java MD5 加密代码的实现

Bertha 。 2021-07-24 15:21 389阅读 0赞

### 代码 ###

package util;
    
    import java.security.MessageDigest;
    import java.security.NoSuchAlgorithmException;
    
    public class HashUtil {
    
       private static MessageDigest digest = null;
    
        public synchronized static final String hash(String data) {
            if (digest == null) {
                try {
                    digest = MessageDigest.getInstance("MD5");
                } catch (NoSuchAlgorithmException nsae) {
                    System.err.println("Failed to load the MD5 MessageDigest. " +
                            "Jive will be unable to function normally.");
                    nsae.printStackTrace();
                }
            }
            // Now, compute hash.
            digest.update(data.getBytes());
            return encodeHex(digest.digest());
        }
    
        public static final String encodeHex(byte[] bytes) {
            StringBuffer buf = new StringBuffer(bytes.length * 2);
            int i;
    
            for (i = 0; i < bytes.length; i++) {
                if (((int) bytes[i] & 0xff) < 0x10) {
                    buf.append("0");
                }
                buf.append(Long.toString((int) bytes[i] & 0xff, 16));
            }
            return buf.toString();
        }
    
        public static final byte[] decodeHex(String hex) {
            char[] chars = hex.toCharArray();
            byte[] bytes = new byte[chars.length / 2];
            int byteCount = 0;
            for (int i = 0; i < chars.length; i += 2) {
                byte newByte = 0x00;
                newByte |= hexCharToByte(chars[i]);
                newByte <<= 4;
                newByte |= hexCharToByte(chars[i + 1]);
                bytes[byteCount] = newByte;
                byteCount++;
            }
            return bytes;
        }
        
        private static final byte hexCharToByte(char ch) {
            switch (ch) {
                case '0':
                    return 0x00;
                case '1':
                    return 0x01;
                case '2':
                    return 0x02;
                case '3':
                    return 0x03;
                case '4':
                    return 0x04;
                case '5':
                    return 0x05;
                case '6':
                    return 0x06;
                case '7':
                    return 0x07;
                case '8':
                    return 0x08;
                case '9':
                    return 0x09;
                case 'a':
                    return 0x0A;
                case 'b':
                    return 0x0B;
                case 'c':
                    return 0x0C;
                case 'd':
                    return 0x0D;
                case 'e':
                    return 0x0E;
                case 'f':
                    return 0x0F;
            }
            return 0x00;
        }
    
    }

### 调用 ###

public static void main(String[] args)
       {
          String pwd = "aabbcc";
          String pwdMd5 =  HashUtil.hash(pwd);
          System.out.println(pwdMd5);
       }

### 输出 ###

61a60170273e74a5be90355ffe8e86ad