Saturday, October 1, 2011

import* ;
import* ;
import java.util.* ;

public final class webserver2
public static void main(String argv[]) throws Exception
// Set the port number.
int port = 9999;

// Establish the listen socket.
ServerSocket welcomeSocket = new ServerSocket(port);

// Process HTTP service requests in an infinite loop.
while (true) {
// Listen for a TCP connection request.
Socket connectionSocket = welcomeSocket.accept();

// Construct an object to process the HTTP request message.
HttpRequest request = new HttpRequest( connectionSocket );

// Create a new thread to process the request.
Thread thread = new Thread(request);

// Start the thread.

final class HttpRequest implements Runnable
final static String CRLF = "\r\n";//returning carriage return (CR) and a line feed (LF)
Socket socket;

// Constructor
public HttpRequest(Socket socket) throws Exception
this.socket = socket;

// Implement the run() method of the Runnable interface.
//Within run(), we explicitly catch and handle exceptions with a try/catch block.
public void run()
try {processRequest();}catch (Exception e) {System.out.println(e);}

private void processRequest() throws Exception
// Get a reference to the socket's input and output streams.
InputStream instream = socket.getInputStream();
DataOutputStream os = new DataOutputStream(socket.getOutputStream());

// Set up input stream filters.
// Page 169 10th line down or so...
BufferedReader br = new BufferedReader(new InputStreamReader(instream));//reads the input data

// Get the request line of the HTTP request message.
String requestLine = br.readLine();// get /path/file.html version of http

// Display the request line.
// Extract the filename from the request line.
StringTokenizer tokens = new StringTokenizer(requestLine);// this is a input method with deliminators
tokens.nextToken(); // skip over the method, which should be "GET"
String fileName = tokens.nextToken();

// Prepend a "." so that file request is within the current directory.
fileName = "." + fileName;

//Open the requested file.

FileInputStream fis = null;
boolean fileExists = true;
try {
fis = new FileInputStream(fileName);
} catch (FileNotFoundException e) {
fileExists = false;

//Construct the response message.
String statusLine = null;
String contentTypeLine = null;
String entityBody = null;

if (fileExists) {
statusLine = "HTTP/1.0 200 OK" + CRLF; //common success message
contentTypeLine = "Content-type: " + contentType( fileName ) + CRLF;}//content info

else {
statusLine = "HTTP/1.0 404 Not Found" + CRLF;//common error message
contentTypeLine = "Content-type: " + "text/html" + CRLF;//content info
entityBody = "<HTML>" +
"<HEAD><TITLE>Not Found</TITLE></HEAD>" +
"<BODY>Not Found</BODY></HTML>";

//Send the status line.

//Send the content type line.

//Send a blank line to indicate the end of the header lines.

//Send the entity body.
if (fileExists) {
sendBytes(fis, os);
os.writeBytes(statusLine);//Send the status line.
os.writeBytes(contentTypeLine);//Send the content type line.
} else {
os.writeBytes(statusLine);//Send the status line.
os.writeBytes(entityBody);//Send the an html error message info body.
os.writeBytes(contentTypeLine);//Send the content type line.

System.out.println(fileName);//print out file request to console
// Get and display the header lines.
String headerLine = null;
while ((headerLine = br.readLine()).length() != 0) {

//code from part 1
// Right here feed the client something
//os.writeBytes("<html><body><h1>My First Heading</h1>");
//os.writeBytes( "<p>My first paragraph.</p></body></html> ");

// Close streams and socket.

//return the file types
private static String contentType(String fileName)
if(fileName.endsWith(".htm") || fileName.endsWith(".html")) {return "text/html";}
if(fileName.endsWith(".jpg") || fileName.endsWith(".jpeg")) {return "image/jpeg";}
if(fileName.endsWith(".gif")) {return "image/gif";}
return "application/octet-stream";

//set up input output streams
private static void sendBytes(FileInputStream fis, OutputStream os) throws Exception
   // Construct a 1K buffer to hold bytes on their way to the socket.
   byte[] buffer = new byte[1024];
   int bytes = 0;

   // Copy requested file into the socket's output stream.
   while((bytes = != -1 )// read() returns minus one, indicating that the end of the file
      os.write(buffer, 0, bytes);


  1. question my "content-type:" is showing read is states that it must be a variable

    if (fileExists){
    statusLine = "HTTP/1.0 200 OK" + CRLF;
    contentTypeLine = "content-type:" = contentType( fileName) + CRLF;}

  2. Hello,
    It is very helpful.
    How to extract an image from HTTP body without using third-party libraries?