收藏一个MD5例子

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
 
public class MD5Utils { 
	private final static String[] strDigits = { "0", "1", "2", "3", "4", "5",
			"6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
	public MD5Utils() {
		     
	} 
     
	// return Hexadecimal
	private static String byteToArrayString(byte bByte) {
		int iRet = bByte; 
		if (iRet < 0) { 
			iRet += 256;
		}  
		int iD1 = iRet / 16;
		int iD2 = iRet % 16;
		return strDigits[iD1] + strDigits[iD2];
	}

	// 转换字节数组为16进制字串
	private static String byteToString(byte[] bByte) {
		StringBuffer sBuffer = new StringBuffer();
		for (int i = 0; i < bByte.length; i++) {
			sBuffer.append(byteToArrayString(bByte[i]));
		}
		return sBuffer.toString().toUpperCase();
	}

	public static String GetMD5Code(String strObj) {
		String resultString = null;
		try {
			resultString = new String(strObj);
			MessageDigest md = MessageDigest.getInstance("MD5");
			// md.digest() 该函数返回值为存放哈希值结果的byte数组
			resultString = byteToString(md.digest(strObj.getBytes()));
		} catch (NoSuchAlgorithmException ex) {
			ex.printStackTrace();
		}
		return resultString;
	}

	public static void main(String[] args) {
		System.out.println(MD5Utils.GetMD5Code("aaaa"));
	}
}