/**
 * 模拟客户端
 */
public class Client {
    public static void main(String[] args) throws UnknownHostException {
        Socket socket=null;
        OutputStream outputStream=null;
        try {
            //1、 创建socket对象 指明服务器ip地址和端口号
            InetAddress inet=InetAddress.getByName("localhost");//调用的地址
            socket=new Socket(inet,9999);//调用的端口
            //2、获取一个输入流 用于输出数据
            outputStream= socket.getOutputStream();
            //3、写入数据
            outputStream.write("客户端xxxx发送".getBytes(StandardCharsets.UTF_8));
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //4、关闭资源
            try{
                if (outputStream!=null)
                    outputStream.close();
            }catch (Exception e){
                e.printStackTrace();
            }
            try{
                if (socket!=null)
                    socket.close();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
//        System.out.println(InetAddress.getLocalHost());
    }
}

 
/**
 * 服务端（先开启）
 */
public class Server {
    public static void main(String[] args) throws IOException {
        InputStream inputStream=null;
        ServerSocket socketServer=new ServerSocket(9999);//设置服务器端口
 
        Socket accept = socketServer.accept();//获取获取 客户端的消息 获取sicket对象
        inputStream = accept.getInputStream();//将消息写入流
 
        int len;
        byte [] buf=new byte[5];
        ByteArrayOutputStream arrayOutputStream=new ByteArrayOutputStream();
        //将网络传输的流读取下来
        while ((len=inputStream.read(buf))!=-1){
            arrayOutputStream.write(buf,0,len);
        }
        System.out.println(accept.getInetAddress());
        System.out.println(arrayOutputStream.toString("utf-8"));
        //关闭资源
        arrayOutputStream.close();
        inputStream.close();
        accept.close();
        socketServer.close();
 
    }
}

• 案例演示

实现客户端服务器发送文件 并发通知

 
/**
 * 网络 发送文件 将文件上传
 */
public class ClentToFile {
    public static void main(String[] args) throws Exception {
        //创建网络通信
        Socket socket = null;
        //创建 输出流 写入网络通信
        OutputStream outputStream = null;
        //指定要传输的对象
        socket = new Socket("127.0.0.1", 9999);
        outputStream = socket.getOutputStream();
        //获取 要传输的 文件流
        FileInputStream fileInputStream = new FileInputStream(new File("E:\\springboot_dome\\IOdome\\dbcp.txt"));
        byte[] buf = new byte[5];
        int len;
        while ((len = fileInputStream.read(buf)) != -1) {
            //把输入流  写到 网络通信的输出流
            outputStream.write(buf, 0, len);
        }
        System.out.println("图片传输完成");
        //关闭数据流传输  告诉服务器我的数据流传输完成
        socket.shutdownOutput();
 
        //5.收到源自服务器的数据，打印纸控制台
        InputStream atServerStream= socket.getInputStream();
        ByteArrayOutputStream byteArrayOutputStream=new ByteArrayOutputStream();
        byte[] bufc = new byte[5];
        int lenc;
        while ((lenc=atServerStream.read(bufc))!=-1){
            byteArrayOutputStream.write(bufc,0,lenc);
        }
        System.out.println(byteArrayOutputStream.toString());
 
 
        //建议用try catch
        outputStream.close();
        fileInputStream.close();
        socket.close();
        byteArrayOutputStream.close();
        atServerStream.close();
 
    }
}

 
/**
 * 网络 发送文件 将文件下载
 */
public class ServerToFile {
    public static void main(String[] args)throws Exception {
        ServerSocket serverSocket=new ServerSocket(9999);
        InputStream inputStream=null;
 
        Socket accept = serverSocket.accept();
        inputStream = accept.getInputStream();
        // 文件写出的目标文件
        FileOutputStream fileOutputStream=new FileOutputStream("SocketFile1.txt");
 
        byte [] buf=new byte[1024];
        int len;
        while ((len=inputStream.read(buf))!=-1){
            fileOutputStream.write(buf,0,len);
        }
        //服务器反馈给客户端信息
        OutputStream osToClient= accept.getOutputStream();
        osToClient.write("服务器已收到".getBytes(StandardCharsets.UTF_8));
 
        fileOutputStream.close();
        inputStream.close();
        serverSocket.close();
        osToClient.close();
        accept.close();
 
    }
}