threadedserver.java

Icarnegie university SSD8电子书和全部练习答案

/**
* @author lu hongyong 043742
* @see <code>Client.java</code> and
* @version 1.0
*
* The class is a simple web server class that can respond to the user's request,
* and it can deal with the more than one requests for the same time.
*/

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

/**
* The class <code>Handler</code>implements the abstract interface--"Runnable". 
* 
*/
class Handler implements Runnable{

private Socket socket;


public Handler(Socket s){

Thread t;
socket = s;
t = new Thread(this, "Handler Thread");
t.start();
} 

/**
* This method is used to implement the thread function.
* 
* @param void
* @return void
* @exception <code>Exception</code>
*/
public void run() {
try {

// Read the request from client
BufferedReader inFromClient =
new BufferedReader(new InputStreamReader(socket.getInputStream()));

String requestMessageLine;
requestMessageLine = inFromClient.readLine();

// Process the request
StringTokenizer tokenizedLine =
new StringTokenizer(requestMessageLine);

if (tokenizedLine.nextToken().equals("GET")) {

String fileName;
// Parse URL to retrieve file name
fileName = tokenizedLine.nextToken();

if (fileName.startsWith("/") == true )
fileName = "C:\\www\\test\\" + fileName.substring(1);

File file = new File(fileName);
int numOfBytes = (int) file.length();

FileInputStream inFile = new FileInputStream (fileName);

byte[] fileInBytes = new byte[numOfBytes];
inFile.read(fileInBytes);

// Get output stream
DataOutputStream outToClient =
new DataOutputStream(socket.getOutputStream());

// Generate response header
outToClient.writeBytes("HTTP/1.0 200 Document Follows\r\n");

if (fileName.endsWith(".jpg"))
outToClient.writeBytes("Content-Type: image/jpeg\r\n");
if (fileName.endsWith(".gif"))
outToClient.writeBytes("Content-Type: image/gif\r\n");

outToClient.writeBytes("Content-Length: " + numOfBytes + "\r\n");
outToClient.writeBytes("\r\n");

// Send file content
outToClient.write(fileInBytes, 0, numOfBytes);

// Close connection
socket.close();

} else { 

System.out.println("Bad Request Message");
}
} catch (Exception e) {

System.out.println("Error");
} // End of catch

} // End of run()
}


/**
* The class <code>ThreadedServer</code> invoks the class <code>Handler</code> to 
* get the multithread method that can control the concurrency event.
*
*/
class ThreadedServer {

// The connetion port number.
private static final int serverPort = 6789;

public static void main(String args[]) {

// Create server socket
ServerSocket listenSocket = null;

try {

listenSocket = new ServerSocket(serverPort);
} catch (IOException e) {

System.err.println("IO erro when \"ServerSocket(serverPort)\" ");
e.printStackTrace();
}

System.out.println("server listening at " + listenSocket);

while (true) {

// Take a ready connection from the accepted queue
Socket connectionSocket = null;
try {

connectionSocket = listenSocket.accept();
} catch (IOException e) {

System.err.println("IO erro when \"listenSocket.accept()\" ");
e.printStackTrace();
}


System.out.println("receive request from " + connectionSocket);

// Dispatch a request server
new Handler( connectionSocket );

} // End of while (true)

} // End of main


}