微信开发手册（3）
1、前一篇文章里我们已经把微信公众平台接口中消息及相关操作都进行了封装，本章节将主要介绍如何接收微信服务器发送的消息并做出响应。
明确在哪接收消息:
从微信公众平台接口消息指南中可以了解到，当用户向公众帐号发消息时，微信服务器会将消息通过POST方式提交给我们在接口配置信息中填写的URL，而我们就需要在URL所指向的WeiXinAction中Post请求中接收消息、处理消息和响应消息。
package edu.siso.action;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.interceptor.ServletRequestAware;
import org.apache.struts2.interceptor.ServletResponseAware;
import com.opensymphony.xwork2.ActionSupport;
import edu.siso.service.CoreService;
import edu.siso.util.SignUtil;
public class WeiXinAction extends ActionSupport implements ServletRequestAware,
ServletResponseAware {
private static final String GET = "GET";
private static final String POST = "POST";
private HttpServletRequest request;
private HttpServletResponse response;
private String signature;
private String timestamp;
private String nonce;
private String echostr;
private static final long serialVersionUID = 1L;
@Override
public String execute() throws Exception {
if (request.getMethod().equals(GET)) {
// 通过检验signature对请求进行校验，若校验成功则原样返回echostr，表示接入成功，否则接入失败
if (SignUtil.checkSignature(signature, timestamp, nonce)) {
response.getWriter().write(echostr);
}
}
if (request.getMethod().equals(POST)) {
request.setCharacterEncoding("UTF-8");
response.setCharacterEncoding("UTF-8");
String respMessage = CoreService.processRequest(request);
response.getWriter().write(respMessage);
}
return null;
}
@Override
public void setServletResponse(HttpServletResponse response) {
// TODO Auto-generated method stub
this.response = response;
}
@Override
public void setServletRequest(HttpServletRequest request) {
// TODO Auto-generated method stub
this.request = request;
}
public String getSignature() {
return signature;
}
public void setSignature(String signature) {
this.signature = signature;
}
public String getTimestamp() {
return timestamp;
}
public void setTimestamp(String timestamp) {
this.timestamp = timestamp;
}
public String getNonce() {
return nonce;
}
public void setNonce(String nonce) {
this.nonce = nonce;
}
public String getEchostr() {
return echostr;
}
public void setEchostr(String echostr) {
this.echostr = echostr;
}
}
2、代码说明：
1）微信服务器POST消息时用的是UTF-8编码，在接收时也要用同样的编码，否则中文会乱码；
2）在响应消息（回复消息给用户）时，也将编码方式设置为UTF-8，原理同上；
3）调用CoreService类的processRequest方法接收、处理消息，并得到处理结果；
4）调用response.getWriter().write()方法将消息的处理结果返回给用户，从处理Post请求的实现可以看到，它是通过调用CoreService类的processRequest方法接收、处理消息的，这样做的目的是为了解耦，即业务相关的操作都不在Action里处理，而是完全交由业务核心类CoreService去做。下面来看CoreService类的代码实现：
package edu.siso.service;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import edu.siso.resp.Article;
import edu.siso.resp.NewsMessage;
import edu.siso.resp.TextMessage;
import edu.siso.util.BaseUtil;
import edu.siso.util.MessageUtil;
public class CoreService {
/**
* 处理微信发来的请求
*
* @param request
* @return
*/
public static String processRequest(HttpServletRequest request) {
String respMessage = null;
try {
// 默认返回的文本消息内容
String respContent = "请求处理异常，请稍候尝试！";
// xml请求解析
Map<String, String> requestMap = MessageUtil.parseXml(request);
// 发送方帐号（open_id）
String fromUserName = requestMap.get("FromUserName");
// 公众帐号
String toUserName = requestMap.get("ToUserName");
// 消息类型
String msgType = requestMap.get("MsgType");
// 回复文本消息
TextMessage textMessage = new TextMessage();
textMessage.setToUserName(fromUserName);
textMessage.setFromUserName(toUserName);
textMessage.setCreateTime(new Date().getTime());
textMessage.setMsgType(MessageUtil.RESP_MESSAGE_TYPE_TEXT);
textMessage.setFuncFlag(0);
respContent = BaseUtil.getMainMenu();
textMessage.setContent(respContent);
respMessage = MessageUtil.textMessageToXml(textMessage);
// 文本消息
if (msgType.equals(MessageUtil.REQ_MESSAGE_TYPE_TEXT)) {
String Content = requestMap.get("Content");
// 创建图文消息
NewsMessage newsMessage = new NewsMessage();
newsMessage.setToUserName(fromUserName);
newsMessage.setFromUserName(toUserName);
newsMessage.setCreateTime(new Date().getTime());
newsMessage.setMsgType(MessageUtil.RESP_MESSAGE_TYPE_NEWS);
newsMessage.setFuncFlag(0);
if (Content.equals("1")) {
respContent = "<a href=\"http://www.baidu.com/\">百度</a>";
textMessage.setContent(respContent);
respMessage = MessageUtil.textMessageToXml(textMessage);
}
if (Content.equals("2")) {
List<Article> articleList = new ArrayList<Article>();
Article article = new Article();
article.setTitle("我能开发微信啦");
article.setDescription("努力的程序员—钟仁，历时三天，成功开发微信...");
article.setPicUrl("http://a.hiphotos.baidu.com/baike/c0%3Dbaike80%2C5%2C5%2C80%2C26%3Bt%3Dgif/sign=3bb6b7b60db30f242197e451a9fcba26/64380cd7912397dde17b84d35b82b2b7d1a287e2.jpg");
article.setUrl("http://baike.baidu.com/view/5160047.htm?fr=aladdin");
articleList.add(article);
Article article2 = new Article();
article2.setTitle("第一天");
article2.setDescription("");
article2.setPicUrl("http://a.hiphotos.baidu.com/baike/c0%3Dbaike80%2C5%2C5%2C80%2C26%3Bt%3Dgif/sign=3bb6b7b60db30f242197e451a9fcba26/64380cd7912397dde17b84d35b82b2b7d1a287e2.jpg");
article2.setUrl("http://baike.baidu.com/view/5160047.htm?fr=aladdin");
articleList.add(article2);
Article article3 = new Article();
article3.setTitle("第二天");
article3.setDescription("");
article3.setPicUrl("http://a.hiphotos.baidu.com/baike/c0%3Dbaike80%2C5%2C5%2C80%2C26%3Bt%3Dgif/sign=3bb6b7b60db30f242197e451a9fcba26/64380cd7912397dde17b84d35b82b2b7d1a287e2.jpg");
article3.setUrl("http://baike.baidu.com/view/5160047.htm?fr=aladdin");
articleList.add(article3);
// 设置图文消息个数
newsMessage.setArticleCount(articleList.size());
// 设置图文消息包含的图文集合
newsMessage.setArticles(articleList);
// 将图文消息对象转换成xml字符串
respMessage = MessageUtil.newsMessageToXml(newsMessage);
}
if (BaseUtil.isQqFace(Content)) {
respContent = Content;
textMessage.setContent(respContent);
respMessage = MessageUtil.textMessageToXml(textMessage);
}
}
// 图片消息
else if (msgType.equals(MessageUtil.REQ_MESSAGE_TYPE_IMAGE)) {
respContent = "您发送的是图片消息！";
}
// 地理位置消息
else if (msgType.equals(MessageUtil.REQ_MESSAGE_TYPE_LOCATION)) {
respContent = "您发送的是地理位置消息！";
}
// 链接消息
else if (msgType.equals(MessageUtil.REQ_MESSAGE_TYPE_LINK)) {
respContent = "您发送的是链接消息！";
}
// 音频消息
else if (msgType.equals(MessageUtil.REQ_MESSAGE_TYPE_VOICE)) {
respContent = "您发送的是音频消息！";
}
// 事件推送
else if (msgType.equals(MessageUtil.REQ_MESSAGE_TYPE_EVENT)) {
// 事件类型
String eventType = requestMap.get("Event");
// 订阅
if (eventType.equals(MessageUtil.EVENT_TYPE_SUBSCRIBE)) {
respContent = "谢谢您的关注！";
textMessage.setContent(respContent);
respMessage = MessageUtil.textMessageToXml(textMessage);
}
// 取消订阅
else if (eventType.equals(MessageUtil.EVENT_TYPE_UNSUBSCRIBE)) {
// TODO 取消订阅后用户再收不到公众号发送的消息，因此不需要回复消息
}
// 自定义菜单点击事件
else if (eventType.equals(MessageUtil.EVENT_TYPE_CLICK)) {
// TODO 自定义菜单权没有开放，暂不处理该类消息
String eventKey = requestMap.get("EventKey");
if (eventKey.equals("11")) {
respContent = "百度菜单项被点击！";
} else if (eventKey.equals("12")) {
respContent = "公交查询菜单项被点击！";
} else if (eventKey.equals("13")) {
respContent = "周边搜索菜单项被点击！";
} else if (eventKey.equals("14")) {
respContent = "历史上的今天菜单项被点击！";
} else if (eventKey.equals("21")) {
respContent = "最新动态！";
} else if (eventKey.equals("22")) {
respContent = "我要专接本！";
}
textMessage.setContent(respContent);
respMessage = MessageUtil.textMessageToXml(textMessage);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return respMessage;
}
}
3、代码说明：
1）调用消息工具类MessageUtil解析微信发来的xml格式的消息，解析的结果放在HashMap里；
2）从HashMap中取出消息中的字段；
3）组装要返回的文本消息对象；
4）演示了如何接收微信发送的各类型的消息，根据MsgType判断属于哪种类型的消息；
5）调用消息工具类MessageUtil将要返回的文本消息对象TextMessage转化成xml格式的字符串；