接口规则

## 协议规则
传输方式：采用HTTP传输(生产环境建议HTTPS)
提交方式：`POST` 或 `GET`
内容类型：`application/json`
字符编码：`UTF-8`
签名算法：`RAS2`
## 参数规范
交易金额：默认为人民币交易，单位为分，参数值不能带小数。
时间参数：所有涉及时间参数均使用精确到毫秒的13位数值，如：1622016572190。时间戳具体是指从格林尼治时间1970年01月01日00时00分00秒起至现在的毫秒数。
## 签名算法
`签名生成的通用步骤如下`
第一步： 设所有发送或者接收到的数据为集合，提取指定字段`{"mchNo","appId","transferId","refundOrderId","channelOrderNo","mchRefundNo","refundAmount","mchOrderNo","wayCode","amount","notifyUrl","returnUrl","payOrderId","ifCode","state", "version", "payData"}`（不存在的字段跳过） 将提取出来的字段非空参数值的参数按照参数名ASCII码从小到大排序（字典序），使用URL键值对的格式（即key1=value1&key2=value2…）拼接成字符串stringA。
特别注意以下重要规则：
◆ 参数名ASCII码从小到大排序（字典序）；
◆ 如果参数的值为空不参与签名；
◆ 参数名区分大小写；
◆ 验证调用返回或支付中心主动通知签名时，传送的sign参数不参与签名，将生成的签名与该sign值作校验。
◆ 支付中心接口可能增加字段，验证签名时必须支持增加的扩展字段
第二步： 提取 采用RSA2对stringA进行加签得到sign值signValue
获取签名部分代码如下：
```java
public static void main(String[] args) throws Exception {
	//签名生成
	Map<String,Object> params = new HashMap<>();
	params.put("mchNo", "M123456789");
	params.put("appId", "664970095f763b7c914394e2");
	params.put("mchOrderNo", "M0123456789101");
	params.put("wayCode","ALI_WAP");
	params.put("body","接口调试");
	params.put("amount", "10000");
	params.put("clientIp", "192.168.0.1");
	params.put("subject","接口调试");
	params.put("returnUrl", "https://www.baidu.com");
	params.put("notifyUrl", "https://www.baidu.com");
	params.put("version", "1.0");
	params.put("signType","RAS2");
	
	// 待签名字符串
    String signStr = getSignStr(params);
	// 商户私钥
    String privateKey = "xxx"; // 商户后台获取的私钥
	//获取签名
    String sign = sign(signStr,privateKey);
}

public static String getSignStr(Map<String,Object> map){
    String[] signKeys = {"mchNo","appId","transferId", "refundOrderId", "channelOrderNo", "mchRefundNo", "refundAmount","mchOrderNo","wayCode","amount","notifyUrl","returnUrl","payOrderId","ifCode","state", "version", "payData"};
    ArrayList<String> list = new ArrayList<String>();
    for(Map.Entry<String,Object> entry:map.entrySet()){
        if(null != entry.getValue() && !"".equals(entry.getValue()) && Arrays.asList(signKeys).contains(entry.getKey())){
            list.add(entry.getKey() + "=" + entry.getValue());
        }
    }
    int size = list.size();
    String [] arrayToSort = list.toArray(new String[size]);
    Arrays.sort(arrayToSort, String.CASE_INSENSITIVE_ORDER);
    StringBuilder sb = new StringBuilder();
    for(int i = 0; i < size; i ++) {
        sb.append(arrayToSort[i]);
        if (i != size - 1){
            sb.append("&");
        }
    }
    String result = sb.toString();
    return result;
}

/**
* 对已加密数据进行签名
* @param data       已加密的数据
* @param privateKey 私钥
* @return 对已加密数据生成的签名
* @throws Exception
*/
public static String sign(String dataStr, String privateKey) throws Exception {
	byte[] data = dataStr.getBytes(StandardCharsets.UTF_8);
	byte[] keyBytes = Base64.decode(privateKey);
	PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
	KeyFactory keyFactory = KeyFactory.getInstance("RSA");
	PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
	Signature signature = Signature.getInstance("SHA256withRSA");
	signature.initSign(privateK);
	signature.update(data);
	return Base64.encode(signature.sign());
}
```
第三步： 将sign加入到请求参数里请求
`最终请求支付系统参数：`
```json
https://pay.trust-pay.cn/api/pay/unifiedOrder
{
    "mchNo": "M123456789",
    "appId": "664970095f763b7c914394e2",
    "mchOrderNo": "M0123456789101",
    "wayCode": "ALI_WAP",
    "body": "接口调试",
    "clientIp": "192.168.0.1",
    "amount": 10000,
    "subject": "接口调试",
	"returnUrl": "https://www.baidu.com",
    "notifyUrl": "https://www.baidu.com",
    "version": "1.0",
    "signType": "RAS2",
    "sign": "第二步生成的签名"
}
```

## 验签
支付成功后回调。为了验证是否是支付宝返回的数据，防止在传递过程中被篡改，是为了保证信息的安全性。

```java
public static void main(String[] args) throws Exception {

JSONObject params = getReqParamJSON();// 接收到的参数
	String sign = params.getSign();  // 提取sign
    params.remove("sign"); //除去sign
	
	// 待签名字符串
    String signStr = getSignStr(params);
	// 平台私钥
    String publicKey = "xxx"; // 商户后台获取的平台公钥
	//获取签名
	if (verify(signStr,publicKey,sign)){
        //验签成功
    }
}
/*
* 获取待签名字符串
* */
public static String getSignStr(Map<String,Object> map){
	String[] signKeys = {"mchNo","appId","transferId", "refundOrderId", "channelOrderNo", "mchRefundNo", "refundAmount","mchOrderNo","wayCode","amount","notifyUrl","returnUrl","payOrderId","ifCode","state", "version", "payData"};
	ArrayList<String> list = new ArrayList<String>();
	for(Map.Entry<String,Object> entry:map.entrySet()){
		if(null != entry.getValue() && !"".equals(entry.getValue()) && Arrays.asList(signKeys).contains(entry.getKey())){
			list.add(entry.getKey() + "=" + entry.getValue());
		}
	}
	int size = list.size();
	String [] arrayToSort = list.toArray(new String[size]);
	Arrays.sort(arrayToSort, String.CASE_INSENSITIVE_ORDER);
	StringBuilder sb = new StringBuilder();
	for(int i = 0; i < size; i ++) {
		sb.append(arrayToSort[i]);
		if (i != size - 1){
			sb.append("&");
		}
	}
	String result = sb.toString();
	return result;
}
	
	
/**
  * 验签
  *
  * @param dataStr      签名之前的数据
  * @param publicKey 商户后台里的平台公钥
  * @param sign      回调的sign值
  * @return 验签是否成功
  * @throws Exception
 */
public static boolean verify(String dataStr, String publicKey, String sign) throws Exception {
    byte[] data = dataStr.getBytes(StandardCharsets.UTF_8);
    byte[] keyBytes = Base64.decode(publicKey);
    X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    PublicKey publicK = keyFactory.generatePublic(keySpec);
    Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
    signature.initVerify(publicK);
    signature.update(data);
    return signature.verify(Base64.decode(sign));
 }
```