微信公众平台java开发详解

说明：
本次的教程主要是对微信公众平台开发者模式的讲解，网络上很多类似文章，但很多都让初学微信开发的人一头雾水，所以总结自己的微信开发经验，将微信开发的整个过程系统的列出，并对主要代码进行讲解分析，让初学者尽快上手。

在阅读本文之前，应对微信公众平台的官方开发文档有所了解，知道接收和发送的都是xml格式的数据。另外，在做内容回复时用到了图灵机器人的api接口，这是一个自然语言解析的开放平台，可以帮我们解决整个微信开发过程中最困难的问题，此处不多讲，下面会有其详细的调用方式。

1.1 在登录微信官方平台之后，开启开发者模式，此时需要我们填写url和token，所谓url就是我们自己服务器的接口，用WechatServlet.java来实现，相关解释已经在注释中说明，代码如下：

package demo.servlet;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import demo.process.WechatProcess;/** * 微信服务端收发消息接口 *  * @author pamchen-1 *  */public class WechatServlet extends HttpServlet {/** * The doGet method of the servlet. <br> *  * This method is called when a form has its tag value method equals to get. *  * @param request *            the request send by the client to the server * @param response *            the response send by the server to the client * @throws ServletException *             if an error occurred * @throws IOException *             if an error occurred */public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {request.setCharacterEncoding("UTF-8");response.setCharacterEncoding("UTF-8");/** 读取接收到的xml消息 */StringBuffer sb = new StringBuffer();InputStream is = request.getInputStream();InputStreamReader isr = new InputStreamReader(is, "UTF-8");BufferedReader br = new BufferedReader(isr);String s = "";while ((s = br.readLine()) != null) {sb.append(s);}String xml = sb.toString();//次即为接收到微信端发送过来的xml数据String result = "";/** 判断是否是微信接入激活验证，只有首次接入验证时才会收到echostr参数，此时需要把它直接返回 */String echostr = request.getParameter("echostr");if (echostr != null && echostr.length() > 1) {result = echostr;} else {//正常的微信处理流程result = new WechatProcess().processWechatMag(xml);}try {OutputStream os = response.getOutputStream();os.write(result.getBytes("UTF-8"));os.flush();os.close();} catch (Exception e) {e.printStackTrace();}}/** * The doPost method of the servlet. <br> *  * This method is called when a form has its tag value method equals to * post. *  * @param request *            the request send by the client to the server * @param response *            the response send by the server to the client * @throws ServletException *             if an error occurred * @throws IOException *             if an error occurred */public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

1.2 相应的web.xml配置信息如下，在生成WechatServlet.java的同时，可自动生成web.xml中的配置。前面所提到的url处可以填写例如：http;//服务器地址/项目名/wechat.do

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  <servlet>    <description>This is the description of my J2EE component</description>    <display-name>This is the display name of my J2EE component</display-name>    <servlet-name>WechatServlet</servlet-name>    <servlet-class>demo.servlet.WechatServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>WechatServlet</servlet-name>    <url-pattern>/wechat.do</url-pattern>  </servlet-mapping>  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list></web-app>

1.3 通过以上代码，我们已经实现了微信公众平台开发的框架，即开通开发者模式并成功接入、接收消息和发送消息这三个步骤。

下面就讲解其核心部分——解析接收到的xml数据，并以文本类消息为例，通过图灵机器人api接口实现智能回复。


2.1 首先看一下整体流程处理代码，包括：xml数据处理、调用图灵api、封装返回的xml数据。

package demo.process;import java.util.Date;import demo.entity.ReceiveXmlEntity;/** * 微信xml消息处理流程逻辑类 * @author pamchen-1 * */public class WechatProcess {/** * 解析处理xml、获取智能回复结果（通过图灵机器人api接口） * @param xml 接收到的微信数据 * @return最终的解析结果（xml格式数据） */public String processWechatMag(String xml){/** 解析xml数据 */ReceiveXmlEntity xmlEntity = new ReceiveXmlProcess().getMsgEntity(xml);/** 以文本消息为例，调用图灵机器人api接口，获取回复内容 */String result = "";if("text".endsWith(xmlEntity.getMsgType())){result = new TulingApiProcess().getTulingResult(xmlEntity.getContent());}/** 此时，如果用户输入的是“你好”，在经过上面的过程之后，result为“你也好”类似的内容  *  因为最终回复给微信的也是xml格式的数据，所有需要将其封装为文本类型返回消息 * */result = new FormatXmlProcess().formatXmlAnswer(xmlEntity.getFromUserName(), xmlEntity.getToUserName(), result);return result;}}

2.2 解析接收到的xml数据，此处有两个类，ReceiveXmlEntity.java和ReceiveXmlProcess.java，通过反射的机制动态调用实体类中的set方法，可以避免很多重复的判断，提高代码效率，代码如下：

package demo.entity;/** * 接收到的微信xml实体类 * @author pamchen-1 * */public class ReceiveXmlEntity {private String ToUserName="";private String FromUserName="";private String CreateTime="";private String MsgType="";private String MsgId="";private String Event="";private String EventKey="";private String Ticket="";private String Latitude="";private String Longitude="";private String Precision="";private String PicUrl="";private String MediaId="";private String Title="";private String Description="";private String Url="";private String Location_X="";private String Location_Y="";private String Scale="";private String Label="";private String Content="";private String Format="";private String Recognition="";public String getRecognition() {return Recognition;}public void setRecognition(String recognition) {Recognition = recognition;}public String getFormat() {return Format;}public void setFormat(String format) {Format = format;}public String getContent() {return Content;}public void setContent(String content) {Content = content;}public String getLocation_X() {return Location_X;}public void setLocation_X(String locationX) {Location_X = locationX;}public String getLocation_Y() {return Location_Y;}public void setLocation_Y(String locationY) {Location_Y = locationY;}public String getScale() {return Scale;}public void setScale(String scale) {Scale = scale;}public String getLabel() {return Label;}public void setLabel(String label) {Label = label;}public String getTitle() {return Title;}public void setTitle(String title) {Title = title;}public String getDescription() {return Description;}public void setDescription(String description) {Description = description;}public String getUrl() {return Url;}public void setUrl(String url) {Url = url;}public String getPicUrl() {return PicUrl;}public void setPicUrl(String picUrl) {PicUrl = picUrl;}public String getMediaId() {return MediaId;}public void setMediaId(String mediaId) {MediaId = mediaId;}public String getEventKey() {return EventKey;}public void setEventKey(String eventKey) {EventKey = eventKey;}public String getTicket() {return Ticket;}public void setTicket(String ticket) {Ticket = ticket;}public String getLatitude() {return Latitude;}public void setLatitude(String latitude) {Latitude = latitude;}public String getLongitude() {return Longitude;}public void setLongitude(String longitude) {Longitude = longitude;}public String getPrecision() {return Precision;}public void setPrecision(String precision) {Precision = precision;}public String getEvent() {return Event;}public void setEvent(String event) {Event = event;}public String getMsgId() {return MsgId;}public void setMsgId(String msgId) {MsgId = msgId;}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 String getCreateTime() {return CreateTime;}public void setCreateTime(String createTime) {CreateTime = createTime;}public String getMsgType() {return MsgType;}public void setMsgType(String msgType) {MsgType = msgType;}}

package demo.process;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.util.Iterator;import org.dom4j.Document;import org.dom4j.DocumentHelper;import org.dom4j.Element;import demo.entity.ReceiveXmlEntity;/** * 解析接收到的微信xml，返回消息对象 * @author pamchen-1 * */public class ReceiveXmlProcess {/** * 解析微信xml消息 * @param strXml * @return */public ReceiveXmlEntity getMsgEntity(String strXml){ReceiveXmlEntity msg = null;try {if (strXml.length() <= 0 || strXml == null)return null; // 将字符串转化为XML文档对象Document document = DocumentHelper.parseText(strXml);// 获得文档的根节点Element root = document.getRootElement();// 遍历根节点下所有子节点Iterator<?> iter = root.elementIterator();// 遍历所有结点msg = new ReceiveXmlEntity();//利用反射机制，调用set方法//获取该实体的元类型Class<?> c = Class.forName("demo.entity.ReceiveXmlEntity");msg = (ReceiveXmlEntity)c.newInstance();//创建这个实体的对象while(iter.hasNext()){Element ele = (Element)iter.next();//获取set方法中的参数字段（实体类的属性）Field field = c.getDeclaredField(ele.getName());//获取set方法，field.getType())获取它的参数数据类型Method method = c.getDeclaredMethod("set"+ele.getName(), field.getType());//调用set方法method.invoke(msg, ele.getText());}} catch (Exception e) {// TODO: handle exceptionSystem.out.println("xml 格式异常: "+ strXml);e.printStackTrace();}return msg;}}

2.3 调用图灵机器人api接口，获取智能回复内容：

package demo.process;import java.io.IOException;import java.io.UnsupportedEncodingException;import java.net.URLEncoder;import org.apache.http.HttpResponse;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.methods.HttpGet;import org.apache.http.impl.client.HttpClients;import org.apache.http.util.EntityUtils;import org.json.JSONException;import org.json.JSONObject;/** * 调用图灵机器人api接口，获取智能回复内容 * @author pamchen-1 * */public class TulingApiProcess {/** * 调用图灵机器人api接口，获取智能回复内容，解析获取自己所需结果 * @param content * @return */public String getTulingResult(String content){/** 此处为图灵api接口，参数key需要自己去注册申请，先以11111111代替 */String apiUrl = "http://www.tuling123.com/openapi/api?key=11111111&info=";String param = "";try {param = apiUrl+URLEncoder.encode(content,"utf-8");} catch (UnsupportedEncodingException e1) {// TODO Auto-generated catch blocke1.printStackTrace();} //将参数转为url编码/** 发送httpget请求 */HttpGet request = new HttpGet(param);String result = "";try {HttpResponse response = HttpClients.createDefault().execute(request);if(response.getStatusLine().getStatusCode()==200){result = EntityUtils.toString(response.getEntity());}} catch (ClientProtocolException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}/** 请求失败处理 */if(null==result){return "对不起，你说的话真是太高深了……";}try {JSONObject json = new JSONObject(result);//以code=100000为例，参考图灵机器人api文档if(100000==json.getInt("code")){result = json.getString("text");}} catch (JSONException e) {// TODO Auto-generated catch blocke.printStackTrace();}return result;}}

2.4 将结果封装为微信规定的xml格式，并返回给1.1中创建的servlet接口。

package demo.process;import java.util.Date;/** * 封装最终的xml格式结果 * @author pamchen-1 * */public class FormatXmlProcess {/** * 封装文字类的返回消息 * @param to * @param from * @param content * @return */public String formatXmlAnswer(String to, String from, String content) {StringBuffer sb = new StringBuffer();Date date = new Date();sb.append("<xml><ToUserName><![CDATA[");sb.append(to);sb.append("]]></ToUserName><FromUserName><![CDATA[");sb.append(from);sb.append("]]></FromUserName><CreateTime>");sb.append(date.getTime());sb.append("</CreateTime><MsgType><![CDATA[text]]></MsgType><Content><![CDATA[");sb.append(content);sb.append("]]></Content><FuncFlag>0</FuncFlag></xml>");return sb.toString();}}