MD5 hash 雜湊演算法__java

package com.mkyong.test; import java.io.FileInputStream;import java.security.MessageDigest; public class MD5CheckSumExample {    public static void main(String[] args)throws Exception    {        MessageDigest md = MessageDigest.getInstance("MD5");        FileInputStream fis = new FileInputStream("c:\\loging.log");         byte[] dataBytes = new byte[1024];         int nread = 0;         while ((nread = fis.read(dataBytes)) != -1) {          md.update(dataBytes, 0, nread);        };        byte[] mdbytes = md.digest();         //convert the byte to hex format method 1        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());         //convert the byte to hex format method 2        StringBuffer hexString = new StringBuffer();    for (int i=0;i<mdbytes.length;i++) {    String hex=Integer.toHexString(0xff & mdbytes[i]);        if(hex.length()==1) hexString.append('0');        hexString.append(hex);    }    System.out.println("Digest(in hex format):: " + hexString.toString());    }}

public class MD5Hash {  public ThreadLocal<MessageDigest> local = new ThreadLocal() {    protected MessageDigest initialValue() {      try {        return MessageDigest.getInstance("MD5"); } catch (NoSuchAlgorithmException e) {      }      throw new IllegalStateException("MD5 Algorithm is not found");    }  };  public long hash(byte[] value)  {    MessageDigest md5 = (MessageDigest)this.local.get();    md5.reset();    md5.update(value);    byte[] bKey = md5.digest();    long res = (bKey[3] & 0xFF) << 24 |       (bKey[2] & 0xFF) << 16 |       (bKey[1] & 0xFF) << 8 | bKey[0] & 0xFF;    return res;  }}