Receiving and replying to messages developed by WeChat public account

Encapsulation of various message types (only text and pictures are tested here):

public class WXConstants {
    //different message types
    public static final String MESSAGE_TEXT = "text";//Text message
    public static final String MESSAGE_NEWS = "news";//Graphic message
    public static final String MESSAGE_IMAGE = "image";//image message
    public static final String MESSAGE_VOICE = "voice";//Voice message
    public static final String MESSAGE_VIDEO = "video";//Video message
    public static final String MESSAGE_SHORTVIDEO = "shortvideo";//Short video message
    public static final String MESSAGE_MUSIC = "music";//Music message
    public static final String MESSAGE_LINK = "link";//Link message
    public static final String MESSAGE_LOCATION = "location";//Upload location
    public static final String MESSAGE_EVENT = "event";//Event push
    public static final String MESSAGE_SUBSCRIBE = "subscribe";//关注
    public static final String MESSAGE_UNSUBSCRIBE = "unsubscribe";//Unfollow
    public static final String MESSAGE_CLICK = "CLICK";//Menu click - trigger click when clicking the menu to get the message
    public static final String MESSAGE_VIEW = "VIEW";//The view is triggered when the menu jump link is clicked
    public static final String MESSAGE_SCAN = "SCAN";//Scan the QR code with parameters - trigger subscribe when not following / trigger scan when following
}

The structure of the push XML data package for each message type is as follows:

text message

<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>

parameter	describe
ToUserName	Developer WeChat
FromUserName	Sender account number (an OpenID)
CreateTime	message creation time (integer)
MsgType	text
Content	text message content
MsgId	message id, 64-bit integer

Code:

Message entity (all messages have the following four properties, which can be extracted and encapsulated): BaseMeassage.java

public class BaseMessage {
    private String ToUserName;
    private String FromUserName;
    private Long CreateTime;
    private String MsgType;

    public BaseMessage(String toUserName, String fromUserName, Long createTime, String msgType) {
        ToUserName = toUserName;
        FromUserName = fromUserName;
        CreateTime = createTime;
        MsgType = msgType;
    }
    public BaseMessage(){}

    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;
    }

}

Text message entity: TextMessage.java

public class TextMessage extends BaseMessage{
    private String Content;
    private String MsgId;

    public TextMessage(String toUserName, String fromUserName, Long createTime, String msgType, String content, String msgId) {
        super (toUserName, fromUserName, createTime, msgType);
        Content = content;
        MsgId = msgId;
    }
    public TextMessage(){
        super();
    }
    public String getContent() {
        return Content;
    }

    public void setContent(String content) {
        Content = content;
    }

    public String getMsgId() {
        return MsgId;
    }

    public void setMsgId(String msgId) {
        MsgId = msgId;
    }
}

Initialize text message:

    /**
     * Initialize reply message
     */
    public static String initText(String toUSerName,String fromUserName,String content){
        TextMessage text = new TextMessage();
        text.setFromUserName(toUSerName);//When the original [receiving message user] becomes the reply [sending message user]
        text.setToUserName (fromUserName);
        text.setMsgType(WXConstants.MESSAGE_TEXT);
        text.setCreateTime(new Date().getTime());//Create the current time as the message time
        text.setContent(content);
        return MessageUtil.TextMessageToXml(text);
    }
    /**
     * Convert text message object to XML format
     * @param message text message object
     * @return returns the converted XML format
     */
    public static String TextMessageToXml(TextMessage message){
        XStream xs = new XStream();
        //Because the xml root node defaults to class after conversion, it needs to be converted to <xml>
        xs.alias("xml", message.getClass());
        return xs.toXML(message);
    }

picture message

<xml> <ToUserName>< ![CDATA[toUser] ]></ToUserName> <FromUserName>< ![CDATA[fromUser] ]></FromUserName> <CreateTime>1348831860</CreateTime> <MsgType>< ![CDATA[image] ]></MsgType> <PicUrl>< ![CDATA[this is a url] ]></PicUrl> <MediaId>< ![CDATA[media_id] ]></MediaId> <MsgId>1234567890123456</MsgId> </xml>

parameter	describe
ToUserName	Developer WeChat
FromUserName	Sender account number (an OpenID)
CreateTime	message creation time (integer)
MsgType	image
PicUrl	Image link (generated by the system)
MediaId	Image message media id, you can call the multimedia file download interface to pull data.
MsgId	message id, 64-bit integer

Image message entity: ImageMessage.java

public class ImageMessage extends BaseMessage{
    private String PicUrl; //Picture link (generated by the system)
    private Image Image; //Image message media id, you can call the multimedia file download interface to pull data.
    private String MsgId; //message id, 64-bit integer
    public ImageMessage(String toUserName, String fromUserName, Long createTime, String msgType, String picUrl, Image image, String msgId) {
        super(toUserName, fromUserName, createTime, msgType);
        this.PicUrl = picUrl;
        this.Image = image;
        this.MsgId = msgId;
    }

    public Image getImage() {
        return Image;
    }

    public void setImage(Image image) {
        this.Image = image;
    }

    public String getPicUrl() {
        return PicUrl;
    }

    public void setPicUrl(String picUrl) {
        this.PicUrl = picUrl;
    }

    public String getMsgId() {
        return MsgId;
    }

    public void setMsgId(String msgId) {
        this.MsgId = msgId;
    }
}

初始化图片消息：

    /**
     * 初始化图片消息
     */
    public static String initImage(String toUSerName, String fromUserName, String mediaId) {
        ImageMessage imageMessage = new ImageMessage();
        Image image = new Image();
        image.setMediaId("v_4wmRsJaJ9RrbKipapX8badYe1FZJFyLoFgOXGsFLwcKj567od_I1cRdCDiZSsh");//Define yourself here, which can be generated through the multimedia file upload interface
        imageMessage.setFromUserName(toUSerName);//When the original [receiving message user] becomes the reply [sending message user]
        imageMessage.setToUserName (fromUserName);
        imageMessage.setMsgType(WXConstants.MESSAGE_IMAGE);
        imageMessage.setCreateTime(new Date().getTime());//Create current time as message time
        imageMessage.setImage(image);
        return MessageUtil.ImageMessageToXml(imageMessage);
    }
    /**
     * Convert image message object to XML format
     *
     * @param message image message object
     * @return returns the converted XML format
     */
    public static String ImageMessageToXml(ImageMessage message) {
        XStream xs = new XStream();
        //Because the xml root node defaults to class after conversion, it needs to be converted to <xml>
        xs.alias("xml", message.getClass());
        return xs.toXML(message);
    }

Test for text and picture messages:

@Controller
@RequestMapping("/wechat")
public class WxController {

    private final static String MEDIATYPE_CHARSET_JSON_UTF8 = MediaType.APPLICATION_JSON_VALUE + ";charset=UTF-8";
    private static Logger log = LoggerFactory.getLogger(WxController.class);

    @RequestMapping(value = "/chat", method = {RequestMethod.GET, RequestMethod.POST}, produces = MEDIATYPE_CHARSET_JSON_UTF8)
    public void get(HttpServletRequest request, HttpServletResponse response) throws Exception {
        //如果为get请求，则为开发者模式验证
        if ("get".equals(request.getMethod().toLowerCase())) {
            doGet();//在开发者模式验证中已处理，在此省略
        } else {
            request.setCharacterEncoding("UTF-8");
            response.setCharacterEncoding("UTF-8");
            PrintWriter out = response.getWriter();
            try {
                Map<String, String> map = MessageUtil.xmlToMap(request);
                String ToUserName = map.get("ToUserName");
                String FromUserName = map.get("FromUserName");
                request.getSession().setAttribute("openid",FromUserName);
                String CreateTime = map.get("CreateTime");
                String MsgType = map.get("MsgType");
                String message = null;
                if (MsgType.equals(WXConstants.MESSAGE_TEXT)) {//判断消息类型是否是文本消息(text)
                    String Content = map.get("Content");
                    message = MessageUtil.initText(ToUserName, FromUserName, "你输入的内容："+Content);
                } else if (MsgType.equals(WXConstants.MESSAGE_IMAGE)) {
                    String mediaId = map.get("MediaId");
                    message = MessageUtil.initImage(ToUserName, FromUserName, mediaId);
                }
                out.print(message); //返回转换后的XML字符串
            } catch (DocumentException e) {
                e.printStackTrace();
            }
            out.close();
        }
    }
}

xmlToMap方法：

    /**
     * 新建方法，将接收到的XML格式，转化为Map对象
     * @param request 将request对象，通过参数传入
     * @return 返回转换后的Map对象
     */
    public static Map<String, String> xmlToMap(HttpServletRequest request) throws IOException, DocumentException {
        Map<String, String> map = new HashMap<String, String>();
        //从dom4j的jar包中，拿到SAXReader对象。
        SAXReader reader = new SAXReader();
        InputStream is = request.getInputStream();//从request中，获取输入流
        Document doc = (Document) reader.read(is);//从reader对象中,读取输入流
        Element root = doc.getRootElement();//获取XML文档的根元素
        List<Element> list = root.elements();//获得根元素下的所有子节点
        for (Element e : list) {
            map.put(e.getName(), e.getText());//遍历list对象，并将结果保存到集合中
        }
        is.close();
        return map;
    }

测试结果：