Silverlight_Rest_WCF系列之四：Rest调用者,RestInvoker.

还记得上篇文章中的PUT调用Rest服务的代码吗？不记得没关系，下面就是它的代码。

#region 使用WebRequest

            WebRequest webRequest =WebRequestCreator.ClientHttp.Create(
                new Uri("http://localhost:19598/ProductService.svc/Product"));
            webRequest.ContentType = "application/json";
            webRequest.Method = "PUT";
            webRequest.BeginGetRequestStream(requestAsyncCallback =>
                {
                    Stream requestStream = webRequest.EndGetRequestStream(requestAsyncCallback);

                    JsonObject jo = new JsonObject();
                    jo["Id"] = Guid.NewGuid().ToString();
                    jo["Name"] = "test";

                    string jsonString = jo.ToString();
                    byte[] buffer = System.Text.Encoding.Unicode.GetBytes(jsonString);
                    requestStream.Write(buffer, 0, buffer.Length);
                    requestStream.Close();

                    webRequest.BeginGetResponse(responseAsyncCallback =>
                        {
                            WebResponse webResponse = webRequest.EndGetResponse(responseAsyncCallback);
                            using (StreamReader reader = new StreamReader(webResponse.GetResponseStream()))
                            {
                                string result = reader.ReadToEnd();
                                //MessageBox.Show(result);
                                this.Dispatcher.BeginInvoke(() =>
                                {
                                    MessageBox.Show(result);
                                });
                            }
                        }, null);
                }, null);

            #endregion

如果说每次调用服务都需要写这么多代码的话，那估计程序员会疯的。所以我决定对他进行包装。

在这段代码中有几个地方可以封装。

1：创建WebRequest的代码可以封装。

WebRequest webRequest =WebRequestCreator.ClientHttp.Create(
                new Uri("http://localhost:19598/ProductService.svc/Product"));
            webRequest.ContentType = "application/json";
            webRequest.Method = "PUT";

 2：序列化数据到requestStream对象中可以封装。

 Stream requestStream = webRequest.EndGetRequestStream(requestAsyncCallback);

                    JsonObject jo = new JsonObject();
                    jo["Id"] = Guid.NewGuid().ToString();
                    jo["Name"] = "test";

                    string jsonString = jo.ToString();
                    byte[] buffer = System.Text.Encoding.Unicode.GetBytes(jsonString);
                    requestStream.Write(buffer, 0, buffer.Length);
                    requestStream.Close();

3：对返回结果执行的操作可以封装。

WebResponse webResponse = webRequest.EndGetResponse(responseAsyncCallback);
                            using (StreamReader reader = new StreamReader(webResponse.GetResponseStream()))
                            {
                                string result = reader.ReadToEnd();
                                //MessageBox.Show(result);
                                this.Dispatcher.BeginInvoke(() =>
                                {
                                    MessageBox.Show(result);
                                });
                            }

按照1，2，3的方式我们先从1开始。代码如下：

1:使用GetWebRequest函数获取WebRequest对象，当然了你也可以用factory，但是在目前而言，一个函数就足够了。

/// <summary>
        /// 获取WebRequest对象
        /// </summary>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="httpMethod">请求的方法：GET,PUT,POST,DELETE</param>
        /// <param name="contentType">请求的类型，json:"application/json"</param>
        /// <returns></returns>
        public static HttpWebRequest GetWebRequest(string requestUriString,
                                                    string httpMethod,
                                                    string contentType)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequestCreator.ClientHttp.Create(new Uri(requestUriString));
            request.Method = httpMethod;
            
            if (!string.IsNullOrWhiteSpace(contentType))
            {
                request.ContentType = contentType;
            }

            return request;
        }

2:封装序列化到RequestStream的过程。

Stream requestStream = webRequest.EndGetRequestStream(requestAsyncResult);
                SerializeDataToRequestStream(data,requestStream);
                requestStream.Close();

 SerializeDataToRequestStream方法可以对JsonObject,匿名类，DataContract修饰的类进行序列化。

private static void SerializeDataToRequestStream<T>(T data, Stream requestStream)
        {
            if (data.GetType() == typeof(System.Json.JsonObject))
            {
                string jsonString = data.ToString();
                byte[] buffer = System.Text.Encoding.Unicode.GetBytes(jsonString);
                requestStream.Write(buffer, 0, buffer.Length);
            }
            else if(data.GetType().FullName.Contains("AnonymousType")) //如果是匿名类
            {
                #region 使用反射获取属性和值，可以使用FastInvoker来优化。

                PropertyInfo[] pis = data.GetType().GetProperties();
                System.Json.JsonObject jo = new System.Json.JsonObject();
                foreach(PropertyInfo pi in pis)
                {
                    jo[pi.Name] = pi.GetValue(data, null).ToString();
                }

                #endregion

                string jsonString = jo.ToString();
                byte[] buffer = System.Text.Encoding.Unicode.GetBytes(jsonString);
                requestStream.Write(buffer, 0, buffer.Length);
            }
            else
            {
                DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
                serializer.WriteObject(requestStream, data);
            }
        }

 3：处理WebResponse。如果T是String类型则直接返回Json的string，否则使用DataContractJsonSerializer 反序列化成对象进行操作。

 /// <summary>
        /// 处理WebResponse
        /// </summary>
        /// <typeparam name="T">WebResponse返回结果的类型</typeparam>
        /// <param name="webResponse">webResponse对象</param>
        /// <param name="action">对结果的操作</param>
        private static void HandleWebResponse<T>(WebResponse webResponse, Action<T> action)
        {
            using (Stream responseStream = webResponse.GetResponseStream())
            {
                DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
                if (typeof(T) == typeof(string))
                {
                    T responseObject = (T)(object)GetStringFromStream(responseStream);
                    action(responseObject);
                }
                else
                {
                    T responseObject = (T)serializer.ReadObject(responseStream);
                    action(responseObject);
                }

            }
        }

好了，基本框架已经搭建好了，尝试下调用GET服务吧。

/// <summary>
        /// 调用GET方法
        /// </summary>
        /// <typeparam name="T">结果的类型</typeparam>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="action">对结果的操作</param>
        public static void InvokeGet<T>(string requestUriString, Action<T> action)
        {
            HttpWebRequest webRequest = GetWebRequest(requestUriString, "GET", string.Empty);
            webRequest.BeginGetResponse((asyncResult) =>
            {
                WebResponse response = webRequest.EndGetResponse(asyncResult);
                HandleWebResponse(response, action);                
            }, null);
        }

调用GET服务比较简单，使用GET从指定的URL下载数据就可以了，那么调用POST,PUT,DELETE呢？

其实原理都比较简单，就是GetRequestStream--->写数据到RequestStream--->GetResponse。

所以可以写一个通用方法来调用PUT，POST，DELETE。

/// <summary>
        /// 调用PUT/POST/DELETE方法
        /// </summary>
        /// <typeparam name="TData">请求数据的类型</typeparam>
        /// <typeparam name="TResult">结果的类型</typeparam>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="data">请求的数据</param>
        /// <param name="action">对结果的操作</param>
        /// <param name="httpMethod">请求的具体方法，PUT/POST/DELETE</param>
        public static void InvokePutPostDelete<TData, TResult>(string requestUriString, TData data, Action<TResult> action, string httpMethod)
        {
            HttpWebRequest webRequest = GetWebRequest(requestUriString, httpMethod, "application/json");

            webRequest.BeginGetRequestStream((requestAsyncResult) =>
            {
                Stream requestStream = webRequest.EndGetRequestStream(requestAsyncResult);
                SerializeDataToRequestStream(data,requestStream);
                requestStream.Close();

                webRequest.BeginGetResponse((responseAsyncResult) =>
                {
                    WebResponse response = webRequest.EndGetResponse(responseAsyncResult);
                    HandleWebResponse(response, action);
                }, null);
            }, null);
        }

RestInvoker的完整代码如下：

public class RestInvoker
    {
        /// <summary>
        /// 获取WebRequest对象
        /// </summary>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="httpMethod">请求的方法：GET,PUT,POST,DELETE</param>
        /// <param name="contentType">请求的类型，json:"application/json"</param>
        /// <returns></returns>
        public static HttpWebRequest GetWebRequest(string requestUriString,
                                                    string httpMethod,
                                                    string contentType)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequestCreator.ClientHttp.Create(new Uri(requestUriString));
            request.Method = httpMethod;
            
            if (!string.IsNullOrWhiteSpace(contentType))
            {
                request.ContentType = contentType;
            }

            return request;
        }

        /// <summary>
        /// 调用GET方法
        /// </summary>
        /// <typeparam name="T">结果的类型</typeparam>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="action">对结果的操作</param>
        public static void InvokeGet<T>(string requestUriString, Action<T> action)
        {
            HttpWebRequest webRequest = GetWebRequest(requestUriString, "GET", string.Empty);
            webRequest.BeginGetResponse((asyncResult) =>
            {
                WebResponse response = webRequest.EndGetResponse(asyncResult);
                HandleWebResponse(response, action);                
            }, null);
        }

        /// <summary>
        /// 调用PUT方法
        /// </summary>
        /// <typeparam name="TData">请求数据的类型</typeparam>
        /// <typeparam name="TResult">结果的类型</typeparam>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="data">请求的数据</param>
        /// <param name="action">对结果的操作</param>
        public static void InvokePut<TData,TResult>(string requestUriString, TData data, Action<TResult> action)
        {
            InvokePutPostDelete(requestUriString, data, action, "PUT");
        }

        /// <summary>
        /// 调用POST方法
        /// </summary>
        /// <typeparam name="TData">请求数据的类型</typeparam>
        /// <typeparam name="TResult">结果的类型</typeparam>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="data">请求的数据</param>
        /// <param name="action">对结果的操作</param>
        public static void InvokePost<TData, TResult>(string requestUriString, TData data, Action<TResult> action)
        {
            InvokePutPostDelete(requestUriString, data, action, "POST");
        }

        /// <summary>
        /// 调用DELETE方法
        /// </summary>
        /// <typeparam name="TData">请求数据的类型</typeparam>
        /// <typeparam name="TResult">结果的类型</typeparam>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="data">请求的数据</param>
        /// <param name="action">对结果的操作</param>
        public static void InvokeDelete<TData, TResult>(string requestUriString, TData data, Action<TResult> action)
        {
            InvokePutPostDelete(requestUriString, data, action, "DELETE");
        }

        /// <summary>
        /// 调用PUT/POST/DELETE方法
        /// </summary>
        /// <typeparam name="TData">请求数据的类型</typeparam>
        /// <typeparam name="TResult">结果的类型</typeparam>
        /// <param name="requestUriString">请求的地址</param>
        /// <param name="data">请求的数据</param>
        /// <param name="action">对结果的操作</param>
        /// <param name="httpMethod">请求的具体方法，PUT/POST/DELETE</param>
        public static void InvokePutPostDelete<TData, TResult>(string requestUriString, TData data, Action<TResult> action, string httpMethod)
        {
            HttpWebRequest webRequest = GetWebRequest(requestUriString, httpMethod, "application/json");

            webRequest.BeginGetRequestStream((requestAsyncResult) =>
            {
                Stream requestStream = webRequest.EndGetRequestStream(requestAsyncResult);
                SerializeDataToRequestStream(data,requestStream);
                requestStream.Close();

                webRequest.BeginGetResponse((responseAsyncResult) =>
                {
                    WebResponse response = webRequest.EndGetResponse(responseAsyncResult);
                    HandleWebResponse(response, action);
                }, null);
            }, null);
        }

        /// <summary>
        /// 序列化对象到RequestStream中
        /// </summary>
        /// <typeparam name="T">请求数据的类型</typeparam>
        /// <param name="data">请求的数据</param>
        /// <param name="requestStream">RequestStream</param>
        private static void SerializeDataToRequestStream<T>(T data, Stream requestStream)
        {
            if (data.GetType() == typeof(System.Json.JsonObject))
            {
                string jsonString = data.ToString();
                byte[] buffer = System.Text.Encoding.Unicode.GetBytes(jsonString);
                requestStream.Write(buffer, 0, buffer.Length);
            }
            else if(data.GetType().FullName.Contains("AnonymousType")) //如果是匿名类
            {
                #region 使用反射获取属性和值，可以使用FastInvoker来优化。

                PropertyInfo[] pis = data.GetType().GetProperties();
                System.Json.JsonObject jo = new System.Json.JsonObject();
                foreach(PropertyInfo pi in pis)
                {
                    jo[pi.Name] = pi.GetValue(data, null).ToString();
                }

                #endregion

                string jsonString = jo.ToString();
                byte[] buffer = System.Text.Encoding.Unicode.GetBytes(jsonString);
                requestStream.Write(buffer, 0, buffer.Length);
            }
            else
            {
                DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
                serializer.WriteObject(requestStream, data);
            }
        }

        /// <summary>
        /// 处理WebResponse
        /// </summary>
        /// <typeparam name="T">WebResponse返回结果的类型</typeparam>
        /// <param name="webResponse">webResponse对象</param>
        /// <param name="action">对结果的操作</param>
        private static void HandleWebResponse<T>(WebResponse webResponse, Action<T> action)
        {
            using (Stream responseStream = webResponse.GetResponseStream())
            {
                DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
                if (typeof(T) == typeof(string))
                {
                    T responseObject = (T)(object)GetStringFromStream(responseStream);
                    action(responseObject);
                }
                else
                {
                    T responseObject = (T)serializer.ReadObject(responseStream);
                    action(responseObject);
                }

            }
        }

        /// <summary>
        /// 从Stream中获取String
        /// </summary>
        /// <param name="stream"></param>
        /// <returns></returns>
        public static string GetStringFromStream(Stream stream)
        {
            byte[] buffer = new byte[32768];
            stream.Position = 0; //重置读取位置
            while (true)
            {
                int read = stream.Read(buffer, 0, buffer.Length);
                if (read <= 0)
                    break;
            }

            return System.Text.Encoding.UTF8.GetString(buffer, 0, (int)stream.Length);
        }

        /// <summary>
        /// 复制流
        /// </summary>
        /// <param name="input">输入流</param>
        /// <param name="output">输出流</param>
        private static void CopyStream(Stream input, Stream output)
        {
            byte[] buffer = new byte[32768];
            input.Position = 0; //重置读取位置
            while (true)
            {
                int read = input.Read(buffer, 0, buffer.Length);
                if (read <= 0)
                    return;
                output.Write(buffer, 0, read);
            }
        }

    }

但是我们还没有解决跨线程问题，还记得上篇文章中的this.Dispatcher.BeginInvoker吗？

但是在某些特定情况下，客户端不想调用BeginInvoker。

我们下回要修改RestInvoker,让它可以跨线程。 下回分解。。。