ExternCallServlet.java

package com.capgemini.adc.infra.remote.server;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Map;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.capgemini.adc.infra.exception.InfrastructureTechnicalException;
import com.capgemini.adc.infra.log.LogFactory;


/**ExternCallServlet 1.1
 * Routage des appels FWK1 vers FWK3.
 * Lors du premier appel du FWK 3 on ouvre une session (matérialisé par le FWK session cookie).
 * Ce cookie est stocké en tant que attribut dans la session du FWK1 et réutilisé pour les appels suivants.
 *
 * @author Thomas Kasten
 */
@SuppressWarnings("serial")
public class ExternCallServlet extends HttpServlet {
	// static file upload parameters
	final static String crlf = "\r\n";
	final static String twoHyphens = "--";
	final static String boundary =  "*****";

	/* On vient d'une action FWK 1 (ajax) ou du <c:import/> de la page pontv2.jsp.
	 *
	 * parametres
	 * 		requestPath : l'url externe à appeler
	 * 		uploadFileName : nom d'un éventuel fichier à uploader
	 * 		paramètres métier divers
	 */
	@Override
    public void service(HttpServletRequest req, HttpServletResponse res)
			throws javax.servlet.ServletException {

		URL url;
		HttpURLConnection conn;
		InputStream in;
        OutputStream out;
		byte[] chunk = new byte[2048];
		String fw3sessionCookie; // cookie identifiant la session distante avec le FWK 3
		String uploadFilePath = null;
		int bytesRead;
		int maxFollowRedirect = 3; // number of max. allowed 302 answers from server
		int serverResponseCode = -1;

		try {
			String requestPath = req.getAttribute("requestPath") != null ? String.valueOf(req.getAttribute("requestPath")) :  req.getParameter("requestPath"); 
			url = new URL (buildUrlWithParameters(req, getInitParameter("externcall.url"), requestPath)); // ajout paramètres GET
			LogFactory.logDebug("Extern call to " + url,"");
			do { // retry if servers answers 302-redirected
			    LogFactory.logDebug("Calling : " + url.toString());
				conn = (HttpURLConnection) url.openConnection();
				HttpURLConnection.setFollowRedirects(false);
				conn.setUseCaches(false);

				// utilisation du cookie de session fw3 pour se raccrocher à une session existante
				fw3sessionCookie = (String)req.getSession().getAttribute("FW3_session");
				if (fw3sessionCookie != null) {
				    LogFactory.logDebug("Using knwon FW3 session cookie : " + fw3sessionCookie);
					conn.setRequestProperty("Cookie", 	"JSESSIONID=" + fw3sessionCookie + ";");
				}
				else{
				    LogFactory.logDebug("NO FW3 session cookie available");
				}
				conn.setDoOutput(true);
				conn.setRequestProperty("Connection", "Keep-Alive");
				conn.setRequestProperty("Cache-Control", "no-cache");
				if(serverResponseCode != HttpServletResponse.SC_FOUND && "POST".equals(req.getParameter("requestMethod"))){ // ajout paramètres POST
					conn.setRequestMethod("POST");
					prepareExternPost(req, conn);
					uploadFilePath = req.getParameter("uploadFile");
					// fileupload
					if(uploadFilePath != null){
						writeFileDataIntoRequest(req, conn, uploadFilePath);
					}
				}
				else {
				    conn.setRequestMethod("GET");
				}
				
				serverResponseCode = conn.getResponseCode();
				if (serverResponseCode == HttpServletResponse.SC_FOUND /* 302 */)
					url = new URL(conn.getHeaderField("Location"));
				LogFactory.logDebug("Fw3 response code: " + conn.getResponseCode());
				// obtention et stockage d'un cookie de session fw3 pour réutilisation ultérieure
				fw3sessionCookie = getServerCookie(conn, "JSESSIONID");

				if(fw3sessionCookie != null){
					req.getSession().setAttribute("FW3_session",fw3sessionCookie );
					LogFactory.logDebug("Obtained new FW3 session cookie : " + fw3sessionCookie);
				} else
				    LogFactory.logDebug("Fw3 response without session cookie");
			} while(maxFollowRedirect-- > 0 && serverResponseCode == HttpServletResponse.SC_FOUND /* 302 */);

			in =  conn.getInputStream();
			res.setContentType(conn.getContentType());
			out = res.getOutputStream();

			while( (bytesRead = in.read(chunk)) > 0 ){
				out.write(chunk, 0, bytesRead);
			}
		} catch (MalformedURLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}


    private void writeFileDataIntoRequest(HttpServletRequest req, HttpURLConnection conn,
            String uploadFilePath) throws IOException, FileNotFoundException,
            InfrastructureTechnicalException {
        DataOutputStream uploadData;
        InputStream inFile = new FileInputStream(uploadFilePath);
        byte[] buf = new byte[2048];
        int nbBytesRead;
        String filename;
        filename = req.getParameter("file");
        conn.setDoInput(true);
        conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
        uploadData = new DataOutputStream(conn.getOutputStream());
        uploadData.writeBytes(twoHyphens + boundary + crlf);
        uploadData.writeBytes("Content-Disposition: form-data; name=\"" + "file" + "\";filename=\"" + filename + "\"" + crlf);
        uploadData.writeBytes(crlf);
        while ((nbBytesRead = inFile.read(buf)) > -1) {
            uploadData.write(buf, 0, nbBytesRead);
        }
        inFile.close();
        uploadData.writeBytes(crlf);
        uploadData.writeBytes(twoHyphens + boundary + twoHyphens + crlf);
        LogFactory.logDebug("File uploaded: " + filename + ". (" +uploadFilePath+")");
    }



	protected String buildUrlWithParameters(HttpServletRequest req, String extAppUrl, String urlPath) throws Exception {
		boolean isFirst = true;
		StringBuffer buf = new StringBuffer();

		buf.append(extAppUrl);
		//Ajout du "/" si manquant.
		if(!urlPath.startsWith("/")) {
		    buf.append("/");
		}
		buf.append(urlPath);

		if(!"POST".equals(req.getParameter("requestMethod"))){ // ajout des paramètres GET
			for(String key : req.getParameterMap().keySet()){
				if("requestPath".equals(key) || "requestMethod".equals(key))
						continue;
				if(isFirst){
					isFirst = false;
					buf.append("?");
				}
				else
					buf.append("&");
				buf.append(key.toString());
				buf.append("=");
				buf.append(URLEncoder.encode(req.getParameter(key), "UTF-8"));
			}

		}
		return buf.toString();
	}

	/**
	 * Ajout des paramètres au corps de la requête HTTP.
	 * @param req
	 * @param conn
	 * @throws IOException
	 */
    protected void prepareExternPost(HttpServletRequest req, HttpURLConnection conn)
            throws IOException {
        Map<String, String[]> parameterMap = req.getParameterMap();
        if (!parameterMap.isEmpty()) {
            StringBuilder paramsBuilder = new StringBuilder();
            for(String key : req.getParameterMap().keySet()) {
                paramsBuilder.append(key);
                paramsBuilder.append("=");
                paramsBuilder.append(req.getParameter(key));
                paramsBuilder.append("&");
            }
            String urlParameters = paramsBuilder.toString();
            if (urlParameters.endsWith("&")) {
                urlParameters = urlParameters.substring(0,
                        urlParameters.length() - 1);
            }
            ;
            DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
            wr.writeBytes(urlParameters);
            wr.flush();
            wr.close();
        }
    }

	public String getServerCookie(HttpURLConnection conn, String cookieName)
	        throws InfrastructureTechnicalException {
		String[] fields = null;
		String[] cookie;

		for (int i = 0;; i++) {

			String headerName = conn.getHeaderFieldKey(i); // sends request
			String headerValue = conn.getHeaderField(i);
			// Launcher.println(headerName + ": " + headerValue);
			if (headerName == null && headerValue == null) {
				// No more headers
				break;
			}
			if ("Set-Cookie".equalsIgnoreCase(headerName)) {
				// Parse cookie
				fields = headerValue.split(";\\s*");
				cookie = fields[0].split("=");
				try {
				    LogFactory.logDebug(cookie[0] + "=" +  cookie[1]);
				} catch (ArrayIndexOutOfBoundsException x) {
				    LogFactory.logDebug(cookie[0] + "=" +  cookie[1]);
				}
				if(cookieName.equals(cookie[0]))
					return cookie[1];
			}
		}
		return null;
	}

}