transferring files from client to server 1

[alex75]

I'd like to know how to transfer files (like sounds, images, ...) from client to server in a easy way ?<br>I know I have to use either CGI, servlet or RMI. But could you give me a hint ? Many thanks. Alex.

 

[phimlob]

If you have all the necessary rights on your server, you dont have to use cgi, servlets or rmi. you can just make a connection. heres an example:<br><br>**** Client side: make sure you import all the right packages...<br><br>/** sends a java object to the reciever and returns whatever object the server sent back. */<br>&nbsp;&nbsp;&nbsp;&nbsp; public Object sendObject(Object o) throws Exception, UnknownHostException, ConnectException {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; Object objectFromServer = null;<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; socket = new Socket(server, port);<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; ObjectOutputStream objOut = new ObjectOutputStream(new BufferedOutputStream(socket.getOutputStream()));<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objOut.writeObject(o);<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objOut.flush();<br> <br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; ObjectInputStream&nbsp;&nbsp;objIn&nbsp;&nbsp;= new ObjectInputStream(new BufferedInputStream(socket.getInputStream()));<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objectFromServer = objIn.readObject();<br> <br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objIn.close();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objOut.close();<br> <br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; try { socket.close(); }<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; catch (IOException ioe1) {/*Do nothing*/}<br> <br> <br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; return objectFromServer;<br>&nbsp;&nbsp;&nbsp;&nbsp; }<br><br>to send something, call sendObject(new yourObject())<br>remember to make sure that your class is serializable.<br><br>and on the server side:<br><br>import java.net.*;<br>import java.io.*;<br>import java.util.*;<br><br>public class Server {<br>&nbsp;&nbsp;&nbsp;&nbsp; private ServerSocket serverSocket = null; <br> <br>&nbsp;&nbsp;&nbsp;&nbsp; public static void main(String[] args) throws IOException {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; System.out.println(&quot;Initiating Server...&quot;<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; Server s = new Server(); <br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; try {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; s.initServer();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; } catch (Exception e) { System.out.println(e.toString());}<br>&nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp; /** Initializes the server.<br>&nbsp;&nbsp;&nbsp;&nbsp; */<br>&nbsp;&nbsp;&nbsp;&nbsp; public void initServer() throws IOException {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; try {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; serverSocket = new ServerSocket(5700); // the port<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; } catch (IOException e) {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; System.out.println(&quot;Another application is listening to port 5700.\n&quot;+e);<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; System.exit(0);<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; }<br> <br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; // infinite loop<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; boolean listening = true;<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; while (listening) {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; Socket s = serverSocket.accept();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; ServerThread st = new ServerThread(s, this);<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; st.start();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; serverSocket.close();<br>&nbsp;&nbsp;&nbsp;&nbsp; }<br>}<br><br>class ServerThread extends Thread {<br>&nbsp;&nbsp;&nbsp;&nbsp; private Socket socket = null;<br>&nbsp;&nbsp;&nbsp;&nbsp; private Server server;<br> <br>&nbsp;&nbsp;&nbsp;&nbsp; /** constructor. */<br>&nbsp;&nbsp;&nbsp;&nbsp; public ServerThread(Socket socket, Server server) {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; super(&quot;ServerThread&quot;<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; this.socket = socket;<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; this.server = server;<br>&nbsp;&nbsp;&nbsp;&nbsp; }<br> <br>&nbsp;&nbsp;&nbsp;&nbsp; /** <br>&nbsp;&nbsp;&nbsp;&nbsp; * Here, I take the socket given to me in the <br>&nbsp;&nbsp;&nbsp;&nbsp; * constructor and I extract the object sent to me from the client.&lt;BR&gt;<br>&nbsp;&nbsp;&nbsp;&nbsp; */<br>&nbsp;&nbsp;&nbsp;&nbsp; public void run() {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; Object objectFromClient = null;<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; try {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; ObjectInputStream objIn = new ObjectInputStream(new BufferedInputStream(socket.getInputStream()));<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objectFromClient = objIn.readObject();<br><br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; if (objectFromClient.getClass().equals(String.class)) {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; System.out.println(&quot;&gt;&gt; String object recieved&gt;&gt;&quot;+objectFromClient.toString());<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; reply(&quot;String object recieved by server&quot;<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; join();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; } <br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; catch (StreamCorruptedException sce) {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; System.err.println(sce.toString());<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; catch (Exception e) {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; e.printStackTrace();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp;&nbsp; }<br><br>&nbsp;&nbsp;&nbsp;&nbsp; /**<br>&nbsp;&nbsp;&nbsp;&nbsp; * takes the recieved object and sends it to the client.<br> */<br>&nbsp;&nbsp;&nbsp;&nbsp; private void reply(Object obj) {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; try {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; ObjectOutputStream objOut = new ObjectOutputStream(new BufferedOutputStream(socket.getOutputStream()));<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objOut.writeObject(obj);<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objOut.flush();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; objOut.close();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; catch (Exception e) {<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; e.printStackTrace();<br>&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp;&nbsp; }<br>}<br><br><br>Of course you can do it with CGI, RMI or Servlets- if you find this stuff interesting you should give Objectspace Voyager a look, or if you write in several languages, you should try CORBA.<br><br>Good luck<br>Mattias<br>