用Socket实现TCP，UDP通信

用Socket实现TCP，UDP通信

用Socket实现UDP通信

UDP适用于一次只传送少量数据、对可靠性要求不高的应用环境。

public class UDPServer {    public static void main(String[] args) {        try {            DatagramSocket ds = new DatagramSocket();            byte[] buffer = "udp test".getBytes();            DatagramPacket dp = new DatagramPacket(buffer, buffer.length, InetAddress.getByName("localhost"), 8000);            // 将localhost换为255.255.255.255可以发送广播，对该局域网内所有机器发送消息            ds.send(dp);            ds.close();        } catch (SocketException e) {            e.printStackTrace();        } catch (UnknownHostException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}public class UDPClient {    public static void main(String[] args) {        try {            DatagramSocket ds = new DatagramSocket(8000);            byte[] buffer = new byte[1024];            DatagramPacket dp = new DatagramPacket(buffer, buffer.length);            ds.receive(dp);            String ip = dp.getAddress().getHostAddress();            String data = new String(dp.getData(), 0, dp.getLength());            int port = dp.getPort();            System.out.println("ip: " + ip + "; data: " + data + "; port: " + port);            ds.close();        } catch (SocketException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}

用Socket实现TCP通信

TCP因为要经过三次“对话”，传输可靠，适用于传输大文件，速度比UDP慢。

public class TCPServer {    public static void main(String[] args) {        try {            ServerSocket server = new ServerSocket(8001);            boolean flag = true;            while (flag) {                final Socket client = server.accept();                System.out.println("Connect to client " + client + " remote add: " + client.getRemoteSocketAddress());                new Thread(new Runnable() {                    @Override                    public void run() {                        try {                            PrintStream ps = new PrintStream(client.getOutputStream());                            BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));                            while (true) {                                String line = br.readLine();                                System.out.println("client: " + line);                                ps.println(line + " copied");                                if ("bye".equals(line)) {                                    break;                                }                            }                            ps.close();                            br.close();                            client.close();                        } catch (IOException e) {                            e.printStackTrace();                        }                    }                }).start();            }        } catch (IOException e) {            e.printStackTrace();        }    }}public class TCPClient {    public static void main(String[] args) {        try {            Socket client = new Socket("localhost", 8001);            client.setSoTimeout(10000);            BufferedReader input = new BufferedReader(new InputStreamReader(System.in));            PrintStream out = new PrintStream(client.getOutputStream());            BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));            while (true) {                System.out.print("input: ");                String str = input.readLine();                out.println(str);                if ("bye".equals(str)) {                    break;                }                String read = br.readLine();                System.out.println("server: " + read);            }            input.close();            client.close();        } catch (UnknownHostException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}