微信公众平台C#开发系列（四）：获取access token凭证

微信公众平台开发 C#如何获取到access token的简单例子

access_token是微信公众号的全局唯一接口调用凭据，公众号开发调用各接口时都需使用access_token。

此篇内容记录了调用access_token接口调用凭据的完整C#例子

官方接口API文档：

https://developers.weixin.qq.com/doc/offiaccount/Basic_Information/Get_access_token.html#

文档有请求说明返回结果是json格式的结果

///接口正常返回的结果
{
     "access_token":"ACCESS_TOKEN",
     "expires_in":7200
}

///接口请求错误是返回结果
{
      "errcode":40013,
      "errmsg":"invalid appid"
}

公共基类：因为所有接口的错误格式是通用的 所以定义一个公共错误实体类 （用于所有接口结果类用来作为基类继承）

namespace YuanTK.WeiXin.Wrapper
{
    /// <summary>
    /// 接口错误信息 接口基类
    /// </summary>
    public class ErrorMessage
    {
        /// <summary> 
        /// 错误码
        /// </summary>
        public int errcode { get; set; }
        /// <summary>
        /// 错误信息
        /// </summary>
        public string errmsg { get; set; }
    }
}

根据这个 AccessToken接口返回的 json字符串，定义AccessTokenResponse类 并继承自 ErrorMessage

namespace YuanTK.WeiXin.Wrapper
{
    /// <summary>
    /// 凭证接口输出结果
    /// </summary>
    public class AccessTokenResponse: ErrorMessage
    {
        /// <summary>
        /// 获取到的凭证
        /// </summary>
        public string access_token { get; set; }

        /// <summary>
        /// 凭证有效时间，单位：秒
        /// </summary>
        public string expires_in { get; set; }
    }
}

定义一个IWeiXin 泛型接口类 泛型约束ErrorMessage

namespace YuanTK.WeiXin
{
    /// <summary>
    /// 定义微信通用接口
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public interface IWeiXin<T>where T: ErrorMessage
    {
        /// <summary>
        /// 输出结果
        /// </summary>
        /// <returns></returns>
        T GetResponse();
    }
}

创建WeiXinRequest 接口请求公共方法类 泛型约束 ErrorMessage

namespace YuanTK.WeiXin.Common
{
    /// <summary>
    /// 微信接口请求方法
    /// </summary>
    public class WeiXinRequest<T> where T : ErrorMessage
    {
        /// <summary>
        /// Get请求
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="url"></param>
        /// <returns></returns>
        public T Get(string url)
        {
            HttpWebRequest ApiRequest = (HttpWebRequest)WebRequest.Create(url);
            ApiRequest.Method = "GET";//post方式
            ApiRequest.Accept = "text/html, application/xhtml+xml, */*";
            ApiRequest.ContentType = "application/x-www-form-urlencoded";
            HttpWebResponse response = (HttpWebResponse)ApiRequest.GetResponse();
            T TResponse = default(T);
            using (StreamReader reader = new StreamReader(response.GetResponseStream(), System.Text.Encoding.UTF8))
            {
                string jsonStr = reader.ReadToEnd();
                TResponse = Newtonsoft.Json.JsonConvert.DeserializeObject<T>(jsonStr);
            }
            return TResponse;
        }

        /// <summary>
        /// POST请求
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="url"></param>
        /// <param name="poststr"></param>
        /// <returns></returns>
        public T Post(string url, string poststr)
        {
            HttpWebRequest ApiRequest = (HttpWebRequest)WebRequest.Create(url);
            ApiRequest.Method = "POST";//post方式
            ApiRequest.Accept = "text/html, application/xhtml+xml, */*";
            ApiRequest.ContentType = "application/x-www-form-urlencoded";
            if (!string.IsNullOrEmpty(poststr))
            {
                byte[] buffer = Encoding.UTF8.GetBytes(poststr);
                ApiRequest.ContentLength = buffer.Length;
                ApiRequest.GetRequestStream().Write(buffer, 0, buffer.Length);
            }
            HttpWebResponse response = (HttpWebResponse)ApiRequest.GetResponse();
            T TResponse = default(T);
            using (StreamReader reader = new StreamReader(response.GetResponseStream(), System.Text.Encoding.UTF8))
            {
                string jsonStr = reader.ReadToEnd();
                TResponse = Newtonsoft.Json.JsonConvert.DeserializeObject<T>(jsonStr);
            }
            return TResponse;
        }
    }
}

基本的公共类或方法类 准备好了 再定义一个AccessToken类方法继承自 WeiXinRequest 并绑定接口 IWeiXin

namespace YuanTK.WeiXin
{
    /// <summary>
    /// AccessToken接口
    /// </summary>
    public class AccessToken : WeiXinRequest<AccessTokenResponse>,IWeiXin<AccessTokenResponse>
    {
        String api;
        public AccessToken(string appid, string secret)
        {
            api = $"https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid={appid}&secret={secret}";
        }

        /// <summary>
        /// 调用接口获取结果
        /// </summary>
        /// <returns></returns>
        public AccessTokenResponse GetResponse()
        {
            return this.Get(api);
        }
    }
}

微信公众号接口调用access_token凭据使用例子

 //微信公众号平台分配的appid
 string appid = "wx*3dc7*************";
  //微信公众号平台分配的appid
 string secret = "***bca72d5bbb***********";
 //初始化接口方法
 IWeiXin<AccessTokenResponse> api = new AccessToken(appid, secret);
 //调用接口并输出结果
 AccessTokenResponse token = api.GetResponse();

获取成功效果图