Json在Java中的操作和转换

Question

我有一个输入 json，例如：

{
    "Employee": [
      {
        "employee1.id": 1
      },
      {
        "employee1.name": "John"
      },
      {
        "employee1.address.street": "main street"
      },
      {
        "employee1.address.pin": "123456"
      },
      {
        "employee2.id": 2
      },
      {
        "employee2.name": "Mike"
      },
      {
        "employee2.address.street": "51 street"
      },
      {
        "employee2.address.pin": "234543"
      }
    ]
}

我正在尝试将其转换为：

{
    "employee1":{
        "id": 1,
        "name": "John",
        "address": {
            "street": "main street",
            "pin": "123456"
        }
    },
        "employee2":{
        "id": 2,
        "name": "Mike",
        "address": {
            "street": "51 street",
            "pin": "234543"
        }
    }
}

我试图用点 ie ' 拆分输入 json 中的密钥。 ' 并尝试迭代构建一个 map: Map<String, Object> 但问题是输入 json 键深度可以超过 2 go 即将来输入键可以像：

{
    "employee1.address.tempAddress.street": "main street"
},
{
    "employee1.address.permanentAddress.street": "main street"
}

那么，是否有任何库可用于实现此目的，或者与此密切相关的任何我可以用来实现此目的的库？

Answer 1

关于输入格式“怪异”（礼貌地说）的评论是正确的：这是一种表示简单层次数据的复杂方式。

但有时我们不得不处理次优输入格式，这就是为什么我们可以这样修复它们：

  private static JSONObject arrayToStructure(JSONArray inputArray) {
    JSONObject output = new JSONObject();
    for (Object o : inputArray) {
      assert o instanceof JSONObject;
      JSONObject jso = (JSONObject) o;
      assert jso.length() == 1;
      String key = jso.keys().next();
      Object value = jso.get(key);
      setJsonPath(output, key, value);
    }
    return output;
  }

  private static void setJsonPath(JSONObject target, String key, Object value) {
    String[] keyParts = key.split("\\.");
    JSONObject parent = target;
    for (int i = 0; i < keyParts.length - 1; i++) {
      String keyPart = keyParts[i];
      if (parent.has(keyPart)) {
        parent = parent.getJSONObject(keyPart);
      } else {
        JSONObject child = new JSONObject();
        parent.put(keyPart, child);
        parent = child;
      }
    }
    assert !parent.has(keyParts[keyParts.length - 1]);
    parent.put(keyParts[keyParts.length - 1], value);
  }

此代码使用JSON-Java ，可能更广为人知的名称是org.json:json 。

它可以这样使用：

  public static void main(String[] args) {
    String input = """
        [
          {
            "employee1.id": 1
          },
          {
            "employee1.name": "John"
          },
          {
            "employee1.address.street": "main street"
          },
          {
            "employee1.address.pin": "123456"
          },
          {
            "employee2.id": 2
          },
          {
            "employee2.name": "Mike"
          },
          {
            "employee2.address.street": "51 street"
          },
          {
            "employee2.address.pin": "234543"
          }
        ]""";
    JSONArray inputArray = new JSONArray(input);
    JSONObject structure = arrayToStructure(inputArray);
    System.out.println(structure.toString(2));
  }

请注意，这段代码缺乏适当的健全性检查（其中一些我已经暗示过使用assert ），并且这种“协议”的性质意味着您可能会得到误导性的、模棱两可的或直接的恶意输入。 例如，没有什么能阻止输入同时包含"employee1.id": 1和"employee1.id": 2 。 如何解释它取决于解析器，这种歧义是错误和潜在安全问题的重要来源。

Answer 2

Library Josson可以通过一个表达式来完成转换。

https://github.com/octomix/josson

Josson josson = Josson.fromJsonString(
    "{" +
    "  \"Employee\": [" +
    "    {" +
    "      \"employee1.id\": 1" +
    "    }," +
    "    {" +
    "      \"employee1.name\": \"John\"" +
    "    }," +
    "    {" +
    "      \"employee1.address.street\": \"main street\"" +
    "    }," +
    "    {" +
    "      \"employee1.address.pin\": \"123456\"" +
    "    }," +
    "    {" +
    "      \"employee2.id\": 2" +
    "    }," +
    "    {" +
    "      \"employee2.name\": \"Mike\"" +
    "    }," +
    "    {" +
    "      \"employee2.address.street\": \"51 street\"" +
    "    }," +
    "    {" +
    "      \"employee2.address.pin\": \"234543\"" +
    "    }" +
    "  ]" +
    "}");
JsonNode node = josson.getNode("Employee.mergeObjects().unflatten('.')");
System.out.println(node.toPrettyString());

Output

{
  "employee1" : {
    "id" : 1,
    "name" : "John",
    "address" : {
      "street" : "main street",
      "pin" : "123456"
    }
  },
  "employee2" : {
    "id" : 2,
    "name" : "Mike",
    "address" : {
      "street" : "51 street",
      "pin" : "234543"
    }
  }
}