asp.net mvc 5 微信接入VB版 - 获取AccessToken

获取AccessToken是微信接入的又一个基础操作。很多微信接口需要这个2小时一刷新的AccessToken作为参数。

转载请说明作者Nukepayload2

首先根据开发文档把获取AccessToken需要Get的那个链接拼凑出来。

Const AccessToken = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=" & AppId & "&secret=" & Secret

注意这里不要使用字符串内插，因为那个不能给常量表达式用。

文档上写着返回的是Json，那就把Newtonsoft.Json装上。

然后写这个函数放到某个模块里面备用。

Public Async Function GetJsonPopulateObjectAsync(url As String, obj As Object) As Task
Dim httpClient As New HttpClient
httpClient.DefaultRequestHeaders.Accept.Add(New MediaTypeWithQualityHeaderValue("application/json"))
Dim response = Await httpClient.GetAsync(url)
If response.IsSuccessStatusCode Then
Dim str = Await response.Content.ReadAsStringAsync()
JsonConvert.PopulateObject(str, obj)
End If
End Function

接下来就是写获取数据了。AccessToken适合单实例的对象，那么我们新建模块。

用一个嵌套的类把需要反序列化的数据描述一下，并且初始化。

这里注意一下，Await是不能在SyncLock里面用的，所以要利用Monitor。

Imports System.Threading
Imports System.Threading.Tasks

Module AccessToken
Dim dat As New Data

Sub New()
CreateTime = Date.Now
End Sub
Public Async Function GetValueAsync() As Task(Of String)
Try
Monitor.Enter(dat)
If IsExpiredOrEmpty Then
Await GetJsonFillObjectAsync(WeChatGlobalValues.AccessToken, dat)
_CreateTime = Date.Now
WeChatException.Assert(dat.errcode)
End If
Return dat.access_token
Finally
Monitor.Exit(dat)
End Try
End Function
Public ReadOnly Property CreateTime As Date
Public ReadOnly Property IsExpiredOrEmpty As Boolean
Get
Return Date.Now >= CreateTime.AddSeconds(dat.expires_in)
End Get
End Property
Private Class Data
Public Property access_token$
Public Property expires_in% = -1
Public Property errcode%
Public Property errmsg$
End Class
End Module

如果出错，微信会产生错误码。根据错误码表编写异常类

Public Class WeChatException
Inherits Exception
Public ReadOnly Property ErrorCode%
Sub New()
MyBase.New("调用微信服务时发生异常")
End Sub
Sub New(ErrorCode%)
MyBase.New(ErrorMap(ErrorCode))
_ErrorCode = ErrorCode
End Sub
''' <summary>
''' 断言这个错误码并不代表出错。如果断言失败则抛出异常。
''' </summary>
''' <param name="ErrorCode%">错误码</param>
Public Shared Sub Assert(ErrorCode%)
If ErrorCode <> 0 Then Throw New WeChatException(ErrorCode)
End Sub
Shared ErrorMap As New Dictionary(Of Integer, String) From {
{-1, "系统繁忙，此时请开发者稍候再试"},
{0, "请求成功"},
{40001, "获取access_token时AppSecret错误，或者access_token无效。请开发者认真比对AppSecret的正确性，或查看是否正在为恰当的公众号调用接口"},
{40002, "不合法的凭证类型"},
{40003, "不合法的OpenID，请开发者确认OpenID（该用户）是否已关注公众号，或是否是其他公众号的OpenID"},
{40004, "不合法的媒体文件类型"},
{40005, "不合法的文件类型"},
{40006, "不合法的文件大小"},
{40007, "不合法的媒体文件id"},
{40008, "不合法的消息类型"},
{40009, "不合法的图片文件大小"},
{40010, "不合法的语音文件大小"},
{40011, "不合法的视频文件大小"},
{40012, "不合法的缩略图文件大小"},
{40013, "不合法的AppID，请开发者检查AppID的正确性，避免异常字符，注意大小写"},
{40014, "不合法的access_token，请开发者认真比对access_token的有效性（如是否过期），或查看是否正在为恰当的公众号调用接口"},
{40015, "不合法的菜单类型"},
{40016, "不合法的按钮个数"},
{40017, "不合法的按钮个数"},
{40018, "不合法的按钮名字长度"},
{40019, "不合法的按钮KEY长度"},
{40020, "不合法的按钮URL长度"},
{40021, "不合法的菜单版本号"},
{40022, "不合法的子菜单级数"},
{40023, "不合法的子菜单按钮个数"},
{40024, "不合法的子菜单按钮类型"},
{40025, "不合法的子菜单按钮名字长度"},
{40026, "不合法的子菜单按钮KEY长度"},
{40027, "不合法的子菜单按钮URL长度"},
{40028, "不合法的自定义菜单使用用户"},
{40029, "不合法的oauth_code"},
{40030, "不合法的refresh_token"},
{40031, "不合法的openid列表"},
{40032, "不合法的openid列表长度"},
{40033, "不合法的请求字符，不能包含\uxxxx格式的字符"},
{40035, "不合法的参数"},
{40038, "不合法的请求格式"},
{40039, "不合法的URL长度"},
{40050, "不合法的分组id"},
{40051, "分组名字不合法"},
{40117, "分组名字不合法"},
{40118, "media_id大小不合法"},
{40119, "button类型错误"},
{40120, "button类型错误"},
{40121, "不合法的media_id类型"},
{40132, "微信号不合法"},
{40137, "不支持的图片格式"},
{41001, "缺少access_token参数"},
{41002, "缺少appid参数"},
{41003, "缺少refresh_token参数"},
{41004, "缺少secret参数"},
{41005, "缺少多媒体文件数据"},
{41006, "缺少media_id参数"},
{41007, "缺少子菜单数据"},
{41008, "缺少oauth code"},
{41009, "缺少openid"},
{42001, "access_token超时，请检查access_token的有效期，请参考基础支持-获取access_token中，对access_token的详细机制说明"},
{42002, "refresh_token超时"},
{42003, "oauth_code超时"},
{43001, "需要GET请求"},
{43002, "需要POST请求"},
{43003, "需要HTTPS请求"},
{43004, "需要接收者关注"},
{43005, "需要好友关系"},
{44001, "多媒体文件为空"},
{44002, "POST的数据包为空"},
{44003, "图文消息内容为空"},
{44004, "文本消息内容为空"},
{45001, "多媒体文件大小超过限制"},
{45002, "消息内容超过限制"},
{45003, "标题字段超过限制"},
{45004, "描述字段超过限制"},
{45005, "链接字段超过限制"},
{45006, "图片链接字段超过限制"},
{45007, "语音播放时间超过限制"},
{45008, "图文消息超过限制"},
{45009, "接口调用超过限制"},
{45010, "创建菜单个数超过限制"},
{45015, "回复时间超过限制"},
{45016, "系统分组，不允许修改"},
{45017, "分组名字过长"},
{45018, "分组数量超过上限"},
{46001, "不存在媒体数据"},
{46002, "不存在的菜单版本"},
{46003, "不存在的菜单数据"},
{46004, "不存在的用户"},
{47001, "解析JSON/XML内容错误"},
{48001, "api功能未授权，请确认公众号已获得该接口，可以在公众平台官网-开发者中心页中查看接口权限"},
{50001, "用户未授权该api"},
{50002, "用户受限，可能是违规后接口被封禁"},
{61451, "参数错误(invalid parameter)"},
{61452, "无效客服账号(invalid kf_account)"},
{61453, "客服帐号已存在(kf_account exsited)"},
{61454, "客服帐号名长度超过限制(仅允许10个英文字符，不包括@及@后的公众号的微信号)(invalid kf_acount length)"},
{61455, "客服帐号名包含非法字符(仅允许英文+数字)(illegal character in kf_account)"},
{61456, "客服帐号个数超过限制(10个客服账号)(kf_account count exceeded)"},
{61457, "无效头像文件类型(invalid file type)"},
{61450, "系统错误(system error)"},
{61500, "日期格式错误"},
{61501, "日期范围错误"},
{9001001, "POST数据参数不合法"},
{9001002, "远端服务不可用"},
{9001003, "Ticket不合法"},
{9001004, "获取摇周边用户信息失败"},
{9001005, "获取商户信息失败"},
{9001006, "获取OpenID失败"},
{9001007, "上传文件缺失"},
{9001008, "上传素材的文件类型不合法"},
{9001009, "上传素材的文件尺寸不合法"},
{9001010, "上传失败"},
{9001020, "帐号不合法"},
{9001021, "已有设备激活率低于50%，不能新增设备"},
{9001022, "设备申请数不合法，必须为大于0的数字"},
{9001023, "已存在审核中的设备ID申请"},
{9001024, "一次查询设备ID数量不能超过50"},
{9001025, "设备ID不合法"},
{9001026, "页面ID不合法"},
{9001027, "页面参数不合法"},
{9001028, "一次删除页面ID数量不能超过10"},
{9001029, "页面已应用在设备中，请先解除应用关系再删除"},
{9001030, "一次查询页面ID数量不能超过50"},
{9001031, "时间区间不合法"},
{9001032, "保存设备与页面的绑定关系参数错误"},
{9001033, "门店ID不合法"},
{9001034, "设备备注信息过长"},
{9001035, "设备申请参数不合法"},
{9001036, "查询起始值begin不合法"}
}
End Class