Java - Play Framework - Leetchi API

Leetchi.java

package controllers;

import java.io.*;
import java.net.*;
import java.security.*;
import java.security.spec.*;
import sun.misc.BASE64Encoder;
import play.*;
import play.mvc.*;

public class Leetchi extends Controller{
  
	// Attributes for Leetchi
	protected static String partnerId = "partnerid";
	
	// RSA KeyImport
	public static PrivateKey getPrivateKey(String filename) throws Exception {
	    File f = new File(filename);
	    FileInputStream fis = new FileInputStream(f);
	    DataInputStream dis = new DataInputStream(fis);
	    byte[] keyBytes = new byte[(int)f.length()];
	    dis.readFully(keyBytes);
	    dis.close();
	    PKCS8EncodedKeySpec spec =
	      new PKCS8EncodedKeySpec(keyBytes);
	    KeyFactory kf = KeyFactory.getInstance("RSA");
	    return kf.generatePrivate(spec);
	}
	public static PublicKey getPublicKey(String filename) throws Exception {
		    File f = new File(filename);
		    FileInputStream fis = new FileInputStream(f);
		    DataInputStream dis = new DataInputStream(fis);
		    byte[] keyBytes = new byte[(int)f.length()];
		    dis.readFully(keyBytes);
		    dis.close();
		    X509EncodedKeySpec spec =
		      new X509EncodedKeySpec(keyBytes);
		    KeyFactory kf = KeyFactory.getInstance("RSA");
		    return kf.generatePublic(spec);
	}
	
	// Signature calculus
	public static String computeSignature(String request) throws Exception {
		Signature sig = Signature.getInstance("SHA1withRSA");
		sig.initSign(getPrivateKey("privatekey.pem"));
		sig.update(request.getBytes("UTF8"));
		byte[] signatureBytes = sig.sign();
		String signature = new BASE64Encoder().encode(signatureBytes);
		return signature;
	}
	
	// Request transfer to external API
	public static String sendRequest(String method, String urlPath, String body) throws Exception {
		String baseUrl = "http://api-preprod.leetchi.com/v1/partner/";
		String url = baseUrl + partnerId + urlPath + "?ts=" + System.currentTimeMillis();
		String toBeEncrypted = method.toUpperCase() + "|" + url + "|";
		if (!method.equals("GET")) {
			toBeEncrypted = toBeEncrypted + body+"|";
		}
		String signature = computeSignature(toBeEncrypted);
		URL targetUrl;
	    HttpURLConnection connection = null;  
	    try {
	    	
	      //Create connection
	      targetUrl = new URL(url);
	      connection = (HttpURLConnection)targetUrl.openConnection();
	      connection.setRequestMethod(method.toUpperCase());
	      connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
		  connection.setRequestProperty("X-Leetchi-Signature", signature);
	      connection.setRequestProperty("Content-Length", "" + Integer.toString(body.getBytes().length));  
	      connection.setUseCaches (false);
	      connection.setDoInput(true);
	      connection.setDoOutput(true);
	      
	      //Send request
	      DataOutputStream wr = new DataOutputStream (connection.getOutputStream ());
	      wr.writeBytes (body);
	      wr.flush ();
	      wr.close ();
	      
	      //Get Response	
	      InputStream is = connection.getInputStream();
	      BufferedReader rd = new BufferedReader(new InputStreamReader(is));
	      String line;
	      StringBuffer response = new StringBuffer(); 
	      while((line = rd.readLine()) != null) {
	        response.append(line);
	        response.append('\r');
	      }
	      rd.close();
	      return response.toString();

	    } catch (Exception e) {

	      e.printStackTrace();
	      return null;

	    } finally {

	      if(connection != null) {
	        connection.disconnect(); 
	      }
	    }
	}
}