JavaExercises/Java 2/J2Lesson7/SimpleServer.java at master · biblelamp/JavaExercises · GitHub

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/**

* Java. Level 2. Lesson 7

* Simple server for chat

* @author Sergey Iryupin

* @version 0.2.2 dated Jan 15, 2018

import java.io.*;

import java.net.*;

import java.sql.*;

class SimpleServer implements IConstants {

public static void main(String[] args) {

new SimpleServer();

}

SimpleServer() {

int clientCount = 0;

System.out.println(SERVER_START);

try (ServerSocket server = new ServerSocket(SERVER_PORT)) {

while (true) {

Socket socket = server.accept();

System.out.println("#" + (++clientCount) + CLIENT_JOINED);

new Thread(new ClientHandler(socket, clientCount)).start();

}

} catch (Exception ex) {

System.out.println(ex.getMessage());

}

System.out.println(SERVER_STOP);

}

/**

* checkAuthentication: check login and password

* @param login for checking

* @param passwd for checking

* @return if the pair login/passwd is found in the database,

* authentication is successful

private boolean checkAuthentication(String login, String passwd) {

boolean result = false;

try {

// loads a class, including running its static initializers

Class.forName(DRIVER_NAME);

// connect db

Connection connect = DriverManager.getConnection(SQLITE_DB);

// looking for login && passwd in db

PreparedStatement pstmt = connect.prepareStatement(SQL_SELECT);

// replace "?" to the login

pstmt.setString(1, login);

// returns ResultSet object generated by the query

ResultSet rs = pstmt.executeQuery();

// process rows from the query result

while (rs.next())

result = rs.getString(PASSWD_COL).equals(passwd);

// close all

rs.close();

pstmt.close();

connect.close();

} catch (ClassNotFoundException | SQLException ex) {

ex.printStackTrace();

return false;

}

return result;

}

/**

* ClientHandler: service requests of clients

class ClientHandler implements Runnable {

BufferedReader reader;

PrintWriter writer;

Socket socket;

String name;

ClientHandler(Socket clientSocket, int clientCount) {

try {

socket = clientSocket;

reader = new BufferedReader(

new InputStreamReader(socket.getInputStream()));

writer = new PrintWriter(socket.getOutputStream());

name = "Client #" + clientCount;

} catch(Exception ex) {

System.out.println(ex.getMessage());

}

@Override

public void run() {

String message;

try {

do {

message = reader.readLine();

if (message != null) {

System.out.println(name + ": " + message);

if (message.startsWith(AUTH_SIGN)) {

String[] wds = message.split(" ");

if (checkAuthentication(wds[1], wds[2])) {

name = wds[1];

writer.println("Hello, " + name);

writer.println("\0");

} else {

System.out.println(name + ": " + AUTH_FAIL);

writer.println(AUTH_FAIL);

message = EXIT_COMMAND;

}

} else if (!message.equalsIgnoreCase(EXIT_COMMAND)) {

writer.println("echo: " + message);

writer.println("\0");

}

writer.flush();

}

} while (!message.equalsIgnoreCase(EXIT_COMMAND));

socket.close();

System.out.println(name + CLIENT_DISCONNECTED);

} catch(Exception ex) {

System.out.println(ex.getMessage());

}

JavaExercises/Java 2/J2Lesson7/SimpleServer.java at master · biblelamp/JavaExercises · GitHub

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