为给定字符串生成MD5指纹

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

import org.apache.commons.codec.binary.Hex;

public class MD5Util {

    private static MessageDigest md = null;

    static{
        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取MD5签名
     * @param content
     * @return
     */
    public static String getMD5Sign(String content){

        if(md == null || content == null || content.equals("")) return null;

        md.reset();

        return new String(Hex.encodeHex(md.digest(content.getBytes())));

    }

}