Small http server using java?

Question

I have created the following test server using java:

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

class tcpServer{
    public static void main(String args[]){
        ServerSocket s = null;
        try{
            s = new ServerSocket(7896);
            //right now the stream is open.
            while(true){
                Socket clientSocket = s.accept();
                Connection c = new Connection(clientSocket);
                //now the connection is established
            }
        }catch(IOException e){
            System.out.println("Unable to read: " + e.getMessage());
        }
    }
}
class Connection extends Thread{
    Socket clientSocket;
    BufferedReader din;
    OutputStreamWriter outWriter;

    public Connection(Socket clientSocket){
        try{
            this.clientSocket = clientSocket;
            din = new BufferedReader(new InputStreamReader(clientSocket.getInputStream(), "ASCII"));
            outWriter = new OutputStreamWriter(clientSocket.getOutputStream());
            this.start();
        }catch(IOException e){
            System.out.println("Connection: " + e.getMessage());
        }   
    }
    public void run(){
        try{
        String line = null;
        while((line = din.readLine())!=null){
            System.out.println("Read" + line);
            if(line.length()==0)    
                break;
        }
        //here write the content type etc details:
        System.out.println("Someone connected: " + clientSocket);
        outWriter.write("HTTP/1.1 200 OK\r\n");
        outWriter.write("Date: Tue, 11 Jan 2011 13:09:20 GMT\r\n");
        outWriter.write("Expires: -1\r\n");
        outWriter.write("Cache-Control: private, max-age=0\r\n");
        outWriter.write("Content-type: text/html\r\n");
        outWriter.write("Server: vinit\r\n");
        outWriter.write("X-XSS-Protection: 1; mode=block\r\n");
        outWriter.write("<html><head><title>Hello</title></head><body>Hello world from my server</body></html>\r\n");
        }catch(EOFException e){
            System.out.println("EOF: " + e.getMessage());
        }
        catch(IOException e){
            System.out.println("IO at run: " + e.getMessage());
        }finally{
            try{
                            outWriter.close();  
                clientSocket.close();
            }catch(IOException e){
                System.out.println("Unable to close the socket");
            }
        }
    }
}

Now i want this server to respond to my browser. that's why i gave url: http://localhost:7896 and as a result i receive at the server side:

ReadGET / HTTP/1.1
ReadHost: localhost:7896
ReadConnection: keep-alive
ReadCache-Control: max-age=0
ReadAccept: application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
ReadUser-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/8.0.552.224 Safari/534.10
ReadAccept-Encoding: gzip,deflate,sdch
ReadAccept-Language: en-US,en;q=0.8
ReadAccept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
ReadCookie: test_cookie=test cookie
Read
Someone connected: Socket[addr=/0:0:0:0:0:0:0:1,port=36651,localport=7896]

And a blank white screen at my browser and source code also blank. In google chrome browser.

So can anyone please tell me where i m wrong. actually i am new to this thing. so please correct me.

Thanks in advance

Ok this worked after adding one more \n after the headers. So thanks all for their support — codeomnitrix
– codeomnitrix, Commented Jan 11, 2011 at 9:12
Hey but still one thing that seems me odd that addr of browser being 0:0:0:0:0:0:0:1?? what this means — codeomnitrix
– codeomnitrix, Commented Jan 11, 2011 at 9:14
A pointer to you if you dont know already - "How Tomcat Works" by Budi Kurniawan , Paul Deck is a good start point. — Sandeep Jindal
– Sandeep Jindal, Commented Jan 11, 2011 at 10:00

Jon Skeet · Accepted Answer · 2011-01-11 09:56:00Z

6

You almost certainly don't want to be using DataOutputStream on the response - and writeUTF certainly isn't going to do what you want. DataOutputStream is designed for binary protocols, basically - and writeUTF writes a length-prefixed UTF-8 string, whereas HTTP just wants CRLF-terminated lines of ASCII text.

You want to write headers out a line at a time - so create an OutputStreamWriter around the socket output stream, and write to that:

writer.write("HTTP/1.1 200 OK\r\n");
writer.write("Date: Tue, 11 Jan 2011 13:09:20 GMT\r\n");

etc.

You may want to write your own writeLine method to write out a line including the CRLF at the end (don't use the system default line terminator), to make the code cleaner.

Add a blank line between the headers and the body as well, and then you should be in reasonable shape.

EDIT: Two more changes:

Firstly, you should read the request from the client. For example, change din to a BufferedReader, and initialize it like this:

din = new BufferedReader(new InputStreamReader(clientSocket.getInputStream(),
                                               "ASCII"));

then before you start to write the output, read the request like this:

String line;
while ((line = din.readLine()) != null) {
    System.out.println("Read " + line);
    if (line.length() == 0) {
        break;
    }
}

EDIT: As noted in comments, this wouldn't be appropriate for a full HTTP server, as it wouldn't handle binary PUT/POST data well (it may read the data into its buffer, meaning you couldn't then read it as binary data from the stream). It's fine for the test app though.

Finally, you should also either close the output writer or at least flush it - otherwise it may be buffering the data.

After making those changes, your code worked for me.

edited Jan 11, 2011 at 9:56

answered Jan 11, 2011 at 8:01

Jon Skeet

1.5m893 gold badges9.3k silver badges9.3k bronze badges

Sign up to request clarification or add additional context in comments.

9 Comments

codeomnitrix Over a year ago

Hey jon i have done that as you told me but still getting the same error

Jon Skeet Over a year ago

@codeomnitrix: You need to close the writer before you close the socket - either that, or at least flush the writer. Will edit to mention that.

Jon Skeet Over a year ago

@codeomnitrix: You also need to read the request, at least from Chrome - I've edited the answer in include that. But note that the code in your question still doesn't have a blank line between the headers and the body. You need an empty line, e.g. outWriter.write("\r\n").

codeomnitrix Over a year ago

hey jon i have done that much and pretty good response as error gone away but still blank browser screen without any source code. And secondly would you please tell me what does that means by having close the writer earlier than socket.

b_erb Over a year ago

The BufferedReader is not appropriate for reading incoming HTTP requests as soon as there is a message entity which might contain binary data (i.e. file upload of an image using PUT/POST).

|

b_erb · Accepted Answer · 2011-01-11 09:23:13Z

2

If you're interested in learning the design and development of network servers like HTTP servers in Java, you might also have a look at this repo:

https://github.com/berb/java-web-server

It's a small HTTP server in Java I started for educational purposes. Though, it shouldn't be used in production or serious use cases yet. I'm still adding new features. It currently provides multi-threading, static file handling, Basic Authentication, logging and a in-memory cache.

EDIT

An obvious error in your code is the missing \r\n between your Response Header and your HTML. Just append an additional \r\n to your last header. Additionally, you must provide the content length, unless you're using Chuncked Encoding:

String out = "<html><head><title>Hello</title></head><body>Hello world from my server</body></html>\r\n";

outWriter.write("Content-Length: "+out.getBytes().length+"\r\n\r\n");
outWriter.write(out);

edited Jan 11, 2011 at 9:23

answered Jan 11, 2011 at 8:31

b_erb

21.3k8 gold badges58 silver badges64 bronze badges

2 Comments

codeomnitrix Over a year ago

kk thanks partlycloudy that solved but what does the address or browser means which is 0:0:0:0:0:0:0:1

b_erb Over a year ago

0:0:0:0:0:0:0:1 is localhost when using IPv6.

Nicolas Repiquet · Accepted Answer · 2011-01-11 08:00:04Z

1

The HTTP protocol is ASCII based, exept the body which depends on the Content-Type header. So, no UTF-8 headers!
Headers and body must be separated by an empty line.
Why do you set your Transfert-Encoding to chuncked? Your body is not.

answered Jan 11, 2011 at 8:00

Nicolas Repiquet

9,3273 gold badges36 silver badges54 bronze badges

1 Comment

codeomnitrix Over a year ago

hey can you please give me a single line as an example how to write the headers

Abdullah Jibaly · Accepted Answer · 2011-01-11 08:11:58Z

0

Check this out, it's already done for you:

http://www.mcwalter.org/technology/java/httpd/tiny/index.html

answered Jan 11, 2011 at 8:11

Abdullah Jibaly

55.1k45 gold badges129 silver badges201 bronze badges

Comments

Abdullah Jibaly · Accepted Answer · 2011-01-11 08:02:43Z

-1

I'm not sure if you have can use writeUTF instead, instead you may need to use writeBytes. Also, you need to terminate each line with a '\n'.

answered Jan 11, 2011 at 8:02

Abdullah Jibaly

55.1k45 gold badges129 silver badges201 bronze badges

3 Comments

codeomnitrix Over a year ago

Hey i have made changes to my code but still getting the same error on google chrome. please check this

codeomnitrix Over a year ago

Hey abdullah i have edited the code and now its working but i found a blank output at google chrome with page source also blank

user207421 Over a year ago

You need to terminate each header with \r\n. You don't need to line-terminate the body at all.

Collectives™ on Stack Overflow

Small http server using java?

5 Answers 5

9 Comments

2 Comments

1 Comment

Comments

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

9 Comments

2 Comments

1 Comment

Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related