[C#]Google Url Shortening
Google Url Shortening是Google所提供的短網址服務，能將長網址縮短成短網址，或將縮短後的短網址還原成長網址，另外它也提供了分析資訊與使用者歷史記錄等功能。
使用時有的地方像是縮短網址那邊會用到API Key，需先連至APIs Console將你要的服務開啟。
再至API Access取得API Key。
在縮短網址那邊，處理上是向https://www.googleapis.com/urlshortener/v1/url發送APIKey與Post訊息，ContentType為application/json，其Post內容為{"longUrl": "[長網址]"}。
Content-Type: application/json
{"longUrl": "http://www.google.com/"}
回傳的內容會像下面這樣，有kind、 id、與longUrl，我們多半只需要取得id即可。
"kind": "urlshortener#url",
"id": "http://goo.gl/fbsS",
"longUrl": "http://www.google.com/"
}
以C#實做此概念程式如下；
{
if (String.IsNullOrEmpty(url))
throw new ArgumentNullException("url");
if (m_APIKey.Length == 0)
throw new Exception("APIKey not set!");
const string POST_PATTERN = @"{{""longUrl"": ""{0}""}}";
const string MATCH_PATTERN = @"""id"": ?""(?<id>.+)""";
var post = string.Format(POST_PATTERN, url);
var request = (HttpWebRequest)WebRequest.Create(string.Format(URL_SHORTENER_URL_PATTERN, m_APIKey));
request.Method = "POST";
request.ContentLength = post.Length;
request.ContentType = "application/json";
request.Headers.Add("Cache-Control", "no-cache");
using (Stream requestStream = request.GetRequestStream())
{
var buffer = Encoding.ASCII.GetBytes(post);
requestStream.Write(buffer, 0, buffer.Length);
}
using (var responseStream = request.GetResponse().GetResponseStream())
{
using (StreamReader sr = new StreamReader(responseStream))
{
return Regex.Match(sr.ReadToEnd(), MATCH_PATTERN).Groups["id"].Value;
}
}
return string.Empty;
}
而在展開短網址方面就更為簡單了，展開的動作只需在https://www.googleapis.com/urlshortener/v1/url後面加上shortUrl的參數，將短網址帶入。
即會回傳像下面這樣的資訊，我們需要的展開後網址即回傳的longUrl。
"kind": "urlshortener#url",
"id": "http://goo.gl/fbsS",
"longUrl": "http://www.google.com/",
"status": "OK"
}
以C#實做此概念的話程式如下：
{
HttpWebRequest request = (WebRequest.Create(url)) as HttpWebRequest;
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
using (StreamReader sr = new StreamReader(response.GetResponseStream()))
{
return sr.ReadToEnd();
}
}
public String Expand(string url)
{
const string MATCH_PATTERN = @"""longUrl"": ?""(?<longUrl>.+)""";
var expandUrl = string.Format(EXPAND_URL_PATTERN, url);
var response = GetHTMLSourceCode(expandUrl);
return Regex.Match(response, MATCH_PATTERN).Groups["longUrl"].Value;
}
這邊有整理個較為完整的Class，有需要的直接取用。
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;
using System.Text.RegularExpressions;
namespace LevelUp.Google
{
public class GoogleUrlShortener
{
#region Const
const String BASE_API_URL = @"https://www.googleapis.com/urlshortener/v1/url";
const String SHORTENER_URL_PATTERN = BASE_API_URL + @"?key={0}";
const String EXPAND_URL_PATTERN = BASE_API_URL + @"?shortUrl={0}";
#endregion
#region Var
private String _apiKey;
#endregion
#region Private Property
private String m_APIKey
{
get
{
if (_apiKey == null)
return string.Empty;
return _apiKey;
}
set
{
_apiKey = value;
}
}
#endregion
#region Constructor
public GoogleUrlShortener(string apiKey)
{
if (string.IsNullOrEmpty(apiKey))
throw new ArgumentNullException("apiKey");
this.m_APIKey = apiKey;
}
#endregion
#region Private Method
private string GetHTMLSourceCode(string url)
{
HttpWebRequest request = (WebRequest.Create(url)) as HttpWebRequest;
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
using (StreamReader sr = new StreamReader(response.GetResponseStream()))
{
return sr.ReadToEnd();
}
}
#endregion
#region Public Method
public string Shorten(string url)
{
if (String.IsNullOrEmpty(url))
throw new ArgumentNullException("url");
if (m_APIKey.Length == 0)
throw new Exception("APIKey not set!");
const string POST_PATTERN = @"{{""longUrl"": ""{0}""}}";
const string MATCH_PATTERN = @"""id"": ?""(?<id>.+)""";
var post = string.Format(POST_PATTERN, url);
var request = (HttpWebRequest)WebRequest.Create(string.Format(SHORTENER_URL_PATTERN, m_APIKey));
request.Method = "POST";
request.ContentLength = post.Length;
request.ContentType = "application/json";
request.Headers.Add("Cache-Control", "no-cache");
using (Stream requestStream = request.GetRequestStream())
{
var buffer = Encoding.ASCII.GetBytes(post);
requestStream.Write(buffer, 0, buffer.Length);
}
using (var responseStream = request.GetResponse().GetResponseStream())
{
using (StreamReader sr = new StreamReader(responseStream))
{
return Regex.Match(sr.ReadToEnd(), MATCH_PATTERN).Groups["id"].Value;
}
}
return string.Empty;
}
public String Expand(string url)
{
const string MATCH_PATTERN = @"""longUrl"": ?""(?<longUrl>.+)""";
var expandUrl = string.Format(EXPAND_URL_PATTERN, url);
var response = GetHTMLSourceCode(expandUrl);
return Regex.Match(response, MATCH_PATTERN).Groups["longUrl"].Value;
}
#endregion
}
}