asp.net访问WebService的各种方式

WebService的访问形式主要有：SOAP调用、XMLHTTP POST、GET调用、MicroSoft.XMLDOMC调用、webbehavior.htc调用

我们知道的在C#后台本地调用Webservice最简单、快捷的调用WebService的方法即通过鼠标手动添加web服务引用的方式。实际操作中我们会使用到另外一种方式，即通过HttpWebRequest构造请求。这种方式下以Post和Get两种请求为主，另外还有通用方式调用。一共三种。下面我们来看实际操作的实现方法。

由于这三种方式在实现原理上是相似的。只是具体的方式不同（哈哈，我的表述不是很专业，能理解是怎么回事就行）。于是我们抽象出公共的基类:WebServiceCaller

/// <summary>
/// 访问webservice基类
/// </summary>
public abstract class WebServiceCaller
{
    /// <summary>
    /// 请求WebService
    /// </summary>
    /// <param name="URL">WebService的路径</param>
    /// <param name="MethodName">方法名</param>
    /// <param name="Pars">参数</param>
    /// <returns></returns>
    abstract public System.Xml.XmlDocument RequestWebService(ResquestParams rp);

    /// <summary>
    /// 设置凭证与超时时间
    /// </summary>
    /// <param name="request"></param>
    public static void SetWebRequest(HttpWebRequest request)
    {
        request.Credentials = CredentialCache.DefaultCredentials;
        request.Timeout = 10000;
    }

    /// <summary>
    /// 读取响应输出流
    /// </summary>
    /// <param name="response"></param>
    /// <returns></returns>
    public static XmlDocument ReadXmlResponse(WebResponse response)
    {
        StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
        String retXml = sr.ReadToEnd();
        sr.Close();
        XmlDocument doc = new XmlDocument();
        doc.LoadXml(retXml);
        return doc;
    }

    public static String ParsToString(Hashtable Pars)
    {
        StringBuilder sb = new StringBuilder();
        foreach (string k in Pars.Keys)
        {
            if (sb.Length > 0)
            {
                sb.Append("&");
            }
            sb.Append(HttpUtility.UrlEncode(k) + "=" + HttpUtility.UrlEncode(Pars[k].ToString()));
        }
        return sb.ToString();
    }
}

Post方式调用Webservice类的实现代码:

/// <summary>
/// Post方式访问
/// </summary>
public class WebServiceCallerByPost : WebServiceCaller
{
    public override XmlDocument RequestWebService(ResquestParams rp)
    {
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(rp.URL + "/" + rp.MethodName);
        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";
        SetWebRequest(request);
        byte[] data = EncodePars(rp.Parames);
        WriteRequestData(request, data);
        return ReadXmlResponse(request.GetResponse());
    }

    /// <summary>
    /// 参数编码
    /// </summary>
    /// <param name="Pars"></param>
    /// <returns></returns>
    private static byte[] EncodePars(Hashtable Pars)
    {
        return Encoding.UTF8.GetBytes(ParsToString(Pars));
    }

    /// <summary>
    /// 添加请求参数
    /// </summary>
    /// <param name="request"></param>
    /// <param name="data"></param>
    private static void WriteRequestData(HttpWebRequest request, byte[] data)
    {
        request.ContentLength = data.Length;
        System.IO.Stream writer = request.GetRequestStream();
        writer.Write(data, 0, data.Length);
        writer.Close();
    }

}

Get方式调用Webservice类的实现代码:

/// <summary>
/// Get方式访问
/// </summary>
public class WebServiceCallerByGet : WebServiceCaller
{
    public override XmlDocument RequestWebService(ResquestParams rp)
    {
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(rp.URL + "/" + rp.MethodName + "?" + ParsToString(rp.Parames));
        request.Method = "GET";
        request.ContentType = "application/x-www-form-urlencoded";
        SetWebRequest(request);
        return ReadXmlResponse(request.GetResponse());
    }
}

通用方式调用Webservice类的实现代码:

/// <summary>
/// 通用方式调用webservice
/// </summary>
public class SoapWebService : WebServiceCaller
{

    public override XmlDocument RequestWebService(ResquestParams rp)
    {
        if (_xmlNamespaces.ContainsKey(rp.URL))
        {
            return QuerySoapWebService(rp.URL, rp.MethodName, rp.Parames, _xmlNamespaces[rp.URL].ToString());
        }
        else
        {
            return QuerySoapWebService(rp.URL, rp.MethodName, rp.Parames, GetNamespace(rp.URL));
        }
    }

    private static XmlDocument QuerySoapWebService(String URL, String MethodName, Hashtable Pars, string XmlNs)
    {
        _xmlNamespaces[URL] = XmlNs;//加入缓存，提高效率
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(URL);
        request.Method = "POST";
        request.ContentType = "text/xml; charset=utf-8";
        request.Headers.Add("SOAPAction", "\"" + XmlNs + (XmlNs.EndsWith("/") ? "" : "/") + MethodName + "\"");
        SetWebRequest(request);

        byte[] data = EncodeParsToSoap(Pars, XmlNs, MethodName);

        WriteRequestData(request, data);
        XmlDocument doc = new XmlDocument(), doc2 = new XmlDocument();
        doc = ReadXmlResponse(request.GetResponse());

        XmlNamespaceManager mgr = new XmlNamespaceManager(doc.NameTable);
        mgr.AddNamespace("soap", "http://schemas.xmlsoap.org/soap/envelope/");


        String RetXml = doc.SelectSingleNode("//soap:Body/*/*", mgr).InnerXml;

        doc2.LoadXml("<root>" + RetXml + "</root>");

        AddDelaration(doc2);

        return doc2;
    }

    private static string GetNamespace(String URL)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL + "?WSDL");
        SetWebRequest(request);
        WebResponse response = request.GetResponse();
        System.IO.StreamReader sr = new System.IO.StreamReader(response.GetResponseStream(), Encoding.UTF8);
        XmlDocument doc = new XmlDocument();
        doc.LoadXml(sr.ReadToEnd());
        sr.Close();
        return doc.SelectSingleNode("//@targetNamespace").Value;
    }

    private static byte[] EncodeParsToSoap(Hashtable Pars, String XmlNs, String MethodName)
    {
        XmlDocument doc = new XmlDocument();
        doc.LoadXml("<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\"></soap:Envelope>");
        AddDelaration(doc);
        //XmlElement soapBody = doc.createElement_x_x("soap", "Body", "http://schemas.xmlsoap.org/soap/envelope/");
        XmlElement soapBody = doc.CreateElement("soap", "Body", "http://schemas.xmlsoap.org/soap/envelope/");
        //XmlElement soapMethod = doc.createElement_x_x(MethodName);
        XmlElement soapMethod = doc.CreateElement(MethodName);
        soapMethod.SetAttribute("xmlns", XmlNs);
        foreach (string k in Pars.Keys)
        {
            //XmlElement soapPar = doc.createElement_x_x(k);
            XmlElement soapPar = doc.CreateElement(k);
            soapPar.InnerXml = ObjectToSoapXml(Pars[k]);
            soapMethod.AppendChild(soapPar);
        }
        soapBody.AppendChild(soapMethod);
        doc.DocumentElement.AppendChild(soapBody);
        return Encoding.UTF8.GetBytes(doc.OuterXml);
    }

    private static void WriteRequestData(HttpWebRequest request, byte[] data)
    {
        request.ContentLength = data.Length;
        System.IO.Stream writer = request.GetRequestStream();
        writer.Write(data, 0, data.Length);
        writer.Close();
    }

    private static void AddDelaration(XmlDocument doc)
    {
        XmlDeclaration decl = doc.CreateXmlDeclaration("1.0", "utf-8", null);
        doc.InsertBefore(decl, doc.DocumentElement);
    }

    private static string ObjectToSoapXml(object o)
    {
        XmlSerializer mySerializer = new XmlSerializer(o.GetType());
        MemoryStream ms = new MemoryStream();
        mySerializer.Serialize(ms, o);
        XmlDocument doc = new XmlDocument();
        doc.LoadXml(Encoding.UTF8.GetString(ms.ToArray()));
        if (doc.DocumentElement != null)
        {
            return doc.DocumentElement.InnerXml;
        }
        else
        {
            return o.ToString();
        }
    }

    private static Hashtable _xmlNamespaces = new Hashtable();//缓存xmlNamespace，避免重复调用GetNamespace

在编码调用时可以考虑设计一个请求参数类

public class ResquestParams
{
    /// <summary>
    /// WebService地址
    /// </summary>
    public string URL { get; set; }
    /// <summary>
    /// web方法
    /// </summary>
    public string MethodName { get; set; }
    /// <summary>
    /// 方法参数
    /// </summary>
    public Hashtable Parames { get; set; }
}

另外我们在aspx前台页面也会通过js代码来调用Webservice。此处略带"串烧"一下

$.post():

$(document).ready(function () {
    $("#btnRequest").click(function () {
        $.ajax({
            type: "post",
            contentType: "application/json",
            url: "http://localhost:5158/TestWebService.asmx/Add",
            data: "{m:12,n:2}", //注意区别于get方式的参数格式
            datatype: "json",
            error: function (x, e) {
                alert(x.responseText);
            },
            success: function (result) {
                alert(result.d);
            }
        });
    });
});

$.get():

$(document).ready(function () {
    $("#btnRequest").click(function () {
        $.ajax({
            type: "get",
            contentType: "application/json",
            url: "http://localhost:5158/TestWebService.asmx/Add",
            data: {'m':'12','n':'2'},
            datatype: "json",
            error: function (x, e) {
                alert(x.responseText);
            },
            success: function (result) {
                alert(result.d);
            }
        });
    });
});

注1：如果采用以上HTTP GET方式在后台访问WebService总是报500异常的话，那么很可能是你需要在WebService所在的站点下的配置文件中加上如下配置：

<webServices> 
   <protocols> 
       <add name= "HttpPost " /> 
       <add name= "HttpGet " /> 
    </protocols> 
</webServices>

注2：如果以上通过ajax.get()方式访问WebService时候提示这样的错误：尝试使用GET请求调用方法xx，但是不允许这样做。那么就是所调用的方法不支持脚本通过GET方式调用，需要在所调用的方法加上[ScriptMethod(UseHttpGet=true)]就ok了。

这里仅仅介绍如何消费WebService，其实要完整地学习它，我们还要了解它的历史沿革。好了就介绍到这儿。