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")

}

}

网络的Socket数据传输是一种特殊的I/O，Socket也是一种文件描述符。Socket也具有一个类似于打开文件的函数调用Socket()，该函数返回一个整型的Socket描述符，随后的连接建立、数据传输等操作都是通过该Socket实现的。

下面用Socket实现一个windows下的c语言socket通信例子，这里我们客户端传递一个字符串，服务器端进行接收。

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【服务器端】

#include "stdafx.h"

#include <stdio.h>

#include <winsock2.h>

#include <winsock2.h>

#define SERVER_PORT 5208 //侦听端口

void main()

{

WORD wVersionRequested

WSADATA wsaData

int ret, nLeft, length

SOCKET sListen, sServer//侦听套接字，连接套接字

struct sockaddr_in saServer, saClient//地址信息

char *ptr//用于遍历信息的指针

//WinSock初始化

wVersionRequested=MAKEWORD(2, 2)//希望使用的WinSock DLL 的版本

ret=WSAStartup(wVersionRequested, &wsaData)

if(ret!=0)

{

printf("WSAStartup() failed!\n")

return

}

//创建Socket,使用TCP协议

sListen=socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)

if (sListen == INVALID_SOCKET)

{

WSACleanup()

printf("socket() faild!\n")

return

}

//构建本地地址信息

saServer.sin_family = AF_INET//地址家族

saServer.sin_port = htons(SERVER_PORT)//注意转化为网络字节序

saServer.sin_addr.S_un.S_addr = htonl(INADDR_ANY)//使用INADDR_ANY 指示任意地址

//绑定

ret = bind(sListen, (struct sockaddr *)&saServer, sizeof(saServer))

if (ret == SOCKET_ERROR)

{

printf("bind() faild! code:%d\n", WSAGetLastError())

closesocket(sListen)//关闭套接字

WSACleanup()

return

}

//侦听连接请求

ret = listen(sListen, 5)

if (ret == SOCKET_ERROR)

{

printf("listen() faild! code:%d\n", WSAGetLastError())

closesocket(sListen)//关闭套接字

return

}

printf("Waiting for client connecting!\n")

printf("Tips: Ctrl+c to quit!\n")

//阻塞等待接受客户端连接

while(1)//循环监听客户端，永远不停止，所以，在本项目中，我们没有心跳包。

{

length = sizeof(saClient)

sServer = accept(sListen, (struct sockaddr *)&saClient, &length)

if (sServer == INVALID_SOCKET)

{

printf("accept() faild! code:%d\n", WSAGetLastError())

closesocket(sListen)//关闭套接字

WSACleanup()

return

}

char receiveMessage[5000]

nLeft = sizeof(receiveMessage)

ptr = (char *)&receiveMessage

while(nLeft>0)

{

//接收数据

ret = recv(sServer, ptr, 5000, 0)

if (ret == SOCKET_ERROR)

{

printf("recv() failed!\n")

return

}

if (ret == 0) //客户端已经关闭连接

{

printf("Client has closed the connection\n")

break

}

nLeft -= ret

ptr += ret

}

printf("receive message:%s\n", receiveMessage)//打印我们接收到的消息。

}

// closesocket(sListen)

// closesocket(sServer)

// WSACleanup()

}

【客户端】

#include "stdafx.h"

#include <stdio.h>

#include <stdlib.h>

#include <winsock2.h>

#define SERVER_PORT 5208 //侦听端口

void main()

{

WORD wVersionRequested

WSADATA wsaData

int ret

SOCKET sClient//连接套接字

struct sockaddr_in saServer//地址信息

char *ptr

BOOL fSuccess = TRUE

//WinSock初始化

wVersionRequested = MAKEWORD(2, 2)//希望使用的WinSock DLL的版本

ret = WSAStartup(wVersionRequested, &wsaData)

if(ret!=0)

{

printf("WSAStartup() failed!\n")

return

}

//确认WinSock DLL支持版本2.2

if(LOBYTE(wsaData.wVersion)!=2 || HIBYTE(wsaData.wVersion)!=2)

{

WSACleanup()

printf("Invalid WinSock version!\n")

return

}

//创建Socket,使用TCP协议

sClient = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)

if (sClient == INVALID_SOCKET)

{

WSACleanup()

printf("socket() failed!\n")

return

}

//构建服务器地址信息

saServer.sin_family = AF_INET//地址家族

saServer.sin_port = htons(SERVER_PORT)//注意转化为网络节序

saServer.sin_addr.S_un.S_addr = inet_addr("192.168.1.127")

//连接服务器

ret = connect(sClient, (struct sockaddr *)&saServer, sizeof(saServer))

if (ret == SOCKET_ERROR)

{

printf("connect() failed!\n")

closesocket(sClient)//关闭套接字

WSACleanup()

return

}

char sendMessage[]="hello this is client message!"

ret = send (sClient, (char *)&sendMessage, sizeof(sendMessage), 0)

if (ret == SOCKET_ERROR)

{

printf("send() failed!\n")

}

else

printf("client info has been sent!")

closesocket(sClient)//关闭套接字

WSACleanup()

}

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