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;

	/**
	 * 請求校驗(yàn)（確認(rèn)請求來自微信服務(wù)器）
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		// 微信服務(wù)端發(fā)來的加密簽名
		String signature = request.getParameter("signature");
		// 時(shí)間戳
		String timestamp = request.getParameter("timestamp");
		// 隨機(jī)數(shù)
		String nonce = request.getParameter("nonce");
		// 隨機(jī)字符串
		String echostr = request.getParameter("echostr");
		
		PrintWriter out = response.getWriter();
		// 請求校驗(yàn)，若校驗(yàn)成功則原樣返回echostr，表示接入成功，否則接入失敗
		if (SignUtil.checkSignature(signature, timestamp, nonce)) {
			out.print(echostr);
		}
		out.close();
		out = null;
	}

	/**
	 * 請求校驗(yàn)與處理
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		// 將請求、響應(yīng)的編碼均設(shè)置為UTF-8（防止中文亂碼）
		request.setCharacterEncoding("UTF-8");
		response.setCharacterEncoding("UTF-8");
		
		// 接收參數(shù)微信加密簽名、 時(shí)間戳、隨機(jī)數(shù)
		String signature = request.getParameter("signature");
		String timestamp = request.getParameter("timestamp");
		String nonce = request.getParameter("nonce");

		PrintWriter out = response.getWriter();
		// 請求校驗(yàn)
		if (SignUtil.checkSignature(signature, timestamp, nonce)) {
			Message msgObj = XMLUtil.getMessageObject(request);	// 讀取微信客戶端發(fā)來的消息(xml字符串)，并將其轉(zhuǎn)換為消息對象
			if(msgObj != null){
				String xml = "<xml>" +
						 "<ToUserName><![CDATA[" + msgObj.getFromUserName() + "]]></ToUserName>" +	// 接收方帳號（收到的OpenID）
						 "<FromUserName><![CDATA[" + msgObj.getToUserName() + "]]></FromUserName>" +	// 開發(fā)者微信號
						 "<CreateTime>12345678</CreateTime>" +
						 "<MsgType><![CDATA[text]]></MsgType>" +
						 "<Content><![CDATA[你好，"+ msgObj.getFromUserName() +"]]></Content>" +
						 "</xml>";
				out.write(xml);	// 回復(fù)微信客戶端的消息(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 
{
	/**
	 * 從request中讀取用戶發(fā)給公眾號的消息內(nèi)容
	 * @param request
	 * @return 用戶發(fā)給公眾號的消息內(nèi)容
	 * @throws IOException
	 */
	public static String readRequestContent(HttpServletRequest request) throws IOException
	{
		// 從輸入流讀取返回內(nèi)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);
		}
		
		// 釋放資源
		bufferedReader.close();
		inputStreamReader.close();
		inputStream.close();
		
		return buffer.toString();
	}
	
	/**
	 * 將xml文檔的內(nèi)容轉(zhuǎn)換成map
	 * @param xmlDoc
	 * @return map
	 */
	public static Map<String, String> xmlToMap(String xmlDoc)
	{
		//創(chuàng)建一個新的字符串
        StringReader read = new StringReader(xmlDoc);
        //創(chuàng)建新的輸入源SAX 解析器將使用 InputSource 對象來確定如何讀取 XML 輸入
        InputSource source = new InputSource(read);
        //創(chuàng)建一個新的SAXBuilder
        SAXBuilder sb = new SAXBuilder();
        
        Map<String, String> xmlMap = new HashMap<String, String>();
        try {
            Document doc = sb.build(source);	//通過輸入源構(gòu)造一個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(根元素的子節(jié)點(diǎn)，不包括孫子節(jié)點(diǎn))
            Element et = null;
            for(int i=0;i<cNodes.size();i++){
                et = (Element) cNodes.get(i);	//循環(huán)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;
	}
	
	/**
	 * 將保存xml內(nèi)容的map轉(zhuǎn)換成對象
	 * @param map
	 * @return
	 */
	public static Message getMessageObject(Map<String, String> map)
	{
		if(map != null){
			String MsgType = map.get("MsgType");
			
			// 消息類型(文本消息:text, 圖片消息:image, 語音消息:voice, 視頻消息:video, 
			// 地理位置消息:location, 鏈接消息: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;
	}
	
	/**
	 * 將保存xml內(nèi)容的map轉(zhuǎn)換成對象
	 * @param map
	 * @return
	 * @throws IOException 
	 */
	public static Message getMessageObject(HttpServletRequest request) throws IOException
	{
		String xmlDoc = XMLUtil.readRequestContent(request);	// 讀取微信客戶端發(fā)了的消息(xml)
		Map<String, String> map = XMLUtil.xmlToMap(xmlDoc);		// 將客戶端發(fā)來的xml轉(zhuǎn)換成Map
		if(map != null){
			String MsgType = map.get("MsgType");
			
			// 消息類型(文本消息:text, 圖片消息:image, 語音消息:voice, 視頻消息:video, 
			// 地理位置消息:location, 鏈接消息: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):

/**
 * 微信消息基類
 * @author yuanfang
 * @date 2015-03-23
 */
public class Message 
{
	private String MsgId;	// 消息id，64位整型
	private String MsgType;	// 消息類型(文本消息:text, 圖片消息:image, 語音消息:voice, 視頻消息:video, 地理位置消息:location, 鏈接消息:link)
	private String ToUserName;	//開發(fā)者微信號
	private String FromUserName; // 發(fā)送方帳號（一個OpenID）
	private String CreateTime;	// 消息創(chuàng)建時(shí)間 （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;	// 文本消息內(nèi)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!