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问从JSON多维数组中按键获取值
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Stack Overflow用户

提问于 2022-07-07 13:10:58

回答 3查看 131关注 0票数 0

JSON:

[{"id":141741,"name":"Group","nodeTypeId":3,"deleted":false,"hasNodeAccesses":false,"children": [{"id":141742,"name":"Division","nodeTypeId":14,"deleted":false,"hasNodeAccesses":false,"children":[{"id":141743,"name":"Site 1","nodeTypeId":4,"deleted":false,"hasNodeAccesses":false,"children":[{"id":141746,"name":"Converting","nodeTypeId":5,"deleted":false,"hasNodeAccesses":false,"children":[]}]},{"id":141744,"name":"Site 2","nodeTypeId":4,"deleted":false,"hasNodeAccesses":false,"children":[{"id":141748,"name":"Converting","nodeTypeId":5,"deleted":false,"hasNodeAccesses":false,"children":[]}]},{"id":141745,"name":"Site 3","nodeTypeId":4,"deleted":false,"hasNodeAccesses":false,"children":[{"id":141750,"name":"Converting","nodeTypeId":5,"deleted":false,"hasNodeAccesses":false,"children":[]}]},{"id":141752,"name":"ML1","nodeTypeId":12,"deleted":false,"hasNodeAccesses":false,"children":[{"id":141755,"nodeTypeId":4,"deleted":false,"hasNodeAccesses":false,"children":[]}]},{"id":141753,"name":"ML2","nodeTypeId":12,"deleted":false,"hasNodeAccesses":false,"children":[{"id":141756,"nodeTypeId":4,"deleted":false,"hasNodeAccesses":false,"children":[]}]},{"id":141754,"name":"ML3","nodeTypeId":12,"deleted":false,"hasNodeAccesses":false,"children":[{"id":141757,"nodeTypeId":4,"deleted":false,"hasNodeAccesses":false,"children":[]}]}]}]}]

代码：

public List<String> getCapexStrategyNodeNames() {
        JsonNode capexStrategyNodeList = client.getCapexStrategyNodes();
        JSONArray nodes = capexStrategyNodeList.getArray();
        List<JSONObject> nodeList = nodes.toList();
        return retrieveValues(nodeList, "name");
    }

private List<String> retrieveValues(List<JSONObject> list, String key) {
    return list.stream()
            .map(val -> val.getString(key))
            .collect(Collectors.toList());
}

输出：

[Group]

我只检索第一个值

如何从嵌套的JSON数组中检索所有名称值？

提前感谢！

multidimensional-array

java

json

rest

回答 3

Stack Overflow用户

回答已采纳

发布于 2022-07-07 13:51:41

使用当前的实现，您将获得JsonNode对象，并且正在读取它的name属性，但是您不会读取该属性，因为它是chlildren (内部对象)。

您必须递归地查询所有嵌套对象，并获得字段name的值。

在我看来，实现这一目标的最简单方法是使用JsonPath。

在pom.xml文件中添加此依赖项：

<dependency>
    <groupId>com.jayway.jsonpath</groupId>
    <artifactId>json-path</artifactId>
    <version>2.4.0</version>
</dependency>

下面是代码片段：

public static void main(String[] args) throws JsonProcessingException {
        String json = "[{\"id\":141741,\"name\":\"Group\",\"nodeTypeId\":3,\"deleted\":false,\"hasNodeAccesses\":false,\"children\": [{\"id\":141742,\"name\":\"Division\",\"nodeTypeId\":14,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141743,\"name\":\"Site 1\",\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141746,\"name\":\"Converting\",\"nodeTypeId\":5,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141744,\"name\":\"Site 2\",\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141748,\"name\":\"Converting\",\"nodeTypeId\":5,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141745,\"name\":\"Site 3\",\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141750,\"name\":\"Converting\",\"nodeTypeId\":5,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141752,\"name\":\"ML1\",\"nodeTypeId\":12,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141755,\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141753,\"name\":\"ML2\",\"nodeTypeId\":12,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141756,\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141754,\"name\":\"ML3\",\"nodeTypeId\":12,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141757,\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]}]}]}]";
        List<Object> names= JsonPath.parse(json)
                .read("$..name"); //Recursive descent: Searches for the/specified property name recursively and returns an array of all values with this property name. Always returns a list, even if just one property is found.

        System.out.println(names);

    }

如果运行此代码，将看到如下输出：

["Group","Division","Site 1","Converting","Site 2","Converting","Site 3","Converting","ML1","ML2","ML3"]

票数 1

Stack Overflow用户

发布于 2022-07-07 13:56:06

您的json只有一个对象，所以您的输出只有一个项是正确的。

这是第一级数组中唯一存在的对象。

[{
    "id": 141741,
    "name": "Group",
    "nodeTypeId": 3,
    "deleted": false,
    "hasNodeAccesses": false,
    "children": [...]
}]

因此，您的代码应该返回“组”，并且它是正确的。您可能需要在子程序中导航，可能需要递归地导航到任何嵌套的子级。在这种情况下，您需要更改算法。

票数 0

Stack Overflow用户

发布于 2022-10-03 19:21:06

库Josson也有这样的能力。输出是一个ArrayNode。

https://github.com/octomix/josson

Josson josson = Josson.fromJsonString("[{\"id\":141741,\"name\":\"Group\",\"nodeTypeId\":3,\"deleted\":false,\"hasNodeAccesses\":false,\"children\": [{\"id\":141742,\"name\":\"Division\",\"nodeTypeId\":14,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141743,\"name\":\"Site 1\",\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141746,\"name\":\"Converting\",\"nodeTypeId\":5,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141744,\"name\":\"Site 2\",\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141748,\"name\":\"Converting\",\"nodeTypeId\":5,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141745,\"name\":\"Site 3\",\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141750,\"name\":\"Converting\",\"nodeTypeId\":5,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141752,\"name\":\"ML1\",\"nodeTypeId\":12,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141755,\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141753,\"name\":\"ML2\",\"nodeTypeId\":12,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141756,\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]},{\"id\":141754,\"name\":\"ML3\",\"nodeTypeId\":12,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[{\"id\":141757,\"nodeTypeId\":4,\"deleted\":false,\"hasNodeAccesses\":false,\"children\":[]}]}]}]}]");
JsonNode node = josson.getNode("cumulateCollect(name, children)");
System.out.println(node.toPrettyString());

输出

[ "Group", "Division", "Site 1", "Converting", "Site 2", "Converting", "Site 3", "Converting", "ML1", "ML2", "ML3" ]

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/72898440

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