1. Basic Principles

Before you start doing it, you may be very interested in this, but at a loss. Is it complicated? Is it difficult to learn?

In fact, it’s just the opposite, it’s very simple. In order to dispel everyone's concerns, I first briefly introduce the basic principles of the WeChat public platform.

The WeChat server is equivalent to a forwarding server. The terminal (mobile phone, Pad, etc.) initiates a request to the WeChat server, and the WeChat server then forwards the request to the custom service (this is our specific implementation).

After the service is processed, it is then evaporated to the WeChat server, and the WeChat server then replies with a specific response to the terminal.

The communication protocol is: HTTP

The data format is: XML

The specific process is as shown in the figure below:

Basic principles of WeChat public platform development and message reception

# #Actually, what we need to do is respond to HTTP requests.

We will parse the specific request content according to the specific XML format. After processing, we will also return it according to the specific XML format.

We only need a simple implementation of HttpHandler.

Of course, the WeChat platform can also implement more complex businesses. For example, WeChat can be used as an embedded browser. We can open the htm interface through the WeChat link and then implement our own logic.

2. Message interface (official document)

Apply for message interface

Click to apply. Fill in the URL and token. The token can be filled in by the developer to generate a signature.

Website access

After the public platform user submits the information, the WeChat server will send a GET request to the filled-in URL with four parameters:

ParametersDescriptionsignatureWeChat encrypted signaturetimestampTimestampnonceRandom numberechostrRandom string

#Developers verify the request by checking the signature (the verification method is below). If it is confirmed that this GET request comes from the WeChat server, please return the echostr parameter content as it is, then the access will take effect, otherwise the access will fail.

signature combines the token parameter filled in by the developer with the timestamp parameter and nonce parameter in the request.

加密/校验流程：
1. 将token、timestamp、nonce三个参数进行字典序排序
2. 将三个参数字符串拼接成一个字符串进行sha1加密
3. 开发者获得加密后的字符串可与signature对比，标识该请求来源于微信

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Message push

When an ordinary WeChat user sends a message to a public account, the WeChat server will POST the message to the filled-in URL. The structure is as follows:

Text message

 <xml>
 <ToUserName><![CDATA[toUser]]></ToUserName>
 <FromUserName><![CDATA[fromUser]]></FromUserName> 
 <CreateTime>1348831860</CreateTime>
 <MsgType><![CDATA[text]]></MsgType>
 <Content><![CDATA[this is a test]]></Content>
 <MsgId>1234567890123456</MsgId>
 </xml>

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ParametersDescriptionToUserNameFromUserNameSender account (an OpenID)CreateTimeMessage creation time (integer)MsgTypetextContentText message contentMsgIdMessage id, 64-bit integer


	DeveloperWeChat ID

Picture Message

 <xml>
 <ToUserName><![CDATA[toUser]]></ToUserName>
 <FromUserName><![CDATA[fromUser]]></FromUserName>
 <CreateTime>1348831860</CreateTime>
 <MsgType><![CDATA[image]]></MsgType>
 <PicUrl><![CDATA[this is a url]]></PicUrl>
 <MsgId>1234567890123456</MsgId>
 </xml>

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ParametersDescriptionToUserName FromUserNameSender account (an OpenID)CreateTimeMessage creation time (integer)MsgTypeimage PicUrlPicture linkMsgIdMessage id, 64-bit integer


	DeveloperWeChat ID

Geolocation message

<xml>
<ToUserName><![CDATA[toUser]]></ToUserName>
<FromUserName><![CDATA[fromUser]]></FromUserName>
<CreateTime>1351776360</CreateTime>
<MsgType><![CDATA[location]]></MsgType>
<Location_X>23.134521</Location_X>
<Location_Y>113.358803</Location_Y>
<Scale>20</Scale>
<Label><![CDATA[位置信息]]></Label>
<MsgId>1234567890123456</MsgId>
</xml>

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ParametersDescriptionToUserNameFromUserNameSender account (an OpenID) CreateTimeMessage creation time (integer)MsgTypelocationLocation_XLocation latitudeLocation_YLocation longitudeScaleMap zoom size LabelGeographical location informationMsgIdMessage id, 64-bit integer

链接消息

<xml>
<ToUserName><![CDATA[toUser]]></ToUserName>
<FromUserName><![CDATA[fromUser]]></FromUserName>
<CreateTime>1351776360</CreateTime>
<MsgType><![CDATA[link]]></MsgType>
<Title><![CDATA[公众平台官网链接]]></Title>
<Description><![CDATA[公众平台官网链接]]></Description>
<Url><![CDATA[url]]></Url>
<MsgId>1234567890123456</MsgId>
</xml>

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	DeveloperWeChat ID

参数	描述
ToUserName	接收方微信号
FromUserName	发送方微信号，若为普通用户，则是一个OpenID
CreateTime	消息创建时间
MsgType	消息类型，link
Title	消息标题
Description	消息描述
Url	消息链接
MsgId	消息id，64位整型

事件推送

事件推送只支持微信4.5版本，目前开启自定义菜单接口事件推送、关注与取消关注事件推送。其余功能即将开放，敬请期待。

<xml><ToUserName><![CDATA[toUser]]></ToUserName>
<FromUserName><![CDATA[FromUser]]></FromUserName>
<CreateTime>123456789</CreateTime>
<MsgType><![CDATA[event]]></MsgType>
<Event><![CDATA[EVENT]]></Event>
<EventKey><![CDATA[EVENTKEY]]></EventKey>
</xml>

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参数	描述
ToUserName	接收方微信号
FromUserName	发送方微信号，若为普通用户，则是一个OpenID
CreateTime	消息创建时间
MsgType	消息类型，event
Event	事件类型，subscribe(订阅)、unsubscribe(取消订阅)、CLICK(自定义菜单点击事件)
EventKey	事件KEY值，与自定义菜单接口中KEY值对应

消息回复

对于每一个POST请求，开发者在响应包中返回特定xml结构，对该消息进行响应（现支持回复文本、图文、语音、视频、音乐）。

微信服务器在五秒内收不到响应会断掉连接。

回复xml结构如下：

回复文本消息

 <xml>
 <ToUserName><![CDATA[toUser]]></ToUserName>
 <FromUserName><![CDATA[fromUser]]></FromUserName>
 <CreateTime>12345678</CreateTime>
 <MsgType><![CDATA[text]]></MsgType>
 <Content><![CDATA[content]]></Content>
 </xml>

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参数	描述
ToUserName	接收方帐号（收到的OpenID）
FromUserName	开发者微信号
CreateTime	消息创建时间
MsgType	text
Content	回复的消息内容,长度不超过2048字节

回复音乐消息

 <xml>
 <ToUserName><![CDATA[toUser]]></ToUserName>
 <FromUserName><![CDATA[fromUser]]></FromUserName>
 <CreateTime>12345678</CreateTime>
 <MsgType><![CDATA[music]]></MsgType>
 <Music>
 <Title><![CDATA[TITLE]]></Title>
 <Description><![CDATA[DESCRIPTION]]></Description>
 <MusicUrl><![CDATA[MUSIC_Url]]></MusicUrl>
 <HQMusicUrl><![CDATA[HQ_MUSIC_Url]]></HQMusicUrl>
 </Music>
 </xml>

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参数	描述
ToUserName	接收方帐号（收到的OpenID）
FromUserName	开发者微信号
CreateTime	消息创建时间
MsgType	music
MusicUrl	音乐链接
HQMusicUrl	高质量音乐链接，WIFI环境优先使用该链接播放音乐

回复图文消息

 <xml>
 <ToUserName><![CDATA[toUser]]></ToUserName>
 <FromUserName><![CDATA[fromUser]]></FromUserName>
 <CreateTime>12345678</CreateTime>
 <MsgType><![CDATA[news]]></MsgType>
 <ArticleCount>2</ArticleCount>
 <Articles>
 <item>
 <Title><![CDATA[title1]]></Title> 
 <Description><![CDATA[description1]]></Description>
 <PicUrl><![CDATA[picurl]]></PicUrl>
 <Url><![CDATA[url]]></Url>
 </item>
 <item>
 <Title><![CDATA[title]]></Title>
 <Description><![CDATA[description]]></Description>
 <PicUrl><![CDATA[picurl]]></PicUrl>
 <Url><![CDATA[url]]></Url>
 </item>
 </Articles>
 </xml>

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参数	描述
ToUserName	接收方帐号（收到的OpenID）
FromUserName	开发者微信号
CreateTime	消息创建时间
MsgType	news
ArticleCount	图文消息个数，限制为10条以内
Articles	多条图文消息信息，默认第一个item为大图
Title	图文消息标题
Description	图文消息描述
PicUrl	图片链接，支持JPG、PNG格式，较好的效果为大图640320，小图8080。
Url	点击图文消息跳转链接