【Java梳理】网络操作

1.使用TCP协议
Tcp协议是一个保证送达的网络层传输协议，它的特点是保证数据完整的送达。
监听TCP端口，编写一个TCP服务器

public static void main(String[] args){

        try {
            System.out.println("server start...");
            ServerSocket ss = new ServerSocket(10005);
            Socket s = ss.accept();
            BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
            String receiveDataStr = null;
            while ((receiveDataStr = br.readLine()) != null) {
                System.out.println("receive data:" + receiveDataStr);
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }

发送TCP数据,TCP客户端

public static void main(String[] args){
        try {
            System.out.println("client start...");
            Socket s = new Socket("127.0.0.1", 10005);
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
            String sendDataStr = null;
            while ((sendDataStr = br.readLine()) != null) {
                if (sendDataStr.equals("end")){
                    break;
                }

                bw.write(sendDataStr);
                bw.newLine();
                bw.flush();
            }
            bw.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

同时运行上面两段代码，在client的控制台中输入字符串并回车，server可以收到并打印出来,这是最简单的TCP程序。

2使用UDP协议

Udp协议是只管发送，不保证数据送达的协议实现。
监听端口，使用12000作为收发数据的端口

public static void main(String[] args){

        try (DatagramSocket socket = new DatagramSocket(12000)) {
            while (true) {
                try {
                    DatagramPacket request = new DatagramPacket(new byte[1024], 1024);
                    socket.receive(request);

                    String daytime = new Date().toString();
                    byte[] data = daytime.getBytes("ASCII");
                    DatagramPacket response = new DatagramPacket(data, data.length, request.getAddress(), request.getPort());
                    socket.send(response);
                    System.out.println(daytime + " " + request.getAddress());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

发送数据

 public static void main(String[] args){
        //传入0表示让操作系统分配一个端口号
        try (DatagramSocket socket = new DatagramSocket(0)) {
            socket.setSoTimeout(10000);
            InetAddress host = InetAddress.getByName("127.0.0.1");
            //指定包要发送的目的地
            DatagramPacket request = new DatagramPacket(new byte[1], 1, host, 12000);
            //为接受的数据包创建空间
            DatagramPacket response = new DatagramPacket(new byte[1024], 1024);
            socket.send(request);
            socket.receive(response);
            String result = new String(response.getData(), 0, response.getLength(), "ASCII");
            System.out.println(result);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

DatagramSocket 表示发送和接收数据包的socket对象，DatagramPacket 则是数据报文。关于TCP和UDP的更详细介绍请参考 计算机网络原理