DNDownload.java

package cz.syntea.dn.web2.server;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cz.syntea.dn.jul.Logger;

/**
 * DNDownload
 *
 * Stahovani souboru se jnmenem z parametru fileName naplneneho textem z parametru content, a typu z parametru mimeType<br/>
 * priklad: ../DNDoenload?fileName=readme&content=Ahoj%Svete&mimeType=text/html&
 * @author Daniel Kec <daniel.kec at syntea.cz>
 * @since Aug 29, 2011
 * @version 1.0
 * @class cz.syntea.dn.web2.server.DNDownload
 */
public class DNDownload extends HttpServlet {
	private static Logger LOG = Logger.getLogger(DNDownload.class);
    private static final long serialVersionUID = 1L;

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String fileName = getParam(request, "fileName");
        String content = getParam(request, "content");
        String mimeType = getParam(request, "mimeType");
            doDownload(request, response,
                    fileName,
                    content,
                    mimeType);
    }

    /**
     * Presmeruje se automaticky na doPost
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doPost(request, response);
    }

    private void doDownload(HttpServletRequest req, HttpServletResponse resp,
            String fileName, String content, String mimeType)
            throws IOException {
    	LOG.entering(DNDownload.class.getCanonicalName(), "doDownload");
    	LOG.config("DNDownload: Priprava ke stazeni souboru "+fileName+" typu "+mimeType);

        InputStream istr = null;
        OutputStream ostr = null;
        resp.setContentType(mimeType);
        resp.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\";");
        try {
        	// tohle kodovani je tu kvuli chybe v tomcatu ktery moc neumi s cestinou, zda se ze ve websphere je taky, nahoda?
            istr = new ByteArrayInputStream(content.getBytes("ISO-8859-1"));
            ostr = resp.getOutputStream();
            int curByte = -1;

            while ((curByte = istr.read()) != -1) {
                ostr.write(curByte);
            }

            ostr.flush();
        } catch (Exception ex) {
            LOG.severe("Chyba pri odesilani souboru "+fileName+" typu "+mimeType+": ", ex);
        } finally {
            try {
                if (istr != null) {
                    istr.close();
                }
                if (ostr != null) {
                    ostr.close();
                }
            } catch (Exception ex) {
            	LOG.severe("Chyba pri uzavirani streamu: ", ex);
            }
        }
        try {
            resp.flushBuffer();
        } catch (Exception ex) {
        	LOG.severe("Chyba pri flushovani odpovedi servletu: ", ex);
        }
        LOG.config("DNDownload: Soubor "+fileName+" typu "+mimeType+" byl odeslan prohlizeci.");
        LOG.exiting(DNDownload.class.getCanonicalName(), "doDownload");
    }

    /**
     * Vraci pozadovany parametr z requestu podle zadaneho jmena
     * @param request ze ktereho chceme ziskat parametr
     * @param name jmeno parametru
     * @return hodnota paramtru
     */
    private String getParam(HttpServletRequest request, String name) {
        String result = request.getParameter(name);
        if (result != null) {
            return result.trim();
        }
        return "";
    }
}