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Java Socket Program Hangs

Posted on 2009-04-01
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Last Modified: 2013-11-24
This Java program acquires web content from a website.  I'm having issues with msnbc.com.  After the 24th loop of acquiring content the progam hangs.

So after about the 24th i:, the program stops and then, eventually the socket resets.

Any ideas what could be the problem?  Any suggestions to fix?
OutputStream os = null;

        ByteArrayOutputStream byteContainer = new ByteArrayOutputStream();

        try {

            Socket socket = new Socket("www.msnbc.msn.com", 80);
 

            String r = new String("GET / HTTP/1.1\n" +

                    "Host: www.msnbc.msn.com\n" +

                    "User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.12) Gecko/20080201 Firefox/2.0.0.12\n" +

                    "Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5\n" +

                    "Accept-Language: en-us,en;q=0.5\n" +

                    "Accept-Encoding: gzip,deflate\n" +

                    "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7\n" +

                    "Keep-Alive: 300\n" +

                    "Connection: keep-alive\n" +

                    "Cookie: MC1=GUID=e72def902864496fa1074688e1697ab7; TZM=-240; __g_c=w%3A0; PageNo=1; s_cc=true; s_sq=%5B%5BB%5D%5D; MUID=F496E73B351C49BF8120BEECED8B6A98\n");
 

            System.out.println("Connecting using the following get request: " + r);
 

            os = socket.getOutputStream();

            boolean autoflush = true;

            PrintWriter out = new PrintWriter(socket.getOutputStream(), autoflush);

            out.println(new String(r));

            out.println('\r');

            out.println('\n');

            out.flush();

            socket.shutdownOutput();
 

            // Read the response

            byte[] b = new byte[1024];

            InputStream in = socket.getInputStream();

            int i = in.read(b);

            while (i != -1) {

                byteContainer.write(b, 0, i);

                i = in.read(b);

                System.out.println("i: " + i);

            }
 

            socket.close();

            in.close();

            out.close();

            os.close();
 

            byte[] content = byteContainer.toByteArray();

            byteContainer.close();
 

        } catch (IOException ex) {

            ex.printStackTrace();

        }

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Question by:lcor
5 Comments
 
LVL 17

Assisted Solution

by:Thomas4019
Thomas4019 earned 100 total points
ID: 24044552
Maybe their website is categorizing you calls as excessive. Maybe try waiting for a few hundred milliseconds between each call.
0
 
LVL 92

Accepted Solution

by:
objects earned 200 total points
ID: 24044555
0
 

Author Comment

by:lcor
ID: 24044978
Thomas4019,
I added a Thread.sleep(300) in the while loop.

Each i comes back with a value of 1024 but it eventually ends up hanging.
0
 
LVL 8

Assisted Solution

by:n_sachin1
n_sachin1 earned 200 total points
ID: 24047181
IMHO, the read method of an inputstream is supposed to block till the end of stream is reached or there was an IO error/exception, if there is no more data available to be read. Thats what is happening in your program.

With HTTP1.1 calls, that have persistent connections, the server does not drop the connection after writing the data, but instead, sends information in the packets that the current response is complete(via content-length, etc.). You should look towards using the HTTP classes instead of plain Sockets, as they are higher level abstractions and understand the HTTP packets better.

Use java.net.HttpURLConnection as the entry point, or use the Apache Http Client library which is simpler to use.



0
 

Author Closing Comment

by:lcor
ID: 31565568
n_sachin1 and objects are the solution but Thomas4019 was helpful with debug
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