簡單的MD5

import java.security.MessageDigest;

public class MD5 {

private MD5() {}

public final static String getMessageDigest(byte[] buffer) {
	char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
	try {
		MessageDigest mdTemp = MessageDigest.getInstance("MD5");
		mdTemp.update(buffer);
		byte[] md = mdTemp.digest();
		int j = md.length;
		char str[] = new char[j * 2];
		int k = 0;
		for (int i = 0; i < j; i++) {
			byte byte0 = md[i];
			str[k++] = hexDigits[byte0 >>> 4 & 0xf];
			str[k++] = hexDigits[byte0 & 0xf];
		}
		return new String(str);
	} catch (Exception e) {
		return null;
	}
}

}