网络基础

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TCP

import java.net.*;import java.io.*;public class TCPServer2{public static void main(String[]args)throws Exception{ServerSocket s=new ServerSocket(6666);while(true){Socket ss=s.accept();DataInputStream dis=new DataInputStream(ss.getInputStream());System.out.println(dis.readUTF());         //阻塞式dis.close();ss.close();  System.out.println("A client connected!");}}}

import java.net.*;import java.io.*;public class TCPClient2{public static void main(String[] args)throws Exception{Socket s=new Socket("127.0.0.1",6666);OutputStream os=s.getOutputStream();DataOutputStream dos=new DataOutputStream(os);Thread.sleep(3000);dos.writeUTF("Hello Server");dos.flush();dos.close();s.close();}}

UDP

利用UDP传递字符串：

import java.net.*;public class TestUDPServer{public static void main(String []args) throws Exception{byte buf[]=new byte[1024];DatagramPacket dp=new DatagramPacket(buf,buf.length);DatagramSocket ds=new DatagramSocket(1234);while(true){ds.receive(dp);System.out.println(new String(buf,0,dp.getLength()));            //dp.getLength()  !!!}}}

import java.net.*;public class TestUDPClient{public static void main(String[]args) throws Exception{byte buf[]=(new String("hello")).getBytes();DatagramPacket dp=new DatagramPacket(buf,buf.length,new InetSocketAddress("127.0.0.1",1234)); //目的主机IP和端口DatagramSocket ds=new DatagramSocket(9999);   //本机端口ds.send(dp);ds.close();}}

利用UDP传递long型数值：

import java.net.*;import java.io.*;public class TestUDPServer2{public static void main(String[] args) throws Exception{  byte buf[]=new byte[1024];    DatagramPacket dp=new DatagramPacket(buf,0,buf.length);DatagramSocket ds=new DatagramSocket(1234);while(true){ds.receive(dp);ByteArrayInputStream bais=new ByteArrayInputStream(buf);DataInputStream dis=new DataInputStream(bais);System.out.println(dis.readLong());}}}

import java.net.*;import java.io.*;public class TestUDPClient2{public static void main(String[] args)throws Exception{long n=1000;ByteArrayOutputStream baos=new ByteArrayOutputStream();DataOutputStream dos=new DataOutputStream(baos);dos.writeLong(n);byte buf[]=baos.toByteArray();DatagramPacket dp=new DatagramPacket(buf,buf.length,new InetSocketAddress("127.0.0.1",1234));DatagramSocket ds=new DatagramSocket(8888);ds.send(dp);ds.close();}}