通过在Java中传递键，在运行时读取JSON键值

hts6caw3 于 2023-01-03 发布在 Java

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我正在尝试解析JSON并根据输入键拉取值。JSON结构并不相同，下面是示例JSON结构，JSON以[]开头和结尾，有时{}

[
    {
        "id": "0001",
        "type": "donut",
        "name": "Cake",
        "ppu": 0.55,
        "days": {
            "weekdays": "Friday",
            "weekends": "Sunday",
        },
        "batters": {
            "batter": [
                {
                    "id": "1001",
                    "type": "Regular"
                },
                {
                    "id": "1002",
                    "type": "Chocolate"
                },
            ]
        },
        "topping": [
            {
                "id": "5001",
                "type": "None"
            },
            {
                "id": "5002",
                "type": "Glazed"
            },
        ]
    }
]

{
        "id": "0001",
        "type": "donut",
        "name": "Cake",
        "ppu": 0.55,
        "days": {
            "weekdays": "Friday",
            "weekends": "Sunday",
        },
        "batters": {
            "batter": [
                {
                    "id": "1001",
                    "type": "Regular"
                },
                {
                    "id": "1002",
                    "type": "Chocolate"
                },
            ]
        },
        "topping": [
            {
                "id": "5001",
                "type": "None"
            },
            {
                "id": "5002",
                "type": "Glazed"
            },
        ]
    }

我尝试以下代码

import org.json.simple.*;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

    public static void main(String[] args) throws IOException, Exception {

        File InputFolder = new File(System.getProperty("user.dir") + "//Files//new.json");

        JsonElementFromFile(InputFolder,"name");        
    }

public static void JsonElementFromFile(File FilePath, String key) throws IOException, Exception {
  
   JSONParser parser = new JSONParser();
   FileReader reader = new FileReader(FilePath);
   JSONArray obj = (JSONArray) parser.parse(reader);  
   for (Object o : obj) { 
      JSONObject json = (JSONObject) o; 
      String jsonKeyValue = (String)json.get(key).toString(); 
      System.out.println(key + " : " + jsonKeyValue); }
  
  }

1.上述代码在JSON数据以"["开头时有效，但在以"{"开头时无效，不管我应该能够获取值的任何结构
1.我能够从第一个对象键"id"，"type"，"name"，"ppu"只拉值，但当我通过键作为"days.weekdays"它不是拉.即使我有更多的数组和objectsi应该能够拉只是通过键的路径，例如："击球手.击球手[0]. id"或"击球手.击球手[1]. type"**
1.基本上，我正在寻找可重用的代码，以拉值的基础上传递的关键字，不想硬编码任何值从JSON。
谢谢

JSON

来源：https://stackoverflow.com/questions/74965664/read-json-key-values-at-run-time-by-passing-keys-in-java

1条答案

按热度按时间

dfty9e191#

如果不想硬编码不同的JSON结构，解决方案是使用JSON查询库。
https://github.com/octomix/josson

反序列化数组

Josson array = Josson.fromJsonString(
    "[" +
    "    {" +
    "        \"id\": \"0001\"," +
    "        \"type\": \"donut\"," +
    "        \"name\": \"Cake\"," +
    "        \"ppu\": 0.55," +
    "        \"days\": {" +
    "            \"weekdays\": \"Friday\"," +
    "            \"weekends\": \"Sunday\"" +
    "        }," +
    "        \"batters\": {" +
    "            \"batter\": [" +
    "                {" +
    "                    \"id\": \"1001\"," +
    "                    \"type\": \"Regular\"" +
    "                }," +
    "                {" +
    "                    \"id\": \"1002\"," +
    "                    \"type\": \"Chocolate\"" +
    "                }" +
    "            ]" +
    "        }," +
    "        \"topping\": [" +
    "            {" +
    "                \"id\": \"5001\"," +
    "                \"type\": \"None\"" +
    "            }," +
    "            {" +
    "                \"id\": \"5002\"," +
    "                \"type\": \"Glazed\"" +
    "            }" +
    "        ]" +
    "    }," +
    "    {" +
    "        \"batters\": {" +
    "            \"batter\": [" +
    "                {" +
    "                    \"id\": \"1003\"," +
    "                    \"type\": \"Special\"" +
    "                }," +
    "                {" +
    "                    \"id\": \"1004\"," +
    "                    \"type\": \"DarkChocolate\"" +
    "                }" +
    "            ]" +
    "        }" +
    "    }" +
    "]");

反序列化对象

Josson object = Josson.fromJsonString(
    "{" +
    "    \"id\": \"0001\"," +
    "    \"type\": \"donut\"," +
    "    \"name\": \"Cake\"," +
    "    \"ppu\": 0.55," +
    "    \"days\": {" +
    "        \"weekdays\": \"Friday\"," +
    "        \"weekends\": \"Sunday\"" +
    "    }," +
    "    \"batters\": {" +
    "        \"batter\": [" +
    "            {" +
    "                \"id\": \"1001\"," +
    "                \"type\": \"Regular\"" +
    "            }," +
    "            {" +
    "                \"id\": \"1002\"," +
    "                \"type\": \"Chocolate\"" +
    "            }" +
    "        ]" +
    "    }," +
    "    \"topping\": [" +
    "        {" +
    "            \"id\": \"5001\"," +
    "            \"type\": \"None\"" +
    "        }," +
    "        {" +
    "            \"id\": \"5002\"," +
    "            \"type\": \"Glazed\"" +
    "        }" +
    "    ]" +
    "}");

查询

System.out.println(array.getString("batters.batter[0].id"));       // 1001
System.out.println(object.getString("batters.batter[0].id"));      // 1001
System.out.println(array.getString("batters.batter[1].type"));     // Chocolate
System.out.println(object.getString("batters.batter[1].type"));    // Chocolate
System.out.println(array.getString("[0].batters.batter[1].id"));   // 1002
System.out.println(array.getString("[1].batters.batter[1].type")); // DarkChocolate
System.out.println(array.getString("batters.batter[3].type"));     // DarkChocolate

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通过在Java中传递键，在运行时读取JSON键值

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