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Server Program - Responding To Post Requests From HTML pg.

John Winstanley
Greenhorn

Joined: Apr 08, 2003
Posts: 14
Hello All At The Java Ranch,
I want to write a simple Java Server Program That Responds To Post Requests From A HTML page.
I've got a html page on apache with a form
<form method="post" action="http://localhost:5000/">
<input type="hidden" name="hiddenfield" value="yesitshidden"><p><input type="text"
name="query"> <input type="submit"> </p>
</form>
And I need to write a simple program that will listen to port 5000 and then redirect the user to who submitted the form to a HTML page the program also generates. I don't know how to write the server part of this program, I've looked at the sockets and url tutorials that sun provide but no luck!
This program acts as the server part to a client server apllication and listens to a port 5000 is there anyway to adapt it to accept requests from a html form??

Thanks Guys
Code tags added by M^2
[ August 02, 2003: Message edited by: Michael Morris ]

John
Michael Morris
Ranch Hand

Joined: Jan 30, 2002
Posts: 3451
Hi John,
Welcome to JavaRanch. Wouldn't it be easier to do this with a Servlet? Servlets take care of all the nasty details of POST and GET requests so you can concentrate on just responding. You can do this with sockets but it's going to be a lot tougher, and I'm not sure that UDP is the best way to go anyway since there is no guarantee that the message will ever be delivered.


Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage - to move in the opposite direction. - Ernst F. Schumacher
John Winstanley
Greenhorn

Joined: Apr 08, 2003
Posts: 14
It would be easier to do this with a servlet. That was my first approach for the application and it worked well. But I wanted this to be easy to install no servelt container and no Java SDK.
Using datagrams wasn't the way to go its just that I'd used that code for another application and it was similar. I found this code which was a very good start to what I wanted.
/ * An example of a very simple, multi-threaded HTTP server.
* Implementation notes are in WebServer.html, and also
* as comments in the source code.
*/
import java.io.*;
import java.net.*;
import java.util.*;
class WebServer implements HttpConstants {
/* static class data/methods */
/* print to stdout */
protected static void p(String s) {
System.out.println(s);
}
/* print to the log file */
protected static void log(String s) {
synchronized (log) {
log.println(s);
log.flush();
}
}
static PrintStream log = null;
/* our server's configuration information is stored
* in these properties
*/
protected static Properties props = new Properties();
/* Where worker threads stand idle */
static Vector threads = new Vector();
/* the web server's virtual root */
static File root;
/* timeout on client connections */
static int timeout = 0;
/* max # worker threads */
static int workers = 5;

/* load www-server.properties from java.home */
static void loadProps() throws IOException {
File f = new File
(System.getProperty("java.home")+File.separator+
"lib"+File.separator+"www-server.properties");
if (f.exists()) {
InputStream is =new BufferedInputStream(new
FileInputStream(f));
props.load(is);
is.close();
String r = props.getProperty("root");
if (r != null) {
root = new File(r);
if (!root.exists()) {
throw new Error(root + " doesn't exist as server root");
}
}
r = props.getProperty("timeout");
if (r != null) {
timeout = Integer.parseInt(r);
}
r = props.getProperty("workers");
if (r != null) {
workers = Integer.parseInt(r);
}
r = props.getProperty("log");
if (r != null) {
p("opening log file: " + r);
log = new PrintStream(new BufferedOutputStream(
new FileOutputStream(r)));
}
}
/* if no properties were specified, choose defaults */
if (root == null) {
root = new File(System.getProperty("user.dir"));
}
if (timeout <= 1000) {
timeout = 5000;
}
if (workers < 25) {
workers = 5;
}
if (log == null) {
p("logging to stdout");
log = System.out;
}
}
static void printProps() {
p("root="+root);
p("timeout="+timeout);
p("workers="+workers);
}
public static void main(String[] a) throws Exception {
int port = 8080;
if (a.length > 0) {
port = Integer.parseInt(a[0]);
}
loadProps();
printProps();
/* start worker threads */
for (int i = 0; i < workers; ++i) {
Worker w = new Worker();
(new Thread(w, "worker #"+i)).start();
threads.addElement(w);
}
ServerSocket ss = new ServerSocket(port);
while (true) {
Socket s = ss.accept();
Worker w = null;
synchronized (threads) {
if (threads.isEmpty()) {
Worker ws = new Worker();
ws.setSocket(s);
(new Thread(ws, "additional worker")).start();
} else {
w = (Worker) threads.elementAt(0);
threads.removeElementAt(0);
w.setSocket(s);
}
}
}
}
}

class Worker extends WebServer implements HttpConstants, Runnable {
final static int BUF_SIZE = 2048;
static final byte[] EOL = {(byte)'\r', (byte)'\n' };
/* buffer to use for requests */
byte[] buf;
/* Socket to client we're handling */
private Socket s;
Worker() {
buf = new byte[BUF_SIZE];
s = null;
}
synchronized void setSocket(Socket s) {
this.s = s;
notify();
}
public synchronized void run() {
while(true) {
if (s == null) {
/* nothing to do */
try {
wait();
} catch (InterruptedException e) {
/* should not happen */
continue;
}
}
try {
handleClient();
} catch (Exception e) {
e.printStackTrace();
}
/* go back in wait queue if there's fewer
* than numHandler connections.
*/
s = null;
Vector pool = WebServer.threads;
synchronized (pool) {
if (pool.size() >= WebServer.workers) {
/* too many threads, exit this one */
return;
} else {
pool.addElement(this);
}
}
}
}
void handleClient() throws IOException {
InputStream is = new BufferedInputStream(s.getInputStream());
PrintStream ps = new PrintStream(s.getOutputStream());
/* we will only block in read for this many milliseconds
* before we fail with java.io.InterruptedIOException,
* at which point we will abandon the connection.
*/
s.setSoTimeout(WebServer.timeout);
s.setTcpNoDelay(true);
/* zero out the buffer from last time */
for (int i = 0; i < BUF_SIZE; i++) {
buf[i] = 0;
}
try {
/* We only support HTTP GET/HEAD, and don't
* support any fancy HTTP options,
* so we're only interested really in
* the first line.
*/
int nread = 0, r = 0;
outerloop:
while (nread < BUF_SIZE) {
r = is.read(buf, nread, BUF_SIZE - nread);
if (r == -1) {
/* EOF */
return;
}
int i = nread;
nread += r;
for (; i < nread; i++) {
if (buf[i] == (byte)'\n' || buf[i] == (byte)'\r') {
/* read one line */
break outerloop;
}
}
}
/* are we doing a GET or just a HEAD */
boolean doingGet;
/* beginning of file name */
int index;
if (buf[0] == (byte)'G' &&
buf[1] == (byte)'E' &&
buf[2] == (byte)'T' &&
buf[3] == (byte)' ') {
doingGet = true;
index = 4;
} else if (buf[0] == (byte)'H' &&
buf[1] == (byte)'E' &&
buf[2] == (byte)'A' &&
buf[3] == (byte)'D' &&
buf[4] == (byte)' ') {
doingGet = false;
index = 5;
} else {
/* we don't support this method */
ps.print("HTTP/1.0 " + HTTP_BAD_METHOD +
" unsupported method type: ");
ps.write(buf, 0, 5);
ps.write(EOL);
ps.flush();
s.close();
return;
}
int i = 0;
/* find the file name, from:
* GET /foo/bar.html HTTP/1.0
* extract "/foo/bar.html"
*/
for (i = index; i < nread; i++) {
if (buf[i] == (byte)' ') {
break;
}
}
String fname = (new String(buf, 0, index,
i-index)).replace('/', File.separatorChar);
if (fname.startsWith(File.separator)) {
fname = fname.substring(1);
}
File targ = new File(WebServer.root, fname);
if (targ.isDirectory()) {
File ind = new File(targ, "index.html");
if (ind.exists()) {
targ = ind;
}
}
boolean OK = printHeaders(targ, ps);
if (doingGet) {
if (OK) {
sendFile(targ, ps);
} else {
send404(targ, ps);
}
}
} finally {
s.close();
}
}
boolean printHeaders(File targ, PrintStream ps) throws IOException {
boolean ret = false;
int rCode = 0;
if (!targ.exists()) {
rCode = HTTP_NOT_FOUND;
ps.print("HTTP/1.0 " + HTTP_NOT_FOUND + " not found");
ps.write(EOL);
ret = false;
} else {
rCode = HTTP_OK;
ps.print("HTTP/1.0 " + HTTP_OK+" OK");
ps.write(EOL);
ret = true;
}
log("From " +s.getInetAddress().getHostAddress()+": GET " +
targ.getAbsolutePath()+"-->"+rCode);
ps.print("Server: Simple java");
ps.write(EOL);
ps.print("Date: " + (new Date()));
ps.write(EOL);
if (ret) {
if (!targ.isDirectory()) {
ps.print("Content-length: "+targ.length());
ps.write(EOL);
ps.print("Last Modified: " + (new
Date(targ.lastModified())));
ps.write(EOL);
String name = targ.getName();
int ind = name.lastIndexOf('.');
String ct = null;
if (ind > 0) {
ct = (String) map.get(name.substring(ind));
}
if (ct == null) {
ct = "unknown/unknown";
}
ps.print("Content-type: " + ct);
ps.write(EOL);
} else {
ps.print("Content-type: text/html");
ps.write(EOL);
}
}
return ret;
}
void send404(File targ, PrintStream ps) throws IOException {
ps.write(EOL);
ps.write(EOL);
ps.println("Not Found\n\n"+
"The requested resource was not found.\n");
}
void sendFile(File targ, PrintStream ps) throws IOException {
InputStream is = null;
ps.write(EOL);
if (targ.isDirectory()) {
listDirectory(targ, ps);
return;
} else {
is = new FileInputStream(targ.getAbsolutePath());
}
try {
int n;
while ((n = is.read(buf)) > 0) {
ps.write(buf, 0, n);
}
} finally {
is.close();
}
}
/* mapping of file extensions to content-types */
static java.util.Hashtable map = new java.util.Hashtable();
static {
fillMap();
}
static void setSuffix(String k, String v) {
map.put(k, v);
}
static void fillMap() {
setSuffix("", "content/unknown");
setSuffix(".uu", "application/octet-stream");
setSuffix(".exe", "application/octet-stream");
setSuffix(".ps", "application/postscript");
setSuffix(".zip", "application/zip");
setSuffix(".sh", "application/x-shar");
setSuffix(".tar", "application/x-tar");
setSuffix(".snd", "audio/basic");
setSuffix(".au", "audio/basic");
setSuffix(".wav", "audio/x-wav");
setSuffix(".gif", "image/gif");
setSuffix(".jpg", "image/jpeg");
setSuffix(".jpeg", "image/jpeg");
setSuffix(".htm", "text/html");
setSuffix(".html", "text/html");
setSuffix(".text", "text/plain");
setSuffix(".c", "text/plain");
setSuffix(".cc", "text/plain");
setSuffix(".c++", "text/plain");
setSuffix(".h", "text/plain");
setSuffix(".pl", "text/plain");
setSuffix(".txt", "text/plain");
setSuffix(".java", "text/plain");
}
void listDirectory(File dir, PrintStream ps) throws IOException {
ps.println("<TITLE>Directory listing</TITLE><P>\n");
ps.println("<A HREF=\"..\">Parent Directory</A><BR>\n");
String[] list = dir.list();
for (int i = 0; list != null && i < list.length; i++) {
File f = new File(dir, list[i]);
if (f.isDirectory()) {
ps.println("<A HREF=\""+list[i]+"/\">"+list[i]+"/</A><BR>");
} else {
ps.println("<A HREF=\""+list[i]+"\">"+list[i]+"</A><BR");
}
}
ps.println("<P><HR><BR><I>" + (new Date()) + "</I>");
}
}
interface HttpConstants {
/** 2XX: generally "OK" */
public static final int HTTP_OK = 200;
public static final int HTTP_CREATED = 201;
public static final int HTTP_ACCEPTED = 202;
public static final int HTTP_NOT_AUTHORITATIVE = 203;
public static final int HTTP_NO_CONTENT = 204;
public static final int HTTP_RESET = 205;
public static final int HTTP_PARTIAL = 206;
/** 3XX: relocation/redirect */
public static final int HTTP_MULT_CHOICE = 300;
public static final int HTTP_MOVED_PERM = 301;
public static final int HTTP_MOVED_TEMP = 302;
public static final int HTTP_SEE_OTHER = 303;
public static final int HTTP_NOT_MODIFIED = 304;
public static final int HTTP_USE_PROXY = 305;
/** 4XX: client error */
public static final int HTTP_BAD_REQUEST = 400;
public static final int HTTP_UNAUTHORIZED = 401;
public static final int HTTP_PAYMENT_REQUIRED = 402;
public static final int HTTP_FORBIDDEN = 403;
public static final int HTTP_NOT_FOUND = 404;
public static final int HTTP_BAD_METHOD = 405;
public static final int HTTP_NOT_ACCEPTABLE = 406;
public static final int HTTP_PROXY_AUTH = 407;
public static final int HTTP_CLIENT_TIMEOUT = 408;
public static final int HTTP_CONFLICT = 409;
public static final int HTTP_GONE = 410;
public static final int HTTP_LENGTH_REQUIRED = 411;
public static final int HTTP_PRECON_FAILED = 412;
public static final int HTTP_ENTITY_TOO_LARGE = 413;
public static final int HTTP_REQ_TOO_LONG = 414;
public static final int HTTP_UNSUPPORTED_TYPE = 415;
/** 5XX: server error */
public static final int HTTP_SERVER_ERROR = 500;
public static final int HTTP_INTERNAL_ERROR = 501;
public static final int HTTP_BAD_GATEWAY = 502;
public static final int HTTP_UNAVAILABLE = 503;
public static final int HTTP_GATEWAY_TIMEOUT = 504;
public static final int HTTP_VERSION = 505;
}
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: Server Program - Responding To Post Requests From HTML pg.
 
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