本文介绍了如何使用 Josson 库，根据特定条件对 JSON 数组中的键值进行聚合。通过分组和映射操作，可以高效地对满足相同条件的 JSON 对象进行数值累加，从而生成汇总后的 JSON 数据。本文提供了详细的代码示例和步骤说明，帮助读者理解和应用 Josson 库解决实际问题。
在处理 JSON 数据时，经常会遇到需要根据某些键的值对其他键的值进行聚合的情况。例如，在金融数据分析中，可能需要根据用户ID、交易组、交易品种等条件，对交易量、手续费等进行汇总。手动编写代码实现这种聚合逻辑通常比较繁琐且容易出错。Josson 库提供了一种简洁高效的方式来解决这类问题。
Josson 是一个用于转换和查询 JSON 数据的 Java 库。它提供了一种类似于 SQL 的查询语言，可以方便地对 JSON 数据进行过滤、排序、分组、聚合等操作。
使用 Josson 进行 JSON 数据聚合
以下步骤展示了如何使用 Josson 库按条件聚合 JSON 数组中的键值：
- 添加 Josson 依赖
首先，需要在项目中添加 Josson 库的依赖。如果使用 Maven，可以在 pom.xml 文件中添加以下依赖：
```xml``` com.octomix josson 最新版本
请替换 最新版本 为 Josson 库的最新版本号。
- 准备 JSON 数据
假设有如下 JSON 数组，需要根据 userid、groupname、segment、accountcode、symbol、exchange 和 expirydate 相同的条件，对 bfqty、bfrate、bfamt、buyqty、sellqty、netqty、cfqty、cfamt、ltp、grossmtm、brokerageamt 和 netmtm 进行求和：
```json
[
{
"userid": "CNAF01",
"groupname": "Abhay",
"segment": "CosCLFIN",
"accountcode": "66CN-063CC",
"symbol": "INX22",
"exchange": "SGXFO",
"expirydate": "24NOV2022",
"scripcode": "7536847",
"securitytype": "FUT",
"strikeprice": 0,
"opttype": "XX",
"bfqty": -107,
"bfrate": 18462.05,
"bfamt": 3950878.6999999997,
"buyqty": 21,
"sellqty": 59,
"netqty": -38,
"cfqty": -145,
"cfamt": 5358027.699999999,
"ltp": "18433.5",
"grossmtm": 0,
"brokerageamt": 48,
"netmtm": 0,
"currency": "USD",
"usdrate": 81.33,
"clientsharing": 50,
"broksharing": 0,
"comsharing": 50,
"multiplier": 2
},
{
"userid": "CNAF01",
"groupname": "Abhay",
"segment": "CosCLFIN",
"accountcode": "CW05",
"symbol": "NIFTY",
"exchange": "NSEFO",
"expirydate": "24NOV2022",
"scripcode": "61349",
"securitytype": "OPT",
"strikeprice": 17800,
"opttype": "CE",
"bfqty": 4050,
"bfrate": 673.3,
"bfamt": -2726865,
"buyqty": 1650,
"sellqty": 300,
"netqty": 1350,
"cfqty": 5400,
"cfamt": -3677257.5,
"ltp": "657.0",
"grossmtm": 0,
"brokerageamt": 1038.81126525,
"netmtm": 0,
"currency": "INR",
"usdrate": 1,
"clientsharing": 0,
"broksharing": 0,
"comsharing": 100,
"multiplier": 1
},
{
"userid": "CNAF01",
"groupname": "Abhay",
"segment": "CosCLFIN",
"accountcode": "CW05",
"symbol": "NIFTY",
"exchange": "NSEFO",
"expirydate": "24NOV2022",
"scripcode": "61350",
"securitytype": "OPT",
"strikeprice": 17800,
"opttype": "PE",
"bfqty": -4050,
"bfrate": 14.7,
"bfamt": 59535,
"buyqty": 300,
"sellqty": 1650,
"netqty": -1350,
"cfqty": -5400,
"cfamt": 78900,
"ltp": "13.6",
"grossmtm": 0,
"brokerageamt": 31.850901,
"netmtm": 0,
"currency": "INR",
"usdrate": 1,
"clientsharing": 0,
"broksharing": 0,
"comsharing": 100,
"multiplier": 1
}
]
```- 使用 Josson 进行聚合
使用以下 Java 代码，利用 Josson 库对 JSON 数据进行聚合：
```java
import com.octomix.josson.Josson;
import com.octomix.josson.JsonNode;
import javax.json.JsonString;
public class JossonAggregation {
public static void main(String[] args) {
String jsonString = "[{\"userid\":\"CNAF01\",\"groupname\":\"Abhay\",\"segment\":\"CosCLFIN\",\"accountcode\":\"66CN-063CC\",\"symbol\":\"INX22\",\"exchange\":\"SGXFO\",\"expirydate\":\"24NOV2022\"," +
"\"scripcode\":\"7536847\",\"securitytype\":\"FUT\",\"strikeprice\":0,\"opttype\":\"XX\",\"bfqty\":-107,\"bfrate\":18462.05,\"bfamt\":3950878.6999999997,\"buyqty\":21,\"sellqty\":59,\"netqty\":-38," +
"\"cfqty\":-145,\"cfamt\":5358027.699999999,\"ltp\":\"18433.5\",\"grossmtm\":0,\"brokerageamt\":48,\"netmtm\":0,\"currency\":\"USD\",\"usdrate\":81.33,\"clientsharing\":50,\"broksharing\":0," +
"\"comsharing\":50,\"multiplier\":2}," +
"{\"userid\":\"CNAF01\",\"groupname\":\"Abhay\",\"segment\":\"CosCLFIN\",\"accountcode\":\"CW05\",\"symbol\":\"NIFTY\",\"exchange\":\"NSEFO\"," +
"\"expirydate\":\"24NOV2022\",\"scripcode\":\"61349\",\"securitytype\":\"OPT\",\"strikeprice\":17800,\"opttype\":\"CE\",\"bfqty\":4050,\"bfrate\":673.3,\"bfamt\":-2726865,\"buyqty\":1650," +
"\"sellqty\":300,\"netqty\":1350,\"cfqty\":5400,\"cfamt\":-3677257.5,\"ltp\":\"657.0\",\"grossmtm\":0,\"brokerageamt\":1038.81126525,\"netmtm\":0,\"currency\":\"INR\",\"usdrate\":1,\"clientsharing\":0," +
"\"broksharing\":0,\"comsharing\":100,\"multiplier\":1}," +
"{\"userid\":\"CNAF01\",\"groupname\":\"Abhay\",\"segment\":\"CosCLFIN\",\"accountcode\":\"CW05\",\"symbol\":\"NIFTY\",\"exchange\":\"NSEFO\"," +
"\"expirydate\":\"24NOV2022\",\"scripcode\":\"61350\",\"securitytype\":\"OPT\",\"strikeprice\":17800,\"opttype\":\"PE\",\"bfqty\":-4050,\"bfrate\":14.7,\"bfamt\":59535,\"buyqty\":300,\"sellqty\":1650," +
"\"netqty\":-1350,\"cfqty\":-5400,\"cfamt\":78900,\"ltp\":\"13.6\",\"grossmtm\":0,\"brokerageamt\":31.850901,\"netmtm\":0,\"currency\":\"INR\",\"usdrate\":1,\"clientsharing\":0,\"broksharing\":0," +
"\"comsharing\":100,\"multiplier\":1}]";
Josson josson = Josson.fromJsonString(jsonString);
JsonNode node = josson.getNode(
"group(map(userid,groupname,segment,accountcode,symbol,exchange,expirydate," +
" currency,usdrate,clientsharing,broksharing,comsharing,multiplier))" +
".map(key.userid," +
" key.groupname," +
" key.segment," +
" key.accountcode," +
" key.symbol," +
" key.exchange," +
" key.expirydate," +
" key.currency," +
" key.usdrate," +
" key.clientsharing," +
" key.broksharing," +
" key.comsharing," +
" key.multiplier," +
" elements.bfqty.sum()," +
" elements.bfrate.sum()," +
" elements.bfamt.sum()," +
" elements.buyqty.sum()," +
" elements.sellqty.sum()," +
" elements.netqty.sum()," +
" elements.cfqty.sum()," +
" elements.cfamt.sum()," +
" elements.ltp.sum()," +
" elements.grossmtm.sum()," +
" elements.brokerageamt.sum()," +
" elements.netmtm.sum())");
System.out.println(node.toPrettyString());
}
}
```这段代码首先使用 Josson.fromJsonString() 方法将 JSON 字符串转换为 Josson 对象。然后，使用 getNode() 方法执行 Josson 查询。
- group(map(...)) 根据指定的键对 JSON 数组进行分组。
- map(...) 对每个分组后的元素进行映射，生成新的 JSON 对象。
- key.键名 引用分组的键值。
- elements.键名.sum() 对分组后的元素的指定键进行求和。
- 查看结果
运行以上代码，将得到以下结果：
```json
[ {
"userid" : "CNAF01",
"groupname" : "Abhay",
"segment" : "CosCLFIN",
"accountcode" : "66CN-063CC",
"symbol" : "INX22",
"exchange" : "SGXFO",
"expirydate" : "24NOV2022",
"currency" : "USD",
"usdrate" : 81.33,
"clientsharing" : 50,
"broksharing" : 0,
"comsharing" : 50,
"multiplier" : 2,
"bfqty" : -107.0,
"bfrate" : 18462.05,
"bfamt" : 3950878.6999999997,
"buyqty" : 21.0,
"sellqty" : 59.0,
"netqty" : -38.0,
"cfqty" : -145.0,
"cfamt" : 5358027.699999999,
"ltp" : 18433.5,
"grossmtm" : 0.0,
"brokerageamt" : 48.0,
"netmtm" : 0.0
}, {
"userid" : "CNAF01",
"groupname" : "Abhay",
"segment" : "CosCLFIN",
"accountcode" : "CW05",
"symbol" : "NIFTY",
"exchange" : "NSEFO",
"expirydate" : "24NOV2022",
"currency" : "INR",
"usdrate" : 1,
"clientsharing" : 0,
"broksharing" : 0,
"comsharing" : 100,
"multiplier" : 1,
"bfqty" : 0.0,
"bfrate" : 688.0,
"bfamt" : -2667330.0,
"buyqty" : 1950.0,
"sellqty" : 1950.0,
"netqty" : 0.0,
"cfqty" : 0.0,
"cfamt" : -3598357.5,
"ltp" : 670.6,
"grossmtm" : 0.0,
"brokerageamt" : 1070.66216625,
"netmtm" : 0.0
} ]
```可以看到，Josson 库成功地根据指定的条件对 JSON 数组中的键值进行了聚合。
注意事项
- Josson 库的查询语言功能强大，可以实现各种复杂的 JSON 数据转换和查询操作。
- 在使用 Josson 库时，需要仔细阅读其文档，了解其语法和用法。
- 对于复杂的 JSON 数据结构，可以使用 Josson 库的调试功能，逐步调试查询语句，确保其正确性。
- 根据实际情况选择合适的分组键和聚合函数，以满足业务需求。
总结
本文介绍了如何使用 Josson 库按条件聚合 JSON 数组中的键值。通过 Josson 库提供的分组和映射功能，可以方便地实现复杂的 JSON 数据聚合逻辑，提高开发效率。Josson 库在处理 JSON 数据时具有很大的优势，值得深入学习和应用。
