File transfer using Java Http

Dale Seng

Ranch Hand

Posts: 275

posted 7 years ago

I've got a program that's using POJO's to do a little web server that takes commands. It works great, and it's tiny. But I'm not sure how to extend it to accept an inbound file transfer. Can anyone give me some coding advice for binary file transfer (sans the advice to install a web server...sorry, just not going to do that, this needs to REMAIN tiny). Below is the code I'm using. It's not going to compile out of the box for you...here to give you an idea about what I'm starting with.

public class TinyWebServer implements Runnable {

public ServerSocket listen_socket;
	public boolean runFlag = true;
    Thread runningThread;
    
	public TinyWebServer(String port) {
		try {
			int servPort = Integer.parseInt(port);
			listen_socket = new ServerSocket(servPort);
		} catch (IOException e) {
			System.err.println(e);
		}
        runningThread = new Thread(this);
		runningThread.start();
	}

public void run() {
        String message = "";
		while (isRunning()) {
			try {
				Socket client_socket = listen_socket.accept(); // blocks
				if (!isRunning()) break;
				new TinyConnection(client_socket);
			} catch (IOException e) {
                message = e.getMessage();
                System.err.println(new Date() + " Error in TinyWebServer.run");
				e.printStackTrace();
			} catch (Throwable t){
                message = t.getMessage();
                System.err.println(new Date() + " Error in TinyWebServer.run");
                t.printStackTrace();
                setRunning(false);
            }
		}
		System.out.println(new Date() + " TinyWebServer ending. " + message);
	}
	
	public synchronized boolean isRunning(){
		return runFlag;
	}
	
	public synchronized void setRunning(boolean running){
		this.runFlag = running;
	}

public static void main(String[] argv) throws Exception {
		if (argv.length < 1) {
			System.out.println("usage: java TinyWebServer <port>");
			return;
		}
		TinyWebServer server = new TinyWebServer(argv[0]);

// Run the server for 2000 seconds
		Thread.sleep(2000000);

// Set run flag to "false" and poke it so it knows to quit
		System.out.println("runFlag set to false"); 
		server.setRunning(false);
		PrintStream out = new PrintStream(new DataOutputStream(new Socket("127.0.0.1", Integer.parseInt(argv[0])).getOutputStream()));
		out.write("GET /noop".getBytes());out.close();

// Give it a moment then make sure it's gone
		Thread.sleep(2000);
		System.out.println("is alive:" + server.runningThread.isAlive());
		System.out.println("end of main.");
		
	}
}

class TinyConnection implements Runnable {
	protected Socket client;
	protected BufferedReader in;
	protected PrintStream out;
    protected CM cm;
    protected TM tM;
	private static final String HEAD = "HTTP/1.0 200 OK\nContent-type: text/html\n\n<html><body><h2>Interface</h2><br>";
    private static final String FOOT = "</body></html>";

public TinyConnection(Socket client_socket) {
		this.client = client_socket;
        this.cm = CM.getInstance();
        this.tM = TM.getInstance();
        
		try {
			in = new BufferedReader(new InputStreamReader(new DataInputStream(client.getInputStream())));
			out = new PrintStream(client.getOutputStream());
		} catch (IOException e) {
			System.err.println(e);
			try {client.close();} catch (IOException e2) {/* ignore */}
			return;
		}
		(new Thread(this)).start();
	}

public void run() {
		String line = null; // read buffer
		String req = null; // first line of request
		try {
			req = in.readLine();
			System.out.println("request [" + req + "]");

// loop through and discard rest of request
			line = req;
			while (line != null && line.length() > 0) {
				line = in.readLine();
				//System.out.println("other data [" + line + "]");
			}

// get properties map 
            Map request = getRequestMap(req);
            
            String action = (String)request.get("action");

if (action.equals("/set")){
                String setItem = null;
                
                setItem = (String)request.get("simulate");
                if (setItem != null && setItem.equals("true")){
                    CM.setSimulate(true);
                    out.print(HEAD + "simulate=true" + FOOT);
                } 
            } else {
                out.print(HEAD + "<br><h2>Command Not Understood</h2><br>" + FOOT);
            }
            out.close();
		} catch (Exception e) {
            System.err.println(new Date() + " Error in TinyConnection.run");
            e.printStackTrace();
            out.print(e.getMessage());
            System.out.println(e.getMessage());
		} finally {
			try {client.close();} catch (IOException e) {}
		}
	}
}

Rob Spoor

Sheriff

Posts: 21052

I like...

posted 7 years ago

A binary file transfer is basically the same as text transfer but without using Writer and Reader, but sticking to InputStream and OutputStream (possibly wrapped in other streams).

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Dale Seng

Ranch Hand

Posts: 275

posted 7 years ago

Rob Prime wrote:A binary file transfer is basically the same as text transfer but without using Writer and Reader, but sticking to InputStream and OutputStream (possibly wrapped in other streams).

Thanks Rob, for the ideas.

As you see in my code, I'm just expecting GET requests and looking at the plain text of the request. If set-up for handling a POST, you suggest I use an input stream and pull the form data, where the other party will have stuffed the binary? Sounds like there's enough here to embark on a trial, but I would expect to be reinventing the wheel (and finding the same bumps in the road others have found). Would you (or anyone) have any suggestions on where to find some sample code?

--Dale--

It is sorta covered in the JavaRanch Style Guide.

File transfer using Java Http

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