java.net.ConnectException：连接被拒绝：连接发生

Question

我正在尝试在 Windows 命令行中运行代码并收到异常：

D:\dasi\java\javaLab>java ServerClient
java.net.ConnectException: Connection refused: connect
java.lang.StringIndexOutOfBoundsException: String index out of range: -2

D:\dasi\java\javaLab>

在另一个命令行windw：

D:\dasi\java\javaLab>java SocketClient
java.net.ConnectException: Connection timed out: connect

D:\dasi\java\javaLab>

服务器代码：

import java.io.*;
import java.net.*;
public class ServerClient {
    public ServerClient(int port) {
        Server server = new Server(port);
        server.start();
        Client client = new Client(port);
        client.start();
    }
    public static void main(String[] args) {
        ServerClient s1 = new ServerClient(7777);
    }
}

class Server extends Thread {
    int port;
    ServerSocket server;
    Socket socket;
    DataOutputStream outStream = null;
    DataInputStream inStream = null;
    public Server(int poort) {
        try {
            this.port = port;
            server = new ServerSocket(port);
        }
        catch(Exception e) {
            System.out.println(e.toString());
        }
    }
    public void run() {
        try {
            socket = server.accept();
            outStream = new DataOutputStream(socket.getOutputStream());
            inStream = new DataInputStream(socket.getInputStream());
            System.out.println("server is ok, please continue!");
            while(true) {
                String str = inStream.readUTF();
                System.out.println("The server receive String:"+str);
                outStream.writeUTF(str);
            }
        }
        catch(Exception e) {
            System.out.println(e.toString());
        }
    }
}

class Client extends Thread {
    int port;
    Socket socket;
    DataInputStream inStream = null;
    DataOutputStream outStream = null;
    public Client(int port) {
        try {
            this.port = port;
            socket = new Socket(InetAddress.getLocalHost(),port);
            inStream = new DataInputStream(socket.getInputStream());
            outStream = new DataOutputStream(socket.getOutputStream());
            System.out.println("client is ok, please continue!");
        }
        catch(Exception e) {
            System.out.println(e.toString());
        }
    }
    public void run() {
        try {
            while(true) {
                byte[] b = new byte[1024];
                String str = "";
                int m = System.in.read(b);
                str = new String(b,0,0,m-1);
                outStream.writeUTF(str);
                str = inStream.readUTF();
                System.out.println("The client receive String:"+str);
            }
        }
        catch(Exception e) {
            System.out.println(e.toString());
        }
    }
}

客户端代码：

import java.net.*;
import java.io.*;
public class SocketClient {
    Socket s = null;
    DataInputStream inStream = null;
    DataOutputStream outStream = null;
    public SocketClient() {
        try {
            init();
            waitData();
        }
        catch(Exception e) {
            System.out.println(e.toString());
        }
    }
    void init() throws Exception {
        s=new Socket("10.15.43.216",8765);
        inStream = new DataInputStream(s.getInputStream());
        outStream = new DataOutputStream(s.getOutputStream());
        s.setSoTimeout(3000);
    }
    void waitData() {
        while(true) {
            try {
                String str = inStream.readUTF();
                System.out.println("Client accept:" +str);
                str = Integer.toString(Integer.parseInt(str)+1);
                outStream.writeUTF(str);
            }
            catch(Exception e) {
                System.out.println(e.toString());
                break;
            }
        }
    }
    public static void main(String[] args) {
        new SocketClient();
    }
}

我想知道我的代码是否有任何问题，或者是我的计算机端口导致了问题。因为当我检查我的计算机端口时，我没有看到 7777。当我发出命令 netstat -nao | findstr 7777，它什么也没返回。

D:\dasi\java\javaLab>netstat -nao | findstr 7777

D:\dasi\java\javaLab>

如果是端口问题，那么如何打开7777端口。 我是这里的新手，请帮助。非常感谢！

Answer 1

替换

 public Server(int poort) {
    try {
        this.port = port;
        ...
    }
}

与

 public Server(int poort) {
    try {
        this.port = port;
        ...
    }
}

或者说端口的默认值是零，那么你的 serverSocket 将绑定 0 端口而不是 7777。

至于这段代码：

public ServerClient(int port) {
    Server server = new Server(port);
    server.start();
    Client client = new Client(port);
    client.start();
}

恐怕很容易给你添麻烦，因为我们不能保证服务器线程会在客户端线程之前执行，如果客户端线程 strong>服务器没有运行时先执行，会报错。而且你已经在另一个java文件中有一个客户端，所以我不明白你为什么在这里有一个客户端。也许你可以删除它们，代码可以是这样的：

public ServerClient(int port) {
    Server server = new Server(port);
    server.start();
}

至于客户端代码 您的服务器套接字是 7777，因此您应该在 init 方法中连接 7777 端口而不是 8765，也许代码可以是这样的：

void init() throws Exception {
    s=new Socket(server name,7777);
    ...
}