distributedComputingExamples/sockets/java/src/MinHTTPServerMultiThread.java at master · thomasWeise/distributedComputingExamples · GitHub

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import java.io.BufferedReader;      import java.io.File;        import java.io.FileInputStream;   import java.io.InputStreamReader;
import java.io.OutputStreamWriter;  import java.io.PrintWriter; import java.net.ServerSocket;     import java.net.Socket;

public class MinHTTPServerMultiThread {
  public static final void main(final String[] args) {
    ServerSocket    server;     Socket          client;
    try {
      server = new ServerSocket(9995); //create server socket (*@\serverBox{1 + 2)}@*)

      for (;;) {  //forever...
        client = server.accept(); //wait for and accept incoming connection (*@\serverBox{3)}@*)
        new Thread(new Job(client)).start(); //create and start a new thread to process the request

      }
    } catch (Throwable t) {
      t.printStackTrace();
    }
  }

  private static final class Job implements Runnable { //the job class: process one request; Runnable is the key interface
    private final Socket m_client; //the client socket to process
    Job(final Socket client){ //create a job for a given socket
      this.m_client=client;
    }

    @Override //this method is executed by the thread that was created with this object as constructor parameter
    public final void run(){ //process the client socket: exactly the same as in the MinHTTPServer example
      BufferedReader  br;   PrintWriter     pw;   String    s;    File  f;
      byte[]          bs;   FileInputStream fis;  Throwable x;    int   i;

      try{
      br = new BufferedReader(new InputStreamReader(this.m_client.getInputStream())); // read character data
      pw = new PrintWriter(new OutputStreamWriter(this.m_client.getOutputStream(), "ISO_8859-1")); //chose the right encoding! (*@\citep{RFC1945,RFC2616}@*)

      process: { //(*@\serverBox{4} + \clientBox{3})@*)
        x = null;
        try {
          while ((s = br.readLine()) != null) { //read text from connection line-by-line until end
            if (s.startsWith("GET ")) {  // try to find the GET command in the HTTP request (*@\citep{RFC1945,RFC2616}@*)
              f   = new File(s.substring(4, s.indexOf(' ', 4)).replace('/', File.separatorChar)); //in a very crude way, extract the requested path from that command
              bs  = new byte[(int) (f.length())];  //allocate a buffer of the right size
              fis = new FileInputStream(f);        //open the file
              i   = fis.read(bs);                  //read the complete file into memory
              fis.close();                         //close the file
              pw.write("HTTP/1.1 200 OK\r\n\r\n");  pw.flush(); //send "success" according to (*@\citep{RFC1945,RFC2616}@*)
              this.m_client.getOutputStream().write(bs, 0, i); //...and the file content  ((*@\serverBox{4} + \clientBox{3})@*))
              break process;                            //ok, we are finished here
            }
          }
        } catch (Throwable t) { x= t; } //if request fails, remember why

        //hm, we did not find the file or had an error (*@\citep{RFC1945,RFC2616}@*)
        pw.write("HTTP/1.1 404 Not Found\r\n\r\n<html><head><title>404</title></head><body><h1>404 - Not found</h1><pre>");
        if(x != null) { x.printStackTrace(pw); } //write the error message (notice the <pre>...</pre> wrapper)
        pw.write("</pre></body></html");         //end the html body
        pw.flush(); //and flush ((*@\serverBox{4} + \clientBox{3})@*))
      }

      this.m_client.close(); }//(*@\clientBox{4)}@*)
      catch(Throwable error) { error.printStackTrace(); }
    }
  }
}