我正在尝试从我的列表中访问数据，但它总是以null或其他内容结束。我运行Class Server public static ArrayList<String> clientUsernameList = new ArrayList<>();
在代码中。如果我的服务器接受套接字，则应该出现以下代码。
package multi.threaded_server_application;
import java.io.DataInputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.time.Clock;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import jdk.nashorn.internal.codegen.CompilerConstants;
/**
*
* @author Seeya
*/
public class Server {
public static ArrayList<String> clientUsernameList = new ArrayList<>();
/**
* @param args the command line arguments
* @throws java.io.IOException
*/
public static void main(String[] args) throws IOException {
int port = 8900; //Port number the ServerSocket is going to use
ServerSocket myServerSocket = null; //Serversocket for sockets to connect
Socket clientSocket = null; //Listerner for accepted clients
ClientThread[] clientsConnected = new ClientThread[20]; //Max clients in this server
DataInputStream IN = null;
try {
myServerSocket = new ServerSocket(port);
System.out.println("Server waiting for clients on port:" + port);
} catch (IOException ex) {
Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
}
while (true) {
try { //Freezes while-loop untill a socket have been accepted or if some failure occur
clientSocket = myServerSocket.accept();
IN = new DataInputStream(clientSocket.getInputStream());
String userName = IN.readUTF();
Server.clientUsernameList.add(userName);
System.out.println("Client have connected from:" + clientSocket.getLocalAddress().getHostName());
System.out.println("Username:" + userName);
System.out.println(Server.clientUsernameList);
} catch (Exception e) {
//Print out exception
System.out.println(e);
}
//For-loop that counts every element in Array-clientsConnected
for (int i = 0; i < clientsConnected.length; i++) {
//If-statement checks if current element is null
if(clientsConnected[i] == null){
//If current element in the Array is null then create a new object from ClientThread class
//With a socket and the object of itself as parameter.
(clientsConnected[i] = new ClientThread(clientSocket, clientsConnected)).start();
//Must have a break otherwise it will create 20 objects (Exit for-loop)
break;
} //Exit if-statement
} //Exit for-loop
} //Exit while-loop
}
}
我在Class Client运行时收到了用户名。我打印出来看看我是否在列表中添加了用户名。现在，当我尝试从我的Class Client访问数据时，我没有收到/ null。
package Server_application;
import java.io.DataInputStream;
import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.Scanner;
import java.util.TimeZone;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* @author Seeya
*/
public class Client extends Thread {
ClientGUI GUI = null;
DataInputStream IN = null;
DataOutputStream OUT = null;
Socket SOCKET = null;
String Message = null;
String userName = null;
String ipAdress = "localhost";
int port = 8900;
public Client(ClientGUI gui,String username) {
this.userName = username;
this.GUI = gui;
}
@Override
public void run() {
try {
//Handle Input/Output from client
SOCKET = new Socket(ipAdress, port);
IN = new DataInputStream(SOCKET.getInputStream());
OUT = new DataOutputStream(SOCKET.getOutputStream());
//Sends username to server!
OUT.writeUTF(userName);
System.out.println(Server.clientUsernameList);
GUI.addToList(Server.clientUsernameList.toString());
while (true) {
CheckForMessages(IN);
}
} catch (IOException ex) {
Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
}
}
//-----------------------------------------------------------------
//Method for sending Messages!
public void write(String s) throws IOException{
//Writes message to server so it can send it to other clients.
//Also sends to clients self GUI
String A = s;
OUT.writeUTF(A);
GUI.writeGUI("You said: " + A);
}
//------------------------------------------------------------------
//Method for listening on messages
private void CheckForMessages(DataInputStream in) throws IOException {
try {
String IncomingMessage = in.readUTF();
System.out.println(IncomingMessage);
GUI.writeGUI(IncomingMessage);
} catch (Exception e) {
System.err.println(e);
}
}
}
所有打印出的内容都是[] Class Client。我如何尝试访问我的静态变量有什么问题吗？
EDIT！ 这是我用来向服务器中的所有客户端发送/接收消息的代码。
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package multi.threaded_server_application;
import com.sun.security.ntlm.Client;
import java.awt.List;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.time.Clock;
import java.util.ArrayList;
import java.util.Date;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.DefaultListModel;
/**
*
* @author Seeya
*/
//THIS CLASS TAKES CARE OF HANDLING MESSAGES TO OTHER CLIENTS!
//-------------------------------------------------------
public class ClientThread extends Thread {
private ClientThread[] clientsConnected;
private Socket SOCKET = null;
private DataInputStream IN = null;
private DataOutputStream OUT = null;
private String userName = null;
//-------------------------------------------------------
//Constructor
public ClientThread(Socket socket, ClientThread[] clientThread) {
this.SOCKET = socket;
this.clientsConnected = clientThread;
}
//This starts as soon as the constructor is done/been created.
@Override
public void run() {
try {
//Handleing the messages
IN = new DataInputStream(SOCKET.getInputStream());
OUT = new DataOutputStream(SOCKET.getOutputStream());
String message = null;
while (true) {
//This will be read second from the socket DataOutPutStream
//We will use this string to send a message to every client that is online
message = IN.readUTF();
//For-loop to check how many people are actually online
//for (ClientThread k : clientsConnected) = For each client in clientsConnected ends up in variable k
for (int i = 0; i < clientsConnected.length; i++) {
//don't send message to yourself
if (clientsConnected[i]!= null && clientsConnected[i].userName != this.userName){
// loops through all the list and calls the objects sendMessage method.
clientsConnected[i].sendMessage(message, userName);
}
}
}
} catch (IOException ex) {
Logger.getLogger(ClientThread.class.getName()).log(Level.SEVERE, null, ex);
}
}
private void sendMessage(String message, String userName) {
try {
Date date = new Date();
DateFormat format = new SimpleDateFormat("HH:mm:ss");
OUT.writeUTF(format.format(date) + " " + userName + " says: " + message);
OUT.flush();
} catch (IOException ex) {
Logger.getLogger(ClientThread.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Something failed to send message");
}
}
}
答案 0 :(得分：1)
如果您希望服务器String中的客户端用户名从中获取static，您将需要使用循环向客户端发送用户名，而客户端将需要代码读入用户名列表。
我不知道这是否会让你的程序成为你想做的事情，但是这将是我想到的概念的足够代码。
在您的服务器类中
while (true) {
try { //Freezes while-loop until a socket have been accepted or if some failure occur
clientSocket = myServerSocket.accept();
IN = new DataInputStream(clientSocket.getInputStream());
String userName = IN.readUTF();
OnConnect(userName); // Where to call the below method.
System.out.println("Client have connected from:" + clientSocket.getLocalAddress().getHostName());
System.out.println("Username:" + userName);
System.out.println(Server.clientUsernameList);
} catch (Exception e) {
//Print out exception
System.out.println(e);
}
//.... More of your code.
String userNamesCSVs = ""
private void OnConnect(String theNewConnectionName){
//For-Each loop says for every ClientThread object in clientsConnected do this block of code
for(ClientThread client : clientsConnected){
//Construct a long string with comma's in it.
userNamesCSVs = userNamesCSVs + client.userName + ",";
}
//Don't forget to count the new name! This was added so you didn't have to do
//tricky stuff in the above for loop with the trailing comma. Also the server
//doesn't have your user name yet.
userNamesCSVs = userNamesCSVs + theNewConnectionName;
//New for loop to start sending a mass message. Same as before.
for(ClientThread client : clientsConnected){
client.sendMessage(userNamesCSVs, userName);
}
//Remember take that static off clientUsernameList. Look up static it's not what you want here.
clientUsernameList.add(userName);
}
在您从服务器接收消息的客户端类中。
String[] userNameArray = new String[20]; //Max users and what not.
//Same method you are using named check for messages. It's needed to get the data from the server.
private void getUserNames(DataInputStream in) throws IOException{
try {
String userNames = in.readUTF();
System.out.println(IncomingMessage);
userNameArray = userNames.split(",")
} catch (Exception e) {
System.err.println(e);
}
for(String user : userNames){
GUI.writeGuid("User connected: " + user);
}
}
旁注：
要查找的另一件事是'serializable'和字节流以及其他很酷的东西。一旦掌握了通过客户端和服务器来回发送字符串，这很容易做到。基本上你可以发送整个对象而不仅仅是字符串，只要它是可序列化的。