微信开发03----------XML解析与封装

　　3.1 解析微信发来的请求

　　  微信服务器发来的请求消息都被封装在request对象中，可以从request对象中将请求参数取出来。通常是用request的getParament()方法获取请求中的参数，而在这里需要使用request对象的getInputStream()方法。通过getInputStream()方法获得输入流，再使用Dome4j读取输入流并解析XML格式的请求，最后将参数放入HashMap中。这样在我们调用此方法时就能轻易的得到回复消息时需要的对应参数。

　　

/**
         * 解析微信发来的请求（XML）
         * 
         * @param request
         * @return Map<String, String>
         * @throws Exception
         */
        //@SuppressWarnings("unchecked")
public static HashMap<String, String> parseXML(HttpServletRequest request) throws Exception {
            // 将解析结果存储在HashMap中
            HashMap<String, String> map = new HashMap<String, String>();

            // 从request中取得输入流
            InputStream inputStream = request.getInputStream();
            // 读取输入流
            SAXReader reader = new SAXReader();
            Document document = reader.read(request.getInputStream());
            // 得到xml根元素
            Element root = document.getRootElement();
            
            recursiveParseXML(root,map);

            inputStream.close();
            inputStream = null;

            return map;
        }

private static void recursiveParseXML(Element root,HashMap<String, String> map){
            // 得到根元素的所有子节点
            List<Element> elementList = root.elements();
            //判断有没有子元素列表
            if(elementList.size() == 0){
                map.put(root.getName(), root.getText());
            }else{
                //遍历
                for (Element e : elementList){
                    recursiveParseXML(e,map);
                }
            }
        }

　　　3.2 回复消息封装成XML 

　　　　公众号服务器在接受并处理完消息后，需要返回特定格式的XML结构进行响应。这里我们使用的是XStream库。

　　

/**
         * 扩展xstream使其支持CDATA
         */
        private static XStream xstream = new XStream(new XppDriver() {
            public HierarchicalStreamWriter createWriter(Writer out) {
                return new PrettyPrintWriter(out) {
                    // 对所有xml节点的转换都增加CDATA标记
                    boolean cdata = true;

                    //@SuppressWarnings("unchecked")
                    public void startNode(String name, Class clazz) {
                        super.startNode(name, clazz);
                    }

                    protected void writeText(QuickWriter writer, String text) {
                        if (cdata) {
                            writer.write("<![CDATA[");
                            writer.write(text);
                            writer.write("]]>");
                        } else {
                            writer.write(text);
                        }
                    }
                };
            }
        });
/**
         * 文本消息对象转换成xml
         * 
         * @param textMessage 文本消息对象
         * @return xml
         */
        public static String messageToXML(TextMessage textMessage) {
            xstream.alias("xml", TextMessage.class);
            return xstream.toXML(textMessage);
        }

        /**
         * 图片消息对象转换成xml
         * 
         * @param imageMessage 图片消息对象
         * @return xml
         */
        public static String messageToXML(ImageMessage imageMessage) {
            xstream.alias("xml", ImageMessage.class);
            return xstream.toXML(imageMessage);
        }
/**
         * 语音消息对象转换成xml
         * 
         * @param voiceMessage 语音消息对象
         * @return xml
         */
        public static String messageToXML(VoiceMessage voiceMessage) {
            xstream.alias("xml", VoiceMessage.class);
            return xstream.toXML(voiceMessage);
        }

        /**
         * 视频消息对象转换成xml
         * 
         * @param videoMessage 视频消息对象
         * @return xml
         */
        public static String messageToXML(VideoMessage videoMessage) {
            xstream.alias("xml", VideoMessage.class);
            return xstream.toXML(videoMessage);
        }

　　　　完整代码：

package com.util;

import java.io.InputStream;
import java.io.Writer;
import java.util.HashMap;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import com.message.ImageMessage;
import com.message.TextMessage;
import com.message.VideoMessage;
import com.message.VoiceMessage;
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.core.util.QuickWriter;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.io.xml.PrettyPrintWriter;
import com.thoughtworks.xstream.io.xml.XppDriver;

/**
 * 
 * @author 黄路飞
 *
 * @data  2016年6月18日21:56:47
 */
public class MessageUtil {
    // 请求消息类型：文本
        public static final String REQ_MESSAGE_TYPE_TEXT = "text";
        // 请求消息类型：图片
        public static final String REQ_MESSAGE_TYPE_IMAGE = "image";
        // 请求消息类型：语音
        public static final String REQ_MESSAGE_TYPE_VOICE = "voice";
        // 请求消息类型：视频
        public static final String REQ_MESSAGE_TYPE_VIDEO = "video";
        // 请求消息类型：地理位置
        public static final String REQ_MESSAGE_TYPE_LOCATION = "location";
        // 请求消息类型：链接
        public static final String REQ_MESSAGE_TYPE_LINK = "link";

        // 请求消息类型：事件推送
        public static final String REQ_MESSAGE_TYPE_EVENT = "event";

        // 事件类型：subscribe(订阅)
        public static final String EVENT_TYPE_SUBSCRIBE = "subscribe";
        // 事件类型：unsubscribe(取消订阅)
        public static final String EVENT_TYPE_UNSUBSCRIBE = "unsubscribe";
        // 事件类型：scan(用户已关注时的扫描带参数二维码)
        public static final String EVENT_TYPE_SCAN = "scan";
        // 事件类型：LOCATION(上报地理位置)
        public static final String EVENT_TYPE_LOCATION = "LOCATION";
        // 事件类型：CLICK(自定义菜单)
        public static final String EVENT_TYPE_CLICK = "CLICK";

        // 响应消息类型：文本
        public static final String RESP_MESSAGE_TYPE_TEXT = "text";
        // 响应消息类型：图片
        public static final String RESP_MESSAGE_TYPE_IMAGE = "image";
        // 响应消息类型：语音
        public static final String RESP_MESSAGE_TYPE_VOICE = "voice";
        // 响应消息类型：视频
        public static final String RESP_MESSAGE_TYPE_VIDEO = "video";
        // 响应消息类型：音乐
        public static final String RESP_MESSAGE_TYPE_MUSIC = "music";
        // 响应消息类型：图文
        public static final String RESP_MESSAGE_TYPE_NEWS = "news";

        /**
         * 解析微信发来的请求（XML）
         * 
         * @param request
         * @return Map<String, String>
         * @throws Exception
         */
        //@SuppressWarnings("unchecked")
        public static HashMap<String, String> parseXML(HttpServletRequest request) throws Exception {
            // 将解析结果存储在HashMap中
            HashMap<String, String> map = new HashMap<String, String>();

            // 从request中取得输入流
            InputStream inputStream = request.getInputStream();
            // 读取输入流
            SAXReader reader = new SAXReader();
            Document document = reader.read(request.getInputStream());
            // 得到xml根元素
            Element root = document.getRootElement();
            
            recursiveParseXML(root,map);

            inputStream.close();
            inputStream = null;

            return map;
        }
        
        private static void recursiveParseXML(Element root,HashMap<String, String> map){
            // 得到根元素的所有子节点
            List<Element> elementList = root.elements();
            //判断有没有子元素列表
            if(elementList.size() == 0){
                map.put(root.getName(), root.getText());
            }else{
                //遍历
                for (Element e : elementList){
                    recursiveParseXML(e,map);
                }
            }
        }

        /**
         * 扩展xstream使其支持CDATA
         */
        private static XStream xstream = new XStream(new XppDriver() {
            public HierarchicalStreamWriter createWriter(Writer out) {
                return new PrettyPrintWriter(out) {
                    // 对所有xml节点的转换都增加CDATA标记
                    boolean cdata = true;

                    //@SuppressWarnings("unchecked")
                    public void startNode(String name, Class clazz) {
                        super.startNode(name, clazz);
                    }

                    protected void writeText(QuickWriter writer, String text) {
                        if (cdata) {
                            writer.write("<![CDATA[");
                            writer.write(text);
                            writer.write("]]>");
                        } else {
                            writer.write(text);
                        }
                    }
                };
            }
        });

        /**
         * 文本消息对象转换成xml
         * 
         * @param textMessage 文本消息对象
         * @return xml
         */
        public static String messageToXML(TextMessage textMessage) {
            xstream.alias("xml", TextMessage.class);
            return xstream.toXML(textMessage);
        }

        /**
         * 图片消息对象转换成xml
         * 
         * @param imageMessage 图片消息对象
         * @return xml
         */
        public static String messageToXML(ImageMessage imageMessage) {
            xstream.alias("xml", ImageMessage.class);
            return xstream.toXML(imageMessage);
        }

        /**
         * 语音消息对象转换成xml
         * 
         * @param voiceMessage 语音消息对象
         * @return xml
         */
        public static String messageToXML(VoiceMessage voiceMessage) {
            xstream.alias("xml", VoiceMessage.class);
            return xstream.toXML(voiceMessage);
        }

        /**
         * 视频消息对象转换成xml
         * 
         * @param videoMessage 视频消息对象
         * @return xml
         */
        public static String messageToXML(VideoMessage videoMessage) {
            xstream.alias("xml", VideoMessage.class);
            return xstream.toXML(videoMessage);
        }

    }