OK，经过前面 10 篇介绍，SAP RFC 接口技术的要领基本上就齐了。之前说过，VBA 并不是一门优雅的语言，专业程序员都看不上。因为 SAP RFC 接口并不限制编程语言，所以接下来用 C# 来演示如何实现与 SAP 的通信。
编程环境：Visual Studio 2012 英文版

ActiveX 控件引用

在 Visual Studio 2012 中添加引用比 VBE 方便，选中 Project 的 Solution Explorer，选中 Reference，右键，Add Reference。因为 ActiveX 是COM 组件，所以类别选择 COM，找到相应控件，打钩即可。

SAPLogonCtrl.Connection 对象

调用 RFC 时候，我们需要一个 Connection 对象，并且 Connection 对象的 IsConnected 属性为 tloRfcConnected。C# 是 OOP 的，所以我们可以利用 OOP 的特性，将 Connection 封装在一个类 SAPConnection 中，该类提供如下方法：

RFC-1-1.jpg

Connection 属性用于外部获取连接的实例。Logon() ，SilentLogon() 和 Logoff() 三个方法用于登陆 SAP，改变 Connection 的 IsConnected的状态。
在 Visual Studio 中，如果想了解对象的属性/方法等，通过菜单 [View] - [Object Browser] 查看。我们注意到，Connection 是一个接口，ConnectionClass 实现了 Connection 接口。但代码中并不能直接使用ConnectionClass。

C# 连接 SAP 代码示例

using System;
using SAPLogonCtrl;

namespace ConnectionProvider
{
    public static class SAPConnection
    {
        // Connection is an interface
        private static Connection connection;
        private static SAPLogonControl sapLogon;

        // Access modifiers are not allowed on static constructors
        static SAPConnection()
        {
            sapLogon = new SAPLogonControl();
        }

        public static bool Logon()
        {
            connection = (Connection)sapLogon.NewConnection();
            return (connection.Logon(null, false) == true ? true : false);
        }

        public static bool SilentLogon(String appServer, String system, int systemNo, String client, String user, String pwd, String language)
        {
            bool result = false;

            //In C#, the following properties should be set on SAPLogonControl
            //while in VBA, they can be set either on SAPLogonControl or Connection
            sapLogon.ApplicationServer = appServer;
            sapLogon.System = system;
            sapLogon.SystemNumber = systemNo;
            sapLogon.Client = client;
            sapLogon.User = user;
            sapLogon.Password = pwd;
            sapLogon.Language = language;

            connection = (Connection) sapLogon.NewConnection();
            result = connection.Logon(null, true);
            return result;
        }

        public static void Logoff()
        {
            if (connection.IsConnected == CRfcConnectionStatus.tloRfcConnected) {
                connection.Logoff();
            }
        }

        public static Connection Connection
        {
            get { return connection; }
        }
    }
}

单元测试

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using ConnectionProvider;

namespace UnitTestProject
{
    [TestClass]
    public class TestConnection
    {
        [TestMethod]
        public void TestLogon()
        {
            bool result = SAPConnection.Logon();
            Console.WriteLine(result);
        }

        [TestMethod]
        public void TestSilentLogon()
        {            
            bool result = SAPConnection.SilentLogon(
                "192.168.65.100", "D01", 00, "001", "STONE", "pwdxxx", "ZH");
            Console.WriteLine(result); // return true or false
        }
    }
}

RFC 调用的代码

还记得 VBA RFC 的第一个例子吗，对，BAPI_COMPANYCODE_GETDETAIL。我的例子都是 FI/CO 模块的，因为本人是FI/CO顾问。C# 仍然使用这个BAPI，方便大家进行语言的对比。

using System;
using System.Collections.Generic;
using SAPLogonCtrl;
using SAPFunctionsOCX;
using ConnectionProvider;


namespace SAPRfcCall
{
    public class RFC
    {
        private Connection connection;

        public List<String> GetCocdDetail(String cocd)
        {
            List<String> info = new List<String>();

            bool isSuccessful = SAPConnection.SilentLogon(
                "192.168.65.100", "D01", 00, "001", "STONE", "pwdxxx", "ZH");

            if (isSuccessful) {
                connection = SAPConnection.Connection;
                info = DoGetCocdDetail(cocd);
                SAPConnection.Logoff();
            }

            return info;
        }

        // Get company code detail and returns a List
        public List<String> DoGetCocdDetail(String cocd)
        {
            var cocdData = new List<String>();

            if (connection.IsConnected != CRfcConnectionStatus.tloRfcConnected) {
                return null;
            }

            SAPFunctions functions = new SAPFunctions();
            functions.Connection = connection;

            Function fm = functions.Add("BAPI_COMPANYCODE_GETDETAIL");
            fm.Exports["COMPANYCODEID"].Value = cocd;
            fm.Call();

            // return value is a structure(SAPFunctionsOCX.Structure)
            Structure cocdDetail = fm.Imports["COMPANYCODE_DETAIL"];

            // index begins from 1 instead of 0
            for (int i = 1; i <= cocdDetail.ColumnCount; i++) {
                String line = String.Format("{0}\t\t{1}",
                    cocdDetail.ColumnName[(short)i], cocdDetail.Value[i].ToString());

                cocdData.Add(line);
            }

            return cocdData;
        }
    }
}

单元测试:

using System;
using SAPRfcCall;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System.Collections.Generic;

namespace UnitTestProject
{
    [TestClass]
    public class TestRFC
    {
        [TestMethod]
        public void TestGetCocdDetail()
        {
            RFC rfc = new RFC();
            List<String> cocdDetail = rfc.GetCocdDetail("Z900");

            // print info
            foreach (String item in cocdDetail) {
                Console.WriteLine(item);
            }
        }
    }
}