RSA in Java given n and e

My application receives the raw pieces of a public RSA key (n and e) and needs to use thes开发者_开发技巧e to encrypt a cipher text. I've been trying to use BouncyCastle but my code isn't working. The problem arises in trying to create the X509EncodedKeySpec.

Can anyone help me get this working? Here's the code I have:

public static PublicKey getPublicKeyFromString(String key) throws Exception
{
    KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
    EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(Base64Encoder.decode(key));

    PublicKey publicKey = keyFactory.generatePublic(publicKeySpec);
    return publicKey;
}

I guess the real problem is that n and e are separate and I don't know how to combine them.

Why are you not using new RSAPublicKeySpec(n,e)?

public static PublicKey getPublicKeyFromString(String key) throws Exception
        {
            BASE64Decoder b64 = new BASE64Decoder();
            KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
            EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(b64.decodeBuffer(key));
            PublicKey publicKey = keyFactory.generatePublic(publicKeySpec);
            return publicKey;
        }