How to retrieve a file from http server

Question

I have the following web server class found here. I need to write an Android application(client) which can retrieve a file from this server. It would be great if anyone would be able to help me to do it. Thank you.

Server host address is: My-PC/ipaddress

When I execute the client it gives an exception.

java.net.ConnectException: Connection refused: connect

WebServer.Java

import java.io.*;
import java.net.*;


public class WebServer extends Thread {

public WebServer() {

    this.start();
}

private void displayString(String string) { //an alias to avoid typing so much!
    System.out.println(string);
}   

private static final int UMBRA_PORT = 30480;
private static final int ROOM_THROTTLE = 200;   
private InetAddress hostAddress;

//this is a overridden method from the Thread class we extended from
public void run() {
    //we are now inside our own thread separated from the gui.
    ServerSocket serversocket = null;
    //To easily pick up lots of girls, change this to your name!!!
    displayString("The simple httpserver v. 0000000000\nCoded by Jon Berg" +
            "<jon.berg[on server]turtlemeat.com>\n\n");
    //Pay attention, this is where things starts to cook!
    try {
        //print/send message to the guiwindow
        displayString("Trying to bind to localhost on port " + Integer.toString(UMBRA_PORT) + "...");
        //make a ServerSocket and bind it to given port,
        //serversocket = new ServerSocket(port);
    }
    catch (Exception e) { //catch any errors and print errors to gui
        displayString("\nFatal Error:" + e.getMessage());
        return;
    }

    // Attempt to get the host address
    try
    {
        hostAddress = InetAddress.getLocalHost();
    }
    catch(UnknownHostException e)
    {
        System.out.println("Could not get the host address.");
        return;
    }
    // Announce the host address
    System.out.println("Server host address is: "+hostAddress);
    // Attempt to create server socket
    try
    {
        serversocket = new ServerSocket(UMBRA_PORT,0,hostAddress);
    }
    catch(IOException e)
    {
        System.out.println("Could not open server socket.");
        return;
    }
    // Announce the socket creation
    System.out.println("Socket "+serversocket+" created.");



    displayString("OK!\n");
    //go in a infinite loop, wait for connections, process request, send response
    while (true) {
        displayString("\nReady, Waiting for requests...\n");        

        try {

            //this call waits/blocks until someone connects to the port we
            //are listening to
            Socket connectionsocket = serversocket.accept();
            //figure out what ipaddress the client commes from, just for show!
            InetAddress client = connectionsocket.getInetAddress();
            //and print it to gui
            displayString(client.getHostName() + " connected to server.\n");
            //Read the http request from the client from the socket interface
            //into a buffer.
            BufferedReader input =
                    new BufferedReader(new InputStreamReader(connectionsocket.
                            getInputStream()));
            //Prepare a outputstream from us to the client,
            //this will be used sending back our response
            //(header + requested file) to the client.
            DataOutputStream output =
                    new DataOutputStream(connectionsocket.getOutputStream());

            //as the name suggest this method handles the http request, see further down.
            //abstraction rules
            http_handler(input, output);
        }
        catch (Exception e) { //catch any errors, and print them
            displayString("\nError:" + e.getMessage());
        }

    } //go back in loop, wait for next request
}

//our implementation of the hypertext transfer protocol
//its very basic and stripped down
private void http_handler(BufferedReader input, DataOutputStream output) {
    int method = 0; //1 get, 2 head, 0 not supported
    String http = new String(); //a bunch of strings to hold
    String path = new String(); //the various things, what http v, what path,
    String file = new String(); //what file
    String user_agent = new String(); //what user_agent
    try {
        //This is the two types of request we can handle
        //GET /index.html HTTP/1.0
        //HEAD /index.html HTTP/1.0
        String tmp = input.readLine(); //read from the stream
        String tmp2 = new String(tmp);
        tmp.toUpperCase(); //convert it to uppercase
        if (tmp.startsWith("GET")) { //compare it is it GET
            method = 1;
        } //if we set it to method 1
        if (tmp.startsWith("HEAD")) { //same here is it HEAD
            method = 2;
        } //set method to 2

        if (method == 0) { // not supported
            try {
                output.writeBytes(construct_http_header(501, 0));
                output.close();
                return;
            }
            catch (Exception e3) { //if some error happened catch it
                displayString("error:" + e3.getMessage());
            } //and display error
        }
        //}

        //tmp contains "GET /index.html HTTP/1.0 ......."
        //find first space
        //find next space
        //copy whats between minus slash, then you get "index.html"
        //it's a bit of dirty code, but bear with me...
        int start = 0;
        int end = 0;
        for (int a = 0; a < tmp2.length(); a++) {
            if (tmp2.charAt(a) == ' ' && start != 0) {
                end = a;
                break;
            }
            if (tmp2.charAt(a) == ' ' && start == 0) {
                start = a;
            }
        }
        path = tmp2.substring(start + 2, end); //fill in the path
    }
    catch (Exception e) {
        displayString("errorr" + e.getMessage());
    } //catch any exception

    //path do now have the filename to what to the file it wants to open
    displayString("\nClient requested:" + new File(path).getAbsolutePath() + "\n");
    FileInputStream requestedfile = null;

    try {

        //try to open the file,
        requestedfile = new FileInputStream(path);
    }
    catch (Exception e) {
        try {
            //if you could not open the file send a 404
            output.writeBytes(construct_http_header(404, 0));
            //close the stream
            output.close();
        }
        catch (Exception e2) {}
        displayString("error" + e.getMessage());
    } //print error to gui

    //happy day scenario
    try {
        int type_is = 0;
        //find out what the filename ends with,
        //so you can construct a the right content type
        if (path.endsWith(".zip") ) {
            type_is = 3;
        }
        if (path.endsWith(".jpg") || path.endsWith(".jpeg")) {
            type_is = 1;
        }
        if (path.endsWith(".gif")) {
            type_is = 2;      
        }
        if (path.endsWith(".ico")) {
            type_is = 4;
        }
        if (path.endsWith(".xml")) {
            type_is = 5;
        }
        //write out the header, 200 ->everything is ok we are all happy.
        output.writeBytes(construct_http_header(200, 5));

        //if it was a HEAD request, we don't print any BODY
        if (method == 1) { //1 is GET 2 is head and skips the body
            byte [] buffer = new byte[1024];
            while (true) {
                //read the file from filestream, and print out through the
                //client-outputstream on a byte per byte base.
                int b = requestedfile.read(buffer, 0,1024);
                if (b == -1) {
                    break; //end of file
                }
                output.write(buffer,0,b);
            }
            //clean up the files, close open handles

        }
        output.close();
        requestedfile.close();
    }

    catch (Exception e) {}

}

//this method makes the HTTP header for the response
//the headers job is to tell the browser the result of the request
//among if it was successful or not.
private String construct_http_header(int return_code, int file_type) {
    String s = "HTTP/1.0 ";
    //you probably have seen these if you have been surfing the web a while
    switch (return_code) {
    case 200:
        s = s + "200 OK";
        break;
    case 400:
        s = s + "400 Bad Request";
        break;
    case 403:
        s = s + "403 Forbidden";
        break;
    case 404:
        s = s + "404 Not Found";
        break;
    case 500:
        s = s + "500 Internal Server Error";
        break;
    case 501:
        s = s + "501 Not Implemented";
        break;
    }

    s = s + "\r\n"; //other header fields,
    s = s + "Connection: close\r\n"; //we can't handle persistent connections
    s = s + "Server: SimpleHTTPtutorial v0\r\n"; //server name

    switch (file_type) {
    //plenty of types for you to fill in
    case 0:
        break;
    case 1:
        s = s + "Content-Type: image/jpeg\r\n";
        break;
    case 2:
        s = s + "Content-Type: image/gif\r\n";
        break;
    case 3:
        s = s + "Content-Type: application/x-zip-compressed\r\n";
        break;
    case 4:
        s = s + "Content-Type: image/x-icon\r\n";
    case 5:
        s = s + "Content-Type: text/xml\r\n";
        break;
    default:
        s = s + "Content-Type: text/html\r\n";
        break;
    }

    ////so on and so on......
    s = s + "\r\n"; //this marks the end of the httpheader
    //and the start of the body
    //ok return our newly created header!
    return s;
}

}

Client.Java

public class WatchMeManagerClient {

private static Socket socket;
private static PrintWriter printWriter;

public static void main(String[] args) throws Exception {
    try {
        URL url;
        URLConnection urlConn;
        DataInputStream dis;

        url = new URL("http://ipaddress/xml/userGroup.xml");

        urlConn = url.openConnection();
        urlConn.setDoInput(true);
        urlConn.setUseCaches(false);

        dis = new DataInputStream(urlConn.getInputStream());
        String s;

        while ((s = dis.readLine()) != null) {
            System.out.println(s);
        }
        dis.close();
    }

    catch (MalformedURLException mue) {
        System.out.println(mue.toString());
    } catch (IOException ioe) {
        System.out.println(ioe.toString());
    }
}
}

When I run the code on PC it works. But when I try to execute it on the Android Device it gives following errors.

Are you connecting to the right port? The server is listening on port 30480, so you should connect to ipaddress:30480/xml/userGroup.xml. — Petter
– Petter, Commented Mar 7, 2012 at 7:56

Sunil Kumar Sahoo · Accepted Answer · 2012-03-07 07:59:22Z

1

Such problems are either due to one of the following:

The port is wrong
Firewall is stopping it.

answered Mar 7, 2012 at 7:59

Sunil Kumar Sahoo

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Comments

Anirudh · Accepted Answer · 2012-03-07 07:54:02Z

0

Using Sockets require the following permission which I think you are missing:

 <uses-permission android:name="android.permission.INTERNET" />

answered Mar 7, 2012 at 7:54

Anirudh

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Comments

josephus · Accepted Answer · 2012-03-07 07:54:12Z

0

Did you allow internet access in your manifest?

<uses-permission android:name="android.permission.INTERNET"/>

answered Mar 7, 2012 at 7:54

josephus

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