4.4.3　封装消息处理工具

在org.liufeng.course.util包下创建一个消息处理工具类MessageUtil，该类主要包含了前述内容讲解的解析请求消息和响应消息对象转XML中涉及的方法。MessageUtil类的源代码如下所示。

  1. package org.liufeng.course.util;
  2.  
  3. import java.io.InputStream;
  4. import java.io.Writer;
  5. import java.util.HashMap;
  6. import java.util.List;
  7. import java.util.Map;
  8. import javax.servlet.http.HttpServletRequest;
  9. import org.dom4j.Document;
  10. import org.dom4j.Element;
  11. import org.dom4j.io.SAXReader;
  12. import org.liufeng.course.message.resp.Article;
  13. import org.liufeng.course.message.resp.ImageMessage;
  14. import org.liufeng.course.message.resp.MusicMessage;
  15. import org.liufeng.course.message.resp.NewsMessage;
  16. import org.liufeng.course.message.resp.TextMessage;
  17. import org.liufeng.course.message.resp.VideoMessage;
  18. import org.liufeng.course.message.resp.VoiceMessage;
  19. import com.thoughtworks.xstream.XStream;
  20. import com.thoughtworks.xstream.core.util.QuickWriter;
  21. import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
  22. import com.thoughtworks.xstream.io.xml.PrettyPrintWriter;
  23. import com.thoughtworks.xstream.io.xml.XppDriver;
  24.  
  25. /**
  26.  * 消息处理工具类
  27.  * 
  28.  * @author liufeng
  29.  * @date 2013-09-15
  30.  */
  31. public class MessageUtil {
  32.   // 请求消息类型：文本
  33.   public static final String REQ_MESSAGE_TYPE_TEXT = "text";
  34.   // 请求消息类型：图片
  35.   public static final String REQ_MESSAGE_TYPE_IMAGE = "image";
  36.   // 请求消息类型：语音
  37.   public static final String REQ_MESSAGE_TYPE_VOICE = "voice";
  38.   // 请求消息类型：视频
  39.   public static final String REQ_MESSAGE_TYPE_VIDEO = "video";
  40.   // 请求消息类型：地理位置
  41.   public static final String REQ_MESSAGE_TYPE_LOCATION = "location";
  42.   // 请求消息类型：链接
  43.   public static final String REQ_MESSAGE_TYPE_LINK = "link";
  44.  
  45.   // 请求消息类型：事件推送
  46.   public static final String REQ_MESSAGE_TYPE_EVENT = "event";
  47.  
  48.   // 事件类型：subscribe(订阅)
  49.   public static final String EVENT_TYPE_SUBSCRIBE = "subscribe";
  50.   // 事件类型：unsubscribe(取消订阅)
  51.   public static final String EVENT_TYPE_UNSUBSCRIBE = "unsubscribe";
  52.   // 事件类型：scan(关注用户扫描带参数二维码)
  53.   public static final String EVENT_TYPE_SCAN = "scan";
  54.   // 事件类型：LOCATION(上报地理位置)
  55.   public static final String EVENT_TYPE_LOCATION = "LOCATION";
  56.   // 事件类型：CLICK(自定义菜单)
  57.   public static final String EVENT_TYPE_CLICK = "CLICK";
  58.  
  59.   // 响应消息类型：文本
  60.   public static final String RESP_MESSAGE_TYPE_TEXT = "text";
  61.   // 响应消息类型：图片
  62.   public static final String RESP_MESSAGE_TYPE_IMAGE = "image";
  63.   // 响应消息类型：语音
  64.   public static final String RESP_MESSAGE_TYPE_VOICE = "voice";
  65.   // 响应消息类型：视频
  66.   public static final String RESP_MESSAGE_TYPE_VIDEO = "video";
  67.   // 响应消息类型：音乐
  68.   public static final String RESP_MESSAGE_TYPE_MUSIC = "music";
  69.   // 响应消息类型：图文
  70.   public static final String RESP_MESSAGE_TYPE_NEWS = "news";
  71.  
  72.   /**
  73.    * 解析微信发来的请求（XML）
  74.    * 
  75.    * @param request
  76.    * @return Map<String, String>
  77.    * @throws Exception
  78.    */
  79.   @SuppressWarnings("unchecked")
  80.   public static Map<String, String> parseXml(HttpServletRequest request)
  81.   throws Exception {
  82.       // 将解析结果存储在HashMap中
  83.       Map<String, String> map = new HashMap<String, String>();
  84.  
  85.       // 从request中取得输入流
  86.       InputStream inputStream = request.getInputStream();
  87.       // 读取输入流
  88.       SAXReader reader = new SAXReader();
  89.       Document document = reader.read(inputStream);
  90.       // 得到XML根元素
  91.       Element root = document.getRootElement();
  92.       // 得到根元素的所有子节点
  93.       List<Element> elementList = root.elements();
  94.  
  95.       // 遍历所有子节点
  96.       for (Element e : elementList)
  97.           map.put(e.getName(), e.getText());
  98.  
  99.       // 释放资源
  100.       inputStream.close();
  101.       inputStream = null;
  102.  
  103.       return map;
  104.   }
  105.  
  106.   /**
  107.    * 扩展xstream使其支持CDATA
  108.    */
  109.   private static XStream xstream = new XStream(new XppDriver() {
  110.       public HierarchicalStreamWriter createWriter(Writer out) {
  111.           return new PrettyPrintWriter(out) {
  112.               // 对所有XML节点的转换都增加CDATA标记
  113.               boolean cdata = true;
  114.  
  115.               @SuppressWarnings("unchecked")
  116.               public void startNode(String name, Class clazz) {
  117.                   super.startNode(name, clazz);
  118.               }
  119.  
  120.               protected void writeText(QuickWriter writer, String text) {
  121.                   if (cdata) {
  122.                       writer.write("<![CDATA[");
  123.                       writer.write(text);
  124.                       writer.write("]]>");
  125.                   } else {
  126.                       writer.write(text);
  127.                   }
  128.               }
  129.           };
  130.       }
  131.   });
  132.  
  133.   /**
  134.    * 文本消息对象转换成XML
  135.    * 
  136.    * @param textMessage 文本消息对象
  137.    * @return xml
  138.    */
  139.   public static String messageToXml(TextMessage textMessage) {
  140.       xstream.alias("xml", textMessage.getClass());
  141.       return xstream.toXML(textMessage);
  142.   }
  143.  
  144.   /**
  145.    * 图片消息对象转换成XML
  146.    * 
  147.    * @param imageMessage 图片消息对象
  148.    * @return xml
  149.    */
  150.   public static String messageToXml(ImageMessage imageMessage) {
  151.       xstream.alias("xml", imageMessage.getClass());
  152.       return xstream.toXML(imageMessage);
  153.   }
  154.  
  155.   /**
  156.    * 语音消息对象转换成XML
  157.    * 
  158.    * @param voiceMessage 语音消息对象
  159.    * @return xml
  160.    */
  161.   public static String messageToXml(VoiceMessage voiceMessage) {
  162.       xstream.alias("xml", voiceMessage.getClass());
  163.       return xstream.toXML(voiceMessage);
  164.   }
  165.  
  166.   /**
  167.    * 视频消息对象转换成XML
  168.    * 
  169.    * @param videoMessage 视频消息对象
  170.    * @return xml
  171.    */
  172.   public static String messageToXml(VideoMessage videoMessage) {
  173.       xstream.alias("xml", videoMessage.getClass());
  174.       return xstream.toXML(videoMessage);
  175.   }
  176.  
  177.   /**
  178.    * 音乐消息对象转换成XML
  179.    * 
  180.    * @param musicMessage 音乐消息对象
  181.    * @return xml
  182.    */
  183.   public static String messageToXml(MusicMessage musicMessage) {
  184.       xstream.alias("xml", musicMessage.getClass());
  185.       return xstream.toXML(musicMessage);
  186.   }
  187.  
  188.   /**
  189.    * 图文消息对象转换成XML
  190.    * 
  191.    * @param newsMessage 图文消息对象
  192.    * @return xml
  193.    */
  194.   public static String messageToXml(NewsMessage newsMessage) {
  195.       xstream.alias("xml", newsMessage.getClass());
  196.       xstream.alias("item", new Article().getClass());
  197.       return xstream.toXML(newsMessage);
  198.   }
  199. }

在MessageUtil类中定义了一系列成员变量，包括请求消息类型（文本、图片、语音、视频、地理位置、链接和事件推送）、事件类型（订阅、取消订阅、扫描带参数二维码、上报地理位置和自定义菜单）和响应消息类型（文本、图片、语音、视频、音乐和图文）。