Java 如何使用 GSON 反序列化 Map<String, Object>
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How to de-serialize a Map<String, Object> with GSON
提问by luuksen
i am fairly new to GSON and get a JSON response of this format (just an easier example, so the values make no sense):
我对 GSON 还很陌生，得到了这种格式的 JSON 响应（只是一个更简单的例子，所以这些值没有意义）：
{
"Thomas": {
"age": 32,
"surname": "Scott"
},
"Andy": {
"age": 25,
"surname": "Miller"
}
}
I want GSON to make it a Map, PersonData is obviously an Object. The name string is the identifier for the PersonData.
我想让 GSON 把它做成一个 Map，PersonData 显然是一个对象。名称字符串是 PersonData 的标识符。
As I said I am very new to GSON and only tried something like:
正如我所说，我对 GSON 很陌生，只尝试过类似的东西：
Gson gson = new Gson();
Map<String, PersonData> decoded = gson.fromJson(jsonString, new TypeToken<Map<String, PersonData>>(){}.getType());
but this threw the error:
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
Any help is appreciated :)
任何帮助表示赞赏:)
采纳答案by Sotirios Delimanolis
The following works for me
以下对我有用
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<String, PersonData> decoded = gson.fromJson(json, new TypeToken<Map<String, PersonData>>(){}.getType());
System.out.println(decoded);
}
and prints
和版画
{"Thomas": {"age": 32,"surname": "Scott"},"Andy": {"age": 25,"surname": "Miller"}}
{Thomas=[age = 32, surname = Scott], Andy=[age = 25, surname = Miller]}
So maybe your PersonDataclass is very different.
所以也许你的PersonData班级很不一样。
回答by Konstantin Yovkov
You can use gson.toJsonTree(Object o)to convert your custom object to JSON format.
您可以使用gson.toJsonTree(Object o)将自定义对象转换为 JSON 格式。
The following works for me:
以下对我有用：
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));
}
and prints:
和打印：
{"kocko":{"age":24,"surname":"Yovkov"},"deyan":{"age":25,"surname":"Vitanov"}}
