微信公共平台开发-（.net实现）5--access

每次在于微信交互时，都要用到access_token，但是这个值限制的是有时间的，但是access_token，在以后的高级功能里面会经常用到，所以这里不得不这里对前面所讲解的access_token改造一下。 另外需要说明的是access_token是变化的,有自己的周期,官方解释为:"

  　　每次在于微信交互时，都要用到access_token，但是这个值限制的是有时间的，但是access_token，在以后的高级功能里面会经常用到，所以这里不得不这里对前面所讲解的access_token改造一下。
　　　另外需要说明的是access_token是变化的,有自己的周期,官方解释为:"有效期为7200秒",这就要求我们把获得的access_token存入一个物理文件或者Application中,请求到过期后修改这些内容,需要用的时候读出来.或者是存入数据库，到期时修改改access_token的值。
　　　有些人可能想到了，如果过期我就在获得一个就好了,不用物理文件和Application也可以达到同样的效果,但是需要注意了微信平台对每天获得，access_token的次数也作了限制，一个用户出发多次，如果用户多，那肯定就超出了。所以我们还是按照以上的思路实现这些功能:
　　  在此之前我们已经了解了获得access_token的方法(连接)http://www.cnblogs.com/QLJ1314/p/3838058.html,现在只需要保证它的随时更新就好了.

      首先建立一个Access_token类

　　

<span> 1</span>     <span>///</span> <span><summary></summary></span>  
<span> 2</span>     <span>///</span><span>Access_token 的摘要说明  
</span><span> 3</span>     <span>///</span> <span></span>  
<span> 4</span>     <span>public</span> <span>class</span><span> Access_token  
</span><span> 5</span> <span>    {  
</span><span> 6</span>         <span>public</span><span> Access_token()  
</span><span> 7</span> <span>        {  
</span><span> 8</span>             <span>//</span>  
<span> 9</span>             <span>//</span><span>TODO: 在此处添加构造函数逻辑  
</span><span>10</span>             <span>//</span>  
<span>11</span> <span>        }  
</span><span>12</span>         <span>string</span><span> _access_token;  
</span><span>13</span>         <span>string</span><span> _expires_in;  
</span><span>14</span>       
<span>15</span>         <span>///</span> <span><summary></summary></span>  
<span>16</span>         <span>///</span><span> 获取到的凭证   
</span><span>17</span>         <span>///</span> <span></span>  
<span>18</span>         <span>public</span> <span>string</span><span> access_token  
</span><span>19</span> <span>        {  
</span><span>20</span>             <span>get</span> { <span>return</span><span> _access_token; }  
</span><span>21</span>             <span>set</span> { _access_token =<span> value; }  
</span><span>22</span> <span>        }  
</span><span>23</span>       
<span>24</span>         <span>///</span> <span><summary></summary></span>  
<span>25</span>         <span>///</span><span> 凭证有效时间，单位：秒  
</span><span>26</span>         <span>///</span> <span></span>  
<span>27</span>         <span>public</span> <span>string</span><span> expires_in  
</span><span>28</span> <span>        {  
</span><span>29</span>             <span>get</span> { <span>return</span><span> _expires_in; }  
</span><span>30</span>             <span>set</span> { _expires_in =<span> value; }  
</span><span>31</span> <span>        }  
</span><span>32</span>     }  

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<span>1</span>     <?xml version=<span>"<span>1.0</span><span>"</span> encoding=<span>"</span><span>utf-8</span><span>"</span>?>  
<span>2</span>     <xml>  
<span>3</span>       <access_token>初始值可以随便写</access_token>  
<span>4</span>       <access_youxrq><span>1990</span>/<span>12</span>/<span>12</span> <span>16</span>:<span>06</span>:<span>38</span></access_youxrq>  
<span>5</span>     </xml>  

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之前获得Access_token的方法改造一下，让他给Access_token实例赋值

<span> 1</span>     <span>public</span> <span>static</span><span> Access_token GetAccess_token()  
</span><span> 2</span> <span>        {  
</span><span> 3</span>             <span>string</span> appid =<span> 你的appid ;  
</span><span> 4</span>             <span>string</span> secret =<span> 你的secret;  
</span><span> 5</span>             <span>string</span> strUrl = <span>"</span><span>https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=</span><span>"</span> + appid + <span>"</span><span>&secret=</span><span>"</span> +<span> secret;  
</span><span> 6</span>             Access_token mode = <span>new</span><span> Access_token();  
</span><span> 7</span>       
<span> 8</span>             HttpWebRequest req =<span> (HttpWebRequest)HttpWebRequest.Create(strUrl);  
</span><span> 9</span>       
<span>10</span>             req.Method = <span>"</span><span>GET</span><span>"</span><span>;  
</span><span>11</span>             <span>using</span> (WebResponse wr =<span> req.GetResponse())  
</span><span>12</span> <span>            {  
</span><span>13</span>                 HttpWebResponse myResponse =<span> (HttpWebResponse)req.GetResponse();  
</span><span>14</span>       
<span>15</span>                 StreamReader reader = <span>new</span><span> StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);  
</span><span>16</span>       
<span>17</span>                 <span>string</span> content =<span> reader.ReadToEnd();  
</span><span>18</span>                 <span>//</span><span>Response.Write(content);  
</span><span>19</span>                 <span>//</span><span>在这里对Access_token 赋值  </span>
<span>20</span>                 Access_token token = <span>new</span><span> Access_token();  
</span><span>21</span>                 token = JsonHelper.ParseFromJson<access_token><span>(content);  
</span><span>22</span>                 mode.access_token =<span> token.access_token;  
</span><span>23</span>                 mode.expires_in =<span> token.expires_in;  
</span><span>24</span> <span>            }  
</span><span>25</span>             <span>return</span><span> mode;  
</span><span>26</span>         }  </access_token>

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以上的方法用到了Json对象的处理，所以我把JsonHelper的代码一贴出来供大家参考，一下就是JsonHelper.cs的代码：

<span> 1</span>     <span>using</span><span> System;  
</span><span> 2</span>     <span>using</span><span> System.IO;  
</span><span> 3</span>     <span>using</span><span> System.Text;  
</span><span> 4</span>     <span>using</span><span> System.Runtime.Serialization.Json;  
</span><span> 5</span>        
<span> 6</span>        
<span> 7</span>       
<span> 8</span>     <span>public</span> <span>class</span><span> JsonHelper  
</span><span> 9</span> <span>    {  
</span><span>10</span>         <span>///</span> <span><summary></summary></span>  
<span>11</span>         <span>///</span><span> 生成Json格式  
</span><span>12</span>         <span>///</span> <span></span>  
<span>13</span>         <span>///</span> <span><typeparam name="T"></typeparam></span>  
<span>14</span>         <span>///</span> <span><param name="obj"></span>  
<span>15</span>         <span>///</span> <span><returns></returns></span>  
<span>16</span>         <span>public</span> <span>static</span> <span>string</span> GetJson<t><span>(T obj)  
</span><span>17</span> <span>        {  
</span><span>18</span>             DataContractJsonSerializer json = <span>new</span><span> DataContractJsonSerializer(obj.GetType());  
</span><span>19</span>             <span>using</span> (MemoryStream stream = <span>new</span><span> MemoryStream())  
</span><span>20</span> <span>            {  
</span><span>21</span> <span>                json.WriteObject(stream, obj);  
</span><span>22</span>                 <span>string</span> szJson = Encoding.UTF8.GetString(stream.ToArray()); <span>return</span><span> szJson;  
</span><span>23</span> <span>            }  
</span><span>24</span> <span>        }  
</span><span>25</span>         <span>///</span> <span><summary></summary></span>  
<span>26</span>         <span>///</span><span> 获取Json的Model  
</span><span>27</span>         <span>///</span> <span></span>  
<span>28</span>         <span>///</span> <span><typeparam name="T"></typeparam></span>  
<span>29</span>         <span>///</span> <span><param name="szJson"></span>  
<span>30</span>         <span>///</span> <span><returns></returns></span>  
<span>31</span>         <span>public</span> <span>static</span> T ParseFromJson<t>(<span>string</span><span> szJson)  
</span><span>32</span> <span>        {  
</span><span>33</span>             T obj = Activator.CreateInstance<t><span>();  
</span><span>34</span>             <span>using</span> (MemoryStream ms = <span>new</span><span> MemoryStream(Encoding.UTF8.GetBytes(szJson)))  
</span><span>35</span> <span>            {  
</span><span>36</span>                 DataContractJsonSerializer serializer = <span>new</span><span> DataContractJsonSerializer(obj.GetType());  
</span><span>37</span>                 <span>return</span><span> (T)serializer.ReadObject(ms);  
</span><span>38</span> <span>            }  
</span><span>39</span> <span>        }  
</span><span>40</span>     }  </t></t></t>

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其实还可以直接饮用Newtonsoft.Json.dll 可以直接操作json,这样更方便一些。

我们还需要写一个判断access_token是否过期如果过期更新XML文件的方法。

<span> 1</span>     <span>///</span> <span><summary></summary></span>  
<span> 2</span>         <span>///</span><span> 根据当前日期 判断Access_Token 是否超期  如果超期返回新的Access_Token   否则返回之前的Access_Token  
</span><span> 3</span>         <span>///</span> <span></span>  
<span> 4</span>         <span>///</span> <span><param name="datetime"></span>  
<span> 5</span>         <span>///</span> <span><returns></returns></span>  
<span> 6</span>         <span>public</span> <span>static</span> <span>string</span><span> IsExistAccess_Token()  
</span><span> 7</span> <span>        {  
</span><span> 8</span>       
<span> 9</span>             <span>string</span> Token = <span>string</span><span>.Empty;  
</span><span>10</span> <span>            DateTime YouXRQ;  
</span><span>11</span>             <span>//</span><span> 读取XML文件中的数据，并显示出来 ，注意文件路径  </span>
<span>12</span>             <span>string</span> filepath = Server.MapPath(<span>"</span><span>XMLFile.xml</span><span>"</span><span>);  
</span><span>13</span>       
<span>14</span>             StreamReader str = <span>new</span><span> StreamReader(filepath, System.Text.Encoding.UTF8);  
</span><span>15</span>             XmlDocument xml = <span>new</span><span> XmlDocument();  
</span><span>16</span> <span>            xml.Load(str);  
</span><span>17</span> <span>            str.Close();  
</span><span>18</span> <span>            str.Dispose();  
</span><span>19</span>             Token = xml.SelectSingleNode(<span>"</span><span>xml</span><span>"</span>).SelectSingleNode(<span>"</span><span>Access_Token</span><span>"</span><span>).InnerText;  
</span><span>20</span>             YouXRQ = Convert.ToDateTime(xml.SelectSingleNode(<span>"</span><span>xml</span><span>"</span>).SelectSingleNode(<span>"</span><span>Access_YouXRQ</span><span>"</span><span>).InnerText);  
</span><span>21</span>       
<span>22</span>             <span>if</span> (DateTime.Now ><span> YouXRQ)  
</span><span>23</span> <span>            {  
</span><span>24</span>                 DateTime _youxrq =<span> DateTime.Now;  
</span><span>25</span>                 Access_token mode =<span> GetAccess_token();  
</span><span>26</span>                 xml.SelectSingleNode(<span>"</span><span>xml</span><span>"</span>).SelectSingleNode(<span>"</span><span>Access_Token</span><span>"</span>).InnerText =<span> mode.access_token;  
</span><span>27</span>                 _youxrq = _youxrq.AddSeconds(<span>int</span><span>.Parse(mode.expires_in));  
</span><span>28</span>                 xml.SelectSingleNode(<span>"</span><span>xml</span><span>"</span>).SelectSingleNode(<span>"</span><span>Access_YouXRQ</span><span>"</span>).InnerText =<span> _youxrq.ToString();  
</span><span>29</span> <span>                xml.Save(filepath);  
</span><span>30</span>                 Token =<span> mode.access_token;  
</span><span>31</span> <span>            }  
</span><span>32</span>             <span>return</span><span> Token;  
</span><span>33</span>         }  

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好了，完成了上面的工作，我只需要在使用到access_token的时调用如下就OK了，“客户再也不用担心token的过期”
string _access_token = IsExistAccess_Token();