WeChat development: processing messages sent by WeChat client

In the previous blog post about WeChat development (How to become a developer in WeChat Development (01)), we turned on the WeChat developer mode. In this blog post, we simply process the messages sent to our public account by WeChat followers.

When turning on the WeChat developer mode, we configured a URL address. When we submit to turn on the WeChat developer mode, Tencent's WeChat server will send a get request to the URL address and carry some parameters. Let's verify. When it comes to get requests, we must talk about post requests. When the WeChat fans who follow our official account send messages and trigger events, Tencent's WeChat server will send a post request to the URL address. The content of the request is an xml document. string in the form.

So the processing method of the get request of this URL address is specially used to enable the WeChat developer mode; while the post request is used to process the messages sent to us by WeChat fans, or the events triggered, so what we do later The starting point of WeChat development work is the post processing method of the URL address.

Let’s deal with the simplest example below: fans send us any text message, and we reply to him with a message: "Hello, + his WeChat openId"

Post it directly below Code:

The processing servlet corresponding to the URL:

public class CoreServlet extends HttpServlet 
{
	private static final long serialVersionUID = 4440739483644821986L;

	/**
	 * 请求校验（确认请求来自微信服务器）
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		// 微信服务端发来的加密签名
		String signature = request.getParameter("signature");
		// 时间戳
		String timestamp = request.getParameter("timestamp");
		// 随机数
		String nonce = request.getParameter("nonce");
		// 随机字符串
		String echostr = request.getParameter("echostr");
		
		PrintWriter out = response.getWriter();
		// 请求校验，若校验成功则原样返回echostr，表示接入成功，否则接入失败
		if (SignUtil.checkSignature(signature, timestamp, nonce)) {
			out.print(echostr);
		}
		out.close();
		out = null;
	}

	/**
	 * 请求校验与处理
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		// 将请求、响应的编码均设置为UTF-8（防止中文乱码）
		request.setCharacterEncoding("UTF-8");
		response.setCharacterEncoding("UTF-8");
		
		// 接收参数微信加密签名、 时间戳、随机数
		String signature = request.getParameter("signature");
		String timestamp = request.getParameter("timestamp");
		String nonce = request.getParameter("nonce");

		PrintWriter out = response.getWriter();
		// 请求校验
		if (SignUtil.checkSignature(signature, timestamp, nonce)) {
			Message msgObj = XMLUtil.getMessageObject(request);	// 读取微信客户端发来的消息(xml字符串)，并将其转换为消息对象
			if(msgObj != null){
				String xml = "<xml>" +
						 "<ToUserName><![CDATA[" + msgObj.getFromUserName() + "]]></ToUserName>" +	// 接收方帐号（收到的OpenID）
						 "<FromUserName><![CDATA[" + msgObj.getToUserName() + "]]></FromUserName>" +	// 开发者微信号
						 "<CreateTime>12345678</CreateTime>" +
						 "<MsgType><![CDATA[text]]></MsgType>" +
						 "<Content><![CDATA[你好，"+ msgObj.getFromUserName() +"]]></Content>" +
						 "</xml>";
				out.write(xml);	// 回复微信客户端的消息(xml字符串)
				out.close();
				return;
			}
		}
		out.write("");
		out.close();
	}
}

xml string processing tool class to realize the conversion of xml message to message object:

public class XMLUtil 
{
	/**
	 * 从request中读取用户发给公众号的消息内容
	 * @param request
	 * @return 用户发给公众号的消息内容
	 * @throws IOException
	 */
	public static String readRequestContent(HttpServletRequest request) throws IOException
	{
		// 从输入流读取返回内容
		InputStream inputStream = request.getInputStream();
		InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");
		BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
		String str = null;
		StringBuilder buffer = new StringBuilder();
		
		while ((str = bufferedReader.readLine()) != null) {
			buffer.append(str);
		}
		
		// 释放资源
		bufferedReader.close();
		inputStreamReader.close();
		inputStream.close();
		
		return buffer.toString();
	}
	
	/**
	 * 将xml文档的内容转换成map
	 * @param xmlDoc
	 * @return map
	 */
	public static Map<String, String> xmlToMap(String xmlDoc)
	{
		//创建一个新的字符串
        StringReader read = new StringReader(xmlDoc);
        //创建新的输入源SAX 解析器将使用 InputSource 对象来确定如何读取 XML 输入
        InputSource source = new InputSource(read);
        //创建一个新的SAXBuilder
        SAXBuilder sb = new SAXBuilder();
        
        Map<String, String> xmlMap = new HashMap<String, String>();
        try {
            Document doc = sb.build(source);	//通过输入源构造一个Document
            Element root = doc.getRootElement();	//取的根元素
            
            List<Element> cNodes = root.getChildren();	//得到根元素所有子元素的集合(根元素的子节点，不包括孙子节点)
            Element et = null;
            for(int i=0;i<cNodes.size();i++){
                et = (Element) cNodes.get(i);	//循环依次得到子元素
                xmlMap.put(et.getName(), et.getText());
            }
        } catch (JDOMException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return xmlMap;
	}
	
	/**
	 * 将保存xml内容的map转换成对象
	 * @param map
	 * @return
	 */
	public static Message getMessageObject(Map<String, String> map)
	{
		if(map != null){
			String MsgType = map.get("MsgType");
			
			// 消息类型(文本消息:text, 图片消息:image, 语音消息:voice, 视频消息:video, 
			// 地理位置消息:location, 链接消息:link)
			if("text".equals(MsgType)){
				TextMessage msg = new TextMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setContent(map.get("Content"));
				return msg;
			}
			if("ImageMessage".equals(MsgType)){
				ImageMessage msg = new ImageMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setPicUrl(map.get("PicUrl"));
				msg.setMediaId(map.get("MediaId"));
				return msg;
			}
			if("video".equals(MsgType)){
				VideoMessage msg = new VideoMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setMediaId(map.get("MediaId"));
				msg.setThumbMediaId(map.get("ThumbMediaId"));
				return msg;
			}
			if("voice".equals(MsgType)){
				VoiceMessage msg = new VoiceMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setMediaId(map.get("MediaId"));
				msg.setFormat(map.get("Format"));
				return msg;
			}
			if("location".equals(MsgType)){
				LocationMessage msg = new LocationMessage();

				msg.setLocation_X(map.get("Location_X"));
				msg.setLocation_Y(map.get("Location_Y"));
				msg.setScale(map.get("Scale"));
				msg.setLabel(map.get("Label"));
				return msg;
			}
			if("link".equals(MsgType)){
				LinkMessage msg = new LinkMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setTitle(map.get("Title"));
				msg.setDescription(map.get("Description"));
				msg.setUrl(map.get("Url"));
				return msg;
			}
		}
		return null;
	}
	
	/**
	 * 将保存xml内容的map转换成对象
	 * @param map
	 * @return
	 * @throws IOException 
	 */
	public static Message getMessageObject(HttpServletRequest request) throws IOException
	{
		String xmlDoc = XMLUtil.readRequestContent(request);	// 读取微信客户端发了的消息(xml)
		Map<String, String> map = XMLUtil.xmlToMap(xmlDoc);		// 将客户端发来的xml转换成Map
		if(map != null){
			String MsgType = map.get("MsgType");
			
			// 消息类型(文本消息:text, 图片消息:image, 语音消息:voice, 视频消息:video, 
			// 地理位置消息:location, 链接消息:link)
			if("text".equals(MsgType)){
				TextMessage msg = new TextMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setContent(map.get("Content"));
				return msg;
			}
			/*if("ImageMessage".equals(MsgType)){
				ImageMessage msg = new ImageMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setPicUrl(map.get("PicUrl"));
				msg.setMediaId(map.get("MediaId"));
				return msg;
			}
			if("video".equals(MsgType)){
				VideoMessage msg = new VideoMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setMediaId(map.get("MediaId"));
				msg.setThumbMediaId(map.get("ThumbMediaId"));
				return msg;
			}
			if("voice".equals(MsgType)){
				VoiceMessage msg = new VoiceMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setMediaId(map.get("MediaId"));
				msg.setFormat(map.get("Format"));
				return msg;
			}
			if("location".equals(MsgType)){
				LocationMessage msg = new LocationMessage();

				msg.setLocation_X(map.get("Location_X"));
				msg.setLocation_Y(map.get("Location_Y"));
				msg.setScale(map.get("Scale"));
				msg.setLabel(map.get("Label"));
				return msg;
			}
			if("link".equals(MsgType)){
				LinkMessage msg = new LinkMessage();
				XMLUtil.initCommonMsg(msg, map);
				
				msg.setTitle(map.get("Title"));
				msg.setDescription(map.get("Description"));
				msg.setUrl(map.get("Url"));
				return msg;
			}*/
		}
		return null;
	}
	
	public static void initCommonMsg(Message msg, Map<String, String> map)
	{
		msg.setMsgId(map.get("MsgId"));
		msg.setMsgType(map.get("MsgType"));
		msg.setToUserName(map.get("ToUserName"));
		msg.setFromUserName(map.get("FromUserName"));
		msg.setCreateTime(map.get("CreateTime"));
	}
}

Messages sent by fans are divided into 6 types (text messages, picture messages, voice messages, video messages, geographical location messages, link messages):

/**
 * 微信消息基类
 * @author yuanfang
 * @date 2015-03-23
 */
public class Message 
{
	private String MsgId;	// 消息id，64位整型
	private String MsgType;	// 消息类型(文本消息:text, 图片消息:image, 语音消息:voice, 视频消息:video, 地理位置消息:location, 链接消息:link)
	private String ToUserName;	//开发者微信号
	private String FromUserName; // 发送方帐号（一个OpenID）
	private String CreateTime;	// 消息创建时间 （整型）
	
	public String getToUserName() {
		return ToUserName;
	}
	public void setToUserName(String toUserName) {
		ToUserName = toUserName;
	}
	public String getFromUserName() {
		return FromUserName;
	}
	public void setFromUserName(String fromUserName) {
		FromUserName = fromUserName;
	}
	public String getCreateTime() {
		return CreateTime;
	}
	public void setCreateTime(String createTime) {
		CreateTime = createTime;
	}
	public String getMsgType() {
		return MsgType;
	}
	public void setMsgType(String msgType) {
		MsgType = msgType;
	}
	public String getMsgId() {
		return MsgId;
	}
	public void setMsgId(String msgId) {
		MsgId = msgId;
	}
	
}

Text message type:

package com.sinaapp.wx.msg;

public class TextMessage extends Message 
{
	private String Content;	// 文本消息内容

	public String getContent() {
		return Content;
	}

	public void setContent(String content) {
		Content = content;
	}
	
}

OK, for fans, send it to our public The simplest processing of any text message of the account is completed. We simply reply to him: Hello, and then add his WeChat openId, similar to: Hello, orJydljfkg3-r0_dj3rkdfvjl

More WeChat development For articles related to processing messages sent from WeChat clients, please pay attention to the PHP Chinese website!