String signature = request.getParameter("signature");//接收微信get请求传过来的签名，
       String timestamp = request.getParameter("timestamp");//接受的签名与时间戳timestamp，nonce随机数，echpstr随机字符串三个经过字典排序，组成一个字符串，然后进行sha1加密，比较一致标示是来自微信的请求
       String nonce = request.getParameter("nonce");
       String echostr = request.getParameter("echostr");
       PrintWriter out = response.getWriter();
       System.out.println("---"+"signature="+signature+"timestamp="+timestamp+"nonce="+nonce+"echostr="+echostr);
       if (this.checkSignature(signature, timestamp, nonce)) {
           out.print(echostr);//只有你返回参数echostr时，他才会认为你这个接口是通的，才会提交成功
       }
        
       out.close();

    public static boolean checkSignature(String signature, String timestamp, String nonce){
        String[] arr = new String[]{token, timestamp, nonce};//存入数组中
        //字典排序
        Arrays.sort(arr);
         
        StringBuilder content = new StringBuilder();//将三个字符串依次连接为StringBuilder的一个对象
        for(int i = 0; i < arr.length; i++){
            content.append(arr[i]);
        }
        MessageDigest md = null;//java自带的加密类
        String tmpStr = null;
          
        try {
            md = MessageDigest.getInstance("SHA-1");
            //SHA-1加密
            byte[] digest = md.digest(content.toString().getBytes());//对组合后的字符串进行 sha1加密
            tmpStr = byteToStr(digest);//将字节转换为字符串
        } catch (NoSuchAlgorithmException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        content = null;
        // 比对 判断
        return tmpStr != null ? tmpStr.equals(signature.toUpperCase()): false;
    }

 private static String byteToStr(byte[] digest) {
         // TODO Auto-generated method stub
         String strDigest = "";
         for(int i = 0; i < digest.length; i++){
             strDigest += byteToHexStr(digest[i]);
         }
         return strDigest;
     }
     private static String byteToHexStr(byte b) {
         
         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[(b >>> 4) & 0X0F];
         tempArr[1] = Digit[b & 0X0F];
           
         String s = new String(tempArr);
         return s;
     }