我有3个类（客户端，服务器和协议），允许用户登录并向另一个用户发送消息。我试图在程序中添加密码功能，但到目前为止我还没有尝试过。我已在下面添加了我的代码，我想在用户名的错误检查完成后提示用户输入密码。应该比较密码并检查它是否匹配，然后用户才能查看其消息并发送消息。
非常感谢任何提示，谢谢！
Client.java
import java.io.*;
import java.net.*;
public class Client {
public static void main(String[] args) {
String messages = "";
// Makes sure there are only two arguments entered
if(args.length != 2) {
System.err.println("Usage: java Client <host name> <port number>");
System.exit(1);
}
// Stores the command line arguments for readability further in the program
String host = args[0];
int port = Integer.parseInt(args[1]);
try (
// Creates the socket to be used
Socket s = new Socket(host, port);
// Reader and Writer to talk with Server
PrintWriter pw =
new PrintWriter(s.getOutputStream(), true);
BufferedReader bf = new BufferedReader(
new InputStreamReader(s.getInputStream()));
) {
// Reader to read from standard input (keyboard)
BufferedReader keyboard =
new BufferedReader(new InputStreamReader(System.in));
// User interface
while (true) {
System.out.println("Please enter your username: ");
String username = keyboard.readLine();
// Check that the login is valid
if (username == null) {
System.out.println("No username entered");
}
else if (username.contains(" ")) {
System.out.println("Username cannot contain spaces");
}
// Send username to server and return number of messages
else {
pw.println(username);
messages = bf.readLine();
System.out.println("You have " + Integer.parseInt(messages) + " messages");
break;
}
}
// Enable the user to continue reading and composing messages until
// they choose to exit
while (true) {
System.out.println("Would you like to READ, COMPOSE or EXIT?");
String choice = keyboard.readLine();
// Shows the messages left for the user
if (choice.equals("READ")) {
pw.println("READ");
messages = bf.readLine();
if (messages == "0") {
System.out.println("NO MESSAGES");
}
else {
String incoming = bf.readLine();
System.out.println(incoming);
incoming = bf.readLine();
System.out.println(incoming);
}
}
// Allows user to write a message to another user
else if (choice.equals("COMPOSE")) {
pw.println("COMPOSE");
System.out.println("Enter message recipient");
String recipient = keyboard.readLine();
if (recipient == null) {
System.out.println("No recipient username entered");
}
else if (recipient.contains(" ")) {
System.out.println("Recipient username cannot contain spaces");
}
else {
pw.println(recipient);
System.out.println("Enter message to be sent");
String im = keyboard.readLine();
pw.println(im);
System.out.println(bf.readLine());
}
}
else if (choice.equals("EXIT")) {
pw.println("EXIT");
System.exit(1);
}
else {
System.out.println("Error: you must either READ, COMPOSE or EXIT");
}
}
}
// Catches the exception in which the server cannot be found
catch(IOException e) {
System.out.println("Error, could not connect to Server");
System.exit(1);
}
}
}
Server.java
import java.io.*;
import java.net.*;
public class Server {
public static void main(String[] args) {
String request;
// Makes sure that the user has specified the correct number of command line arguments
if(args.length != 1) {
System.err.println("Usage: java Server <port number>");
System.exit(1);
}
int port = Integer.parseInt(args[0]);
try (
// Creates a server socket and waits for a connection
ServerSocket ss = new ServerSocket(port);
// A socket to communicate with the client
Socket cs = ss.accept();
// Reader and Writer to talk with Client
PrintWriter pw =
new PrintWriter(cs.getOutputStream(), true);
BufferedReader bf = new BufferedReader(
new InputStreamReader(cs.getInputStream()));
)
// Links the server to the protocol
{
Protocol protocol = new Protocol();
protocol.storeUsername(bf.readLine());
pw.println(protocol.messagesNumber());
// Loop through user input until EXIT is entered
while (true) {
request = bf.readLine();
// Controls output if user inputs READ
if (request.equals("READ")) {
pw.println(protocol.messagesNumber());
pw.println(protocol.readSender());
pw.println(protocol.readMessage());
}
// Controls input if user inputs COMPOSE
else if (request.equals("COMPOSE")) {
String sender = bf.readLine();
String message = bf.readLine();
if (protocol.append(sender, message)) {
pw.println("MESSAGE SENT");
}
else {
pw.println("MESSAGE FAILED");
}
}
// Exits the server
else {
System.exit(1);
}
}
}
// Catches the exception in which the server cannot find a client
catch(IOException e) {
System.out.println("Failed to find a client");
System.exit(1);
}
}
}
Protocol.java
import java.net.*;
import java.io.*;
import java.util.*;
public class Protocol {
private String username;
private String recipient;
private String sender;
private HashMap<String, ArrayList<String>> senderMap = new HashMap<String, ArrayList<String>>();
private HashMap<String, ArrayList<String>> messageMap = new HashMap<String, ArrayList<String>>();
// Stores the username for the logged in user
public void storeUsername(String user) {
username = user;
}
// Stores the recipient name
public void storeRecipient(String name) {
recipient = name;
}
// Returns how many messages the logged in user has
public int messagesNumber() {
if(messageMap.containsKey(username))
return messageMap.get(username).size();
else
return 0;
}
public boolean append(String recipient, String message) {
boolean success = false;
// If there is an entry for that name, just add the message to the end
if(messageMap.containsKey(recipient)) {
senderMap.get(recipient).add(username);
messageMap.get(recipient).add(message);
success = true;
}
// If there is no entry for that name, create a new entry with a list of messages and add the first message
else {
senderMap.put(recipient, new ArrayList<String>());
senderMap.get(recipient).add(username);
messageMap.put(recipient, new ArrayList<String>());
messageMap.get(recipient).add(message);
success = true;
}
return success;
}
public String readSender() {
// If the user has an entry and has at least 1 sender, return the least recent sender and then remove it (the sender first in the list)
if(senderMap.containsKey(username)) {
if(senderMap.get(username).size() > 0) {
String temp = senderMap.get(username).get(0);
senderMap.get(username).remove(0);
return temp;
}
else
// If there are no messages left to read
return "NO MESSAGES";
}
else
// If the login hasn't been created yet
return "NO MESSAGES";
}
public String readMessage() {
// If the user has an entry and has at least 1 unread message, return the least recent unread message and then remove it (the first message in the list)
if(messageMap.containsKey(username)) {
if(messageMap.get(username).size() > 0) {
String temp = messageMap.get(username).get(0);
messageMap.get(username).remove(0);
return temp;
}
else
// If there are no messages left to read
return "NO MESSAGES";
}
else
// If the login hasn't been created yet
return "NO MESSAGES";
}
}