如何在Java中返回多个JSON项目的列表 [英] How to return a list of multiple JSON items in java

问题描述

我试图弄清楚如何返回多个JSON项.现在，我能够返回单个JSON，如下所示:

I am trying to figure out how to return multiple JSON items. Right now I am able, to return a single JSON like so:

{
    "result": {
        "userId": "abcde123",
        "telephoneNumber": "1-555-5555555"
        },
    "error": null
}

但是我想返回多个JSON项目，像这样:

But I would like to return multiple JSON items, like so:

{
    "result": {{
        "userId": "abcde123",
        "telephoneNumber": "1-555-5555555"
        }
        {
        "userId": "fghi456",
        "telephoneNumber": "1-333-3333333"
        }
        },
    "error": null
}

我可以将多个JSON项目作为字符串查看，如下所示，但是我想将其作为多个JSON项目返回，但是我不知道如何做:

I can view the multiple JSON items as string, like below, but I would like to return it as multiple JSON items, but I don't know how:

[LDAPModel(userId=abcde123, telephoneNumber=1-555-5555555), LDAPModel(userId=fghi456, telephoneNumber=1-333-3333333]

我是Java的完全入门者，并且对Java的语法不甚了解.但是我从SpringBoot得到了这些代码(包括下面的代码).我真的不明白它在做什么，所以我不知道如何创建列表的输出.

I am a complete beginner in Java, and I don't know the syntax or much in Java. But I was given these codes (including the one below) from SpringBoot; I really don't understand what it is doing, and so I have no idea how create an output of list.

目前，这就是我得到的:

Currently, this is what I was given:

public Optional<LDAPModel> getDirectReports(String cdsID) {
        LdapQuery ldapQuery = LdapQueryBuilder.query()
                .searchScope(SearchScope.SUBTREE)
                .where("objectclass").is("person")
                .and("managerID").like(cdsID);

        List<LDAPModel> ldapModelList = ldapTemplate.search(ldapQuery, (Attributes attrs) ->
                LDAPModel.builder()
                        .userId(getValue(attrs, "userid"))
                        .telephoneNumber(getValue(attrs, "phoneNumber"))
                        .build());
//        for (int ii = 0; ii < ldapModelList.size(); ii++) {
//            Optional.of(ldapModelList.get(ii));
//            ldapModelList.isEmpty() ? Optional.empty() : Optional.of(ldapModelList.get(ii));
//        }
        return ldapModelList.isEmpty() ? Optional.empty() : Optional.of(ldapModelList.get(0));
    }

我尝试将其放入循环中(如上面注释掉的代码中所示)，但是我不知道如何创建列表.我尝试删除get(0)，但是出现语法错误...我尝试了很多事情，但这没有帮助.

I tried putting it in a loop (like in the commented out code above), but I don't know how create a list. I tried removing the get(0), but there was a syntax error... There are many things I tried, but it just did not help.

有人可以帮忙吗?

更新/谢谢大家的回答.我发布了一个后续问题此处.如果有机会，请帮帮我.谢谢.

Update/ Thank you all for your answers. I posted a follow up question here. If you have a chance, please help me out. Thanks.

推荐答案

首先，我想指出您的JSON格式不正确.当您想用JSON表示多个对象时，应使用方括号并用逗号分隔每个对象:

First of all I would like to point out that your JSON isn't formatted properly. When you want to represent multiple objects in JSON you should use square brackets and separate each object with a comma:

{
    "result": [
        {
          "userId": "abcde123",
          "telephoneNumber": "1-555-5555555"
        },
        {
          "userId": "fghi456",
          "telephoneNumber": "1-333-3333333"
        }
        ],
    "error": null
}

尝试删除get(0)时Java代码不起作用的原因是因为方法 public Optional< LDAPModel>getDirectReports(String cdsID)返回 Optional< LDAPModel> 类型，并且通过删除get(0)，您正在有效地尝试返回 Optional< List< List< LDAPModel>>> .如果您希望该方法返回列表而不是单个对象，则可以将返回类型更改为 Optional< List< LDAPModel>> ，然后安全地删除get(0).

The reason your Java code does not work when you try and remove get(0) is because the method public Optional<LDAPModel> getDirectReports(String cdsID) returns an Optional<LDAPModel> type and by removing get(0) your are effectively trying to return an Optional<List<LDAPModel>>. If you want the method to return a list instead of a single object you can change the return type to Optional<List<LDAPModel>> and then safely remove get(0).

public Optional<List<LDAPModel>> getDirectReports(String cdsID) {
        LdapQuery ldapQuery = LdapQueryBuilder.query()
                .searchScope(SearchScope.SUBTREE)
                .where("objectclass").is("person")
                .and("managerID").like(cdsID);

        List<LDAPModel> ldapModelList = ldapTemplate.search(ldapQuery, (Attributes attrs) ->
                LDAPModel.builder()
                        .userId(getValue(attrs, "userid"))
                        .telephoneNumber(getValue(attrs, "phoneNumber"))
                        .build());

        return ldapModelList.isEmpty() ? Optional.empty() : Optional.of(ldapModelList);
    }

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