解析嵌套的 JSON 并将其保存到 SQLite 中，然后检索它

Question

编辑

我设法只插入了外部 JSON 对象。找不到有关如何插入嵌套对象的信息。每个对象中都有原始字段。这些对象可以在下面的 JSON 示例中看到：“语言”和“货币”。我还想知道如何处理外部 JSON 对象中的“latlng”数组，但最好一次处理这些问题。

我在外部 JSON 对象中插入原始值的代码：

Gson gson = new Gson();
Type listType = new TypeToken<List<Country>>(){}.getType();
List<Country> countriesList = gson.fromJson(jsonString, listType);

for(Country country : countriesList) {
      ContentValues insertValues = new ContentValues();
      insertValues.put(Country.NAME, country.getName());
      //more insertions
}

原来的问题

我用 GSON 解析了一个嵌套的 JSON（可能是错误的，因为这是我第一次）。现在我正在尝试将其插入 SQLite。找不到接下来需要写的内容。当我为插入编写 for 循环时，我收到错误 cannot find symbol class Country。无法在网上找到相关的指导，所以我希望任何人都可以帮助如何前进。

这就是问题的开始：

Country[] countriesArray = gson.fromJson(jsonString, Country[].class);
for (int i = 0; i < countriesArray.length(); i++) {
...
            }

countriesArray.length() 被标记为错误：找不到符号类 Country。

来自 JSON 的一个对象：

[ 
   { 
      "name":"Afghanistan",
      "topLevelDomain":[ 
         ".af"
      ],
      "callingCodes":[ 
         "93"
      ],
      "capital":"Kabul",
      "region":"Asia",
      "subregion":"Southern Asia",
      "population":27657145,
      "latlng":[ 
         33.0,
         65.0
      ],
      "demonym":"Afghan",
      "area":652230.0,
      "gini":27.8,
      "timezones":[ 
         "UTC+04:30"
      ],
      "nativeName":"افغانستان",
      "numericCode":"004",
      "currencies":[ 
         { 
            "name":"Afghan afghani",
            "symbol":"؋"
         }
      ],
      "languages":[ 
         { 
            "name":"Pashto",
            "nativeName":"پښتو"
         },
         { 
            "name":"Uzbek",
            "nativeName":"Oʻzbek"
         },
         { 
            "name":"Turkmen",
            "nativeName":"Türkmen"
         }
      ],
      "translations":{ 
         "de":"Afghanistan",
      },
      "flag":"https://restcountries.eu/data/afg.svg",
      "cioc":"AFG"
   },

我写的模型类只针对我需要的变量对象和数组。

模型类 Country.Java

public class Country implements Parcelable {

    private String name;
    private String capital;
    private String region;
    private String subregion;
    private int population;
    private List<Double> latlng = new ArrayList<Double>();
    private double area;
    private double gini;
    private List<String> timezones = new ArrayList<String>();
    private List<Currency> currencies = new ArrayList<Currency>();
    private List<Language> languages = new ArrayList<Language>();
    private String flag;

    public Country() {}

//getters, setters, toString() and Parcelable methods
}

模型类 Currency.Java

public class Currency implements Parcelable {

    private String name;
    private String symbol;

//getters, setters, toString() and Parcelable methods
}

模型类 Language.Java

public class Language implements Parcelable {

    private String name;
    private String nativeName;

//getters, setters, toString() and Parcelable methods
}

Answer 1

创建一个 typeToken 并将其传递给 fromJson 方法，如下所示

Type listType = new TypeToken<List<Country>>(){}.getType();
List<Country> countryList = gson.fromJson(jsonArray.toString(), listType);

Answer 2

JSON解析时使用GsonTypeToken设置返回对象类型

List<Country> countries  = gson.fromJson(jsonString, new TypeToken<List<Country>>(){}.getType());

for(Country country : countries) {
    //Do your DB operation here
}