基于Web Service的客户端框架搭建三：代理层（Proxy）

前言

　　代理层的主要工作是调用Web Service，将在FCL层序列化好的Json数据字符串Post到Web Service，然后获得Reponse，再从响应流中读取到调用结果Json字符串，在Dispatcher反序列化成数据对象，在UI层呈现出来。

HttpHelper类（参考自：http://blog.csdn.net/eriloan/article/details/7000790）

　　刚开始是直接在Proxy类中直接写的Post方法，后来看到这篇帖子，将Http相关的部分封装成了工具类HttpHelper。原帖中还包含了使用TCPSocket发送请求调用WebService的内容。

namespace ProjectmsMGT_Proxy
{
public class HttpHelper
{
/// <summary>
/// Http请求URL
/// </summary>
public string Url { set; get; }

/// <summary>
/// 请求参数Key(约定服务方法参数名同名)
/// 在使用Post方式向服务器端发送请求的时候，请求数据中包含了参数部分，参数部分我们需要告诉WebService接口方法，实参要传给的接口方法行参名，由RequestParaKey指定
/// 当然当接口方法有多个形参时，就不建议单独设计这样一个属性，直接在sendMsg中添加，此处只是为了突出RequestParaKey的重要性
/// </summary>
public string RequestParaKey { set; get; }

/// <summary>
/// 证书文件路径
/// </summary>
public string CertificateFilePath { set; get; }

/// <summary>
/// 证书文件口令
/// </summary>
public string CertificateFilePwd { set; get; }

/// <summary>
/// 构造函数，不使用证书
/// </summary>
/// <param name="url"></param>
/// <param name="requestParaKey"></param>
public HttpHelper(string url, string requestParaKey)
{
this.Url = url;
this.RequestParaKey = requestParaKey;
}

/// <summary>
/// 构造函数，使用证书
/// </summary>
/// <param name="url"></param>
/// <param name="requestParaKey"></param>
/// <param name="certFilePath"></param>
/// <param name="certFilePwd"></param>
public HttpHelper(string url, string requestParaKey, string certFilePath, string certFilePwd)
{
this.Url = url;
this.RequestParaKey = requestParaKey;
this.CertificateFilePath = certFilePath;
this.CertificateFilePwd = certFilePwd;
}

/// <summary>
/// 使用Get方式，发送Http请求
/// </summary>
/// <param name="methodName">所请求的接口方法名</param>
/// <param name="isLoadCert">是否加载证书</param>
/// <returns>响应字符串</returns>
public string CreateHttpGet(string methodName, bool isLoadCert)
{
HttpWebRequest request = CreateHttpRequest(methodName, @"GET", isLoadCert);

return CreateHttpResponse(request);
}

/// <summary>
/// 使用Post方式，发送Http请求
/// </summary>
/// <param name="methodName">所请求的接口方法名</param>
/// <param name="sendMsg">请求参数(不包含RequestParaKey部分)</param>
/// <param name="isLoadCert">是否加载证书</param>
/// <returns>响应字符串</returns>
public string CreateHttpPost(string methodName, string sendMsg, bool isLoadCert)
{
//创建Http请求
HttpWebRequest request = CreateHttpRequest(methodName, @"POST", isLoadCert);
if (null != sendMsg && !"".Equals(sendMsg))
{
//添加请求参数
AddHttpRequestParams(request, sendMsg);
}

//获得响应
return CreateHttpResponse(request);
}

/// <summary>
/// 将请求参数写入请求流
/// </summary>
/// <param name="request"></param>
/// <param name="sendMsg"></param>
private void AddHttpRequestParams(HttpWebRequest request, string sendMsg)
{
//将请求参数进行URL编码
string paraUrlCoded = System.Web.HttpUtility.UrlEncode(RequestParaKey) + "=" +
System.Web.HttpUtility.UrlEncode(sendMsg);

byte[] data = Encoding.UTF8.GetBytes(paraUrlCoded);
request.ContentLength = data.Length;
Stream requestStream = null;
using (requestStream = request.GetRequestStream())
{
//将请求参数写入流
requestStream.Write(data, 0, data.Length);
}

requestStream.Close();
}

/// <summary>
/// 创建HttpRequest
/// </summary>
/// <param name="methodName"></param>
/// <param name="requestType">POST或者GET</param>
/// <param name="isLoadCert"></param>
/// <returns>HttpWebRequest对象</returns>
private HttpWebRequest CreateHttpRequest(string methodName, string requestType, bool isLoadCert)
{
HttpWebRequest request = null;
try
{
string requestUriString = Url + "/" + methodName;
request = (HttpWebRequest)WebRequest.Create(requestUriString);
if (isLoadCert)
{
//创建证书
X509Certificate2 cert = CreateX509Certificate2();
//添加证书认证
request.ClientCertificates.Add(cert);
}
request.KeepAlive = true;
request.ContentType = "application/x-www-form-urlencoded";
request.Method = requestType;
}
catch (Exception)
{
//Console.WriteLine("创建HttpRequest失败。原因：" + e.Message);
request = null;
}

return request;
}

/// <summary>
/// 创建请求响应
/// </summary>
/// <param name="request"></param>
/// <returns>响应字符串</returns>
private string CreateHttpResponse(HttpWebRequest request)
{
String str;
HttpWebResponse response = null;
Stream responseStream = null;
XmlTextReader responseReader = null;
try
{
using (response = (HttpWebResponse)request.GetResponse())
{
//获得响应流
responseStream = response.GetResponseStream();
responseReader = new XmlTextReader(responseStream);
responseReader.MoveToContent();
str = responseReader.ReadInnerXml();
}
}
catch (Exception e)
{
str = "[{\"Rescode\":\"0\",\"Resmsg\":\"通信失败。原因：" + e.Message + "\"}]";
}
finally
{
if (null != response)
{
responseReader.Close();
responseStream.Close();
response.Close();
}
}

return str;
}

/// <summary>
/// 创建证书
/// </summary>
/// <returns>X509Certificate2对象</returns>
private X509Certificate2 CreateX509Certificate2()
{
X509Certificate2 cert = null;
try
{
cert = new X509Certificate2(CertificateFilePath, CertificateFilePwd);
ServicePointManager.ServerCertificateValidationCallback =
new RemoteCertificateValidationCallback(ServerCertificateValidationCallback);
}
catch (Exception)
{
//Console.WriteLine("创建X509Certificate2失败。原因：" + e.Message);
cert = null;
}
return cert;
}

/// <summary>
/// Verifies the remote Secure Sockets Layer (SSL) certificate used for authentication
/// </summary>
/// <param name="obj">An object that contains state information for this validation</param>
/// <param name="cer">The certificate used to authenticate the remote party</param>
/// <param name="chain">The chain of certificate authorities associated with the remote certificate</param>
/// <param name="error">One or more errors associated with the remote certificate</param>
/// <returns>A Boolean value that determines whether the specified certificate is accepted for authentication</returns>
private bool ServerCertificateValidationCallback(object obj, X509Certificate cer, X509Chain chain, System.Net.Security.SslPolicyErrors error)
{
return true;
}
}
}

　　HttpHelper中把SSL证书的部分也包含进来，但是证书认证机制部分ServerCertificateValidationCallback还没设计，各位大神可以自行发挥。

代理类Proxy

　　有了HttpHelper之后，代理类的代码就比较明了了。

namespace ProjectmsMGT_Proxy
{
public class ProjectmsProxy
{
private readonly string Url = "http://59.68.29.106:8087/IFT_Project.asmx";//通过配置文件获取Web Service地址
private readonly string requestParaKey = "paramaters";//服务端所有接口函数统一的参数名
private HttpHelper httpHelper;

public ProjectmsProxy()
{
//初始化
Initialize();
}

private void Initialize()
{
httpHelper = new HttpHelper(this.Url, this.requestParaKey);
}

/// <summary>
/// 使用Get方式调用WebService，不带参数
/// </summary>
/// <param name="methodName"></param>
/// <param name="parasJsonStr"></param>
/// <param name="requestType"></param>
/// <returns></returns>
public string Excute(string methodName, string parasJsonStr, string requestType)
{
return httpHelper.CreateHttpGet(methodName, false);
}

/// <summary>
/// 默认使用Post方式调用WebService，带参数
/// </summary>
/// <param name="methodName"></param>
/// <param name="parasJsonStr"></param>
/// <returns></returns>
public string Excute(string methodName, string parasJsonStr)
{
return httpHelper.CreateHttpPost(methodName, parasJsonStr, false);
}

/// <summary>
/// 默认使用Post方式调用WebService，不带参数
/// </summary>
/// <param name="methodName"></param>
/// <returns></returns>
public string Excute(string methodName)
{
return httpHelper.CreateHttpPost(methodName, null, false);
}
}
}

　　Proxy中重载了Excute方法，三个参数的表示使用Get方式调用WebService（因为不建议在Get方式下传参给Web Service），两个参数和一个参数的Excute默认是使用Post方式带参数和不带参数的情况。

总结

　　将方法名作为参数Post到Web Service可以减少很多重复代码，不需要对服务端的每个接口函数做写一个代理函数，这是使用Post方式比使用添加Web服务引用方式更加灵活。