有一個 Student 類，包含了 id 和 name 兩個屬性，使用 SpringMVC 和 gson 整合，默認 gson 將該實體會序列化為：
{
"id" : 1,
"name" : "StuName"
}
目前希望將 Student 序列化為：
{
"Type" : "Student",
"Property": {
"id" : 1,
"name" : "StuName"
}
}
請問大家該如何做呢？（gson 版本為 2.8.0，使用 TypeAdapter 我一直得不到想要的效果。使用 Jackson 的時候，可以直接定義一個 JsonSerializer 并將其使用 @JsonSerialize(using = xxx.class) 注解來自定義序列化的格式，不知道在 gson 中有沒有提供的方式）
2 回答
陪伴而非守候
TA貢獻1757條經驗 獲得超8個贊
用：JsonSerializer/JsonDeserializer
public static class StudentJsonSerializer implements JsonSerializer<Student> {
@Override
public JsonElement serialize(Student src, Type typeOfSrc, JsonSerializationContext context) {
final JsonObject propEle = new JsonObject();
propEle.addProperty("id", src.getId());
propEle.addProperty("name", src.getName());
final JsonObject root = new JsonObject();
root.addProperty("Type", "Student");
root.add("Property", propEle);
return root;
}
}
public static class StudentJsonDeserializer implements JsonDeserializer<Student> {
public Student deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
final JsonObject root = json.getAsJsonObject();
JsonObject propEle = root.getAsJsonObject("Property");
Student student = new Student();
student.setId(propEle.get("id").getAsInt());
student.setName(propEle.get("name").getAsString());
return student;
}
}
@Test
public void test_1010000010436869() {
Gson gson = new GsonBuilder().registerTypeAdapter(Student.class, new StudentJsonSerializer())
.registerTypeAdapter(Student.class, new StudentJsonDeserializer()).create();
Student student = new Student();
student.setId(1);
student.setName("StuName");
String json = gson.toJson(student);
System.out.println(json);
Student student2 = gson.fromJson(json, Student.class);
System.out.println(student2);
}
繁星點點滴滴
TA貢獻1803條經驗 獲得超3個贊
通過繼承 GsonHttpMessageConverter 并覆寫 writeInternal 方法達到了想要的效果，但不知道有沒有更加優雅的方法。
public class MyGsonHttpMessageConverter extends GsonHttpMessageConverter {
@Override
protected void writeInternal(Object o, Type type, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
if (o instanceof Student) {
Student s = (Student) o;
JsonObject stuObj = new JsonObject();
stuObj.addProperty("id", s.getId());
stuObj.addProperty("name", s.getName());
JsonObject entity = new JsonObject();
entity.addProperty("Type", "Student");
entity.add("property", stuObj);
try (OutputStreamWriter writer = new OutputStreamWriter(outputMessage.getBody(), DEFAULT_CHARSET)) {
Gson gson = super.getGson();
gson.toJson(entity, writer);
} catch (JsonIOException ex) {
throw new HttpMessageNotWritableException("Could not write JSON: " + ex.getMessage(), ex);
}
} else {
super.writeInternal(o, type, outputMessage);
}
}
}
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