在C#中从客户端向服务器发送字符串

Question

我正在编写一个简单的测试程序,用于将字符串从客户端发送到服务器,然后在服务器程序上显示文本.我该怎么做呢

这是我的客户端代码.

using System;
using System.Net;
using System.Net.Sockets;


    class client
    {

        static String hostName = Dns.GetHostName();

        public static void Main(String[] args)
        {
            String test = Console.ReadLine();

            IPHostEntry ipEntry = Dns.GetHostByName(hostName);
            IPAddress[] addr = ipEntry.AddressList;

            //The first one in the array is the ip address of the hostname
           IPAddress ipAddress = addr[0];


            TcpClient client = new TcpClient();

            //First parameter is Hostname or IP, second parameter is port on which server is listening
            client.Connect(ipAddress, 8);


            client.Close();
        }
    }

这是我的服务器代码

using System;
using System.Net;
using System.Net.Sockets;

class server
{
    static int port = 8;
    static String hostName = Dns.GetHostName();
    static IPAddress ipAddress;

    public static void Main(String[] args)
    {
        IPHostEntry ipEntry = Dns.GetHostByName(hostName);

        //Get a list of possible ip addresses
        IPAddress[] addr = ipEntry.AddressList;

        //The first one in the array is the ip address of the hostname
        ipAddress = addr[0];

        TcpListener server = new TcpListener(ipAddress,port);

        Console.Write("Listening for Connections on " + hostName + "...\n");

        //start listening for connections
        server.Start();

        //Accept the connection from the client, you are now connected
        Socket connection = server.AcceptSocket();

        Console.Write("You are now connected to the server\n\n");


        int pauseTime = 10000;
        System.Threading.Thread.Sleep(pauseTime);

        connection.Close();


    }


}

Answer 1

你可以使用Send和Receive重载Socket.异步版本也存在,通过BeginSomething& EndSomething方法.

你发送原始字节,所以你需要决定一个简单的协议.要发送一些文本,请选择一个编码(我将使用UTF-8)并获取原始字节Encoding.GetBytes.

例:

Byte[] bytes = Encoding.UTF8.GetBytes("Royale With Cheese");

UTF8是类中的静态属性Encoding,它是为了您的方便.

然后,您可以使用以下命令将数据发送到服务器/客户端:

int sent = connection.Send(bytes);

接收:

Byte[] bytes = new Bytes[100]; 
int received = connection.Receive(bytes);

这看起来很简单,但有一些警告.可以随时删除连接,因此您必须为异常做好准备,尤其是SocketException.此外,如果你看一下例子,你可以看到,我有两个变量sent和received.它们保存了多少字节Send并Receive实际发送.您不能依赖套接字发送或接收所有数据(特别是在接收时不会,如果对方发送的数据少于您的预期会怎样？)

一种方法是循环并发送,直到所有数据都表示为已发送:

var bytes = Encoding.UTF8.GetBytes("Royale With Cheese");
int count = 0;
while (count < bytes.Length) // if you are brave you can do it all in the condition.
{
    count += connection.Send(
        bytes, 
        count, 
        bytes.Length - count, // This can be anything as long as it doesn't overflow the buffer, bytes.
        SocketFlags.None)
}

Send并且Receive是同步的,它们会阻止,直到它们发送了一些东西.您应该在套接字上设置某种超时值(Socket.SendTimeout&Socket.ReceiveTimeout.)默认值为0,这意味着它们可能永远阻塞.

接受怎么样？让我们尝试做一个类似的循环.

int count = 0;
var bytes = new Byte[100];
do
{
    count += connection.Receive(
        bytes,
        count,
        bytes.Length - count,
        SocketFlags.None);
} while (count < bytes.Length);

嗯.那么......如果客户端发送的数据少于100,会发生什么？我们会阻塞,直到它达到超时,如果有,或者客户端发送足够的数据.如果客户端发送超过100个会发生什么？您将只获得100个第一个字节.

在你的情况下,我们可以尝试阅读非常少量和打印.读,打印,循环:

var sunIsBurning = true;
while (sunIsBurning) {
    var bytes = new Byte[16];
    int received = socket.Receive(bytes);
    if (received > 0)
        Console.Out.WriteLine("Got {0} bytes. START:{1}END;", received, Encoding.UTF8.GetString(bytes));
}

这里我们说"只要sunIsBurning接收16字节块的数据,解码为UTF-8".这意味着另一方发送的数据必须是UTF-8,否则您将获得异常(它应该被您捕获)这也意味着服务器只会在连接失败时停止接收.

如果您已收到15个字节,并且客户端终止连接,则永远不会打印这15个字节.你需要更好的错误处理:)

在大多数情况下,未捕获的异常将终止您的应用程序; 不适合服务器.

"连接失败"可能意味着很多事情,可能是连接被同伴重置或者你的网卡着火了.