import com.google.common.collect.Maps;
import com.google.gson.Gson;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestTemplate;

import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.*;

public class Demo {

  // 商户私钥字符串
  private final String YOUR_PRIVATE_KEY = "your_private_key";
  // 查询订单号 URL
  private final String QUERY_TRADE_URL = "https://api.edgeros.com/pay/v1/transactions/trade";
  // 签名算法
  private String sign_type = "SHA256withRSA";

  /**
   * 查询订单 demo 方法
   */
  public void queryTrade(String transaction_no, String mch_trade_no) {

    // 商户生成随机串
    String nonce = "your nonce";
    // 商户号
    String mch_no = "your merchant number";

    // 收集计算签名所需要的参数
    HashMap<String, Object> signParamMap = new HashMap<>();
    // 请求参数
    signParamMap.put("transaction_no", transaction_no);
    signParamMap.put("mch_trade_no", mch_trade_no);
    // 增加签名相关参数
    signParamMap.put("nonce", nonce);
    signParamMap.put("mch_no", mch_no);
    signParamMap.put("sign_type", sign_type);

    try {
      // 计算签名
      String sign = getSign(signParamMap);
      // 增加请求头
      RestTemplate restTemplate = new RestTemplate();

      HttpHeaders headers = new HttpHeaders();
      headers.add("x-acopay-nonce", nonce);
      headers.add("x-acopay-mch-no", mch_no);
      headers.add("x-acopay-sign-type", sign_type);
      headers.add("x-acopay-sign", sign);
      HttpEntity<String> entity = new HttpEntity<>("", headers);

      // 发送请求
      ResponseEntity<Map> returnMap = restTemplate.exchange(QUERY_TRADE_URL +
         "?mch_trade_no=" + mch_trade_no,
           HttpMethod.GET, entity,
            Map.class);
       // 根据响应是否成功 进行验签、业务处理等操作

    } catch (Exception e) {
      // 进行异常处理
    }
  }

  /**
   * 获取签名值 demo 方法
   */
  public String getSign(Map<String, Object> signParamMap) throws Exception {
    // 过滤空值
    Map<String, Object> filterMap = Maps.filterEntries(signParamMap, x -> !Objects.isNull(x.getValue()));
    // 进行排序
    TreeMap<String, Object> sortedMap = new TreeMap<>();
    sortedMap.putAll(filterMap);
    // 序列化为 json
    String signJson = new Gson().toJson(sortedMap);
    // 进行签名
    String sign = sign(signJson.getBytes("UTF-8"));
    return sign;
  }
  /**
   * 计算签名 demo 方法
   */
  private String sign(byte[] message) throws Exception{

    // 把私钥字符串转换为 PrivateKey
    byte[] buffer = Base64.getDecoder().decode(YOUR_PRIVATE_KEY);
    PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    // 获取 PrivateKey
    PrivateKey privateKey = keyFactory.generatePrivate(keySpec);

    // 用换好的 PrivateKey 进行签名
    Signature signature = Signature.getInstance(sign_type);
    signature.initSign(privateKey);
    signature.update(message);
    return Base64.getEncoder().encodeToString(signature.sign());
  }

}

import com.google.common.collect.Maps;
import com.google.gson.Gson;
import org.apache.commons.lang3.StringUtils;

import java.io.UnsupportedEncodingException;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;
import java.util.*;

public class Demo {

  // 翼辉支付平台公钥字符串
  private final String ACOINFO_PAY_PUBLIC_KEY = "acoinfo_pay_public_key";
  // 签名算法
  private String sign_type = "SHA256withRSA";

  /**
   * 组装验签参数并验签
   */
  public boolean verifySign(Map<String, Object> returnMap) throws Exception {
    // 过滤空值
    Map<String, Object> filterMap = Maps.filterEntries(returnMap, x -> !Objects.isNull(x.getValue()));
    // 利用 TreeMap 进行自然排序
    TreeMap<String, Object> sortedMap = new TreeMap<>();
    sortedMap.putAll(filterMap);
    // 获取业务信息
    Map<String, Object> dataMap = (Map) filterMap.get("data");
    // 签名值
    String sign = "";
    if (!Objects.isNull(dataMap)) {
      // 取 data 字段中的签名值
      sign = (String) dataMap.get("sign");
      // 过滤空值和 sign 字段
      Map<String, Object> filterDataMap = Maps.filterEntries(dataMap, x ->
        (!StringUtils.equals(x.getKey(), "sign") && !Objects.isNull(x.getValue())));
      // 业务数据进行排序
      TreeMap<String, Object> dataSortedMap = new TreeMap<>();
      dataSortedMap.putAll(filterDataMap);
      // 排好后放入 sortedMap 替换原来的无序 data
      sortedMap.put("data", dataSortedMap);
    }
    // 序列化为 json
    String verifyJson = new Gson().toJson(sortedMap);
    return verify(sign, verifyJson);

  }

  /**
   * 验签方法
   */
  private boolean verify(String sign, String verifyJson) throws NoSuchAlgorithmException, InvalidKeySpecException, InvalidKeyException, SignatureException, UnsupportedEncodingException {
    // 把翼辉支付平台公钥字符串转换为 PublicKey
    byte[] buffer = Base64Helper.decode(ACOINFO_PAY_PUBLIC_KEY);
    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
    PublicKey publicKey = keyFactory.generatePublic(keySpec);
    // 进行验签操作
    Signature signature = Signature.getInstance(sign_type);
    signature.initVerify(publicKey);
    signature.update(verifyJson.getBytes("UTF-8"));
    // 签名参数 sign 的值经过 base64 解码后验签
    return signature.verify(Base64.getDecoder().decode(sign));
  }
}