java网络编程应该怎样在客户端和服务器间实现通信？

以前写的，照贴了。。。服务器端：import java.awt.*

import java.awt.event.WindowAdapter

import java.awt.event.WindowEvent

import java.io.*

import java.net.*/*6、 采用UDP协议，编写一个Java网络应用程序，该应用分服务器端程序和客户端程序两部分。

* 客户端指定一个服务器上的文件名，让服务器发回该文件的内容，或者提示文件不存在。

* （20分）（服务端程序和客户端程序分别命名为Server.java和Client.java）*/

public class N4BT6 extends Frame

{

DatagramSocket socket

DatagramPacket packet byte[] buf

File file

FileInputStream input

String message = "该文件不存在"

TextArea text

public N4BT6(String title)

{

super(title)

text = new TextArea(6,4)

add(text)

setSize(400, 300)

setVisible(true)

addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

dispose()

}

})

buf = new byte[1024]

try

{

socket = new DatagramSocket(1230)

packet = new DatagramPacket(buf, buf.length)

socket.receive(packet)

file = new File(new String(packet.getData()))

socket = new DatagramSocket()

}

catch (Exception e)

{e.printStackTrace()

}

if(file.exists())

{

try

{

buf = new byte[(int)file.length()]

packet = new DatagramPacket(buf,buf.length,InetAddress.getLocalHost(),1234)

input = new FileInputStream(file)

input.read(buf)

socket.send(packet)

}

catch (IOException e)

{

e.printStackTrace()

}

}

else

{

try

{

packet = new DatagramPacket(message.getBytes(),message.getBytes().length,

InetAddress.getLocalHost(),1234)

socket.send(packet)

}

catch (Exception e)

{

e.printStackTrace()

}

}

}

public static void main(String[] args)

{

new N4BT6("Server")

}

}

客户端：import java.awt.*

import java.awt.event.*

import java.net.DatagramPacket

import java.net.DatagramSocket

import java.net.InetAddresspublic class N4BT6_2 extends Frame

{

TextArea text

String message = "Q.txt"

DatagramSocket socket

DatagramPacket packet

byte[] buf

public N4BT6_2(String title)

{

super(title)

text = new TextArea(6,4)

add(text)

setSize(400, 300)

setVisible(true)

addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

dispose()

}

})

try

{

socket = new DatagramSocket()

packet = new DatagramPacket(message.getBytes(),message.getBytes().length,

InetAddress.getLocalHost(),1230)

socket.send(packet)

}

catch (Exception e)

{

e.printStackTrace()

}

try

{

buf = new byte[1024]

socket = new DatagramSocket(1234)

packet = new DatagramPacket(buf,buf.length)

socket.receive(packet)

text.append(new String(buf))

}

catch (Exception e)

{

e.printStackTrace()

}

}

public static void main(String[] args)

{

new N4BT6_2("Client")

}

}

服务器端：

public class Server{

public static void main(String[] args){

ServerSocket ss = new ServerSocket(端口号)

Socket s = ss.accept()

BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()))

String str = br.readLine()

System.out.println(str)

br.close()

s.close()

ss.close()

}

}

客户端：

public class Client{

public static void main(String[] args){

Socket s = new Socket(ip,端口)

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()))

bw.write("hello")

bw.flush()

bw.close()

s.close()

}

}

先启动服务器端在启动客户端，两个端口要一致，如果是同一台电脑的ip可写为"127.0.0.1"

搂主说得很对，这个必须使用多线程得原理来做，一个线程用于监听后台事件，一个线程用于客户得操作

即：一个线程初始化类用于服务器端的双线程产生

服务端所有操作都必须是以线程得形式出来（当然如果你能自己实现一个线程池是最好的）。

客户端则是平常得Socket操作

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