1.新建项目WebService1

2.创建APISoapHeader，继承

System.Web.Services.Protocols.SoapHeader

APISoapHeader代码如下：

using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace WebService1 {
   public class APISoapHeader:System.Web.Services.Protocols.SoapHeader     {
   private string _localhostkey = string.Empty; private string _secretkey = string.Empty; /// 
 /// 构造函数 /// 
         public APISoapHeader()         {
   //配置文件的SoapHeader_APIKey             this._localhostkey = System.Configuration.ConfigurationManager.AppSettings.Get("SoapHeader_APIKey");         } /// 
 /// 获取或设置密钥 /// 
         public string SecretKey         {
   get { return this._secretkey; } set { this._secretkey = value; }         } /// 
 /// 是否为安全的API调用 /// 
         public bool IsSafeCall         {
   get             {
   if (this._localhostkey == this._secretkey) return true; else return false;             }         }     } }

WebService1项目的配置文件（web.config）

Service1.asmx 代码结构

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Services; namespace WebService1 {
   /// 
 /// Service1 的摘要说明 /// 
     [WebService(Namespace = "http://tempuri.org/")]     [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]     [System.ComponentModel.ToolboxItem(false)] // 若要允许使用 ASP.NET AJAX 从脚本中调用此 Web 服务，请取消对下行的注释。 // [System.Web.Script.Services.ScriptService]     public class Service1 : System.Web.Services.WebService     {
   public APISoapHeader soapHeader = new APISoapHeader();//声明header         [System.Web.Services.Protocols.SoapHeader("soapHeader")]//表明调用时需要传入header         [WebMethod] public string HelloWorld()         {
   if (!soapHeader.IsSafeCall)//传入的自定义APISoapHeader不正确，讲返回“你好！”             {
   return "你好！";             } return "Hello World";         }     } }

客户端调用：引用服务应用，ServiceReference1

ServiceReference1.Service1SoapClient soap = new WebApplication1.ServiceReference1.Service1SoapClient(); protected void Page_Load(object sender, EventArgs e)         {
              ServiceReference1.APISoapHeader SoapHeader = new WebApplication1.ServiceReference1.APISoapHeader(); //设置SoapHeader Key            SoapHeader.SecretKey = "1127d575-5633-4b97-a0fd-bb6bfb0d27de 5"; //WebService的方法HelloWorld没有使用APISoapHeader作参数，但是声明了 [System.Web.Services.Protocols.SoapHeader("soapHeader")]            Response.Write(soap.HelloWorld(SoapHeader));         }