微信公众号开发_Java（３）－－接收普通消息

一、前言

今天开始讲解微信公众号开发如何接收普通消息，包括文本消息、图片消息、语音消息以及视频消息等。

不妥当之处多多指正。

二、消息的POST过程

2.1 POST过程图解

消息在微信服务器和开发者服务器之间的传输过程如下，不同之处在于，普通微信用户向公众账号发送的消息，微信服务器将消息进行XML形式的封装，封装成XML数据包，然后将消息的XML数据包POST到开发者填写的URL上：

2.2 XML数据包示例

以文本消息为例：

一条普通的文本消息共有以下几个属性，XML将这些属性封装成XML的形式进行POST传送。

<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>

2.3 消息传输的全过程

如2.1图示，开发者服务器在接收到来自微信服务器的XML数据包后，需要将XML数据包1.解析，然后进行2.业务处理，然后将业务处理的结果再次进行3.封装成XML数据，4.POST到微信服务器，再又5.微信服务器发送到客户端。

下面对各个数据解析和封装过程进行详解。

1.解析XML数据包

　　　/**     * xml转换成Map     */    public static Map<String, String> xmlToMap(HttpServletRequest request) throws IOException, DocumentException {        request.setCharacterEncoding("UTF-8");        Map<String, String> map = new HashMap<String, String>();        SAXReader reader = new SAXReader();        InputStream ins = request.getInputStream();        Document doc = reader.read(ins);        Element root = doc.getRootElement();        List<Element> list = root.elements();        for (Element e : list) {            map.put(e.getName(), e.getText());        }        ins.close();        return map;    }

2.业务处理

略

3.封装成XML数据

　　/**     * text转换成xml     */    public static String textMessageToXml(TextMessage textMessage) {        XStream xstream = new XStream();        xstream.alias("xml", textMessage.getClass());        return xstream.toXML(textMessage);    }

三、实现接收普通消息

完整代码实现。

3.1 消息属性TextMessage

package cn.edu.sdut.model;public class TextMessage {    private String ToUserName;    private String FromUserName;    private long CreateTime;    private String MsgType;    private String Content;    private String MsgId;    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 long getCreateTime() {        return CreateTime;    }    public void setCreateTime(long createTime) {        CreateTime = createTime;    }    public String getMsgType() {        return MsgType;    }    public void setMsgType(String msgType) {        MsgType = msgType;    }    public String getContent() {        return Content;    }    public void setContent(String content) {        Content = content;    }    public String getMsgId() {        return MsgId;    }    public void setMsgId(String msgId) {        MsgId = msgId;    }}

3.2 数据处理MessageUtil

package cn.edu.sdut.service;import java.io.IOException;import java.io.InputStream;import java.util.HashMap;import java.util.List;import java.util.Map;import javax.servlet.http.HttpServletRequest;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.Element;import org.dom4j.io.SAXReader;import com.thoughtworks.xstream.XStream;import cn.edu.sdut.model.TextMessage;public class MessageUtil {    /**     * xml转换成Map     */    public static Map<String, String> xmlToMap(HttpServletRequest request) throws IOException, DocumentException {        request.setCharacterEncoding("UTF-8");        Map<String, String> map = new HashMap<String, String>();        SAXReader reader = new SAXReader();        InputStream ins = request.getInputStream();        Document doc = reader.read(ins);        Element root = doc.getRootElement();        List<Element> list = root.elements();        for (Element e : list) {            map.put(e.getName(), e.getText());        }        ins.close();        return map;    }    /**     * text转换成xml     */    public static String textMessageToXml(TextMessage textMessage) {        XStream xstream = new XStream();        xstream.alias("xml", textMessage.getClass());        return xstream.toXML(textMessage);    }}

3.3 业务处理MessageController

package cn.edu.sdut.controller;import java.io.IOException;import java.io.PrintWriter;import java.util.Date;import java.util.Map;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.dom4j.DocumentException;import cn.edu.sdut.model.TextMessage;import cn.edu.sdut.service.CheckUtil;import cn.edu.sdut.service.MessageUtil;public class WeChatServlet extends HttpServlet {    /**     * 获取值     */    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        String signature = req.getParameter("signature");        String timestamp = req.getParameter("timestamp");        String nonce = req.getParameter("nonce");        String echostr = req.getParameter("echostr");        // 调用逻辑验证        PrintWriter out = resp.getWriter();        if (CheckUtil.checkSignature(signature, timestamp, nonce)) {            out.println(echostr);        }        out.close();        out = null;    }    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {        // 设置一下相应的格式        req.setCharacterEncoding("UTF-8");        resp.setCharacterEncoding("UTF-8");        PrintWriter out = resp.getWriter();// 获取resq的数据流        Map<String, String> map;        try {            map = MessageUtil.xmlToMap(req);            String fromUserName = map.get("FromUserName");            String toUserName = map.get("ToUserName");            String msgType = map.get("MsgType");            String content = map.get("Content");            String format = map.get("Format");            String message = null;            if ("text".equals(msgType)) {                TextMessage text = new TextMessage();                text.setFromUserName(toUserName);                text.setToUserName(fromUserName);                text.setMsgType("text");                text.setCreateTime(new Date().getTime());                text.setContent("您发送的消息类型是:" + msgType + ";");                message = MessageUtil.textMessageToXml(text);// message来接收            }            if ("image".equals(msgType)) {                TextMessage text = new TextMessage();                text.setFromUserName(toUserName);                text.setToUserName(fromUserName);                text.setMsgType("text");                text.setCreateTime(new Date().getTime());                text.setContent("您发送的消息类型是:" + msgType + ";");                message = MessageUtil.textMessageToXml(text);// message来接收            }            if ("voice".equals(msgType)) {                TextMessage text = new TextMessage();                text.setFromUserName(toUserName);                text.setToUserName(fromUserName);                text.setMsgType("text");                text.setCreateTime(new Date().getTime());                text.setContent("您发送的消息类型是:" + msgType + ";");                message = MessageUtil.textMessageToXml(text);// message来接收            }            out.println(message);        } catch (DocumentException e) {            e.printStackTrace();        } finally {            out.close();        }    }}

四、项目代码仓库

详细、完整项目代码请移步：

https://github.com/GaoZiqiang/WeChatDevelopment