Java Language Socket example - reading a web page using a simple socket


Example

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

public class Main {

    public static void main(String[] args) throws IOException {//We don't handle Exceptions in this example 
        //Open a socket to stackoverflow.com, port 80
        Socket socket = new Socket("stackoverflow.com",80);

        //Prepare input, output stream before sending request
        OutputStream outStream = socket.getOutputStream();
        InputStream inStream = socket.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(inStream));
        PrintWriter writer = new PrintWriter(new BufferedOutputStream(outStream));

        //Send a basic HTTP header
        writer.print("GET / HTTP/1.1\nHost:stackoverflow.com\n\n");
        writer.flush();

        //Read the response
        System.out.println(readFully(reader));

        //Close the socket
        socket.close();
    }
    
    private static String readFully(Reader in) {
        StringBuilder sb = new StringBuilder();
        int BUFFER_SIZE=1024;
        char[] buffer = new char[BUFFER_SIZE]; // or some other size, 
        int charsRead = 0;
        while ( (charsRead  = rd.read(buffer, 0, BUFFER_SIZE)) != -1) {
          sb.append(buffer, 0, charsRead);
        }
    }
}

You should get a response that starts with HTTP/1.1 200 OK, which indicates a normal HTTP response, followed by the rest of the HTTP header, followed by the raw web page in HTML form.

Note the readFully() method is important to prevent a premature EOF exception. The last line of the web page may be missing a return, to signal the end of line, then readLine() will complain, so one must read it by hand or use utility methods from Apache commons-io IOUtils

This example is meant as a simple demonstration of connecting to an existing resource using a socket, it's not a practical way of accessing web pages. If you need to access a web page using Java, it's best to use an existing HTTP client library such as Apache's HTTP Client or Google's HTTP Client