MD5编码工具类

package util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Crypter {

	
	public static String md5Encrypt(String originalString){
		
		StringBuffer sb = new StringBuffer();
		//if((null != str) || (0 != (str.trim().length())) || !"null".equals(str))
		if(StringHelper.isNotBlank(originalString)){
			try{
				MessageDigest md5 = MessageDigest.getInstance("MD5");
			    md5.update(originalString.getBytes());
			    byte[] b = md5.digest();
			    for (int i = 0; i < b.length; i++) {
			      int v = b[i];
			      v = v < 0 ? 256 + v : v;
			      String cc = Integer.toHexString(v);
			      if (cc.length() == 1) sb.append('0');
			      sb.append(cc);
			    }
			}catch (NoSuchAlgorithmException e) {
				return null;
			}
		}
	    return sb.toString();
	}
}

StringHelper类也是一个单独的工具类，MD5编码这个类用到了判断字符串不为空这个类