GsonHttpMessageConverter

---

정의

GsonHttpMessageConverter 란

Spring MVC 에서 Json Data를 처리하는데 사용되는 HTTP MessageConverter 중 하나

역할

• Java 객체를 JSON 형식으로 변환하여 HTTP Response Body에 포함시킴
• HTTP Request Body에 포함된 Json Data를 Java 객체로 변환하여 Controller에 전달

적용

WebMvcConfigurer 를 사용한 기본 설정

@Configuration  
@EnableWebMvc  
@ComponentScan(basePackages = "org.infinity.server.controller.api")
public class APIConfiguration implements WebMvcConfigurer {  
	...
	
    @Override  
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {  
        Gson gson = new GsonBuilder().create();
  
        GsonHttpMessageConverter converter = new GsonHttpMessageConverter(gson);  
        converters.add(converter);  
    }  
}

GsonHttpMessageConverter에 Custom Class 등록

1. JsonSerializer<>를 구현하는 CustomSerializer 추가

public class LocalDateSerializer implements JsonSerializer<LocalDate> {  
    private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");  
  
    @Override  
    public JsonElement serialize(LocalDate localDate, Type type, JsonSerializationContext jsonSerializationContext) {  
        return new JsonPrimitive(formatter.format(localDate));  
    }  
}

2. MessageConverter에 등록

@Configuration  
@EnableWebMvc  
@ComponentScan(basePackages = "org.infinity.server.controller.api")
public class APIConfiguration implements WebMvcConfigurer {  
	...
	
    @Override  
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {  
        Gson gson = new GsonBuilder()  
                .registerTypeAdapter(LocalDate.class, new LocalDateSerializer())  
                .create();  
  
        GsonHttpMessageConverter converter = new GsonHttpMessageConverter(gson);  
        converters.add(converter);  
    }  
}

3. 타입에 따른 converter 등록

public static GsonHttpMessageConverter createGsonHttpMessageConverter() {  
    Gson gson = new GsonBuilder()  
            .registerTypeAdapter(DateTime.class, new GsonDateTimeTypeAdapter())  
            .registerTypeAdapter(String.class, new GsonStringXssTypeAdapter())  
            .registerTypeAdapter(Json.class, new GsonSpringfoxJsonSerializer())  
            .create();  
	...
}

---

연결문서

• WebMvcConfigurer
• MessageConverter
• @ResponseBody
• @Controller