微信公众号开发：消息与事件处理

淡淡的烟草味﹌ 2022-05-30 00:55 242阅读 0赞

> 在成功接入微信公众平台之后（如何接入请参考[《微信公众号开发：账号申请与接入》][Link 1]），就可以对微信服务器POST过来的消息或者事件XML数据包进行监听与处理了。   
> 
> 
> 在[《微信公众号开发：账号申请与接入》][Link 1]的 WeChatController 控制器中， handleMsgAndEvent() 方法用来监听并处理消息与事件，示例项目的完整目录层次如下图所示。
> 
> ![20180228234946877][]
> 
> 本示例使用了Maven来构建工程，除了要引入基本的SpringMVC-WEB依赖，还需引入以下三个工具包。  
>  
> 
>     <dependency>
>     			<groupId>dom4j</groupId>
>     			<artifactId>dom4j</artifactId>
>     		</dependency>
>     		<dependency>
>     			<groupId>xstream</groupId>
>     			<artifactId>xstream</artifactId>
>     			<version>1.2.2</version>
>     		</dependency>
>     		<dependency>
>     			<groupId>org.projectlombok</groupId>
>     			<artifactId>lombok</artifactId>
>     		</dependency>
> 
> WeChatController 控制器和 WeChatEncrypt  加密工具类的完整代码在[《微信公众号开发：账号申请与接入》][Link 1]中已经贴出，此章中不再重复贴出。  
>  WechatSession 是处理所有消息的入口。   
>  
> 
>     import java.io.IOException;
>     import java.io.InputStream;
>     import java.io.PrintWriter;
>     
>     import javax.xml.parsers.DocumentBuilder;
>     import javax.xml.parsers.DocumentBuilderFactory;
>     import javax.xml.parsers.ParserConfigurationException;
>     import javax.xml.transform.TransformerFactory;
>     
>     import org.w3c.dom.Document;
>     import org.xml.sax.SAXException;
>     
>     /**
>      * 处理消息和事件的入口类
>      */
>     public class WechatSession
>     
>     {
>     
>         private InputStream in;
>     
>         private PrintWriter out;
>     
>         public static TransformerFactory tffactory = TransformerFactory.newInstance();
>     
>         private static DocumentBuilder documentBuilder = null;
>     
>         public static DocumentBuilder getDocumentBuilder()
>         {
>             // 先检查实例是否已创建，如果未创建才进入同步块
>             if (null == documentBuilder)
>             {
>                 synchronized (WechatSession.class)
>                 {
>                     // 再次检查实例是否已创建，如果真的未创建才创建实例
>                     if (null == documentBuilder)
>                     {
>                         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
>                         try
>                         {
>                             documentBuilder = factory.newDocumentBuilder();
>                         }
>                         catch (ParserConfigurationException e)
>                         {
>                             e.printStackTrace();
>                         }
>                     }
>                 }
>             }
>             return documentBuilder;
>         }
>     
>         /**
>          * 构造方法
>          * 
>          * @param in
>          * @param out
>          */
>         public WechatSession(InputStream in, PrintWriter out)
>         {
>             this.in = in;
>             this.out = out;
>         }
>     
>         /**
>          * 对接收到的消息和事件进行处理
>          */
>         public void process()
>     
>         {
>             try
>             {
>                 Document document = getDocumentBuilder().parse(in);
>                 String msgType = document.getElementsByTagName("MsgType").item(0).getTextContent();
>     
>                 if ("text".equals(msgType))
>                 {
>                     TextMsg msg = new TextMsg();
>                     msg.read(document);
>                     msg.onTextMsg(out);
>                 }
>                 else if ("event".equals(msgType))
>                 {
>                     EventMsg msg = new EventMsg();
>                     msg.read(document);
>                     msg.onEventMsg(out);
>                 }
>             }
>             catch (SAXException e)
>             {
>                 e.printStackTrace();
>             }
>             catch (IOException e)
>             {
>                 e.printStackTrace();
>             }
>         }
>     
>         public void close()
>     
>         {
>             try
>             {
>                 if (in != null)
>                 {
>                     in.close();
>                 }
>                 if (out != null)
>                 {
>                     out.flush();
>                     out.close();
>                 }
>             }
>             catch (IOException e)
>             {
>                 e.printStackTrace();
>             }
>         }
>     
>     }
> 
> AbstractMsg 是普通消息与事件消息公用的抽象父类，包含了一些通用的基础属性、提供了一些通用的基础方法。   
>  
> 
>     import java.io.IOException;
>     import java.io.StringWriter;
>     
>     import javax.xml.transform.OutputKeys;
>     import javax.xml.transform.Transformer;
>     import javax.xml.transform.dom.DOMSource;
>     import javax.xml.transform.stream.StreamResult;
>     
>     import org.w3c.dom.CDATASection;
>     import org.w3c.dom.Document;
>     import org.w3c.dom.Element;
>     
>     import lombok.Data;
>     
>     /**
>      * 消息与事件的抽象父类
>      */
>     @Data
>     public abstract class AbstractMsg
>     {
>         protected String toUserName;
>         protected String fromUserName;
>         protected String createTime;
>         protected String msgType;
>     
>         /**
>          * 读取Document内容到Java对象
>          * 
>          * @param document
>          */
>         public void read(Document document)
>         {
>             readHead(document);
>             readBody(document);
>         }
>     
>         /**
>          * 获取Java对象的XML字符串
>          */
>         public String write()
>         {
>             Document document = WechatSession.getDocumentBuilder().newDocument();
>             Element root = document.createElement("xml");
>             writeHead(root, document);
>             writeBody(root, document);
>             document.appendChild(root);
>             return readDocument(document);
>         }
>     
>         /**
>          * 读取消息和事件公有的一些基础属性
>          * 
>          * @param document
>          */
>         private void readHead(Document document)
>         {
>             toUserName = document.getElementsByTagName("ToUserName").item(0).getTextContent();
>             fromUserName = document.getElementsByTagName("FromUserName").item(0).getTextContent();
>             createTime = document.getElementsByTagName("CreateTime").item(0).getTextContent();
>             msgType = document.getElementsByTagName("MsgType").item(0).getTextContent();
>     
>         }
>     
>         /**
>          * 消息和事件具体子类需实现该方法，用来读取一些自身独有的属性数据
>          * 
>          * @param document
>          */
>         protected abstract void readBody(Document document);
>     
>         /**
>          * 将Java对象中的基础属性写入Document
>          * 
>          * @param root
>          * @param document
>          */
>         private void writeHead(Element root, Document document)
>         {
>             Element toUserNameElement = document.createElement("ToUserName");
>             CDATASection toUserNameCData = document.createCDATASection(this.toUserName);
>             toUserNameElement.appendChild(toUserNameCData);
>             Element fromUserNameElement = document.createElement("FromUserName");
>             CDATASection fromUserNameCData = document.createCDATASection(this.fromUserName);
>             fromUserNameElement.appendChild(fromUserNameCData);
>             Element createTimeElement = document.createElement("CreateTime");
>             createTimeElement.setTextContent(this.createTime);
>             Element msgTypeElement = document.createElement("MsgType");
>             CDATASection msgTypeCData = document.createCDATASection(this.msgType);
>             msgTypeElement.appendChild(msgTypeCData);
>     
>             root.appendChild(toUserNameElement);
>             root.appendChild(fromUserNameElement);
>             root.appendChild(createTimeElement);
>             root.appendChild(msgTypeElement);
>         }
>     
>         /**
>          * 消息和事件各子类需实现该方法，用来写入一些自身独有的属性数据
>          * 
>          * @param root
>          * @param document
>          */
>         protected abstract void writeBody(Element root, Document document);
>     
>         /**
>          * 获取Document对象中指定元素的内容
>          * 
>          * @param document
>          * @param elementName
>          * @return
>          */
>         protected String getElementContent(Document document, String elementName)
>         {
>             if (document.getElementsByTagName(elementName).getLength() > 0)
>             {
>                 return document.getElementsByTagName(elementName).item(0).getTextContent();
>             }
>             return null;
>         }
>     
>         /**
>          * 读取Document对象为XML字符串
>          * 
>          * @param document
>          */
>         private String readDocument(Document document)
>         {
>             String docXml = "";
>             StringWriter writer = new StringWriter();
>             try
>             {
>                 Transformer transformer = WechatSession.tffactory.newTransformer();
>                 transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");// 设置编码字符集
>                 transformer.setOutputProperty(OutputKeys.INDENT, "yes");// 设置缩进
>     
>                 transformer.transform(new DOMSource(document), new StreamResult(writer));
>                 docXml = writer.getBuffer().toString();
>                 System.out.println(docXml);// 将获取到的XML字符串打印至控制台
>                 writer.close();
>             }
>             catch (Exception e)
>             {
>                 e.printStackTrace();
>             }
>             finally
>             {
>                 if (null != writer)
>                 {
>                     try
>                     {
>                         writer.close();
>                     }
>                     catch (IOException e)
>                     {
>                         e.printStackTrace();
>                     }
>                 }
>             }
>             return docXml;
>     
>         }
>     
>     }
> 
> TextMsg 普通消息Java类。   
>  
> 
>     import java.io.PrintWriter;
>     
>     import org.w3c.dom.CDATASection;
>     import org.w3c.dom.Document;
>     import org.w3c.dom.Element;
>     
>     import lombok.Data;
>     import lombok.EqualsAndHashCode;
>     
>     /**
>      * 普通文本消息
>      */
>     @Data
>     @EqualsAndHashCode(callSuper = false)
>     public class TextMsg extends AbstractMsg
>     {
>         private String content;
>         private String msgId;
>     
>         /**
>          * 从Document中读取普通文本消息独有的属性数据
>          */
>         @Override
>         protected void readBody(Document document)
>         {
>             content = document.getElementsByTagName("Content").item(0).getTextContent();
>             msgId = document.getElementsByTagName("MsgId").item(0).getTextContent();
>         }
>     
>         /**
>          * 回复时专用，将普通文本消息独有的回复内容写入Document中
>          */
>         @Override
>         protected void writeBody(Element root, Document document)
>         {
>             Element contentElement = document.createElement("Content");
>             CDATASection contentCData = document.createCDATASection(this.content);
>             contentElement.appendChild(contentCData);
>             root.appendChild(contentElement);
>         }
>     
>         public void onTextMsg(PrintWriter out)
>         {
>             System.out.println("此处添加处理普通文本消息的业务逻辑，此处简单回复：你好 某某某");
>             TextMsg msg = new TextMsg();
>             msg.setFromUserName(this.toUserName);
>             msg.setToUserName(this.fromUserName);
>             msg.setCreateTime(this.createTime);
>             msg.setMsgType("text");
>             msg.setContent("你好 " + this.fromUserName);
>             out.print(msg.write());
>         }
>     
>     }
> 
> EventMsg 事件消息Java类。   
>  
> 
>     import java.io.PrintWriter;
>     
>     import lombok.Data;
>     import lombok.EqualsAndHashCode;
>     
>     import org.w3c.dom.Document;
>     import org.w3c.dom.Element;
>     
>     /**
>      * 事件统一处理类
>      */
>     @Data
>     @EqualsAndHashCode(callSuper = false)
>     public class EventMsg extends AbstractMsg {
>     	// 事件列表：CLICK(点击自定义菜单)/subscribe(关注)/unsubscribe(取消关注)/SCAN(扫描二维码)/LOCATION(上报地理位置)
>     	private String event;
>     
>     	private String eventKey;
>     	private String ticket;
>     
>     	private String latitude;
>     	private String longitude;
>     	private String precision;
>     
>     	/**
>     	 * 从Document中读取各事件独有的属性数据
>     	 */
>     	@Override
>     	protected void readBody(Document document) {
>     		event = getElementContent(document, "Event").toLowerCase();
>     		switch (event) {
>     		case "click": {
>     			eventKey = getElementContent(document, "EventKey");
>     			break;
>     		}
>     		case "subscribe":
>     		case "unsubscribe":
>     		case "scan": {
>     			eventKey = getElementContent(document, "EventKey");
>     			ticket = getElementContent(document, "Ticket");
>     			break;
>     		}
>     		case "location": {
>     			latitude = getElementContent(document, "Latitude");
>     			longitude = getElementContent(document, "Longitude");
>     			precision = getElementContent(document, "Precision");
>     			break;
>     		}
>     		default: {
>     			break;
>     		}
>     		}
>     	}
>     
>     	/**
>     	 * 回复时专用，由于事件无须回复，在此空实现
>     	 */
>     	@Override
>     	protected void writeBody(Element root, Document document) {
>     	}
>     
>     	public void onEventMsg(PrintWriter out) {
>     		System.out
>     				.println("此处添加处理事件的业务逻辑，对于关注事件回复：尊敬的 某某某 女士/先生，欢迎您关注我的个人公众号！");
>     		switch (event) {
>     			case "subscribe": {
>     				TextMsg msg = new TextMsg();
>     				msg.setFromUserName(this.toUserName);
>     				msg.setToUserName(this.fromUserName);
>     				msg.setCreateTime(this.createTime);
>     				msg.setMsgType("text");
>     				msg.setContent("尊敬的 " + this.fromUserName + " 女士/先生，欢迎您关注我的个人公众号！");
>     				out.print(msg.write());
>     				break;
>     			}
>     		}
>     	}
>     }
> 
> 本文项目源码已上传至CSDN，资源地址：[http://download.csdn.net/download/pengjunlee/10257857][http_download.csdn.net_download_pengjunlee_10257857]

[Link 1]: http://blog.csdn.net/pengjunlee/article/details/79394361
[20180228234946877]: /images/20220530/a2b35326f1c84c5e96a25d6578aadfb3.png
[http_download.csdn.net_download_pengjunlee_10257857]: http://download.csdn.net/download/pengjunlee/10257857