Java与C#基于Socket通信，

Java与C#基于Socket通信，

    由于Java在网络方便的巨大影响力，以及微软推出的Framework .net平台的应用不断扩大，使得Java与C#的网络通信变得愈来愈重要。本文主要介绍java与c#的Socket通信。Java的Socket通信模块由于封装的比较高级，用起来也比较舒服。但是C#虽然有TcpClient等类库的支持，但是要与java实现底层的socket通信任然比较麻烦。本文基于C#的Socket模块与Java的Socke模块t实现底层二进制数据的通信。

一.Java作为服务器:以下是核心代码：

package com.ffg;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
public class MyServer 
{
	public static void main(String args[])
	{
		try
		{
			ServerSocket ss=new ServerSocket(9999);
			System.out.println("Listening on 9999......");
			while(true)
			{
				try
				{
					Socket sc=ss.accept();
					System.out.println("Request come ...");
					DataInputStream din=new DataInputStream(sc.getInputStream());
					DataOutputStream dout=new DataOutputStream(sc.getOutputStream());
					String s=readStr(din);
					System.out.println("Rec:"+s);
					writeStr(dout," Hi C#，I‘m Java Sever。"+s);
					dout.close();
					din.close();
					sc.close();
				}
				catch(Exception e)
				{
					e.printStackTrace();
				}
			}
		}
		catch(Exception e)
		{
			e.printStackTrace();
		}
	}	
	
	public static String readStr(DataInputStream din) throws IOException
	{
		String res=null;;
		byte str[] = null;
		ByteArrayOutputStream out= new ByteArrayOutputStream(1024); 
		try {
			byte[] temp = new byte[1024]; 
			int size = 0; 
			try {//循环接受数据
				int temRev =0;
				byte[] ba=new byte[4];
				din.read(ba);
				int len=byte2Int(ba);
				System.out.println("len:"+len);
				while ((size = din.read(temp)) != -1)
				{ 	
					temRev+=size;
					out.write(temp, 0, size);
					if(temRev>=len)
					{
						break;
					}
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
			str = out.toByteArray();
			res = new String(str, "utf-8");
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			try {out.close();} catch (IOException e) {e.printStackTrace();}
		}
		return res;
	}
	public static void writeStr(DataOutputStream dout,String str) throws IOException
	{
		PrintStream ps= new PrintStream(dout, true);
		ps.println(str);// 将数据写入到SOCKET中，返回客户端。
		dout.flush();
		ps.close();
	}

	@SuppressWarnings("unused")
	private static byte[] int2Byte(int intValue) {
		byte[] b = new byte[4];
		for (int i = 0; i < 4; i++) {
			b[i] = (byte) (intValue >> 8 * (3 - i) & 0xFF);
		}
		return b;
	}
	private static int byte2Int(byte[] b) {
		int intValue = 0;
		for (int i = 0; i < b.length; i++) {
			intValue += (b[i] & 0xFF) << (8 * (3 - i));
		}
		return intValue;
	}

}

二.C#作为客户端，向服务器发起连接:以下是核心代码：

using System;
using System.Collections.Generic;
using System.Text;
using System.Net.Sockets;
using System.Net;
using System.Diagnostics;
using System.IO;
namespace ffg
{
    class SocketUtil
    {
        private static readonly string SERVER_IP = "127.0.0.1";
        private static readonly int SERVER_PORT = "9999";
        private static Socket getConnection()
        {
            try
            {
                Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                IPEndPoint ipep = new IPEndPoint(IPAddress.Parse(SERVER_IP), SERVER_PORT);//服务器的IP和端口
                socket.Connect(ipep);
                return socket;
            }
            catch (Exception e)
            {
                Debug.WriteLine(e.StackTrace);
                return null;
            }
        }
        public static String sendAndGetMsg(String str)
        {
            Socket sockect = getConnection();
            if (sockect == null) return "error sockect is null";
            try
            { 
                byte[] msgStr = Encoding.UTF8.GetBytes(str);
             // byte[] length = BitConverter.GetBytes(msgStr.Length);
                byte[] length = int2Byte(msgStr.Length);
                Debug.WriteLine("msgStr.Length:" + msgStr.Length);
                int lenSent = sockect.Send(length);
                int bytesSent = sockect.Send(msgStr);
                byte[] buffbytes = new byte[2048];
                int bytesRec = sockect.Receive(buffbytes);
                string res =Encoding.ASCII.GetString(buffbytes, 0, bytesRec);
                sockect.Shutdown(SocketShutdown.Both);
                sockect.Close();
                return res;
            }
            catch (SocketException e)
            {
                Debug.WriteLine(e.StackTrace);
                return "error";
            }
        }
        public static String sendBytesAndGetMsg(String str,byte[]data)
        {
            Socket sockect = getConnection();
            if (sockect == null) return "error sockect is null";
            try
            {
                byte[] msgStr = Encoding.UTF8.GetBytes(str);
                byte[] length = int2Byte(msgStr.Length);
                Debug.WriteLine("msgStr.Length:" + msgStr.Length);
                int lenSent = sockect.Send(length);
                int bytesSent = sockect.Send(msgStr);

                byte[] lengthData = int2Byte(data.Length);
                int lenSentData = sockect.Send(lengthData);
                int bytesSentData = sockect.Send(data);
                byte[] buffbytes = new byte[2048];
                int bytesRec = sockect.Receive(buffbytes);
                string res = Encoding.ASCII.GetString(buffbytes, 0, bytesRec);
                sockect.Shutdown(SocketShutdown.Both);
                sockect.Close();
                return res;
            }
            catch (SocketException e)
            {
                Debug.WriteLine(e.StackTrace);
                return "error";
            }
        }
        private static int byte2Int(byte[] b)
        {
            int intValue = 0;
            for (int i = 0; i < b.Length; i++)
            {
                intValue += (b[i] & 0xFF) << (8 * (3 - i));
            }
            return intValue;
        }
        private static byte[] int2Byte(int intValue)
        {
            byte[] b = new byte[4];
            for (int i = 0; i < 4; i++)
            {
                b[i] = (byte)(intValue >> 8 * (3 - i) & 0xFF);
            }
            return b;
        }
    }
}	

        总的来说，就是先将需要发送的数据的长度发送出去，而这个长度用int型表示，而int型使用四个字节编码的，即byte[4]，所以发送时先发送一个byte[4]的数据，表示接下来需要发送数据的长度，再发送实际的数据(也是一个byte[])。而java端接收到时应该知道第一次接收的是byte[4]，表示长度的int，需要将其解码成int，然后在继续接收实际数据的byte[]。