一、UDP socket api的使用
Java 把系统原生的封装了.
核心的类有两个:
1 -> DatagramSocket
操作系统中,有一类文件,就叫socket文件.
socket文件,抽象表示了 " 网卡"这样的硬件设备.
进行网络通信最核心的硬件设备网卡
通过网卡发送数据,就是写socket文件
通过网卡接收数据,就是读socket文件
2 -> DatagramPacket
UDP面向数据报,每次发送接收数据的基本单位,就是一个UDP数据报.
表示了一个UDP数据报
二、回显服务器
这是网络编程中,最简单的程序了,网络编程的hello world
客户端发什么请求返回什么请求
1. socket api的使用
2. 典型的客户端服务器基本工作流程
1.1 服务器代码
private DatagramSocket socket = null;public UdpEchoServer(int port) throws SocketException {socket = new DatagramSocket(port);}//服务器启动逻辑public void start() throws IOException {System.out.println("服务器启动");while(true) {//每次循环,就是一个请求//1.读取请求并解析DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);socket.receive(requestPacket);//读到的字节数组,转成String方便后续的逻辑处理String request = new String(requestPacket.getData(),0,requestPacket.getLength());//2.根据请求计算响应String response = process(request);//3.把响应返回到客户端//构造一个DatagramPacket 作为响应对象DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),response.getBytes().length,requestPacket.getSocketAddress());socket.send(responsePacket);//打印日志System.out.printf("[%s:%d] req: %s,resp: %s\n",requestPacket.getAddress().toString(),requestPacket.getPort(),request,response);}}private String process(String request) {return request;}public static void main(String[] args) throws IOException {UdpEchoServer server = new UdpEchoServer(9090);server.start();}1.2 客户端代码
private DatagramSocket socket = null;private String serverIP;private int serverPort;public UdpEchoClient(String serverIP,int serverPort) throws SocketException {this.serverIP=serverIP;this.serverPort=serverPort;socket = new DatagramSocket();}public void start() throws IOException {System.out.println("客户端启动");Scanner scanner = new Scanner(System.in);while(true){System.out.print("->");if(!scanner.hasNext()){//没有输入就break;break;}String request = scanner.next();DatagramPacket requestPacket = new DatagramPacket(request.getBytes(),request.getBytes().length,InetAddress.getByName(serverIP),serverPort);socket.send(requestPacket);DatagramPacket responsePacket = new DatagramPacket(new byte[4096],4096);socket.receive(responsePacket);String response = new String(responsePacket.getData(),0,responsePacket.getLength());System.out.println(response);}}public static void main(String[] args) throws IOException {UdpEchoClient client = new UdpEchoClient("127.0.0.1",9090);client.start();}
