如果json参数没有值(空字符串)，如何引发异常？

import json

json_str = ""
try:
    data = json.loads(json_str)
    if data is None:
        raise ValueError("JSON参数为空")
except ValueError as e:
    print(str(e))

import com.fasterxml.jackson.databind.ObjectMapper;

String jsonStr = "";
try {
    ObjectMapper objectMapper = new ObjectMapper();
    Object data = objectMapper.readValue(jsonStr, Object.class);
    if (data == null) {
        throw new IllegalArgumentException("JSON参数为空");
    }
} catch (Exception e) {
    System.out.println(e.getMessage());
}