使用TCP网络程序上传图片：编写服务器类PicUploadServer，该类包含一个Socket类型的私有属性，并提供了该属性的有参构造方法。PicUploadServer类实现Runnable接口，重写run()方法，在run()方法内读取客户端上传的图片，并将图片存入服务器指定文件夹中。编写客户端类PicUpLoadClient，该类实现了读取指定图片，向指定端口发送图片数据的功能。 编写测试类Example03,在main()方法中，通过指定的端口号创建ServerSocket对象，并编写死循环，在死循环中，通过ServerSocket对象获取Socket对象，并开启线程服务。

服务器端代码：

import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class PicUploadServer implements Runnable {
    private Socket socket;

    public PicUploadServer(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        try {
            InputStream is = socket.getInputStream();
            String fileName = "upload/" + System.currentTimeMillis() + ".jpg";
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(fileName));
            byte[] buffer = new byte[1024];
            int len;
            while ((len = is.read(buffer)) != -1) {
                bos.write(buffer, 0, len);
            }
            bos.flush();
            bos.close();
            is.close();
            socket.close();
            System.out.println("图片上传成功，保存路径为：" + fileName);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

客户端代码：

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.OutputStream;
import java.net.Socket;

public class PicUploadClient {
    public static void main(String[] args) {
        String serverAddress = "localhost";
        int port = 8888;
        String filePath = "img/1.jpg";
        try {
            Socket socket = new Socket(serverAddress, port);
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(filePath));
            OutputStream os = socket.getOutputStream();
            byte[] buffer = new byte[1024];
            int len;
            while ((len = bis.read(buffer)) != -1) {
                os.write(buffer, 0, len);
            }
            os.flush();
            os.close();
            bis.close();
            socket.close();
            System.out.println("图片上传成功！");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

测试类代码：

import java.net.ServerSocket;
import java.net.Socket;

public class Example03 {
    public static void main(String[] args) {
        int port = 8888;
        try {
            ServerSocket serverSocket = new ServerSocket(port);
            while (true) {
                Socket socket = serverSocket.accept();
                new Thread(new PicUploadServer(socket)).start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}