RSA key to file

KeyWriter

package com.punchouty.ed;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class KeyWriter {	
	
	public static final String BASE_FOLDER = "keys/";
	public static final String PRIVATE_KEY_FILE_NAME = "private.key";
	public static final String PUBLIC_KEY_FILE_NAME = "public.key";
	public static final String PRIVATE_KEY_FILE = BASE_FOLDER + PRIVATE_KEY_FILE_NAME;
	public static final String PUBLIC_KEY_FILE = BASE_FOLDER + PUBLIC_KEY_FILE_NAME;
	public static final String KEY_GENERATION_ALGORITHM = "RSA";
	public static final String ENCRYPTION_DECRYPTION_ALGORITHM = "RSA/ECB/PKCS1Padding";
	private KeyPair generatedKeyPair = null;
	
	public KeyWriter() {
		try {
			KeyPairGenerator keyGen = KeyPairGenerator.getInstance(KEY_GENERATION_ALGORITHM);
			keyGen.initialize(1024);
			generatedKeyPair = keyGen.genKeyPair();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
			System.exit(0);
		}
	}
	
	public void savePrivateKey() throws IOException{
		File keyFile = new File(PRIVATE_KEY_FILE);
		boolean exists = keyFile.exists();
		if(exists) {
			System.err.println("File " + keyFile + " already exists. Please remove it and then run program again");
			System.exit(0);
		}
		else {
			PrivateKey privateKey = generatedKeyPair.getPrivate();
			System.out.println("Saving Private Key: " + getHexString(privateKey.getEncoded()));
			PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(
					privateKey.getEncoded());
			FileOutputStream fos = new FileOutputStream(keyFile);
			fos.write(pkcs8EncodedKeySpec.getEncoded());
			fos.close();
			System.out.println("Saved Private Key successfully");
		}
	}
	
	public void savePublicKey() throws IOException{
		File keyFile = new File(PUBLIC_KEY_FILE);
		boolean exists = keyFile.exists();
		if(exists) {
			System.err.println("File " + keyFile + " already exists. Please remove it and then run program again");
			System.exit(0);
		}
		else {
			PublicKey publicKey = generatedKeyPair.getPublic();
			System.out.println("Saving Public Key: " + getHexString(publicKey.getEncoded()));
			X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(
					publicKey.getEncoded());
			FileOutputStream fos = new FileOutputStream(keyFile);
			fos.write(x509EncodedKeySpec.getEncoded());
			fos.close();
			System.out.println("Saved Public Key successfully");
		}
	}
	
	public static final String getHexString(byte[] b) {
		String result = "";
		for (int i = 0; i < b.length; i++) {
			result += Integer.toString((b[i] & 0xff) + 0x100, 16).substring(1);
		}
		return result;
	}

}