C#调用RESTful API

现在很多的网络服务都用RESTful API来实现。比如百度的搜索推广API介绍使用Rest原因：REST+JSON风格的API相比SOAP+XML，好处是：调用更加灵活，也更容易扩展；JSON格式传输信息比XML减少约30%的数据量，效率更高。因此建议开发者使用REST风格的API。

查找了很多调用Rest API网络碎片资料，总是无法理解或者生效。下面摘一点觉得有效果的作为参考吧。http://www.makeyuan.com/2014/02/27/1117.html

利用该文中Post方法来调用百度搜索推广的API，虽然代码乱，但是总算成功了，下面即是代码：

        public static void send()
        {
            string url = "https://api.baidu.com/json/sms/v3/AccountService/getAccountInfo";
            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
            request.Method = "POST";
            request.ContentType = "application/json";
            string data = "{\n\"header\": {\n\"token\": \"30xxx6aaxxx93ac8cxx8668xx39xxxx\",\n\"username\": \"jdads\",\n\"password\": \"liuqiangdong2010\",\n\"action\": \"\"\n},\n\"body\": {}\n}";

            byte[] byteData = UTF8Encoding.UTF8.GetBytes(data.ToString());
            request.ContentLength = byteData.Length;

            using(Stream postStream = request.GetRequestStream())
            {
                postStream.Write(byteData, 0, byteData.Length);
            }

            using(HttpWebResponse response = request.GetResponse() as HttpWebResponse)
            {
                StreamReader reader = new StreamReader(response.GetResponseStream());
                Console.WriteLine(reader.ReadToEnd());
            }
        }

通过运行，发现json数据部分，当之前没有换行符的时候，使用@表示字符串并双引号用两个来表示时，会报数据错误。

附上链接的文章的几种调用方式：
1、以Get方式获取

using System;
using System.IO;
using System.Net;
using System.Text;

// Create the web request
HttpWebRequest request = WebRequest.Create("http://developer.yahoo.com/") as HttpWebRequest;

// Get response
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
// Get the response stream
StreamReader reader = new StreamReader(response.GetResponseStream());

// Console application output
Console.WriteLine(reader.ReadToEnd());
}

2、以Post方式获取

using System.Web;

Uri address = new Uri("http://api.search.yahoo.com/ContentAnalysisService/V1/termExtraction");

// Create the web request
HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;

// Set type to POST
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";

// Create the data we want to send
string appId = "YahooDemo";
string context = "Italian sculptors and painters of the renaissance"
+ "favored the Virgin Mary for inspiration";
string query = "madonna";

StringBuilder data = new StringBuilder();
data.Append("appid=" + HttpUtility.UrlEncode(appId));
data.Append("&context=" + HttpUtility.UrlEncode(context));
data.Append("&query=" + HttpUtility.UrlEncode(query));

// Create a byte array of the data we want to send
byte[] byteData = UTF8Encoding.UTF8.GetBytes(data.ToString());

// Set the content length in the request headers
request.ContentLength = byteData.Length;

// Write data
using (Stream postStream = request.GetRequestStream())
{
postStream.Write(byteData, 0, byteData.Length);
}

// Get response
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
// Get the response stream
StreamReader reader = new StreamReader(response.GetResponseStream());

// Console application output
Console.WriteLine(reader.ReadToEnd());
}

3、HTTP 验证请求
有些朋友在调用Restful Api时，可能要提供用户名和密码进行Http身份验证，这里我们可以通过为请求增加一个NetworkCredentials实例来完成.

// Create the web request
HttpWebRequest request
= WebRequest.Create("https://api.del.icio.us/v1/posts/recent") as HttpWebRequest;

// Add authentication to request
request.Credentials = new NetworkCredential("username", "password");

// Get response
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
// Get the response stream
StreamReader reader = new StreamReader(response.GetResponseStream());

// Console application output
Console.WriteLine(reader.ReadToEnd());
}