如何从JsonNode获取键值映射？

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

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

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

        ObjectMapper objectMapper = new ObjectMapper();
        try {
            // 将JSON字符串解析为JsonNode
            JsonNode rootNode = objectMapper.readTree(jsonString);

            // 创建一个Map来存储键值对
            Map<String, Object> keyValueMap = new HashMap<>();

            // 遍历JsonNode中的所有字段
            Iterator<Map.Entry<String, JsonNode>> fields = rootNode.fields();
            while (fields.hasNext()) {
                Map.Entry<String, JsonNode> field = fields.next();
                String key = field.getKey();
                JsonNode value = field.getValue();

                // 根据值的类型进行处理
                if (value.isTextual()) {
                    keyValueMap.put(key, value.asText());
                } else if (value.isInt()) {
                    keyValueMap.put(key, value.asInt());
                } else if (value.isDouble()) {
                    keyValueMap.put(key, value.asDouble());
                } else if (value.isBoolean()) {
                    keyValueMap.put(key, value.asBoolean());
                } else if (value.isObject()) {
                    keyValueMap.put(key, value.toString()); // 或者递归处理
                } else if (value.isArray()) {
                    keyValueMap.put(key, value.toString()); // 或者递归处理
                }
            }

            // 输出键值映射
            System.out.println(keyValueMap);

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}