【思前享后】交易平台开发原理

1.交易平台相关功能梳理

1.1.前台展示

前台相关功能

1.2.后台管理

后台相关功能

2.技术难度以及实现方法

2.1.谷歌验证码

2.1.1.相关代码

谷歌验证码工具类：

package com.auth.google; 
  
import java.security.InvalidKeyException; 
import java.security.NoSuchAlgorithmException; 
import java.security.SecureRandom; 
import javax.crypto.Mac; 
import javax.crypto.spec.SecretKeySpec; 
import org.apache.commons.codec.binary.Base32; 
import org.apache.commons.codec.binary.Base64; 
  
/** 
 * 
 * 
 * google身份验证器，java服务端实现 
 * 
 * @author yangbo 
 * 
 * @version 创建时间：2017年8月14日 上午10:10:02 
 * 
 * 
 */
public class GoogleAuthenticator { 
  
 // 生成的key长度( Generate secret key length) 
 public static final int SECRET_SIZE = 10; 
  
 public static final String SEED = "g8GjEvTbW5oVSV7avL47357438reyhreyuryetredLDVKs2m0QN7vxRs2im5MDaNCWGmcD2rvcZx"; 
 // Java实现随机数算法 
 public static final String RANDOM_NUMBER_ALGORITHM = "SHA1PRNG"; 
 // 最多可偏移的时间 
 int window_size = 3; // default 3 - max 17 
  
 /** 
 * set the windows size. This is an integer value representing the number of 
 * 30 second windows we allow The bigger the window, the more tolerant of 
 * clock skew we are. 
 * 
 * @param s 
 *  window size - must be >=1 and <=17. Other values are ignored 
 */
 public void setWindowSize(int s) { 
 if (s >= 1 && s <= 17) 
  window_size = s; 
 } 
  
 /** 
 * Generate a random secret key. This must be saved by the server and 
 * associated with the users account to verify the code displayed by Google 
 * Authenticator. The user must register this secret on their device. 
 * 生成一个随机秘钥 
 * 
 * @return secret key 
 */
 public static String generateSecretKey() { 
 SecureRandom sr = null; 
 try { 
  sr = SecureRandom.getInstance(RANDOM_NUMBER_ALGORITHM); 
  sr.setSeed(Base64.decodeBase64(SEED)); 
  byte[] buffer = sr.generateSeed(SECRET_SIZE); 
  Base32 codec = new Base32(); 
  byte[] bEncodedKey = codec.encode(buffer); 
  String encodedKey = new String(bEncodedKey); 
  return encodedKey; 
 } catch (NoSuchAlgorithmException e) { 
  // should never occur... configuration error 
 } 
 return null; 
 } 
  
 /** 
 * Return a URL that generates and displays a QR barcode. The user scans 
 * this bar code with the Google Authenticator application on their 
 * smartphone to register the auth code. They can also manually enter the 
 * secret if desired 
 * 
 * @param user 
 *  user id (e.g. fflinstone) 
 * @param host 
 *  host or system that the code is for (e.g. myapp.com) 
 * @param secret 
 *  the secret that was previously generated for this user 
 * @return the URL for the QR code to scan 
 */
 public static String getQRBarcodeURL(String user, String host, String secret) { 
 String format = "http://www.google.com/chart?chs=200x200&chld=M%%7C0&cht=qr&chl=otpauth://totp/%s@%s?secret=%s"; 
 return String.format(format, user, host, secret); 
 } 
  
 /** 
 * 生成一个google身份验证器，识别的字符串，只需要把该方法返回值生成二维码扫描就可以了。 
 * 
 * @param user 
 *  账号 
 * @param secret 
 *  密钥 
 * @return 
 */
 public static String getQRBarcode(String user, String secret) { 
 String format = "otpauth://totp/%s?secret=%s"; 
 return String.format(format, user, secret); 
 } 
  
 /** 
 * Check the code entered by the user to see if it is valid 验证code是否合法 
 * 
 * @param secret 
 *  The users secret. 
 * @param code 
 *  The code displayed on the users device 
 * @param t 
 *  The time in msec (System.currentTimeMillis() for example) 
 * @return 
    检查验证码的合法性
 */
 public boolean check_code(String secret, long code, long timeMsec) { 
 Base32 codec = new Base32(); 
 byte[] decodedKey = codec.decode(secret); 
 // convert unix msec time into a 30 second "window" 
 // this is per the TOTP spec (see the RFC for details) 
 long t = (timeMsec / 1000L) / 30L; 
 // Window is used to check codes generated in the near past. 
 // You can use this value to tune how far you're willing to go. 
 for (int i = -window_size; i <= window_size; ++i) { 
  long hash; 
  try { 
  hash = verify_code(decodedKey, t + i); 
  } catch (Exception e) { 
  // Yes, this is bad form - but 
  // the exceptions thrown would be rare and a static 
  // configuration problem 
  e.printStackTrace(); 
  throw new RuntimeException(e.getMessage()); 
  // return false; 
  } 
  if (hash == code) { 
  return true; 
  } 
 } 
 // The validation code is invalid. 
 return false; 
 } 
  
 private static int verify_code(byte[] key, long t) throws NoSuchAlgorithmException, InvalidKeyException { 
 byte[] data = new byte[8]; 
 long value = t; 
 for (int i = 8; i-- > 0; value >>>= 8) { 
  data[i] = (byte) value; 
 } 
 SecretKeySpec signKey = new SecretKeySpec(key, "HmacSHA1"); 
 Mac mac = Mac.getInstance("HmacSHA1"); 
 mac.init(signKey); 
 byte[] hash = mac.doFinal(data); 
 int offset = hash[20 - 1] & 0xF; 
 // We're using a long because Java hasn't got unsigned int. 
 long truncatedHash = 0; 
 for (int i = 0; i < 4; ++i) { 
  truncatedHash <<= 8; 
  // We are dealing with signed bytes: 
  // we just keep the first byte. 
  truncatedHash |= (hash[offset + i] & 0xFF); 
 } 
 truncatedHash &= 0x7FFFFFFF; 
 truncatedHash %= 1000000; 
 return (int) truncatedHash; 
 } 
} 

谷歌验证码测试：

package com.lyw.test.goole;

import org.junit.Test;

import com.lyw.goole.GoogleAuthenticator;

/**
 * 
 * 
 * 身份认证测试
 * 
 * @author yangbo
 * 
 * @version 创建时间：2017年8月14日 上午11:09:23
 * 
 * 
 */
public class AuthTest {
    // 当测试authTest时候，把genSecretTest生成的secret值赋值给它
    private static String secret = "WQACSWXEWMVW4KVV";

    @Test
    public void genSecretTest() {// 生成密钥
        secret = GoogleAuthenticator.generateSecretKey();
        // 把这个qrcode生成二维码，用google身份验证器扫描二维码就能添加成功
        String qrcode = GoogleAuthenticator.getQRBarcode("[email protected]",secret);
        System.out.println("qrcode:" + qrcode + ",key:" + secret);
    }

    /**
     * 对app的随机生成的code,输入并验证
     */
    @Test
    public void verifyTest() {
        long code = 995694;
        long t = System.currentTimeMillis();
        GoogleAuthenticator ga = new GoogleAuthenticator();
        ga.setWindowSize(5);
        boolean r = ga.check_code(secret, code, t);
        System.out.println("检查code是否正确？" + r);
    }
}

  谷歌动态验证码如果别人不知道你的秘钥和账号是没办法知道你的动态验证码的，它就像一个口令一样。具体的实现原理可以参考代码并结合参考文章看。

3.撮合交易

撮合流程

3.1.数据库撮合交易

数据库撮合交易

  这里数据库的撮合交易，如果是买方1，会不断的去数据库查询匹配的数据，一旦查到交易成功，进程中断，然后把交易数据存储到买卖双方的库里。

3.2.内存撮合交易

内存撮合

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参考文章：
【1】http://www.jb51.net/article/121243.htm
【2】http://blog.csdn.net/lonelyroamer/article/details/7656338
【3】撮合系统设计·中生代技术-2016-09-16 23:20:09