微信公众号开发--关注后自动回复（Java记录篇）

转载自 http://blog.csdn.net/lyq8479/article/details/8944988
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文中所用到的jar dom4j XStream的jar包
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开发者通过signature对请求进行校验，若确认此次校验来自微信服务器，请原样返回echostr参数内容，则接入成功，否则接入失败！
打开IDE,创建一个Java Web工程，并新建一个能够处理请求的Servlet，命名任意。

package com.zhenqi.servlet;

import com.zhenqi.util.CheckUtil;
import com.zhenqi.util.MessageUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;

/**
 * Created by wuming on 2017/9/15.
 */
public class HandleWeiXinMessageServlet extends HttpServlet {

    public static final Logger logger = LoggerFactory.getLogger(HandleWeiXinMessageServlet.class);
    /**
     * VersionUID
     */
    private static final long serialVersionUID = 1L;
   

    /*
     * URL验证
     * (non-Javadoc)
     * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        String signature = req.getParameter("signature");
        String timestamp = req.getParameter("timestamp");
        String nonce = req.getParameter("nonce");
        String echostr = req.getParameter("echostr");
        logger.info("echostr" + echostr);
        PrintWriter out = resp.getWriter();
        if(CheckUtil.checkSignature(signature, timestamp, nonce)){
        	out.write(echostr);
        } 
    }

以上servlet doGet方法请求用到了校验signature的方法，以下是CheckUtil.java完整代码。
其中要注意Token要与微信相对应。

package com.zhenqi.util;

import java.security.MessageDigest;
import java.util.Arrays;

public class CheckUtil {
	//与接口配置信息中的Token要一致 
	private static final String token="weixinStudy";
	
	public static boolean checkSignature(String signature,String timestrap,
			String nonce){
		
		String[] arr=new String[]{token,timestrap,nonce};
		// 将token、timestamp、nonce三个参数进行字典序排序 
		Arrays.sort(arr);
		
		StringBuffer buf=new StringBuffer();
		for(int i=0;i>> 4 & 0xf];
				buf[k++]=hexDigits[byTemp & 0xf];
			}
			return new String(buf);
		}catch(Exception e){
			return null;
		}
	}

}

而后再回到servlet请求类里，编写doPost方法。用户关注就是触发一个事件。

protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

    	req.setCharacterEncoding("UTF-8");
        resp.setCharacterEncoding("UTF-8");
        PrintWriter out = resp.getWriter();
        try {
            Map map = MessageUtil.xmlToMap(req);
            String toUserName = map.get("ToUserName");
            String fromUserName = map.get("FromUserName");
            String msgType = map.get("MsgType");
            String content = map.get("Content");    
            //判断请求是否事件类型 event
           if(MessageUtil.MESSAGE_EVENT.equals(msgType)){
                String eventType = map.get("Event");
                //若是关注事件  subscribe
                if(MessageUtil.EVENT_SUB.equals(eventType)){
                    String mycontent = MessageUtil.menuText();
                    message = MessageUtil.initText(toUserName, fromUserName, mycontent);

                }
            } 
            out.print(message);
        } catch (Exception e) {
        	e.printStackTrace();
            out.close();
        }   
       
    }

MessageUtl.java类如下：

public class MessageUtil {
	public static final String MESSAGE_TEXT = "text";
    public static final String MESSAGE_IMAGE = "image";
    public static final String MESSAGE_VOICE = "voice";
    public static final String MESSAGE_VIDEO = "video";
    public static final String MESSAGE_LINK = "link";
    public static final String MESSAGE_LOCATION = "location";
    public static final String MESSAGE_EVENT = "event";

    public static final String EVENT_SUB = "subscribe";
    public static final String EVENT_UNSUB = "unsubscribe";
    public static final String EVENT_CLICK = "CLICK";
    public static final String EVENT_VIEW = "VIEW";

    /**
     * xml转为map
     * @param request
     * @return
     * @throws DocumentException
     * @throws IOException
     */
    public static Map xmlToMap(HttpServletRequest request ) throws DocumentException, IOException
    {
        Map map = new HashMap();

        SAXReader reader = new SAXReader();

        InputStream ins = request.getInputStream();
        Document doc = reader.read(ins);

        Element root = doc.getRootElement();
        List list = root.elements();
        for (Element e : list) {
            map.put(e.getName(), e.getText());
        }
        ins.close();
        return map;
    }

    public static String textMessageToXml(TextMessage textMessage){
        XStream xstream = new XStream();
        xstream.alias("xml", textMessage.getClass());
        return xstream.toXML(textMessage);

    }
    public static String initText(String toUserName, String fromUserName, String content){
        TextMessage text = new TextMessage();
        text.setFromUserName(toUserName);
        text.setToUserName(fromUserName);
        text.setMsgType(MESSAGE_TEXT);
        text.setCreateTime(new Date().getTime());
        text.setContent(content);
        return textMessageToXml(text);
    }

    public static String menuText(){
        StringBuffer sb = new StringBuffer();
        sb.append("      你关注，\n");
        sb.append("     或者不关注，\n");
        sb.append("      【你我杂志刊】都在这里!\n");
        sb.append("     不离，\n");
        sb.append("      不弃！\n\n");
        sb.append("该公众号已实现以下功能：\n");
        sb.append("回复“天气”、“翻译” 将有该功能的介绍与使用，\n");
        sb.append("如您在使用该公众有任何宝贵意见，欢迎反馈！\n\n");
        sb.append("反馈邮箱：[email protected]");
        return sb.toString();       
    }
}

最终效果如下图

扫描下方二维码可关注 你我杂志刊 关注或者 微信搜索公众号 你我杂志刊