網路計算新手，請原諒我的無知：
除了 /caesarcipher 之外，我的所有命令都有效 - 當我輸入它時，在客戶端的下一條訊息之前我不會收到回聲，并且服務器不會開始執行該功能，直到發送了 2 個后續訊息.
任何幫助，將不勝感激！
import java.net.*;
import java.io.*;
import java.util.concurrent.TimeUnit;
public class EchoServer{
public static void main(String[] args) throws Exception {
//Initializes and attempts to connect server
ServerSocket serverSock = null;
try{
serverSock = new ServerSocket(8000);
}
catch (IOException ie){
System.out.println("[SERVER DISCONNECTED!] Can't listen on 8000");
System.exit(1);
}
Socket link = null;
System.out.println("[SERVER CONNECTED!] Listening for connection ...");
try {
link = serverSock.accept();
}
catch (IOException ie){
System.out.println("[SERVER DISCONNECTED!] Accept failed");
System.exit(1);
}
//Connects client if handshake is successful
System.out.println("[CLIENT CONNECTED!] Link Information:" link);
System.out.println("Listening for input ...");
//Initializes input and output streams
PrintWriter output = new PrintWriter(link.getOutputStream(), true);
BufferedReader input = new BufferedReader(new InputStreamReader(link.getInputStream()));
String inputLine;
while ((inputLine = input.readLine())!=null) {
String currentMessage = inputLine;
System.out.println("[SERVER:] " currentMessage);
switch(currentMessage){
case "/myip": //Looks up local IP address of client
MyLocalIPAddress myIP = new MyLocalIPAddress();
String ip = myIP.run();
output.println(ip);
System.out.println(ip);
break;
case "/iplookup": //Looks up IP of user input website
IPFinder ipFinder = new IPFinder();
// TO DO: UrlValidator validator = new UrlValidator();
System.out.println("[REQUESTING URL FROM CLIENT!]");
output.println("Enter Website URL:");
inputLine = input.readLine();
System.out.println("Server: " inputLine);
// TO DO: if(validator.isValid(inputLine)) { //Regex to validate user input
String ipAddress = ipFinder.find(inputLine) " ==> [IPLOOKUP TERMINATING]";
System.out.println(ipAddress);
output.println(ipAddress);
System.out.println("[IPLOOKUP FUNCTION TERMINATING!]");
break;
case "/numbergame": //Starts a number guessing game
boolean isPlaying;
int randomNumber = -1;
final int maxNum = 100;
System.out.println("[CLIENT HAS INITIATED GUESS THE NUMBER GAME!]");
output.println("Would you like to play the number game (Y/N)?");
inputLine = input.readLine();
if(inputLine.equalsIgnoreCase("Y")){
System.out.println("[CLIENT REQUESTS TO BEGIN A GAME!]");
isPlaying = true;
System.out.println("[SERVER IS PICKING A RANDOM NUMBER!]");
output.println("Enter A Number Between 0-100 (/endgame to quit)");
randomNumber = (int) Math.floor(Math.random() * maxNum 1);
System.out.println("[RANDOM NUMBER IS: " randomNumber "]");
}else if(inputLine.equalsIgnoreCase("N")){
System.out.println("[GUESS THE NUMBER GAME ABORTING]");
output.println("Quitting guess the number game");
isPlaying = false;
}else{
System.out.println("[CLIENT PROVIDED FAULTY INPUT, GAME ABORTING!]");
output.println("Input not recognized, game aborting!");
isPlaying = false;
}
while(isPlaying) {
System.out.println("[REQUESTING NUMBER FROM CLIENT!]");
inputLine = input.readLine();
if (inputLine.equalsIgnoreCase("/endgame")) {
isPlaying = false;
}
if (isNumeric(inputLine)) {
int currentGuess = Integer.parseInt(inputLine);
if (randomNumber == currentGuess) {
System.out.println("[CLIENT HAS GUESSED THE CORRECT NUMBER, GAME TERMINATING!]");
output.println("You have guessed correctly! Game ending!");
isPlaying = false;
} else if (currentGuess > randomNumber) {
System.out.println("[CLIENT GUESSED TOO HIGH!]");
output.println("Too high! Guess again!");
} else if (currentGuess < randomNumber) {
System.out.println("[CLIENT GUESSED TOO LOW!]");
output.println("Too low! Guess again!");
}
}else if(inputLine.equalsIgnoreCase("/endgame")){
System.out.println("[CLIENT HAS REQUESTED TO END GAME - TERMINATING...]");
output.println("Quitting game, better luck next time!");
break;
}else{
System.out.println("[CLIENT HAS PROVIDED INCORRECT INPUT]");
output.println("You have not entered a valid number, try again!");
}
}
break;
case "/caesarcipher":
int maxKeyValue = 25;
int randomKey = (int) Math.floor(Math.random() * maxKeyValue 1);
System.out.println("[CLIENT HAS INITIATED CAESAR CIPHER PROGRAM ----- CLIENT CAESAR CIPHER IS "
randomKey " (Type 'bye' to exit)!]");
output.println("Your Caesar Cipher is " randomKey ". Enter a message to encrypt: ");
while((inputLine = input.readLine()) != null) {
if (inputLine.equalsIgnoreCase("/caesarcipher")) {
output.println("Your Caesar Cipher is " randomKey ". Enter a message to encrypt: ");
output.flush();
}else if (inputLine.equalsIgnoreCase("/bye") ||
inputLine.equalsIgnoreCase("bye")) {
System.out.println("[CLIENT HAS REQUESTED TO END CAESAR CIPHER MODE!]");
output.println("Quitting Caesar cipher mode...");
break;
}else{
CaesarCipher caesarCipher = new CaesarCipher();
currentMessage = input.readLine();
String decryptedMessage = caesarCipher.decrypt(currentMessage, randomKey);
System.out.println("[SERVER:] Received: " currentMessage " ==> "
decryptedMessage);
}
}
break;
case "/secretmessage":
System.out.println("?????? Shahnaz ??????");
output.println("?????? Shahnaz ??????");
break;
case "/killserver":
System.out.println("[CLIENT REQUESTED SERVER SHUTDOWN!]");
TimeUnit.SECONDS.sleep(1);
System.out.println("[SERVER IS SHUTTING DOWN!");
TimeUnit.SECONDS.sleep(1);
closeServer(output, input, link, serverSock);
System.exit(1);
break;
case "exit":
case "quit":
case "disconnect":
disconnectClient(output, input, link, serverSock);
break;
default:
output.println(currentMessage);
}
}
}
public static void closeServer(PrintWriter output, BufferedReader input, Socket link, ServerSocket serverSock)
throws IOException {
System.out.println("[CLIENT REQUESTED TO CLOSE SERVER!");
output.close();
input.close();
link.close();
serverSock.close();
}
public static void disconnectClient(PrintWriter output, BufferedReader input, Socket link, ServerSocket serverSock)
throws IOException, InterruptedException {
output.println("[CLIENT REQUESTED TO CLOSE CONNECTION!");
TimeUnit.SECONDS.sleep(5);
output.println("[DISCONNECTING!");
output.close();
input.close();
link.close();
}
//Tests to see if a string contains all numeric values
public static boolean isNumeric(String str) {
for (char c : str.toCharArray()){
if (!Character.isDigit(c)) return false;
}
return true;
}
}
import java.io.*;
import java.net.*;
public class EchoClient{
public static void main(String[] args) throws IOException{
Socket link = null;
PrintWriter output = null;
BufferedReader input = null;
Boolean cipherModeActive = true;
try{
System.out.println("[CONNECTING TO SERVER ON PORT 8000]");
link = new Socket(InetAddress.getLocalHost(), 8000);
output = new PrintWriter(link.getOutputStream(), true);
input = new BufferedReader(new InputStreamReader(link.getInputStream()));
System.out.println("[CONNECTED TO SERVER]");
}
catch(UnknownHostException e)
{
System.out.println("Unknown Host");
System.exit(1);
}
catch (IOException e){
System.out.println("Cannot connect to host");
System.exit(1);
}
BufferedReader stdIn = new BufferedReader((new InputStreamReader(System.in)));
String usrInput;
System.out.println("Welcome to the Server!\n\n"
"----- Here is a List Options: ----- \n "
"/myip ----- will allow you to look up your ip address\n"
"/iplookup ----- will allow you to look up the ip of a URL\n"
"/numbergame ----- allows you to play a guess the number game\n"
"/caesarcipher ----- allows you to encrypt and decrypt server messages using a caesar cipher\n"
"/exit, /quit, /disconnect ---- allows you to disconnect from the server\n\n"
"Enter a message:");
//User Input
boolean cipherActive = false;
while ((usrInput = stdIn.readLine())!=null){
output.println(usrInput);
String message = input.readLine();
if(usrInput.equalsIgnoreCase("/caesarcipher")){
cipherActive = true;
}
if(!cipherActive){
System.out.println("echo: " message);
output.flush();
}
if(cipherActive) {
CaesarCipher caesarCipher = new CaesarCipher();
String serverKeyMessage = message;
int serverKey = Integer.parseInt(serverKeyMessage.replaceAll("[^0-9]", ""));
while ((usrInput = stdIn.readLine()) != null) {
message = usrInput;
if (usrInput.equalsIgnoreCase("/caesarcipher")){
output.flush();
}else if (usrInput.equalsIgnoreCase("/bye")
|| usrInput.equalsIgnoreCase("bye")) {
break;
}
//Encrypts message to send to server
//Prints server response to client
if (!message.equalsIgnoreCase("/caesarcipher")) {
String currentMessage = usrInput;
String encryptedMessage = caesarCipher.encrypt(currentMessage, serverKey);
output.println(encryptedMessage);
System.out.println("echo: " message);
}
}
break;
}
}
switch(usrInput) {
// case "echo: Enter Website URL:":
// case "iplookup terminating...":
// case "Would you like to play the number game (Y/N)?":
// case "You have guessed correctly! Game ending!":
// case "echo: Enter a message to encrypt: ":
// output.flush();
case "echo: /quit":
case "echo: /disconnect":
case "echo: /killserver":
output.close();
input.close();
stdIn.close();
link.close();
break;
}
//Flushes output for number game
if(isNumeric(usrInput)){
output.flush();
}
}
//Checks string for numerical values and returns true if all numeric, false if other characters are present
public static boolean isNumeric(String str) {
for (char c : str.toCharArray()){
if(!Character.isDigit(c)) return false;
}
return true;
}
}
import com.sun.org.apache.bcel.internal.generic.ARETURN;
import java.util.*;
public class CaesarCipher {
public static String encrypt(String stringToEncrypt, int offset) {
String ciphertext = "";
char alphabet;
for(int i=0; i < stringToEncrypt.length();i )
{
// Shift one character at a time
alphabet = stringToEncrypt.charAt(i);
// if alphabet lies between a and z
if(alphabet >= 'a' && alphabet <= 'z')
{
// shift alphabet
alphabet = (char) (alphabet offset);
// if shift alphabet greater than 'z'
if(alphabet > 'z') {
// reshift to starting position
alphabet = (char) (alphabet 'a'-'z'-1);
}
ciphertext = ciphertext alphabet;
}
// if alphabet lies between 'A'and 'Z'
else if(alphabet >= 'A' && alphabet <= 'Z') {
// shift alphabet
alphabet = (char) (alphabet offset);
// if shift alphabet greater than 'Z'
if(alphabet > 'Z') {
//reshift to starting position
alphabet = (char) (alphabet 'A'-'Z'-1);
}
ciphertext = ciphertext alphabet;
}
else {
ciphertext = ciphertext alphabet;
}
}
return(ciphertext);
}
public static String decrypt(String stringToEncrypt, int offset) {
int decryptKey = 26-offset;
String ciphertext = "";
char alphabet;
for(int i=0; i < stringToEncrypt.length();i )
{
// Shift one character at a time
alphabet = stringToEncrypt.charAt(i);
// if alphabet lies between a and z
if(alphabet >= 'a' && alphabet <= 'z')
{
// shift alphabet
alphabet = (char) (alphabet decryptKey);
// if shift alphabet greater than 'z'
if(alphabet > 'z') {
// reshift to starting position
alphabet = (char) (alphabet 'a'-'z'-1);
}
ciphertext = ciphertext alphabet;
}
// if alphabet lies between 'A'and 'Z'
else if(alphabet >= 'A' && alphabet <= 'Z') {
// shift alphabet
alphabet = (char) (alphabet decryptKey);
// if shift alphabet greater than 'Z'
if(alphabet > 'Z') {
//reshift to starting position
alphabet = (char) (alphabet 'A'-'Z'-1);
}
ciphertext = ciphertext alphabet;
}
else {
ciphertext = ciphertext alphabet;
}
}
return(ciphertext);
}
}
import java.net.*;
import java.util.Scanner;
public class IPFinder {
public static String find(String host) throws Exception {
try {
InetAddress address = InetAddress.getByName(host);
return ("IP address: " address);
} catch (UnknownHostException e) {
return (" Could not find " host);
}
}
}
uj5u.com熱心網友回復：
說實話，看的太多了，最好能把你的代碼中的某部分描述的更具體一些，這樣就會有更多的人愿意幫助你。盡管如此，這里有一些關于您的代碼的建議，希望這會有所幫助。
對于您的第一個問題“...在客戶端的下一條訊息之前我沒有收到回聲...”：
EchoClient 的變化：
// ...
CaesarCipher caesarCipher = new CaesarCipher();
String serverKeyMessage = message;
/* --- Delete 1 line : */
// int serverKey = Integer.parseInt(serverKeyMessage.replaceAll("[^0-9]", ""));
/* Add 5 lines : */
int serverKey;
java.util.regex.Matcher m = Pattern.compile(".*([0-9] ).*").matcher(serverKeyMessage);
if (m.matches()) serverKey = Integer.parseInt(m.group(1));
else serverKey = 0;
System.out.println(serverKeyMessage);
// ...
對于您的第二個問題“...直到 2 個后續...才開始執行該功能...”：
EchoServer 的變化 ：
// ...
CaesarCipher caesarCipher = new CaesarCipher();
// currentMessage = input.readLine(); // delete this line
currentMessage = inputLine; // add this line
String decryptedMessage = caesarCipher.decrypt(currentMessage, randomKey);
// ...
轉載請註明出處，本文鏈接：https://www.uj5u.com/qukuanlian/360430.html