如何使用GSON反序列化Map

我是GSON的新手，并获得了这种格式的JSON响应（只是一个更简单的例子，因此值没有意义）：

{ "Thomas": { "age": 32, "surname": "Scott" }, "Andy": { "age": 25, "surname": "Miller" } } 

我希望GSON使它成为一个Map，PersonData显然是一个Object。 名称字符串是PersonData的标识符。

正如我所说，我对GSON很新，只尝试过类似的事情：

 Gson gson = new Gson(); Map decoded = gson.fromJson(jsonString, new TypeToken<Map>(){}.getType()); 

但这引发了错误：

 Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 3141 

任何帮助表示赞赏:)

Answer 1

以下适用于我

 static class PersonData { int age; String surname; public String toString() { return "[age = " + age + ", surname = " + surname + "]"; } } public static void main(String[] args) { String json = "{\"Thomas\": {\"age\": 32,\"surname\": \"Scott\"},\"Andy\": {\"age\": 25,\"surname\": \"Miller\"}}"; System.out.println(json); Gson gson = new Gson(); Map decoded = gson.fromJson(json, new TypeToken>(){}.getType()); System.out.println(decoded); } 

和打印

 {"Thomas": {"age": 32,"surname": "Scott"},"Andy": {"age": 25,"surname": "Miller"}} {Thomas=[age = 32, surname = Scott], Andy=[age = 25, surname = Miller]} 

所以也许你的PersonData类非常不同。

Answer 2

您可以使用gson.toJsonTree(Object o)将自定义对象转换为JSON格式。

以下为我工作：

 private static class PersonData { private int age; private String surname; public PersonData(int age, String surname) { this.age = age; this.surname = surname; } } public static void main(String[] args) { PersonData first = new PersonData(24, "Yovkov"); PersonData second = new PersonData(25, "Vitanov"); Gson gson = new Gson(); JsonObject jsonObject = new JsonObject(); jsonObject.add("kocko", gson.toJsonTree(first)); jsonObject.add("deyan", gson.toJsonTree(second)); System.out.println(gson.toJson(jsonObject)); } 

和打印：

 {"kocko":{"age":24,"surname":"Yovkov"},"deyan":{"age":25,"surname":"Vitanov"}}