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我製作了一個多線程服務器，它連接到MySQL數據庫並接受來自客戶端的請求。服務器應始終從客戶端命令進行偵聽，但這種情況不會發生。它只接受一個命令將其發送到數據庫並獲取我需要的任何內容，然後完成。它不接受任何更多的命令。 我爲您提供客戶端和服務器。Java服務器將只接受來自我的客戶端的一個條目
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.rmi.ConnectException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Scanner;
public class Airlines {
\t public static void main(String[] args) {
\t \t ServerSocket serverSocket = null;
\t \t Socket connection = null;
\t \t int port = 1234;
\t \t try{
\t \t \t serverSocket = new ServerSocket(port);
\t \t \t while ((connection = serverSocket.accept())!=null){
\t \t \t System.out.println("Client connected!");
\t \t \t Thread client = new Thread (new AirlinesThread(connection));
\t \t \t client.start();
\t \t \t }
\t \t }catch (IOException e){
\t \t \t System.out.println("Binding unsuccesful...");
\t \t }
\t }
}
class AirlinesThread implements Runnable{
Socket connection = null;
public AirlinesThread (Socket connection){
\t this.connection = connection;
}
private static Connection connect(String url, String user, String password){
Connection result = null;
try{
result = DriverManager.getConnection(url, user, password);
System.out.println("Database connection successful!");
}
catch(SQLException e){
System.out.println("Could not connect to the database!");
}
return result;
}
\t String url = "jdbc:mysql://localhost:3306/Airlines";
\t String user = "root";
\t String pass = "123456";
\t Connection link = AirlinesThread.connect(url, user, pass);
\t Statement stmt = null;
\t ResultSet resultSet = null;
\t public void run() {
\t \t PrintWriter socketOut = null;
\t \t DataInputStream socketIn = null;
\t \t try{
\t \t socketOut = new PrintWriter(this.connection.getOutputStream(),true);
\t \t socketIn = new DataInputStream(this.connection.getInputStream());
\t \t int command;
\t \t boolean exists = false;
\t \t socketOut.flush();
\t \t loop:do{
\t \t \t socketOut.flush();
\t \t \t command = socketIn.readInt();
\t \t \t switch (command){
\t \t \t case 1:
\t \t \t \t try{
\t \t \t \t stmt = link.createStatement();
\t \t \t \t resultSet = stmt.executeQuery("select Flight.id, Flight.Date, Flight.Time, Flight.Total_Flight_Time, Airports.Departure, Airports.Arrivals FROM Flight, Airports WHERE Flight.id = Airports.Flight");
\t \t \t \t socketOut.flush();
\t \t \t \t socketOut.println("FlightID\tDate\t\tTime\t\tTotal Time\tDeparture\tArrivals");
\t \t \t \t while (resultSet.next()) {
\t \t \t \t \t socketOut.println(resultSet.getString("Flight.id")+"\t\t"+resultSet.getDate("Flight.Date")+"\t"+resultSet.getString("Flight.Time")+"\t"+resultSet.getString("Flight.Total_Flight_Time")+"\t\t"+resultSet.getString("Airports.Departure")+"\t"+resultSet.getString("Airports.Arrivals"));
\t \t \t \t
\t \t \t \t }
\t \t \t \t }
\t \t \t \t catch(SQLException e){
\t \t \t \t \t System.out.println("Something went wrong at 1");
\t \t \t \t }
\t \t \t \t break;
\t \t \t case 2:
\t \t \t \t try{
\t \t \t \t stmt = link.createStatement();
\t \t \t \t resultSet = stmt.executeQuery("select Flight.id, Flight.Date, Flight.Time, Pilots.First_Name, Pilots.Last_Name from Flight RIGHT JOIN Pilots ON Flight.id = Pilots.FlightID;");
\t \t \t \t socketOut.flush();
\t \t \t \t socketOut.println("FlightID\tDate\t\tTime\t\tFirst Name\tLast Name");
\t \t \t \t exists = resultSet.next();
\t \t \t \t if(exists == false){
\t \t \t \t \t socketOut.flush();
\t \t \t \t \t socketOut.println("Wrong request!");
\t \t \t \t \t System.out.println("Wrong query at 2");
\t \t \t \t }
\t \t \t \t while (resultSet.next()) {
\t \t \t \t socketOut.flush();
\t \t \t \t socketOut.println(resultSet.getString("Flight.id")+"\t\t"+resultSet.getDate("Flight.Date")+"\t"+resultSet.getString("Flight.Time")+"\t"+resultSet.getString("Pilots.First_Name")+"\t\t"+resultSet.getString("Pilots.Last_Name"));
\t \t \t \t }
\t \t \t \t }
\t \t \t \t catch(SQLException e){
\t \t \t \t \t System.out.println("Something went wrong at 2");
\t \t \t \t }
\t \t \t \t break;
\t \t \t case 3:
\t \t \t \t try{
\t \t \t \t stmt = link.createStatement();
\t \t \t \t resultSet = stmt.executeQuery("select Food.Breakfast, Airplanes.Plane_Model FROM Food, Airplanes Where Food.FlightID=Airplanes.Plane_Model;");
\t \t \t \t exists = resultSet.next();
\t \t \t \t if(exists == false){
\t \t \t \t \t socketOut.flush();
\t \t \t \t \t socketOut.println("Wrong request!");
\t \t \t \t \t System.out.println("Wrong query at 3");
\t \t \t \t }
\t \t \t \t while (resultSet.next()) {
\t \t \t \t socketOut.flush();
\t \t \t \t socketOut.println(resultSet.getString("Food.Breakfast")+"\t\t"+resultSet.getString("Airplanes.Plane_Model"));
\t \t \t \t
\t \t \t \t }
\t \t \t \t }
\t \t \t \t catch(SQLException e){
\t \t \t \t \t System.out.println("Something went wrong at 3");
\t \t \t \t }
\t \t \t \t break;
\t \t \t case 0 :
\t \t \t \t socketOut.flush();
\t \t \t \t socketOut.println("Exitting...");
\t \t \t \t break loop;
\t \t \t default:
\t \t \t \t System.out.println("Unknown command!");
\t \t \t \t socketOut.println("Unknown command!");
\t \t \t \t break;
\t \t \t }
\t \t }while(command!=0);
\t \t System.out.println("Closing connection to the client!");
\t \t }catch (IOException e){
\t \t \t e.printStackTrace();
\t \t }finally{
\t \t try{
\t \t if (socketIn!=null) socketIn.close();
\t \t if (socketOut!=null) socketOut.close();
\t \t if (connection!=null) connection.close();
\t \t System.out.println("Connection to server closed!");
\t \t }
\t \t catch(IOException e){
\t \t System.err.println("Could not close connection!");
\t \t }
\t }
\t \t try{
\t \t \t if(stmt != null) stmt.close();
\t \t \t if(resultSet != null) resultSet.close();
\t if(link != null) link.close();
\t System.out.println("Database connection closed successfully!");
\t \t }catch(SQLException ex){
\t \t \t System.out.println("Could not close connection to the database!");
\t \t }
}
}客戶端：
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ConnectException;
import java.net.Socket;
import java.util.Scanner;
public class AirlinesClient {
\t public static void main(String[] args) {
\t \t Socket connection = null;
\t \t Scanner socketIn = null;
\t \t DataOutputStream socketOut = null;
\t \t int port = 1234;
\t \t String host = "localhost";
\t \t Scanner keyIn = new Scanner(System.in);
\t \t try{
\t \t \t try{
\t \t \t connection = new Socket(host,port);
\t \t \t socketIn = new Scanner(new BufferedReader(new InputStreamReader(connection.getInputStream())));
\t \t \t socketOut = new DataOutputStream(connection.getOutputStream());
\t \t }catch(ConnectException e){
\t \t \t System.out.println("Could not connect to the host!");
\t \t \t return;
\t \t }
\t \t System.out.println("Successfully connected to the server!");
\t \t System.out.println("Select from the options below:\n1: Check schedules\n2: Check pilots shifts\n3: Check corresponding airplanes and food offered\n4: Possible pilot shift changes");
\t \t loop:do{
\t \t \t int command;
\t \t \t socketOut.flush();
\t \t \t command = keyIn.nextInt();
\t \t \t socketOut.flush();
\t \t \t socketOut.writeInt(command);
\t \t \t while (socketIn.hasNext()){
\t \t \t \t System.out.println(socketIn.nextLine());
\t \t \t }
\t \t \t
\t \t }while(keyIn.nextInt()!=0);
\t \t System.out.println("Closing connection to server!");
\t }catch(IOException e){
\t \t e.printStackTrace();
\t } finally{
\t try{
\t if(socketIn!=null) socketIn.close();
\t if(socketOut!=null) socketOut.close();
\t if(connection!=null) connection.close();
\t }
\t catch(IOException e){
\t System.err.println("Socket could not be closed!");
\t }
\t }
\t \t
\t }
\t
\t
}