假设你的JSON是:
{
"status":"OK",
"reason":"some reason",
"content" :
{
"foo": 123,
"bar": "some value"
}
}
然后,你将获得一个ContentPOJO:
class Content
{
public int foo;
public String bar;
}
然后编写一个反序列化器:
class MyDeserializer implements JsonDeserializer<Content>
{
@Override
public Content deserialize(JsonElement je, Type type, JsonDeserializationContext jdc)
throws JsonParseException
{
// Get the "content" element from the parsed JSON
JsonElement content = je.getAsJsonObject().get("content");
// Deserialize it. You use a new instance of Gson to avoid infinite recursion
// to this deserializer
return new Gson().fromJson(content, Content.class);
}
}
现在,如果你构造一个Gsonwith GsonBuilder并注册反序列化器:
Gson gson =
new GsonBuilder()
.registerTypeAdapter(Content.class, new MyDeserializer())
.create();
你可以将JSON直接反序列化为Content:
Content c = gson.fromJson(myJson, Content.class);
如果你有不同类型的消息,但是它们都有“ content”字段,则可以通过执行以下操作使Deserializer通用:
class MyDeserializer<T> implements JsonDeserializer<T>
{
@Override
public T deserialize(JsonElement je, Type type, JsonDeserializationContext jdc)
throws JsonParseException
{
// Get the "content" element from the parsed JSON
JsonElement content = je.getAsJsonObject().get("content");
// Deserialize it. You use a new instance of Gson to avoid infinite recursion
// to this deserializer
return new Gson().fromJson(content, type);
}
}
Gson gson =
new GsonBuilder()
.registerTypeAdapter(Content.class, new MyDeserializer<Content>())
.registerTypeAdapter(DiffContent.class, new MyDeserializer<DiffContent>())
.create();
当你调用.fromJson()
该类型时,该类型将携带到反序列化器中,因此它应适用于所有类型。
最后,在创建改造实例时:
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(url)
.addConverterFactory(GsonConverterFactory.create(gson))
.build();