服务器端 package com.udp;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.SocketException;public class UDPTextFileServer{    public static void main(String[] args)    {        OutputStream os=null;        DatagramSocket ds=null;        try        {            ds=new DatagramSocket(9001);            System.out.println("在9001端口监听...");                        byte[] b=new byte[1024];            DatagramPacket dp=new DatagramPacket(b,0,b.length);            ds.receive(dp);            byte[] data=dp.getData();            os=new FileOutputStream(new File("text.txt"));            os.write(data, 0, dp.getLength());            System.out.println("文件接收成功");        } catch (SocketException e)        {            e.printStackTrace();        } catch (IOException e)        {            e.printStackTrace();        }        finally        {            try            {                os.close();                ds.close();            } catch (IOException e)            {                e.printStackTrace();            }                    }    }}客户端 package com.udp;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;import java.net.SocketException;public class UDPTextFileClient{    public static void main(String[] args)    {        DatagramSocket ds=null;        InputStream is=null;        try        {            ds=new DatagramSocket(9000);            System.out.println("客户端在 9000 监听");                        is=new FileInputStream(new File("text.txt"));                        byte[] b=new byte[is.available()];            is.read(b);                        DatagramPacket dp=new DatagramPacket(b,0,b.length);            dp.setPort(9001);            dp.setAddress(InetAddress.getByName("192.168.2.102"));                        ds.send(dp);            System.out.println("文件发送成功");        } catch (SocketException e)        {            e.printStackTrace();        } catch (IOException e)        {            e.printStackTrace();        }        finally        {            try            {                is.close();                ds.close();            } catch (IOException e)            {                e.printStackTrace();            }                    }    }}