.NET微信公众号开发之公众号消息处理

一.前言

  微信公众平台的消息处理还是比较完善的，有最基本的文本消息，到图文消息，到图片消息，语音消息，视频消息，音乐消息其基本原理都是一样的，只不过所post的xml数据有所差别，在处理消息之前，我们要认真阅读，官方给我们的文档：。首先我们从最基本的文本消息处理开始。

<xml>
<tousername><![cdata[touser]]></tousername>
<fromusername><![cdata[fromuser]]></fromusername>
<createtime>12345678</createtime>
<msgtype><![cdata[text]]></msgtype>
<content><![cdata[你好]]></content>
</xml>

  我们可以看到这是消息处理的一个最基本的模式，有发送者，接受者，创建时间，类型，内容等等。

首先我们来创建一个消息处理的类，这个类用来捕获，所有的消息请求，根据不同的消息请求类型来处理不同的消息回复。

public class weixinservice
  {
    /// <summary>
    /// token
    /// </summary>
    private const string token = "finder";
    /// <summary>
    /// 签名
    /// </summary>
    private const string signature = "signature";
    /// <summary>
    /// 时间戳
    /// </summary>
    private const string timestamp = "timestamp";
    /// <summary>
    /// 随机数
    /// </summary>
    private const string nonce = "nonce";
    /// <summary>
    /// 随机字符串
    /// </summary>
    private const string echostr = "echostr";
    /// <summary>
    /// 
    /// </summary>
    private httprequest request { get; set; }
    /// <summary>
    /// 构造函数
    /// </summary>
    /// <param name="request"></param>
    public weixinservice(httprequest request)
    {
      this.request = request;
    }
    /// <summary>
    /// 处理请求，产生响应
    /// </summary>
    /// <returns></returns>
    public string response()
    {
      string method = request.httpmethod.toupper();
      //验证签名
      if (method == "get")
      {
        if (checksignature())
        {
          return request.querystring[echostr];
        }
        else
        {
          return "error";
        }
      }

      //处理消息
      if (method == "post")
      {
        return responsemsg();
      }
      else
      {
        return "无法处理";
      }
    }

    /// <summary>
    /// 处理请求
    /// </summary>
    /// <returns></returns>
    private string responsemsg()
    {
      string requestxml = commonweixin.readrequest(this.request);
      ihandler handler = handlerfactory.createhandler(requestxml);
   
      if (handler != null)
      {
        return handler.handlerequest();
      }

      return string.empty;
    }
    /// <summary>
    /// 检查签名
    /// </summary>
    /// <param name="request"></param>
    /// <returns></returns>
    private bool checksignature()
    {
      string signature = request.querystring[signature];
      string timestamp = request.querystring[timestamp];
      string nonce = request.querystring[nonce];

      list<string> list = new list<string>();
      list.add(token);
      list.add(timestamp);
      list.add(nonce);
      //排序
      list.sort();
      //拼串
      string input = string.empty;
      foreach (var item in list)
      {
        input += item;
      }
      //加密
      string new_signature = securityutility.sha1encrypt(input);
      //验证
      if (new_signature == signature)
      {
        return true;
      }
      else
      {
        return false;
      }
    }
  }

在来看看我们的首先是如何捕获消息的。首页default.ashx的代码如下

    public void processrequest(httpcontext context)
    {
      context.response.contenttype = "text/html";
      

      string poststring = string.empty;
      if (httpcontext.current.request.httpmethod.toupper() == "post")
      {
        //由微信服务接收请求，具体处理请求
        weixinservice wxservice = new weixinservice(context.request);
        string responsemsg = wxservice.response();
        context.response.clear();
        context.response.charset = "utf-8";
        context.response.write(responsemsg);
        context.response.end();
      }
      else
      {
        string token = "wei2414201";
        if (string.isnullorempty(token))
        {
          return;
        }

        string echostring = httpcontext.current.request.querystring["echostr"];
        string signature = httpcontext.current.request.querystring["signature"];
        string timestamp = httpcontext.current.request.querystring["timestamp"];
        string nonce = httpcontext.current.request.querystring["nonce"];

        if (!string.isnullorempty(echostring))
        {
          httpcontext.current.response.write(echostring);
          httpcontext.current.response.end();
        }
      }


    }

从上面的代码中我们可以看到weixinservice.cs类中的消息相应至关重要。

    /// <summary>
    /// 处理请求
    /// </summary>
    /// <returns></returns>
    private string responsemsg()
    {
      string requestxml = commonweixin.readrequest(this.request);
      ihandler handler = handlerfactory.createhandler(requestxml);
   
      if (handler != null)
      {
        return handler.handlerequest();
      }

      return string.empty;
    }

ihandler是一个消息处理接口，其下面有eventhandler，texthandler处理类实现这个接口。代码如下

  /// <summary>
  /// 处理接口
  /// </summary>
  public interface ihandler
  {
    /// <summary>
    /// 处理请求
    /// </summary>
    /// <returns></returns>
    string handlerequest();
  }

eventhandler

class eventhandler : ihandler
  {
    /// <summary>
    /// 请求的xml
    /// </summary>
    private string requestxml { get; set; }
    /// <summary>
    /// 构造函数
    /// </summary>
    /// <param name="requestxml"></param>
    public eventhandler(string requestxml)
    {
      this.requestxml = requestxml;
    }
    /// <summary>
    /// 处理请求
    /// </summary>
    /// <returns></returns>
    public string handlerequest()
    {
      string response = string.empty;
      eventmessage em = eventmessage.loadfromxml(requestxml);
      if (em.event.equals("subscribe", stringcomparison.ordinalignorecase))//用来判断是不是首次关注
      {


        pictextmessage tm = new pictextmessage();//我自己创建的一个图文消息处理类
        tm.tousername = em.fromusername;
        tm.fromusername = em.tousername;
        tm.createtime = commonweixin.getnowtime();
        response = tm.generatecontent();

      }

      return response;
    }
  }

texthandler

  /// <summary>
  /// 文本信息处理类
  /// </summary>
  public class texthandler : ihandler
  {
    string openid { get; set; }
    string access_token { get; set; }

    /// <summary>
    /// 请求的xml
    /// </summary>
    private string requestxml { get; set; }
    /// <summary>
    /// 构造函数
    /// </summary>
    /// <param name="requestxml">请求的xml</param>
    public texthandler(string requestxml)
    {
      this.requestxml = requestxml;
    }
    /// <summary>
    /// 处理请求
    /// </summary>
    /// <returns></returns>
    public string handlerequest()
    {
      string response = string.empty;
      textmessage tm = textmessage.loadfromxml(requestxml);
      string content = tm.content.trim();
      if (string.isnullorempty(content))
      {
        response = "您什么都没输入，没法帮您啊。";
      }
      else
      {
          string username = system.configuration.configurationmanager.appsettings["weixinid"].tostring();
          accesstoken token = accesstoken.get(username);
          access_token = token.access_token;
          openid = tm.fromusername;
          response = handleother(content);
        
      }
      tm.content = response;
      //进行发送者、接收者转换
      string temp = tm.tousername;
      tm.tousername = tm.fromusername;
      tm.fromusername = temp;
      response = tm.generatecontent();
      return response;
    }
    /// <summary>
    /// 处理其他消息
    /// </summary>
    /// <param name="tm"></param>
    /// <returns></returns>
    private string handleother(string requestcontent)
    {
      string response = string.empty;
      if (requestcontent.contains("你好") || requestcontent.contains("您好"))
      {
        response = "您也好~";
      }else if (requestcontent.contains("openid") || requestcontent.contains("id") || requestcontent.contains("id"))//用来匹配用户输入的关键字
      {
        response = "你的openid: "+openid;
      }
      else if (requestcontent.contains("token") || requestcontent.contains("access_token"))
      {
        response = "你的access_token: " + access_token;
      }else 
      {
        response = "试试其他关键字吧。";
      }
      return response;
    }
  }

handlerfactory

  /// <summary>
  /// 处理器工厂类
  /// </summary>
  public class handlerfactory
  {
    /// <summary>
    /// 创建处理器
    /// </summary>
    /// <param name="requestxml">请求的xml</param>
    /// <returns>ihandler对象</returns>
    public static ihandler createhandler(string requestxml)
    {
      ihandler handler = null;
      if (!string.isnullorempty(requestxml))
      {
        //解析数据
        xmldocument doc = new system.xml.xmldocument();
        doc.loadxml(requestxml);
        xmlnode node = doc.selectsinglenode("/xml/msgtype");
        if (node != null)
        {
          xmlcdatasection section = node.firstchild as xmlcdatasection;
          if (section != null)
          {
            string msgtype = section.value;

            switch (msgtype)
            {
              case "text":
                handler = new texthandler(requestxml);
                break;
              case "event":
                handler = new eventhandler(requestxml);
                break;
            }
          }
        }
      }

      return handler;
    }
  }

 在这里基本的一些类已经完成了，现在我们来完成，关注我们的微信公众号，我们就发送一条图文消息，同时输入我们的一些关键字，返回一些消息，比如输入id返回用户的openid等等。

二.pictextmessage

public class pictextmessage : message
  {
    /// <summary>
    /// 模板静态字段
    /// </summary>
    private static string m_template;

    /// <summary>
    /// 默认构造函数
    /// </summary>
    public pictextmessage()
    {
      this.msgtype = "news";
    }
    /// <summary>
    /// 从xml数据加载文本消息
    /// </summary>
    /// <param name="xml"></param>
    public static pictextmessage loadfromxml(string xml)
    {
      pictextmessage tm = null;
      if (!string.isnullorempty(xml))
      {
        xelement element = xelement.parse(xml);
        if (element != null)
        {
          tm = new pictextmessage();
          tm.fromusername = element.element(commonweixin.from_username).value;
          tm.tousername = element.element(commonweixin.to_username).value;
          tm.createtime = element.element(commonweixin.create_time).value;
        }
      }

      return tm;
    }
    /// <summary>
    /// 模板
    /// </summary>
    public override string template
    {
      get
      {
        if (string.isnullorempty(m_template))
        {
          loadtemplate();
        }

        return m_template;
      }
    }
    /// <summary>
    /// 生成内容
    /// </summary>
    /// <returns></returns>
    public override string generatecontent()
    {
      this.createtime = commonweixin.getnowtime();
      string str= string.format(this.template, this.tousername, this.fromusername, this.createtime);
      return str;
    }


    /// <summary>
    /// 加载模板
    /// </summary>
    private static void loadtemplate()
    {
      m_template= @"<xml>
              <tousername><![cdata[{0}]]></tousername>
              <fromusername><![cdata[{1}]]></fromusername>
              <createtime>{2}</createtime>
              <msgtype><![cdata[news]]></msgtype>
              <articlecount>1</articlecount>
              <articles>
                <item>
                <title><![cdata[有位停车欢迎你！]]></title> 
                <description><![cdata[如有问题请致电400-6238-136或直接在微信留言，我们将第一时间为您服务!]]></description>
                <picurl><![cdata[http://www.baidu.com/youwei.jpg]]></picurl>
                <url><![cdata[http://www.baidu.com]]></url>
                </item>
              </articles>
            </xml> ";
    }
  }

最后我们的效果如下所示；

以上所述就是本文的全部内容了，希望大家能够喜欢