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display http header

Greenhorn

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posted 12 years ago

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hello.i need help on how to display http headers in a browser using the concept of client - proxy - server in java.
i'm new to networking in java.thanks in advance

Stephan van Hulst

Saloon Keeper

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367

posted 12 years ago

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Hello Varsha, welcome to CodeRanch!

What kind of help do you need? Please take a look at HowToAskQuestionsOnJavaRanch

varsha simla

Greenhorn

Posts: 8

posted 12 years ago

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hello Stephan.
i want help concerning the coding part.

client side

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.Socket;
import java.util.StringTokenizer;

class Client extends Thread 
{
	public static void main(String argv[]) throws Exception
	{
		/*String sentence;
		int modifiedSentence;*/

final String HTML_START ="<html>" + "<title>HTTP Server in java</title>" +"<body>";

final String HTML_END ="</body>" + "</html>";

Socket connectedClient = null;
		BufferedReader inFromClient = null;
		DataOutputStream outToClient = null;
		
		System.out.println("Client-Side");
	//System.out.println( "The Client "+ connectedClient.getInetAddress() + ":" + connectedClient.getPort() + " is connected");
		BufferedReader inFromUser = new BufferedReader( new InputStreamReader(System.in));

Socket clientSocket = new Socket("localhost", 5555);

DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
		BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

String requestString = inFromUser.readLine();
		System.out.println("test: " + requestString);
		
		outToServer.writeBytes(requestString + '\n');

//	modifiedSentence = inFromServer.read();

//	System.out.println("FROM PROXY: " + modifiedSentence);

clientSocket.close();
	}
}

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

public class ProxyServer {

public static final int portNumber = 5555;

public static void main(String[] args){

System.out.println("... Starting Proxy Server ...");
		try {

ServerSocket proxySocket = new ServerSocket(portNumber);

while(true){
				Socket clientSocket = proxySocket.accept();

// reading the request from client

BufferedReader inFromClient =    new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

String clientSentence = inFromClient.readLine();

StringTokenizer tokenizer = new StringTokenizer(clientSentence);
				String httpMethod = tokenizer.nextToken();
				String httpQueryString = tokenizer.nextToken();
				//  host to connect to

System.out.println("" + "\n... Connecting to host ..." );

StringBuffer responseBuffer = new StringBuffer();
			//	responseBuffer.append(" This is the HTTP Server Home Page.... ");
			//	responseBuffer.append("The HTTP Client request is .... ");

System.out.println("The HTTP request string is ....");
				while (inFromClient.ready())
				{
					// Read the HTTP complete HTTP Query
					responseBuffer.append(clientSentence + " ");
					System.out.println(clientSentence);
					clientSentence = inFromClient.readLine();
				}
				handler a=new handler();

if (httpMethod.equals("GET")) {

//send request to server

if (httpQueryString.equals("/")) {
						// The default home page

a.sendResponse(200, responseBuffer.toString(), false);
					} else {
						//This is interpreted as a file name
						String fileName = httpQueryString.replaceFirst("/", "");
						fileName = URLDecoder.decode(fileName);
						if (new File(fileName).isFile()){
							a.sendResponse(200, fileName, true);
						}
						else {
							a.sendResponse(404, "The Requested resource not found ...." +
									"Usage: http://127.0.0.1:5000 or http://127.0.0.1:5000/", false);
						}
					}
				}
				else a.sendResponse(404, "The Requested resource not found ...." +
						"Usage: http://127.0.0.1:5000 or http://127.0.0.1:5000/", false);
				
				//(new myHTTPServer(clientSocket)).start();
			}
		} catch (Exception e) {
			e.printStackTrace();
		}

// forward the response from the proxy to the server
		Socket hostSocket = new Socket("127.0.0.1", 8080);

DataOutputStream sos = new DataOutputStream(hostSocket.getOutputStream());
		System.out.println("\n\tForwarding request to server");
		sos.writeBytes(clientSentence+ '\n');

// receive response from the server to proxy

System.out.println("\n\tReceiving request from server");

BufferedReader FromServer =  new BufferedReader(new InputStreamReader(hostSocket.getInputStream()));
		//System.out.println("666666Accepting Connection\n\n");
		String serverSentence = FromServer.readLine();
		System.out.println("\n\tResponse from Server: " + serverSentence);

// forward the response from the proxy to browser
		DataOutputStream ToClient = new DataOutputStream(clientSocket.getOutputStream());
		ToClient.writeBytes(serverSentence+ '\n');

//closing all sockets
		hostSocket.close();
		clientSocket.close();
		System.out.println("\nEnd of communication");

}
} catch (IOException e) {
	e.printStackTrace();*/
}{//}
	
}}
//}

i have been able to do that much so far by doing some research and now i'm stuck.please help me

varsha simla

Greenhorn

Posts: 8

posted 12 years ago

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import java.io.DataOutputStream;
import java.io.FileInputStream;

public class handler {
	
	public void sendResponse (int statusCode, String responseString, boolean isFile) throws Exception {

String statusLine = null;
		String serverdetails = "Server: Java HTTPServer";
		String contentLengthLine = null;
		String fileName = null;
		String contentTypeLine = "Content-Type: text/html" + "\r\n";
		FileInputStream fin = null;

if (statusCode == 200)
			statusLine = "HTTP/1.1 200 OK" + "\r\n";
		else
			statusLine = "HTTP/1.1 404 Not Found" + "\r\n";

if (isFile) {
			fileName = responseString;
			fin = new FileInputStream(fileName);
			contentLengthLine = "Content-Length: " + Integer.toString(fin.available()) + "\r\n";
			if (!fileName.endsWith(".htm") && !fileName.endsWith(".html"))
				contentTypeLine = "Content-Type: \r\n";
		}
		else {
			responseString = myHTTPServer.HTML_START + responseString + myHTTPServer.HTML_END;
			contentLengthLine = "Content-Length: " + responseString.length() + "\r\n";
		}
		DataOutputStream outToClient = null;
		outToClient.writeBytes(statusLine);
		outToClient.writeBytes(serverdetails);
		outToClient.writeBytes(contentTypeLine);
		outToClient.writeBytes(contentLengthLine);
		outToClient.writeBytes("Connection: close\r\n");
		outToClient.writeBytes("\r\n");

if (isFile) sendFile(fin, outToClient);
		else outToClient.writeBytes(responseString);

outToClient.close();
	}

public void sendFile (FileInputStream fin, DataOutputStream out) throws Exception {
		byte[] buffer = new byte[1024] ;
		int bytesRead;

while ((bytesRead = fin.read(buffer)) != -1 ) {
			out.write(buffer, 0, bytesRead);
		}
		fin.close();
	}
}

Stephan van Hulst

Saloon Keeper

Posts: 15703

367

posted 12 years ago

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What are you stuck with? Can you give a detailed description of the problems you're running into?

varsha simla

Greenhorn

Posts: 8

posted 12 years ago

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the line 26 for the class ProxyServer
the variable clientSentence---cannot be resolved to a variable

i also want to have an overview what is done at a proxy server when i am sending a http get request

is my code logic good?