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| /*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package com.pfe.slide;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.Closeable;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.Comparator;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
*
* @author jowo
*/
public class SlideServlet extends HttpServlet {
// Constants ----------------------------------------------------------------------------------
private static final int DEFAULT_BUFFER_SIZE = 10240; // 10KB.
private static final String IMG_DIRECTORY = "C:\\images";
private static final int NBR_IMG_KEPT = 2;
private static final String IMG_ERROR_DIRECTORY = "C:\\error.png";
private static FileFilter ONLY_FILE_FILTER = new FileFilter() {
@Override
public boolean accept(File pathname) {
return pathname.isFile();
}
};
// Compare la date de modifcation d'un fichier. Les tri est descendant
private static Comparator<File> MODIFIED_FILE_CMP = new Comparator<File>() {
@Override
public int compare(File f1, File f2) {
return (f1.lastModified() == f2.lastModified()) ? 0
: f1.lastModified() > f2.lastModified() ? -1 : 1;
}
};
// Properties ---------------------------------------------------------------------------------
// Actions ------------------------------------------------------------------------------------
// @Override
// protected long getLastModified(HttpServletRequest request) {
// final long result;
// final File slide;
// if ((slide = getLastSlide(request)) != null) {
// result = slide.lastModified();
// }
// else {
// result = -1L;
// }
//System.out.println("LastModification: " + result);
// return result;
// }
//---------------------------------------------------------------------------------------------------
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
final String type = request.getParameter("type");
if (type != null && "filename".equals(type)) {
sendFilename(request, response);
}
else {
sendSlide(request, response);
}
}
// fin doGet-------------------------------------------------------------------------------------
private void sendSlide(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
File slide = getLastSlide();
if (slide == null) {
slide = new File(IMG_ERROR_DIRECTORY);
}
// Init servlet response.---------------------------------------------------------------
//response.reset();
response.setBufferSize(DEFAULT_BUFFER_SIZE);
response.setContentType("image/png");
response.setHeader("Content-Length", String.valueOf(slide.length()));
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// Prepare streams.
BufferedInputStream input = null;
BufferedOutputStream output = null;
try {
// Open streams.
input = new BufferedInputStream(new FileInputStream(slide), DEFAULT_BUFFER_SIZE);
output = new BufferedOutputStream(response.getOutputStream(), DEFAULT_BUFFER_SIZE);
// Write file contents to response.
byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
int length;
while ((length = input.read(buffer)) > -1) {
output.write(buffer, 0, length);
}
output.flush();
System.out.println("Send Slide " + slide.getName());
}
catch(IOException ioe) {
System.out.println("Send Slide IO Error: " + ioe.getMessage());
}
finally {
// Gently close streams.
close(output);
close(input);
}
}
private void sendFilename(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
final String paramFilename = request.getParameter("filename");
final File slide = getLastSlide();
String filename = (slide != null ? slide.getName() : "");
if (paramFilename != null && filename != null && filename.equals(paramFilename)) {
System.out.println("Send Slide Not Modified");
filename = "";
}
filename = "[\"" +filename+ "\"]";
response.setContentType("application/json");
response.setContentLength(filename.length());
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.getWriter().write(filename);
response.getWriter().flush();
System.out.println("Send filename " + filename);
}
private File getLastSlide() {
// On récupère seulement les fichiers du répertoire
final File[] list = new File(IMG_DIRECTORY).listFiles(ONLY_FILE_FILTER);
// Trie par ordre décroissant les dates de la dernière modification
Arrays.sort(list, MODIFIED_FILE_CMP);
//
File slide = null;
if (list.length > 0) {
// Le fichier le plus jeune est en première position
slide = list[0];
//delete old images
for (int i = list.length-1; i >= NBR_IMG_KEPT; --i) {
list[i].delete();
}
}
return slide;
}
// Helpers (can be refactored to public utility class) ----------------------------------------
private static void close(Closeable resource) {
if (resource != null) {
try {
resource.close();
}
catch (IOException e) {
// Do your thing with the exception. Print it, log it or mail it.
e.printStackTrace();
}
}
}
} |
notification update image
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(économiser en octets) donc en premier temps je dois interroger le serveur s'il y a une nouvelle nouvelle si oui on l'affiche genre ce scénario:
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