Java -获取不同数量的json变量

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonExample {
    public static void main(String[] args) {
        String json = "{\"name\":\"John\", \"age\":30, \"city\":\"New York\"}";

        try {
            ObjectMapper objectMapper = new ObjectMapper();
            JsonNode jsonNode = objectMapper.readTree(json);

            // 获取单个JSON变量
            String name = jsonNode.get("name").asText();
            int age = jsonNode.get("age").asInt();
            String city = jsonNode.get("city").asText();

            System.out.println("Name: " + name);
            System.out.println("Age: " + age);
            System.out.println("City: " + city);

            // 获取多个JSON变量
            JsonNode nameNode = jsonNode.get("name");
            JsonNode ageNode = jsonNode.get("age");
            JsonNode cityNode = jsonNode.get("city");

            if (nameNode != null) {
                String name2 = nameNode.asText();
                System.out.println("Name2: " + name2);
            }

            if (ageNode != null) {
                int age2 = ageNode.asInt();
                System.out.println("Age2: " + age2);
            }

            if (cityNode != null) {
                String city2 = cityNode.asText();
                System.out.println("City2: " + city2);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}