Depends on the web server. If you can use servlets, try this :
// UploadServlet.java : Proof of Concept - Mike Smith March 2006
// Accept a file from the client, assume it is an image, rescale it and save it to disk for later display
import javax.servlet.http.;
import javax.imageio.;
import java.io.;
import java.util.;
import java.sql.;
import org.apache.commons.fileupload.;
import org.apache.commons.fileupload.disk.;
import org.apache.commons.fileupload.servlet.;
import java.awt.image.;
import java.awt.;
public class UploadServlet extends HttpServlet {
public static void printHeader(PrintWriter pw) {
pw.println("<HEAD><TITLE>Upload Servlet</TITLE><HEAD>");
pw.println("<BODY>");
}
public static void printTrailer(PrintWriter pw) {
pw.println("<img src=\"../images/poweredby.png\" align=left>");
pw.println("<img src=\"../images/tomcat-power.gif\" align=right>");
pw.println("</BODY></HTML>");
}
public void init() { // Servlet init() : called when the servlet is LOADED (not when invoked)
}
public void service(HttpServletRequest req, HttpServletResponse res) throws IOException {
DiskFileItemFactory dfifact;
ServletFileUpload sfu;
java.util.List items;
Iterator it;
FileItem fi;
String field, filename, contype;
boolean inmem, ismulti;
long sz;
BufferedImage img;
int width, height, nwidth, nheight, pixels;
double scaling;
final int MAXPIXELS = 350 * 350;
res.setContentType("text/html");
PrintWriter pw = res.getWriter();
printHeader(pw);
ismulti = FileUpload.isMultipartContent(req);
if (ismulti) {
pw.println("Great! Multipart detected");
dfifact = new DiskFileItemFactory(999999, new File("/tmp"));
sfu = new ServletFileUpload(dfifact);
try {
items = sfu.parseRequest(req);
} catch (FileUploadException e) {
pw.println("Failed to parse file, error [" + e + "]");
printTrailer(pw);
pw.close();
return;
}
it = items.iterator();
while (it.hasNext()) {
fi = (FileItem) it.next();
if (fi.isFormField()) {
pw.println("Form field [" + fi.getFieldName() + "] value [" + fi.getString() + "]");
}
else { // Its an upload
field = fi.getFieldName();
filename = fi.getName();
contype = fi.getContentType();
inmem = fi.isInMemory();
sz = fi.getSize();
pw.println("Upload field=" + field + " file=" + filename + " content=" + contype + " inmem=" + inmem
+ " size=" + sz);
InputStream istream = fi.getInputStream();
img = ImageIO.read(istream);
nwidth = width = img.getWidth();
nheight = height = img.getHeight();
pixels = width * height;
if (pixels > MAXPIXELS) {
scaling = Math.sqrt((double) MAXPIXELS / (double) pixels);
nheight = (int) ((double) height * scaling);
nwidth = (int) ((double) width * scaling);
}
BufferedImage output = new BufferedImage(nwidth, nheight, BufferedImage.TYPE_3BYTE_BGR);
Graphics2D g = output.createGraphics();
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(img, 0, 0, nwidth, nheight, null);
ImageIO.write(output, "jpeg", new File("/var/tomcat/webapps/pioneer/demo.jpg"));
istream.close();
}
}
}
else
pw.println("Bugger! Multipart not detected");
printTrailer(pw);
pw.close();
}
public void destroy() {
}
}