简介

某同事要用Socket连接外围系统，帮忙写了个简单的Demo。
包含一个客户端和一个服务端的，仅是示例，比较简陋，服务端也没有用多线程。
直接贴代码了。

服务端

import java.io.*;
import java.net.*;

/**
 * Socket服务端示例
 */
public class SocketServer {
    ServerSocket serverSocket;
    Socket connection = null;
    ObjectOutputStream out;
    ObjectInputStream in;
    String message;

    void runServer() {
        try {
            // 创建服务端监听
            serverSocket = new ServerSocket(31313, 10);

            // 等待客户端连接
            System.out.println("等待客户端连接...");
            connection = serverSocket.accept();
            System.out.println("收到客户端连接： " + connection.getInetAddress().getHostName());

            // 获取输入输出流
            out = new ObjectOutputStream(connection.getOutputStream());
            out.flush();
            in = new ObjectInputStream(connection.getInputStream());

            // 连接成功后，首先向客户端发成功消息
            sendMsg("连接成功");

            // 发送接收消息
            do {
                try {
                    message = (String) in.readObject();
                    System.out.println("client>" + message);

                    // 发送退出消息
                    if (message.equals("bye")) {
                        sendMsg("bye");
                    }
                } catch (ClassNotFoundException ex) {
                    ex.printStackTrace();
                    System.err.println("数据格式无效");
                }
            } while (!message.equals("bye"));  //当对方消息为bye时退出循环
        } catch (IOException ex) {
            ex.printStackTrace();
        } finally {
            // 关闭Socket连接
            try {
                in.close();
                out.close();
                serverSocket.close();
            } catch (IOException ioException) {
                ioException.printStackTrace();
            }
        }
    }

    void sendMsg(String msg) {
        try {
            out.writeObject(msg);
            out.flush();
            System.out.println("server>" + msg);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    public static void main(String args[]) {
        SocketServer server = new SocketServer();
        while (true) {
            server.runServer();
        }
    }
}

客户端

import java.io.*;
import java.net.*;

/**
 * Socket客户端示例
 */
public class SocketClient {
    Socket clientSocket;
    ObjectOutputStream out;
    ObjectInputStream in;
    String message;

    void runClient() {
        try {
            // 连接到服务端
            clientSocket = new Socket("localhost", 31313);
            System.out.println("已连接到服务端");

            // 获取输入输出流
            out = new ObjectOutputStream(clientSocket.getOutputStream());
            out.flush();
            in = new ObjectInputStream(clientSocket.getInputStream());

            // 发送接收消息
            do {
                try {
                    // 接收消息
                    message = (String) in.readObject();
                    System.out.println("server>" + message);

                    // 发送消息
                    sendMsg("hello");
                    sendMsg("hello again");

                    // 发送退出消息
                    message = "bye";
                    sendMsg(message);
                } catch (ClassNotFoundException ex) {
                    ex.printStackTrace();
                    System.err.println("数据格式无效");
                }
            } while (!message.equals("bye")); //当对方消息为bye时退出循环
        } catch (UnknownHostException ex) {
            ex.printStackTrace();
            System.err.println("无法连接到服务端");
        } catch (IOException ex) {
            ex.printStackTrace();
        } finally {
            // 关闭Socket连接
            try {
                in.close();
                out.close();
                clientSocket.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }

    void sendMsg(String msg) {
        try {
            out.writeObject(msg);
            out.flush();
            System.out.println("client>" + msg);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    public static void main(String args[]) {
        SocketClient client = new SocketClient();
        client.runClient();
    }
}