string strURL = "http://localhost/Play/CH1/Service1.asmx/doSearch?keyword=";
strURL +=this.textBox1.Text;
System.Net.HttpWebRequest request;
// 创建一个HTTP请求
request = (System.Net.HttpWebRequest)WebRequest.Create(strURL);
//request.Method="get";
System.Net.HttpWebResponse response;
response = (System.Net.HttpWebResponse)request.GetResponse();
System.IO.Stream s;
s = response.GetResponseStream();
XmlTextReader Reader = new XmlTextReader(s);
Reader.MoveToContent();
string strValue = Reader.ReadInnerXml();
strValue = strValue.Replace("<","<");
strValue = strValue.Replace(">",">");
MessageBox.Show(strValue); 
Reader.Close();

string strURL = "http://localhost/Play/CH1/Service1.asmx/doSearch";
System.Net.HttpWebRequest request;

request = (System.Net.HttpWebRequest)WebRequest.Create(strURL);
//Post请求方式
request.Method="POST";
// 内容类型
request.ContentType="application/x-www-form-urlencoded";
// 参数经过URL编码
string paraUrlCoded = System.Web.HttpUtility.UrlEncode("keyword");
paraUrlCoded += "=" + System.Web.HttpUtility.UrlEncode(this.textBox1.Text);
byte[] payload;
//将URL编码后的字符串转化为字节
payload = System.Text.Encoding.UTF8.GetBytes(paraUrlCoded);
//设置请求的 ContentLength 
request.ContentLength = payload.Length;
//获得请 求流
Stream writer = request.GetRequestStream();
//将请求参数写入流
writer.Write(payload,0,payload.Length);
// 关闭请求流
writer.Close();
System.Net.HttpWebResponse response;
// 获得响应流
response = (System.Net.HttpWebResponse)request.GetResponse();
System.IO.Stream s;
s = response.GetResponseStream();
XmlTextReader Reader = new XmlTextReader(s);
Reader.MoveToContent();
string strValue = Reader.ReadInnerXml();
strValue = strValue.Replace("<","<");
strValue = strValue.Replace(">",">");
MessageBox.Show(strValue); 
Reader.Close();