import com.fasterxml.jackson.databind.ObjectMapper;

public class Example {
    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();

        // POJO
        public class User {
            private String name;
            private int age;

            // Getters and setters
        }

        // Сериализация
        User user = new User("Alice", 30);
        String json = mapper.writeValueAsString(user);
        System.out.println(json); // {"name":"Alice","age":30}

        // Десериализация
        String jsonInput = "{\"name\":\"Bob\",\"age\":25}";
        User deserializedUser = mapper.readValue(jsonInput, User.class);
        System.out.println(deserializedUser.getName()); // Bob
    }
}

ObjectMapper mapper = new ObjectMapper();

// Игнорировать неизвестные поля при десериализации
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

// Включить форматирование JSON (pretty print)
mapper.configure(SerializationFeature.INDENT_OUTPUT, true);

// Игнорировать null-поля при сериализации
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

@JsonProperty("customName"): Переименовывает поле в JSON.
@JsonIgnore: Исключает поле из сериализации/десериализации.
@JsonInclude(JsonInclude.Include.NON_NULL): Исключает null-поля.
@JsonFormat: Задает формат для дат, чисел и других типов.
@JsonTypeInfo и @JsonSubTypes: Поддержка полиморфизма.

public class User {
    @JsonProperty("full_name")
    private String name;

    @JsonIgnore
    private String password;

    @JsonFormat(pattern = "yyyy-MM-dd")
    private LocalDate birthDate;
}

List<User> users = mapper.readValue(json, new TypeReference<List<User>>(){});

JsonGenerator generator = mapper.getFactory().createGenerator(new FileOutputStream("output.json"));
generator.writeStartObject();
generator.writeStringField("name", "Alice");
generator.writeEndObject();
generator.close();

public class CustomSerializer extends StdSerializer<CustomType> {
    public CustomSerializer() {
        super(CustomType.class);
    }

    @Override
    public void serialize(CustomType value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeStartObject();
        gen.writeStringField("custom", value.getValue());
        gen.writeEndObject();
    }
}

// Регистрация
mapper.registerModule(new SimpleModule().addSerializer(CustomType.class, new CustomSerializer()));

spring.jackson.serialization.indent-output=true
spring.jackson.deserialization.fail-on-unknown-properties=false
spring.jackson.date-format=yyyy-MM-dd

@Configuration
public class JacksonConfig {
    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        return mapper;
    }
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    @PostMapping
    public User createUser(@RequestBody User user) {
        // user автоматически десериализуется из JSON
        return user;
    }

    @GetMapping
    public List<User> getUsers() {
        // Список автоматически сериализуется в JSON
        return List.of(new User("Alice", 30));
    }
}

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        converter.setObjectMapper(customObjectMapper());
        converters.add(converter);
    }

    @Bean
    public ObjectMapper customObjectMapper() {
        return new ObjectMapper().configure(SerializationFeature.INDENT_OUTPUT, true);
    }
}

@Configuration
public class MongoConfig {
    @Bean
    public MongoTemplate mongoTemplate(MongoDatabaseFactory factory) {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        return new MongoTemplate(factory, new MappingMongoConverter(new DefaultDbRefResolver(factory), new MongoMappingContext()));
    }
}

@Bean
public KafkaTemplate<String, User> kafkaTemplate(ProducerFactory<String, User> producerFactory) {
    return new KafkaTemplate<>(producerFactory);
}

@KafkaListener(topics = "user-topic")
public void listen(@Payload String json, ConsumerRecord<String, String> record) throws IOException {
    User user = new ObjectMapper().readValue(json, User.class);
    System.out.println("Received: " + user);
}

ObjectMapper yamlMapper = new ObjectMapper(new YAMLFactory());
String yaml = yamlMapper.writeValueAsString(user);

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class User {
    private Long id;
    private List<User> friends;
}

@JsonInclude(JsonInclude.Include.NON_NULL)
public class User {
    @JsonProperty("full_name")
    private String name;

    @JsonFormat(pattern = "yyyy-MM-dd")
    private LocalDate birthDate;

    @JsonIgnore
    private String password;

    // Getters and setters
}

@RestController
@RequestMapping("/api/users")
public class UserController {
    @PostMapping
    public ResponseEntity<User> createUser(@RequestBody User user) {
        // Логика сохранения
        return ResponseEntity.ok(user);
    }
}

@Configuration
public class JacksonConfig {
    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.registerModule(new JavaTimeModule()); // Для LocalDate
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        return mapper;
    }
}