我的程序的说明
我使用Java创建了一个聊天室服务器，该服务器由3个类组成：服务器类，用户类和聊天室类。我还创建了一个客户端类以与服务器交互。每次客户端连接到服务器时，服务器都会创建一个用户对象。每个用户对象都会跟踪用户所在的聊天室，并运行一个线程来侦听用户输入。一个服务器对象遍历每个聊天室，以查看它是否在上周使用过。
问题
我想知道如何使用客户端对象实际连接到服务器。目前，我打开了两个eclipse实例。我在一个程序中运行服务器程序，在另一个程序中运行客户端程序，但是在任何一个程序的控制台中我什么都没收到，这是应该发生的，因为服务器应该向客户端发送信息，然后客户端将这些信息显示在控制台上。然后，客户端上的人员可以提供客户端将接受并发送到服务器的输入。
我想知道为什么现在什么都没发生，我能做些什么改进。
主文件
Server.java
/*
* Creates a server that can host up to 10 clients who can join chat rooms, post messages in chatrooms, and view posts made by other clients within the same chat room
*/
public class Server implements Runnable{
protected ArrayList<User> userList; //A list of users, where each user is a client connected to the server
protected LinkedList<Chatroom> chatRooms; //A list of chatrooms where each client can post messages in, where messages can be seen by all clients in the chatroom
private ServerSocket serverSocket; //The socket for the server
/*
* Constructor for the server class. Initializes the server attributes,
*/
public Server() {
this.userList = new ArrayList<User>(10);
this.chatRooms = new LinkedList<Chatroom>();
try {
this.serverSocket = new ServerSocket(5000);
}catch (IOException e) {
e.printStackTrace();
}
}
/*
* Creates a new user when a client connects to the server, and starts a user thread
*/
public void createUser() {
try {
Socket userSocket = serverSocket.accept();
Thread user = new Thread(new User(userSocket, this));
user.start();
} catch (IOException e) {
e.printStackTrace();
}
}
/*
* Creates a chatroom for clients to interact in
* @param roomName: The name of the chat room to be created
*/
protected Chatroom createChatRoom(String roomName) {
Chatroom room = new Chatroom(roomName);
return room;
}
/*
* Receives messages from clients and performs actions based on the requests of the client
* (non-Javadoc)
* @see java.lang.Thread#run()
*/
public void run() {
long currentTime;
while(true) {
try {
currentTime = System.currentTimeMillis() / 1000;
//Loop through each chatroom and check if the chatroom has been used(joined or had a message sent to it) and remove that chatroom if it hasn't been used in a week
for (int i = 0; i < chatRooms.size(); i++) {
if (currentTime - 604800 >= chatRooms.get(i).dateLastUsed) {
chatRooms.remove(i);
//Also remove the chatroom from clients lists of chatrooms
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
public static void main(String args[]) {
Server server = new Server ();
server.run();
}
}
Client.java
public class Client extends Thread{
private String ip = "127.0.0.1";
private int port = 5000 ;
private Socket socket;
private DataInputStream iStream;
private DataOutputStream oStream;
private String input;
public Client() {
try {
this.socket = new Socket(ip, port);
this.iStream = new DataInputStream(socket.getInputStream());
this.oStream = new DataOutputStream(socket.getOutputStream());
}catch (Exception e) {
e.printStackTrace();
}
}
/*
* Sends a message to the user
* @param message: The message to be sent to the user
*/
protected void send (String message) {
try {
oStream.writeUTF(message);
} catch (IOException e) {
e.printStackTrace();
}
}
/*
* Closes the connection to the client
*/
protected void close () {
try {
iStream.close();
oStream.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
/*
* Runs a thread for the client to constantly receive the clients input(non-Javadoc)
* @see java.lang.Thread#run()
*/
public void run() {
try {
Scanner reader = new Scanner(System.in);
input = iStream.readUTF();
String userInput;//Check if there is input from the user
while (input != null) {
input = iStream.readUTF();
System.out.println(input);
userInput = reader.next();
oStream.writeUTF(userInput);
}
reader.close();
}catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String args[]) {
Client client = new Client();
client.run();
}
}
Server.java使用的对象
User.java
//Each user represents a client that has connected to the server
public class User implements Runnable{
private DataInputStream inputStream;
private DataOutputStream outputStream;
private Socket socket;
private String name;
protected LinkedList<Chatroom> chatRooms;
private String input;
private Server server;
/*
* User Constructor, create a user for each client connecting to the server
* @socket The socket that the user will be communicated through
* The client is prompted to create a name for themself, they are they prompted to do an action.
*/
public User(Socket socket, Server server) {
this.socket = socket;
this.server = server;
try {
inputStream = new DataInputStream(socket.getInputStream());
outputStream = new DataOutputStream(socket.getOutputStream());
outputStream.writeUTF("Enter a name");
this.name = inputStream.readUTF();
String message = "Create a chatroom: create \nList Chat Rooms: list \n Join Chat Room: join \n Leave Chat Room: Leave";
send(message);
} catch (IOException e) {
}
}
/*
* Returns the current amount of chatrooms this user is in
*/
protected int chatRoomLength () {
return this.chatRooms.size();
}
/*
* Gets the most recent input from the user
*/
protected String getInput() {
return input;
}
/*
* Puts a user/client in a chatroom
* @param cRoom: The chatroom that the user will join
*/
protected void joinRoom (Chatroom cRoom) {
chatRooms.add(cRoom);
}
/*
* Removes a user/client from a chatroom
*/
protected void leaveRoom (Chatroom c) {
chatRooms.removeFirstOccurrence(c);
}
/*
* Sends a message to the user
* @param message: The message to be sent to the user
*/
protected void send (String message) {
try {
outputStream.writeUTF(message);
} catch (IOException e) {
}
}
/*
* Closes the connection to the client
*/
protected void close () {
try {
inputStream.close();
outputStream.close();
socket.close();
} catch (IOException e) {}
}
/*
* Runs a thread for the client to constantly receive the clients input(non-Javadoc)
* @see java.lang.Thread#run()
*/
public void run() {
try {
input = inputStream.readUTF(); //Check if there is input from the user
//if the user has disconnected from the server, remove them from the list
if (input == null) {
this.close();
this.server.userList.remove(this);
}else if (input.equals("create")){ //create a chat room
this.send("Name the Chatroom");
input = this.getInput();
Chatroom c = this.server.createChatRoom(input);
this.joinRoom(c);
}else if (input.equals("list")) { //List the current chatrooms
String rooms = "";
for (int j = 0; j< server.chatRooms.size(); j++) {
rooms = rooms + server.chatRooms.get(j).getName() + "\n";
}
this.send(rooms);
}else if (input.equals("join")) { //Join the user to a chat room
int end = chatRooms.size();
if (end == 0) {
this.send("There's currently no chat rooms");
}else {
this.send("Which room would you like to join");
input = this.getInput();
for (int k = 0; k < end; k++) {
if (chatRooms.get(k).getName().equals(input)) {
Chatroom joinRoom = chatRooms.get(k);
this.joinRoom(joinRoom);
String message = "Chatroom " + input + " messages. \n";
//Print the current messages in the chatroom to the user
for (int j = 0; j < joinRoom.messages.size(); j++ ) {
message = message + joinRoom.messages.get(j) + "\n";
}
this.send(message);
} else if (k == end - 1) {
this.send("There's no chat rooms by that name");
}
}
}
}else if (input.equals("leave")) { //Remove the user from a chatroom
int end = this.chatRoomLength(); //if the chatroom list of the user is empty
if (end == 0) {
this.send("You are not in any Chat Rooms");
}else {
this.send("Which room would you like to leave");
input = this.getInput();
for (int m = 0; m < end; m++) { //find the chatroom by the same name
if (this.chatRooms.get(m).getName().equals(input)) {
this.chatRooms.remove(m);
this.send("Great! You've been removed from" + input);
} else if (m == end - 1) {
this.send("You're not in a chatroom named" + input);
}
}
}
}else { //All other input is interpreted as a message to be posted in the chatrooms that the user is in
int end = this.chatRoomLength();
if (end == 0) {
this.send("You can't write to any chat rooms because you are not in any");
}
for (int m = 0; m < end; m++) { //Add the users message to ALL the chatrooms the user is in
Chatroom c = this.chatRooms.get(m);
c.addMessage(input);
//Send this added message to all the users in this chatroom
for (int n = 0; n < c.users.size(); n++) {
User u = c.users.get(n);
u.send("Chatroom" + c.getName() + ":" + input);
}
}
}
}catch (IOException e) {
}
}
}
Chatroom.java
public class Chatroom {
private String name; //Name of the chatroom
protected LinkedList<String> messages; //List of text messages that have been sent by users to the chatroom and are displayed in the chatroom
protected long dateLastUsed; //The last time the chatroom was joined or had a message sent to it
protected LinkedList<User> users; //The clients/users that are currently in the chatroom
/*
* Chatroom constructor
* @param name The name of the chatroom, as determined by the user creating it
*/
public Chatroom(String name) {
dateLastUsed = System.currentTimeMillis() / 1000; //Sent the time that the chatroom was used last to the current UNIX Epoch time
messages = new LinkedList<String>();
this.name = name;
}
/*
* Adds a message into the chatroom
* @param message The message to be added to the chatroom
*/
protected void addMessage(String message) {
messages.add(message);
dateLastUsed = System.currentTimeMillis() / 1000;
}
/*
* Returns the name of the chatroom
* @return String equal to the name of the chatroom
*/
protected String getName() {
return this.name;
}
}
答案 0 :(得分：6)
首先，没有对run()的调用，该调用具有接受套接字连接的代码。
接下来是try {
Scanner reader = new Scanner(System.in);
input = iStream.readUTF();
String userInput;//Check if there is input from the user
while (input != null) {
input = iStream.readUTF();
System.out.println(input);
userInput = reader.next();
oStream.writeUTF(userInput);
}
函数中的这段代码，
Enter a name接受套接字后，服务器将打印存储的输入readUTF()，
在while循环内，还有另一个readUTF()调用。
writeUTF()调用的问题在于它被阻塞，即。如果没有来自服务器的try {
Scanner reader = new Scanner(System.in);
String userInput;//Check if there is input from the user
do {
input = iStream.readUTF();
System.out.println(input);
userInput = reader.next();
oStream.writeUTF(userInput);
} while (input != null);
reader.close();
}
调用，它将等待数据。
我通过以下代码段解决了这个问题，
chatRooms即使这也不是最佳解决方案，因为它需要Server每次都将一些内容写入流中。
另一种解决方案是使用不同的线程进行读取和写入，这样我们就可以像聊天一样创建全双工，而不是半双工。
然后由于未初始化protected Chatroom createChatRoom(String roomName) {
Chatroom room = new Chatroom(roomName);
return room;
}
LinkedList而有一些NPE，
加上一些逻辑错误，例如不将chatRooms添加到其列表中。
错误代码：
protected Chatroom createChatRoom(String roomName) {
Chatroom room = new Chatroom(roomName);
this.chatRooms.add(room);
return room;
}
更正的代码：
JTextArea解决所有错误的最好方法是Github和一些贡献者：p