点复杂。我通常通过调用一个返回md5哈希文本的函数来实现它。 首先在你的主类中创建一个名为md5hashing的函数，如下所示。

public static String md5hashing(String text)
    {   String hashtext = null;
        try 
        {
            String plaintext = text;
            MessageDigest m = MessageDigest.getInstance("MD5");
            m.reset();
            m.update(plaintext.getBytes());
            byte[] digest = m.digest();
            BigInteger bigInt = new BigInteger(1,digest);
            hashtext = bigInt.toString(16);
            // Now we need to zero pad it if you actually want the full 32 chars.
            while(hashtext.length() < 32 ){
              hashtext = "0"+hashtext;   
            }
        } catch (Exception e1) 
        {
            // TODO: handle exception
            JOptionPane.showMessageDialog(null,e1.getClass().getName() + ": " + e1.getMessage());   
        }
        return hashtext;     
    }

现在，在需要时调用该函数，如下所示。

String text = textFieldName.getText();
String pass = md5hashing(text);

在这里，您可以看到hashtext被附加了一个0，以使其与PHP中的md5散列匹配。

是我做的…似乎还行-我相信有人会指出错误…

public final class MD5 {
public enum SaltOption {
    BEFORE, AFTER, BOTH, NONE;
}
private static final String ALG = "MD5";
//For conversion to 2-char hex
private static final char[] digits = {
    '0' , '1' , '2' , '3' , '4' , '5' ,
    '6' , '7' , '8' , '9' , 'a' , 'b' ,
    'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
    'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
    'o' , 'p' , 'q' , 'r' , 's' , 't' ,
    'u' , 'v' , 'w' , 'x' , 'y' , 'z'
};

private SaltOption opt;

/**
 * Added the SaltOption constructor since everybody
 * has their own standards when it comes to salting
 * hashes.
 * 
 * This gives the developer the option...
 * 
 * @param option The salt option to use, BEFORE, AFTER, BOTH or NONE.
 */
public MD5(final SaltOption option) {
    //TODO: Add Char Encoding options too... I was too lazy!
    this.opt = option;
}

/**
 * 
 * Returns the salted MD5 checksum of the text passed in as an argument.
 * 
 * If the salt is an empty byte array - no salt is applied.
 * 
 * @param txt The text to run through the MD5 algorithm.
 * @param salt The salt value in bytes.
 * @return The salted MD5 checksum as a <code>byte[]</code>
 * @throws NoSuchAlgorithmException
 */
private byte[] createChecksum(final String txt, final byte[] salt) throws NoSuchAlgorithmException {
    final MessageDigest complete = MessageDigest.getInstance(ALG);
    if(opt.equals(SaltOption.BEFORE) || opt.equals(SaltOption.BOTH)) {
        complete.update(salt);
    }
    complete.update(txt.getBytes());
    if(opt.equals(SaltOption.AFTER) || opt.equals(SaltOption.BOTH)) {
        complete.update(salt);
    }
    return complete.digest();
}

/**
 * 
 * Returns the salted MD5 checksum of the file passed in as an argument.
 * 
 * If the salt is an empty byte array - no salt is applied.
 * 
 * @param fle The file to run through the MD5 algorithm.
 * @param salt The salt value in bytes.
 * @return The salted MD5 checksum as a <code>byte[]</code>
 * @throws IOException
 * @throws NoSuchAlgorithmException
 */
private byte[] createChecksum(final File fle, final byte[] salt)
        throws IOException, NoSuchAlgorithmException {
    final byte[] buffer = new byte[1024];
    final MessageDigest complete = MessageDigest.getInstance(ALG);
            if(opt.equals(SaltOption.BEFORE) || opt.equals(SaltOption.BOTH)) {
            complete.update(salt);
        }
    int numRead;
    InputStream fis = null;
    try {
        fis = new FileInputStream(fle);
        do {
            numRead = fis.read(buffer);
            if (numRead > 0) {
                complete.update(buffer, 0, numRead);
            }
        } while (numRead != -1);
    } finally {
    if (fis != null) {
            fis.close();
        }
    }
            if(opt.equals(SaltOption.AFTER) || opt.equals(SaltOption.BOTH)) {
            complete.update(salt);
        }
    return complete.digest();
}

/**
 * 
 * Efficiently converts a byte array to its 2 char per byte hex equivalent.
 * 
 * This was adapted from JDK code in the Integer class, I just didn't like
 * having to use substrings once I got the result...
 *
 * @param b The byte array to convert
 * @return The converted String, 2 chars per byte...
 */
private String convertToHex(final byte[] b) {
    int x;
    int charPos;
    int radix;
    int mask;
    final char[] buf = new char[32];
    final char[] tmp = new char[3];
    final StringBuilder md5 = new StringBuilder();
    for (int i = 0; i < b.length; i++) {
        x = (b[i] & 0xFF) | 0x100;
        charPos = 32;
        radix = 1 << 4;
        mask = radix - 1;
        do {
            buf[--charPos] = digits[x & mask];
            x >>>= 4;
        } while (x != 0);
        System.arraycopy(buf, charPos, tmp, 0, (32 - charPos));
        md5.append(Arrays.copyOfRange(tmp, 1, 3));
    }
    return md5.toString();
}

/**
 * 
 * Returns the salted MD5 checksum of the file passed in as an argument.
 * 
 * @param fle The file you want want to run through the MD5 algorithm.
 * @param salt The salt value in bytes
 * @return The salted MD5 checksum as a 2 char per byte HEX <code>String</code>
 * @throws NoSuchAlgorithmException
 * @throws IOException
 */
public String getMD5Checksum(final File fle, final byte[] salt)
        throws NoSuchAlgorithmException, IOException {
    return convertToHex(createChecksum(fle, salt));
}

/**
 * 
 * Returns the MD5 checksum of the file passed in as an argument.
 * 
 * @param fle The file you want want to run through the MD5 algorithm.
 * @return The MD5 checksum as a 2 char per byte HEX <code>String</code>
 * @throws NoSuchAlgorithmException
 * @throws IOException
 */
public String getMD5Checksum(final File fle)
        throws NoSuchAlgorithmException, IOException {
    return convertToHex(createChecksum(fle, new byte[0]));
}

/**
 * 
 * Returns the salted MD5 checksum of the text passed in as an argument.
 * 
 * @param txt The text you want want to run through the MD5 algorithm.
 * @param salt The salt value in bytes.
 * @return The salted MD5 checksum as a 2 char per byte HEX <code>String</code>
 * @throws NoSuchAlgorithmException
 * @throws IOException
 */
public String getMD5Checksum(final String txt, final byte[] salt)
        throws NoSuchAlgorithmException {
    return convertToHex(createChecksum(txt, salt));
}

/**
 * 
 * Returns the MD5 checksum of the text passed in as an argument.
 * 
 * @param txt The text you want want to run through the MD5 algorithm.
 * @return The MD5 checksum as a 2 char per byte HEX <code>String</code>
 * @throws NoSuchAlgorithmException
 * @throws IOException
 */
public String getMD5Checksum(final String txt)
        throws NoSuchAlgorithmException {

    return convertToHex(createChecksum(txt, new byte[0]));
}
}