微信公众号关注或取关后再处理我们自己的业务逻辑

/**
 * @description
 */
public class SignUtil {

        /**
         * 验证签名
         * @param token
         * @param signature 签名用来核实最后的结果是否一致
         * @param timestamp 时间标记
         * @param nonce 随机数字标记
         * @return 一个布尔值确定最后加密得到的是否与signature一致
         */
        public static boolean checkSignature(String token, String signature, String timestamp, String nonce) {
            //将传入参数变成一个String数组然后进行字典排序
            String[] arr = new String[] { token, timestamp, nonce };
            // 将token、timestamp、nonce三个参数进行字典排序
            Arrays.sort(arr);
            //创建一个对象储存排序后三个String的结合体
            StringBuilder content = new StringBuilder();
            for (int i = 0; i < arr.length; i++) {
                content.append(arr[i]);
            }
            MessageDigest md = null;
            String tmpStr = null;

            try {
                md = MessageDigest.getInstance("SHA-1");
                byte[] digest = md.digest(content.toString().getBytes());
                tmpStr = byteToStr(digest);
            } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
            }

            content = null;
            // 将sha1加密后的字符串可与signature对比
            return tmpStr != null ? tmpStr.equals(signature.toUpperCase()) : false;
        }

        /**
         * 将字节数组转换为十六进制字符串
         * @param byteArray
         * @return
         */
        private static String byteToStr(byte[] byteArray) {
            String strDigest = "";
            for (int i = 0; i < byteArray.length; i++) {
                strDigest += byteToHexStr(byteArray[i]);
            }
            return strDigest;
        }

        /**
         * 将每一个字节转换为十六进制字符串
         * @param mByte
         * @return
         */
        private static String byteToHexStr(byte mByte) {
            //转位数参照表
            char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
            char[] tempArr = new char[2];
            tempArr[0] = Digit[(mByte >>> 4) & 0X0F];
            tempArr[1] = Digit[mByte & 0X0F];
            //得到进制码的字符串
            String s = new String(tempArr);
            return s;
        }
}

/**
 * @description
 */
public class MsgUtil {

    public static final String MSGTYPE_EVENT = "event";//消息类型--事件
    public static final String MESSAGE_SUBSCIBE = "subscribe";//消息事件类型--订阅事件
    public static final String MESSAGE_UNSUBSCIBE = "unsubscribe";//消息事件类型--取消订阅事件
    public static final String MESSAGE_TEXT = "text";//消息类型--文本消息

    /**
     * 组装文本消息
     */
    public static String textMsg(String toUserName,String fromUserName,String content){
        TextMsg text = new TextMsg();
        text.setFromUserName(toUserName);
        text.setToUserName(fromUserName);
        text.setMsgType(MESSAGE_TEXT);
        text.setCreateTime(new Date().getTime());
        text.setContent(content);
        return XmlUtil.textMsgToxml(text);
    }

    /**
     * 响应订阅事件--回复文本消息
     */
    public static String subscribeForText(String toUserName,String fromUserName,String content){
        return textMsg(toUserName, fromUserName, content);
    }

    /**
     * 响应取消订阅事件
     */
    public static String unsubscribeForText(String toUserName,String fromUserName,String content){
        System.out.println("用户："+ fromUserName +"取消关注~");
        return "";
    }
}

parameter:
  #微信公众号
  publicAppId: 微信公众号AppId
  publicAppSecret: 微信公众号AppSecret

/**
 * @description
 */
@Controller
@RequestMapping(value = "/message/weixin")
public class WxPublicController {

    protected static Logger logger = LoggerFactory.getLogger(WxPublicController.class);
   //填写和公众号后台配置的一样的token
    private static final String TOKENN = "";

    /**
     * 微信公众号appId
     */
    @Value("${parameter.publicAppId}")
    private String publicAppId;
    /**
     * 微信公众号appSecret
     */
    @Value("${parameter.publicAppSecret}")
    private String publicAppSecret;

    @RequestMapping(method = RequestMethod.GET)
    public void get(HttpServletRequest request, HttpServletResponse response) {
        // 微信加密签名，signature结合了开发者填写的token参数和请求中的timestamp参数、nonce参数。
        String signature = request.getParameter("signature");
        // 时间戳
        String timestamp = request.getParameter("timestamp");
        // 随机数
        String nonce = request.getParameter("nonce");
        // 随机字符串
        String echostr = request.getParameter("echostr");
        PrintWriter out = null;
        try {
            out = response.getWriter();
            // 通过检验signature对请求进行校验，若校验成功则原样返回echostr，否则接入失败
            if (SignUtil.checkSignature(TOKENN, signature, timestamp, nonce)) {
                out.print(echostr);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (out != null ) {
                out.close();
            }
        }
    }

    @RequestMapping(method = RequestMethod.POST)
    public void post(HttpServletRequest request, HttpServletResponse response) {
        // 响应消息
        PrintWriter out = null;
        String resMessage = "";
        try {
            request.setCharacterEncoding("UTF-8");
            response.setCharacterEncoding("UTF-8");
            //把微信返回的xml信息转义成map
            Map<String, String> map = XmlUtil.parseXml(request);
            //消息来源用户标识
            String fromUserName = map.get("FromUserName");
            //消息目的用户标识
            String toUserName = map.get("ToUserName");
            //消息创建时间（整型）
            String createTime = map.get("CreateTime");
            //消息类型
            String msgType = map.get("MsgType");
            //事件类型：subscribe/unsubscribe
            String eventType = map.get("Event");
            //如果为事件类型
            if(MsgUtil.MSGTYPE_EVENT.equals(msgType)){
                //处理订阅事件
                if(MsgUtil.MESSAGE_SUBSCIBE.equals(eventType)){
                    resMessage = MsgUtil.subscribeForText(toUserName, fromUserName, "您好，谢谢您的关注！！！");
                    //TODO 业务逻辑
                    //处理取消订阅消息
                } else if(MsgUtil.MESSAGE_UNSUBSCIBE.equals(eventType)) {
                    //TODO 业务逻辑
                }
                logger.info("eventType:"+eventType+",fromUserName:"+fromUserName+",toUserName:"+toUserName+",msgType:"+msgType+",createTime:"+createTime);
            }
            out = response.getWriter();
            out.println(resMessage);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (out != null ) {
                out.close();
            }
        }
    }
}