我试图向特定客户发送消息，例如客户端1想要向客户端2发送消息。客户端1向服务器发送消息，服务器计算答案并将其发送给显示它的客户端2。 我使用HashMap存储每个客户端。它编译，但是当我运行它时，它在发送消息时崩溃并显示
通信服务器问题
我认为错误发生在我发送邮件的循环中，但我看不出它有什么问题，我是否需要在客户端使用单独的代码？
服务器：
import java.net.*;
import java.util.*;
import java.io.*;
public class EchoServer2b extends Thread implements Runnable{
protected static Socket clientSocket;
static String [] logs = new String[100];
//protected static ArrayList<PrintWriter> writers = new ArrayList<PrintWriter>();
static HashMap<String, Socket> clients = new HashMap<String, Socket>();
static int arrayPos = 0;
static int i, clientCount = 0;
static String clientID;
static String receiver="",actualMessage="";
public static void main(String[] args) throws IOException{
ServerSocket serverSocket = null;
try{
serverSocket = new ServerSocket(10008);
System.out.println ("Connection Socket Created");
try {
while (true)
{
System.out.println ("Waiting for Connection");
new EchoServer2b (serverSocket.accept());
++clientCount;
clientID = Integer.toString(clientCount);
clients.put(clientID, clientSocket);
}
}
catch (IOException e)
{
System.err.println("Accept failed.");
System.exit(1);
}
}
catch (IOException e)
{
System.err.println("Could not listen on port: 10008.");
System.exit(1);
}
finally{
try{
serverSocket.close();
}
catch (IOException e)
{
System.err.println("Could not close port: 10008.");
System.exit(1);
}
}
}
private EchoServer2b (Socket clientSoc){
clientSocket = clientSoc;
start();
}
public void run(){
System.out.println ("New Communication Thread Started");
try{
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
System.out.println("Client ID: " + clientID);
String inputLine;
while ((inputLine = in.readLine()) != null) { //reading
System.out.println(inputLine);
String message[]=inputLine.split(", ");
logs[arrayPos] = message[1]; //keep record of all commands sent to server
arrayPos++; //update array position
receiver=message[0];
actualMessage=message[1];
if (actualMessage.equals("Bye.")) //break if client enters 'Bye."
break;
if(actualMessage.equals("Logs.")){ //print out contents of logs if any client enters 'Logs'
for(i=0; i<arrayPos; i++){
System.out.println("Log"+ i + ": " + logs[i]);
}
break;
}
for (Map.Entry<String, Socket> entry: clients.entrySet()) {
String clientName = entry.getKey();
if(clientName.equals(receiver))
{
Socket socket = entry.getValue();
try {
PrintWriter receiverOut = new PrintWriter(socket.getOutputStream(), true);
//DataOutputStream receiverDOS = new DataOutputStream(socket.getOutputStream());
int x, y, result;
String num1, num2, operator;
String [] splitStrings = actualMessage.split(" ");
num1 = splitStrings[0];
x = Integer.parseInt(num1);
operator = splitStrings[1];
num2 = splitStrings[2];
y = Integer.parseInt(num2);
switch(operator){
case "+":
result = x + y;
System.out.println ("Server: " + result);
receiverOut.println(result);
break;
case "-":
result = x - y;
System.out.println ("Server: " + result);
receiverOut.println(result);
break;
case "*":
result = x * y;
System.out.println ("Server: " + result);
receiverOut.println(result);
break;
case "/":
result = x / y;
System.out.println ("Server: " + result);
receiverOut.println(result);
break;
default:
System.out.println("Please enter a more simple equation using one of the 4 main operators i.e. '+, -, *, /'");
break;
}
receiverOut.flush();
receiverOut.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
out.flush();
out.close();
in.close();
clientSocket.close();
}
catch (IOException e){
System.err.println("Problem with Communication Server");
e.printStackTrace();
System.exit(1);
}
}
public void sendMessage(String receiver, String actualMessage) {
}
}
客户端：
import java.io.*;
import java.net.*;
public class EchoClientB {
static boolean flag = true;
public static void main(String[] args) throws IOException{
String serverHostname = new String ("127.0.0.1");
if (args.length > 0)
serverHostname = args[0];
System.out.println ("Attemping to connect to host " + serverHostname + " on port 10008.");
Socket echoSocket = null;
PrintWriter out = null;
BufferedReader in = null;
try{
echoSocket = new Socket(serverHostname, 10008);
out = new PrintWriter(echoSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(echoSocket.getInputStream()));
}catch (UnknownHostException e){
System.err.println("Don't know about host: " + serverHostname);
System.exit(1);
} catch (IOException e){
System.err.println("Couldn't get I/O for " + "the connection to: " + serverHostname);
System.exit(1);
}
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
String userInput = "";
System.out.println ("Type Message (\"Bye.\" to quit)");
//System.out.println("Enter a simple math equation i.e. 2 + 2 separated by a space…");
System.out.println("Enter the ID of the client you want to send the message to and a simple equation.");
System.out.println("Eg:2, 2 + 2 (with each element of the equation separated by a space…)");
while(true){
if(userInput.equals("Bye.")){
break;
}
if((userInput = stdIn.readLine()) != null){
out.println(userInput);
userInput = in.readLine();
System.out.println("echo: " + userInput);
System.out.println("Enter the ID of the client you want to send the message to and a simple equation.");
System.out.println("Eg:2, 2 + 2 (with each element of the equation separated by a space…)");
out.flush();
}
else if(in.ready()){
userInput = in.readLine();
System.out.println("echo: " + userInput);
System.out.println("Enter the ID of the client you want to send the message to and a simple equation.");
System.out.println("Eg:2, 2 + 2 (with each element of the equation separated by a space…)");
out.flush();
}
}
out.close();
in.close();
stdIn.close();
echoSocket.close();
}
}
答案 0 :(得分：0)
你得到一个IOException，因为你正在关闭你想要从第140行读取的流。我建议你在范围内移动所有蒸汽关闭（第142行）。
答案 1 :(得分：0)
在服务器运行方法中，在您向其中一个客户端发送消息的代码的末尾，您有
out.flush();
out.close();
in.close();
clientSocket.close();
}
}
catch (IOException e){
System.err.println("Problem with Communication Server");
System.exit(1);
}
这是关闭套接字，这就是你获得异常的原因。您可能希望将此块移动到您确实要关闭客户端连接的位置