C#发送HttpPost请求调用WebService

　　一、Webservice调用的三种方式:
　　Webservice调用1:浏览器中输入以下URL，然后再返回的页面输入参数，提交实现调用
　　http://localhost/WebService/MyService.asmx?op=MyAction
　　Webservice调用2:html中通过表单提交来实现调用
<form id="form1" runat="server" action="http://10.15.223.56/WebService/MyService.asmx/MyAction">
<input type="text" name="strXml" value="<a ObjID="9"></a>" />
<input type="text" name="strData" value="ContactSign|990011|我的数据" />
<input type="submit" value="Send" />
</form>
　　Webservice调用3:在C#中发送HttpPost请求来调用WebService中的MyAction方法，代码如下：
void UpdateContactSign()
{
string ServerPage ="http://localhost/WebService/MyService.asmx";
try
{
//ServerPage += "?op=TangramAction";
ServerPage += "/MyAction";//MyAction是WebService中的方法
string strXml="<a ObjID="9"></a>"，;//第一个参数
string strData="ContactSign|990011|我的数据";//第二个参数
string res = HttpConnectToServer(ServerPage， strXml， strData);
//MessageBox.Show(res);
}
catch (Exception ex)
{
}
}
//发送消息到服务器
public string HttpConnectToServer(string ServerPage，string strXml，string strData)
{
string postData = "strXml=" + strXml+"&strData="+strData;
byte[] dataArray = Encoding.Default.GetBytes(postData);
//创建请求
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(ServerPage);
request.Method = "POST";
request.ContentLength = dataArray.Length;
request.ContentType = "application/x-www-form-urlencoded";
//创建输入流
Stream dataStream = null;
try
{
dataStream = request.GetRequestStream();
}
catch (Exception)
{
return null;//连接服务器失败
}
//发送请求
dataStream.Write(dataArray， 0， dataArray.Length);
dataStream.Close();
//读取返回消息
string res = string.Empty;
try
{
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream()， Encoding.UTF8);
res = reader.ReadToEnd();
reader.Close();
}
catch (Exception ex)
{
return null;//连接服务器失败
}
return res;
}