# 签名生成步骤说明

**第一步：**

设所有发送或者接收到的数据为集合M，将集合M内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：**

1. 参数名ASCII码从小到大排序（字典序)；
2. app\_id，timestamp为必填参数；timestamp为最近五分钟毫秒级时间戳，超过5分钟失效;
3. 如果参数的值为空不参与签名；
4. 参数名区分大小写；
5. 传送的sign参数不参与签名，将生成的签名与该sign值作校验。

**第二步：**

在stringA最后拼接上key得到stringSignTemp字符串，并对stringSignTemp进行HMAC-SHA256运算，再将得到的字符串所有字符转换为大写，得到sign值signValue。

**伪代码举例**

假设传送的参数如下： channelId: mttest timestamp : 1516320000000 body : test

```
 第一步：对参数按照key=value的格式，并按照参数名ASCII字典序排序如下：
 stringA="channelId=mttest&body=test&timestamp=1516320000000";
 第二步：拼接API密钥：
 stringSignTemp=stringA+"&secret=my_test_secret" 
 sign=hash_hmac("sha256",stringSignTemp,key).toUpperCase()="6A9AE1657590FD6257D693A078E1C3E4BB6BA4DC30B23E0EE2496E54170DACD6" //注：HMAC-SHA256签名方式    
```

**示例代码**

```java
 @Test
     public void deductBalance() throws IOException {
         JTextField field ;
 ​
         String url = "http://localhost:8088/channel/deductBalance";
         //Java中的TreeMap会自动将key按照以ASCII字典进行排序
         TreeMap<String,Object> params = Maps.newTreeMap();
         params.put("orderId","my_order_id");
         params.put("channelId","test91021071617412");
         long timestamp = System.currentTimeMillis();
         params.put("timestamp",timestamp);
 ​
         String channelSign = getChannelSign(params, secret);
         params.put("sign",channelSign);
         System.out.println(url);
         System.out.println(JSON.toJSONString(params));
         String result = HttpUtils.sendRequestBody(url, params);
         System.out.println(result);
     }
 ​
     public static String getChannelSign(Map<String, Object> params,String secret) {
         StringBuilder result = new StringBuilder();
         if (params != null) {
             for (Object key : params.keySet()) {
                 Object value = params.get(key);
 ​
                 result.append(key).append("=").append(value).append("&");
             }
             String tempString = result + "secret=" + secret;
             try {
                 System.out.println(tempString);
                 String sign = EncryptUtils.sha256_HMAC(tempString, secret).toUpperCase();
                 System.out.println(sign);
                 return sign;
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }
         return null;
     }
```

> 代码中参与加密的参数及顺序为：`channelId=test91021071617412&orderId=my_test_id&timestamp=1547987604644&secret=my_secret`


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