如何对嵌套的 JSON 数组进行排序? [英] How can i sort Nested JSON Array?

问题描述

如何对嵌套的 JSON 数组进行排序?就像下面的 JSON...

How can i sort Nested JSON Array? Like for a JSON below...

{
    "id":"rtmc05.lax.someabc.net",
    "name":"rtmc05.lax.someabc.net",

    "tenants":[{
        "id":"rtmc",
        "name":"rtmc"
    },{
        "id":"hrs",
        "name":"hrs"
    },{
        "id":"amotelbe1",
        "name":"amotelbe"
    },{
        "id":"cds",
        "name":"cds"
    },{
        "id":"idx-server",
        "name":"idx-server",

        "tenants":[{
            "id":"amotelbe",
            "name":"amotelbe",

            "tenants":[{
                "id":"amotelui",
                "name":"amotelui"
            }]
        }]
    }]
}

推荐答案

您的问题隐含了一些部分，并且不清楚您在哪里遇到问题:

There's a few parts implicit to your question, and it's not clear where you're having trouble:

1. 如何获取 JSON 字符串并从中生成可用的 Java 对象.(我假设是 Java，而不是 JavaScript，因为您已经用java"标记了您的问题.)
2. 这些物品制作完成后如何分类?
3. 您如何处理嵌套部分的排序?(在您的示例中，idx-server"有子租户.)

不确定您在这方面的哪些部分遇到了问题，所以这里有针对这三个部分的一些注意事项.

Not sure exactly which parts of this you're having trouble with, so here's some notes for all three.

第 1 部分:获取 Java 对象

Part 1: Getting Java objects

我同意另一个人的看法，Jackson 是一个很好的 JSON 解析器.这里有几行代码可以用来解析一些 JSON:

I agree with the other guy that Jackson is a good JSON parser to use. Here's a couple lines of code you could use to parse some JSON:

String jsonString = "..."; // Load this in whatever way makes sense for you
ObjectMapper mapper = new ObjectMapper();
Map<String,Object> parsedJson = mapper.readValue(jsonString, Map.class);

如果您的 JSON 字符串真的很大，那么您可以使用其他 readValue 重载来避免将整个字符串读入内存.

If your JSON string is really huge, then there are other readValue overloads that you can use to avoid reading the whole String into memory.

第 2 部分:对 Java 对象进行排序

Part 2: Sorting Java objects

一旦你得到解析的 JSON，排序就只是调用 Collections.sort(...)，传入租户 数组.另外，您需要编写一个 Comparator定义您想要的排序.例如，这是一个按名称排序的比较器:

Once you've got the parsed JSON, sorting is just a matter of calling Collections.sort(...), passing in the tenants array. Plus you'll need to write a Comparator that defines the ordering that you want. For example, here's a comparator that sorts by name:

public class NameComparator implements Comparator<Map<String,Object>> {
    public int compare(Map<String,Object> o1, Map<String,Object> o2) {
        String name1 = (String) o1.get("name");
        String name2 = (String) o2.get("name");
        return name1.compareTo(name2);
    }
}

然后你得到租户数组(Jackson 将它们变成 ArrayList 对象)并调用 Collections.sort(...).例如，

Then you get the tenants array out (Jackson makes them into ArrayList objects) and call Collections.sort(...). For example,

List<Map<String,Object>> tenants =
        (List<Map<String,Object>>) parsedJson.get("tenants");
Collections.sort(tenants, new NameComparator());

第 3 部分:处理嵌套

Part 3: Handling the nesting

最清晰的方法是添加一些额外的代码来遍历您的 JSON 以查找具有租户数组的任何对象，并对其进行排序.例如，这是一个应该执行此操作的递归函数:

The clearest way to do this is to add some extra code to walk through your JSON looking for any object with a tenants array, and sort it. For example, here's a recursive function that should do it:

public static void recursiveSortTenants(Map<String,Object> jsonObject) {
    List<Map<String,Object>> tenants =
            (List<Map<String,Object>>) jsonObject.get("tenants");
    if (tenants != null) {
        Collections.sort(tenants, new NameComparator());
        // For each tenant, see if it has sub-tenants.  If so,
        // call this function again to sort them.
        for (Map<String,Object> tenant : tenants) {
            if (tenants.containsKey("tenants")) {
                recursiveSortTenants(tenant);
            }
        }
    }
}

希望这会有所帮助！

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