1 if ("get".equalsIgnoreCase(request.getMethod())) {
 2                 StringBuffer sb = new StringBuffer();
 3                 // 从数据库找到该token或者设置token为 固定值
 4                 String token = "";
 5                 //1. 将token、timestamp、nonce三个参数进行字典序排序
 6                 //2. 将三个参数字符串拼接成一个字符串进行sha1加密
 7                 //3. 开发者获得加密后的字符串可与signature对比，标识该请求来源于微信
 8                 //若确认此次GET请求来自微信服务器，请原样返回echostr参数内容，则接入生效，成为开发者成功，否则接入失败。
 9                 String signature = request.getParameter("signature");
10                 String timestamp = request.getParameter("timestamp");
11                 String nonce = request.getParameter("nonce");
12                 String echostr = request.getParameter("echostr");    
13                 if(!WeixinUtil.checkSignature(signature,token,timestamp,nonce))
14                 {
15                     echostr = "";            
16                 }        
17                 sb.append(echostr);
18                 this.inputStream = new ByteArrayInputStream(sb.toString().getBytes("UTF-8"));
19             }

/**
     * 检查是否为合格的请求
     * @param signature
     * @param token
     * @param timestamp
     * @param nonce
     * @return true:合格<br/>
     *        false:不合格
     */
    public static boolean checkSignature(String signature, String token,String timestamp, String nonce) {
        if (signature == null || token == null || timestamp == null || nonce == null) {
            return false;
        }
        List<String> tmpArr = new ArrayList<String>();
        tmpArr.add(token);
        tmpArr.add(timestamp);
        tmpArr.add(nonce);
        Collections.sort(tmpArr);
        String tmpStr = tmpArr.get(0) + tmpArr.get(1) + tmpArr.get(2);
        try {
            MessageDigest md;
            md = MessageDigest.getInstance("SHA-1");
            md.update(tmpStr.getBytes());
            tmpStr = getFormattedText(md.digest());
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        if (tmpStr.equals(signature)) {
            return true;
        } else {
            return false;
        }
    }

 1 /**
 2      * 格式化
 3      * @param bytes
 4      * @return
 5      */
 6     public static String getFormattedText(byte[] bytes) {
 7         int len = bytes.length;
 8         StringBuilder buf = new StringBuilder(len * 2);
 9         for (int j = 0; j < len; j++) {
10             buf.append(HEX_DIGITS[(bytes[j] >> 4) & 0x0f]);
11             buf.append(HEX_DIGITS[bytes[j] & 0x0f]);
12         }
13         return buf.toString();
14     }