JSONPath 提取对象属性值

1. JSONPath

• 官方文档 https://github.com/alibaba/fastjson/wiki/JSONPath

1.1 基础知识

• $表示根
• 语法：$.element （注：路径表达式区分大小写）
• 嵌套查询 $.parentElement.element

2. JSONPath 示例

@Test
public void demo() {
    OrderDTO orderDTO = new OrderDTO("1001", "20230101001", 0);
    // 不加 $ 也行，等价 $.orderCode
    JSONPath compile = JSONPath.compile("orderCode");
    System.out.println(compile.eval(orderDTO));
}

3. 获取属性值

@Test
public void pathValue() {
    OrderDTO orderDTO = new OrderDTO("1001", "20230101001", 0);
    String extendCondition = "fields=orderCode, orderStatus, tradeId;";

    // 解析
    Map<String, String> params = new HashMap<>();
    if (extendCondition.trim().contains(";")) {
        String[] conditionArray = extendCondition.trim().split(";");
        for (String item : conditionArray) {
            if (StringUtils.isNotEmpty(item) && item.contains("=")) {
                params.put(item.split("=")[0].trim(), item.split("=")[1].trim());
            }
        }
    }

    String orderFields = Optional.ofNullable(params.get("fields"))
            .filter(StringUtils::isNotEmpty)
            .orElse("$.orderCode, $.orderStatus, $.tradeId");

    List<JSONPath> jsonPaths = Splitter.on(",").trimResults().omitEmptyStrings()
            .splitToList(orderFields)
            .stream()
            .map(JSONPath::compile)
            .collect(Collectors.toList());

    String orderInfo = Joiner.on(",").skipNulls().join(jsonPaths.stream()
            .map(jsonPath -> jsonPath.eval(orderDTO))
            .map(obj -> {
                if (obj instanceof String) {
                    return (String)obj;
                } else {
                    return String.valueOf(obj);
                }
            })
            .collect(Collectors.toList()));

    System.out.println(orderInfo);
}