SpringBoot中Jackson高级用法教学:序列化脱敏、日期格式统一与流式JSON性能优化

spring:
  jackson:
    date-format: yyyy-MM-dd HH:mm:ss
    time-zone: Asia/Shanghai
    default-property-inclusion: non_null

@Configuration
public class JacksonConfig {
    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jacksonCustomizer() {
        return builder -> {
            builder.serializerByType(LocalDateTime.class,
                    new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
            builder.deserializerByType(LocalDateTime.class,
                    new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
            builder.serializationInclusion(JsonInclude.Include.NON_NULL);
        };
    }
}

public class UserDTO {
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "Asia/Shanghai")
    private LocalDateTime createTime;
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface SensitiveField {
    SensitiveStrategy strategy() default SensitiveStrategy.MOBILE;
}

public enum SensitiveStrategy {
    MOBILE("手机号脱敏"),
    ID_CARD("身份证号脱敏");
    // ...
}

public class SensitiveFieldSerializer extends JsonSerializer<Object> {
    private final JsonSerializer<Object> delegate;
    private final SensitiveStrategy strategy;

    public SensitiveFieldSerializer(JsonSerializer<Object> delegate, SensitiveStrategy strategy) {
        this.delegate = delegate;
        this.strategy = strategy;
    }

    @Override
    public void serialize(Object value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
        if (value == null) {
            gen.writeNull();
            return;
        }
        if (SensitiveContext.isAdmin()) {
            delegate.serialize(value, gen, serializers);
            return;
        }
        String text = value.toString();
        gen.writeString(mask(text, strategy));
    }

    private String mask(String value, SensitiveStrategy strategy) {
        switch (strategy) {
            case MOBILE:
                return value.replaceAll("(\\d{3})\\d{4}(\\d{4})", "$1****$2");
            case ID_CARD:
                return value.replaceAll("(\\d{4})\\d{10}(\\w{4})", "$1**********$2");
            default:
                return value;
        }
    }
}

public class SensitiveBeanSerializerModifier extends BeanSerializerModifier {
    @Override
    public JsonSerializer<?> changePropertySerializer(SerializationConfig config,
            BeanDescription beanDesc, BeanPropertyDefinition property,
            JsonSerializer<?> defaultSerializer) {
        AnnotatedField field = property.getField();
        if (field != null) {
            SensitiveField annotation = field.getAnnotation(SensitiveField.class);
            if (annotation != null) {
                return new SensitiveFieldSerializer((JsonSerializer<Object>) defaultSerializer, annotation.strategy());
            }
        }
        return super.changePropertySerializer(config, beanDesc, property, defaultSerializer);
    }
}

@Configuration
public class JacksonSensitiveConfig {
    @Bean
    public Jackson2ObjectMapperBuilderCustomizer sensitiveCustomizer() {
        return builder -> builder.postConfigurer(mapper -> {
            mapper.setSerializerFactory(mapper.getSerializerFactory().withSerializerModifier(new SensitiveBeanSerializerModifier()));
            return mapper;
        });
    }
}

public class SensitiveContext {
    private static final ThreadLocal<Boolean> ADMIN = new ThreadLocal<>();

    public static void setAdmin(boolean admin) {
        ADMIN.set(admin);
    }

    public static boolean isAdmin() {
        return Boolean.TRUE.equals(ADMIN.get());
    }

    public static void clear() {
        ADMIN.remove();
    }
}

ObjectMapper mapper = new ObjectMapper();
try (JsonGenerator generator = mapper.getFactory().createGenerator(outputStream, JsonEncoding.UTF8)) {
    generator.writeStartArray();
    while (rs.next()) {
        generator.writeStartObject();
        generator.writeStringField("id", rs.getString("id"));
        generator.writeStringField("name", rs.getString("name"));
        generator.writeNumberField("amount", rs.getBigDecimal("amount"));
        generator.writeEndObject();
    }
    generator.writeEndArray();
}

try (JsonGenerator generator = mapper.getFactory().createGenerator(outputStream)) {
    generator.writeStartArray();
    while (cursor.hasNext()) {
        mapper.writeValue(generator, cursor.next());
    }
    generator.writeEndArray();
}

spring:
  jackson:
    property-naming-strategy: SNAKE_CASE

public class UserDTO {
    @JsonProperty("emailAddress")
    private String emailAddress;
}

public class CustomNamingStrategy extends PropertyNamingStrategies.NamingBase {
    @Override
    public String translate(String propertyName) {
        // 自定义转换逻辑
        return propertyName;
    }
}