springboot jackson 配置

springboot 默认使用jackson 进行序列化和反序列化，当我们引入spring-boot-starter-web 依赖的时候就自动引入了jackson 相关依赖，并且对jackson进行了自动装配，并且有默认的Jackson 配置，自动装配类：JacksonAutoConfiguration

修改jackson配置常用方式

1. 通过 yaml 配置

   只能实现部分配置，没法配置LocalDateTime，Long精度丢失等

   spring:
       jackson:
         date-format: yyyy-MM-dd HH:mm:ss # 设置 java.util.Date, Calendar 序列化、反序列化的格式
         locale: zh # 当地时区
         time-zone: GMT+8 # 设置全局时区
         serialization:
           WRITE_DATES_AS_TIMESTAMPS: false # 禁止将 java.util.Date, Calendar 序列化为数字(时间戳)
           FAIL_ON_EMPTY_BEANS: false # 序列化时，对象为 null，是否抛异常
         deserialization:
           FAIL_ON_UNKNOWN_PROPERTIES: false # 反序列化时，json 中包含 pojo 不存在属性时，是否抛异常

2. 通过@Bean 注入Module对象进行扩展

       private static final String DEFAULT_DATETIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
       private static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
       private static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";
   
       @Bean
       public Module javaTimeModule() {
           JavaTimeModule module = new JavaTimeModule();
           // 配置 Jackson 序列化 long类型为String，解决后端返回的Long类型在前端精度丢失的问题
           module.addSerializer(BigInteger.class, BigNumberSerializer.INSTANCE);
           module.addSerializer(Long.class, BigNumberSerializer.INSTANCE);
           module.addSerializer(Long.TYPE, BigNumberSerializer.INSTANCE);
   
           // 配置 Jackson 序列化 LocalDateTime、LocalDate、LocalTime 时使用的格式
           module.addSerializer(new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATETIME_PATTERN)));
           module.addSerializer(new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
           module.addSerializer(new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
   
   
           // 配置 Jackson 反序列化 LocalDateTime、LocalDate、LocalTime 时使用的格式
           module.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATETIME_PATTERN)));
           module.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
           module.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
           return module;
       }

3. 通过@Bean注入 Jackson2ObjectMapperBuilderCustomizer对象进行扩展

   这种方式应该是用的最多的一种

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer customizer() {
           return builder -> {
               // 这部分也可以在 yaml 中配置
               builder
                       // 序列化时，对象为 null，是否抛异常
                       .failOnEmptyBeans(false)
                       // 反序列化时，json 中包含 pojo 不存在属性时，是否抛异常
                       .failOnUnknownProperties(false)
                       // 禁止将 java.util.Date, Calendar 序列化为数字(时间戳)
                       .featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
                       // 设置 java.util.Date, Calendar 序列化、反序列化的格式
                       .dateFormat(new SimpleDateFormat(DEFAULT_DATETIME_PATTERN))
                       // 设置 java.util.Date、Calendar 序列化、反序列化的时区
                       .timeZone(TimeZone.getTimeZone("GMT+8"))
               ;
               // 配置 Jackson 序列化 BigDecimal 时使用的格式
               builder.serializerByType(BigDecimal.class, ToStringSerializer.instance);
   
               // 配置 Jackson 序列化 long类型为String，解决后端返回的Long类型在前端精度丢失的问题
               builder.serializerByType(BigInteger.class, BigNumberSerializer.INSTANCE);
               builder.serializerByType(Long.class, BigNumberSerializer.INSTANCE);
               builder.serializerByType(Long.TYPE, BigNumberSerializer.INSTANCE);
   
               // 配置 Jackson 序列化 LocalDateTime、LocalDate、LocalTime 时使用的格式
               builder.serializers(new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATETIME_PATTERN)));
               builder.serializers(new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
               builder.serializers(new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
   
   
               // 配置 Jackson 反序列化 LocalDateTime、LocalDate、LocalTime 时使用的格式
               builder.deserializerByType(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATETIME_PATTERN)));
               builder.deserializerByType(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
               builder.deserializerByType(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
               log.info("init jackson config");
           };
    }

扩展web Jackson自动装配

扩展Jackson自动装配，做成自动配置common包，其它需要Jackson配置的模块，只需要导入相关包即可，主要如下

1. 创建common-json包，创建自动配置类

/**
 * jackson 配置
 * 注意需要在 JacksonAutoConfiguration.class 之前进行装配，如果在它之后装配，注入的Jackson2ObjectMapperBuilderCustomizer不生效
 * @author LGC
 */
@Slf4j
@AutoConfiguration(before = JacksonAutoConfiguration.class)
public class JsonAutoConfiguration {

    private static final String DEFAULT_DATETIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
    private static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    private static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";

  /**
     * springboot 在构建ObjectMapper时默认使用这个构建器
     *
     * @return
     */
    @Bean
    public Jackson2ObjectMapperBuilderCustomizer customizer() {
        return builder -> {
            // 这部分也可以在 yaml 中配置
            builder
                    // 序列化时，对象为 null，是否抛异常
                    .failOnEmptyBeans(false)
                    // 反序列化时，json 中包含 pojo 不存在属性时，是否抛异常
                    .failOnUnknownProperties(false)
                    // 禁止将 java.util.Date, Calendar 序列化为数字(时间戳)
                    .featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
                    // 设置 java.util.Date, Calendar 序列化、反序列化的格式
                    .dateFormat(new SimpleDateFormat(DEFAULT_DATETIME_PATTERN))
                    // 设置 java.util.Date、Calendar 序列化、反序列化的时区
                    .timeZone(TimeZone.getTimeZone("GMT+8"))
            ;
            // 配置 Jackson 序列化 BigDecimal 时使用的格式
            builder.serializerByType(BigDecimal.class, ToStringSerializer.instance);

            // 配置 Jackson 序列化 long类型为String，解决后端返回的Long类型在前端精度丢失的问题
            builder.serializerByType(BigInteger.class, BigNumberSerializer.INSTANCE);
            builder.serializerByType(Long.class, BigNumberSerializer.INSTANCE);
            builder.serializerByType(Long.TYPE, BigNumberSerializer.INSTANCE);

            // 配置 Jackson 序列化 LocalDateTime、LocalDate、LocalTime 时使用的格式
            builder.serializers(new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATETIME_PATTERN)));
            builder.serializers(new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
            builder.serializers(new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));


            // 配置 Jackson 反序列化 LocalDateTime、LocalDate、LocalTime 时使用的格式
            builder.deserializerByType(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATETIME_PATTERN)));
            builder.deserializerByType(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
            builder.deserializerByType(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
            log.info("init jackson config");
        };
    }

}

2. 超出 JS 最大最小值序列化

   /**
    * 超出 JS 最大最小值 处理
    *
    * @author LGC
    */
   @JacksonStdImpl
   public class BigNumberSerializer extends NumberSerializer {
   
       /**
        * 根据 JS Number.MAX_SAFE_INTEGER 与 Number.MIN_SAFE_INTEGER 得来
        */
       private static final long MAX_SAFE_INTEGER = 9007199254740991L;
       private static final long MIN_SAFE_INTEGER = -9007199254740991L;
   
       /**
        * 提供实例
        */
       public static final BigNumberSerializer INSTANCE = new BigNumberSerializer(Number.class);
   
       public BigNumberSerializer(Class<? extends Number> rawType) {
           super(rawType);
       }
   
       @Override
       public void serialize(Number value, JsonGenerator gen, SerializerProvider provider) throws IOException {
           // 超出范围 序列化位字符串
           if (value.longValue() > MIN_SAFE_INTEGER && value.longValue() < MAX_SAFE_INTEGER) {
               super.serialize(value, gen, provider);
           } else {
               gen.writeString(value.toString());
           }
       }
   }

3. spring 自动配置类导入

   META-INF.spring目录下创建 org.springframework.boot.autoconfigure.AutoConfiguration.imports 文件

   加入 JsonAutoConfiguration 配置类全路径即可

jackson 封装成工具类

jackson 封装成工具类，让其它使用jackson进行序列化和反序列的地方都使用jackson工具类，达到统一效果 比如：

1. Spring Web对传参的反序列化和返回值的序列化
2. springboot cache redis 缓存序列化和反序列化操作RedisCacheConfiguration
3. redis 存储对象时序列化和获取对象时反序列化
4. 业务代码中使用ObjectMapper进行对象与json字符串进行相互转换

工具类如下：

/**
 * JSON 工具类
 *
 * @author LGC
 */
@Slf4j
@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class JsonUtils {
    private static final String DEFAULT_DATETIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
    private static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    private static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";

    public static final Jackson2ObjectMapperBuilderCustomizer CUSTOMIZER = jackson2ObjectMapperBuilderCustomizer();

    public static final ObjectMapper OBJECT_MAPPER = getObjectMapper();

    /**
     * 构建 Jackson 自定义配置
     *
     * @return
     */
    public static Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {
        return builder -> {
            // 这部分也可以在 yaml 中配置
            builder
                    // 序列化时，对象为 null，是否抛异常
                    .failOnEmptyBeans(false)
                    // 反序列化时，json 中包含 pojo 不存在属性时，是否抛异常
                    .failOnUnknownProperties(false)
                    // 禁止将 java.util.Date, Calendar 序列化为数字(时间戳)
                    .featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
                    // 设置 java.util.Date, Calendar 序列化、反序列化的格式
                    .dateFormat(new SimpleDateFormat(DEFAULT_DATETIME_PATTERN))
                    // 设置 java.util.Date、Calendar 序列化、反序列化的时区
                    .timeZone(TimeZone.getTimeZone("GMT+8"))
            ;
            // 配置 Jackson 序列化 BigDecimal 时使用的格式
            builder.serializerByType(BigDecimal.class, ToStringSerializer.instance);

            // 配置 Jackson 序列化 long类型为String，解决后端返回的Long类型在前端精度丢失的问题
            builder.serializerByType(BigInteger.class, BigNumberSerializer.INSTANCE);
            builder.serializerByType(Long.class, BigNumberSerializer.INSTANCE);
            builder.serializerByType(Long.TYPE, BigNumberSerializer.INSTANCE);

            // 配置 Jackson 序列化 LocalDateTime、LocalDate、LocalTime 时使用的格式
            builder.serializers(new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATETIME_PATTERN)));
            builder.serializers(new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
            builder.serializers(new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));


            // 配置 Jackson 反序列化 LocalDateTime、LocalDate、LocalTime 时使用的格式
            builder.deserializerByType(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATETIME_PATTERN)));
            builder.deserializerByType(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
            builder.deserializerByType(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
            log.info("init jackson config");
        };
    }

    /**
     * 根据 Jackson 自定义配置 构建 ObjectMapper
     *
     * @return ObjectMapper
     */
    public static ObjectMapper getObjectMapper() {
        Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
        CUSTOMIZER.customize(builder);
        return builder.build();
    }


    public static String toJsonString(Object object) {
        if (ObjectUtil.isNull(object)) {
            return null;
        }
        try {
            return OBJECT_MAPPER.writeValueAsString(object);
        } catch (JsonProcessingException e) {
            throw new RuntimeException(e);
        }
    }

    public static <T> T parseObject(String text, Class<T> clazz) {
        if (StrUtils.isEmpty(text)) {
            return null;
        }
        try {
            return OBJECT_MAPPER.readValue(text, clazz);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static <T> T parseObject(byte[] bytes, Class<T> clazz) {
        if (ArrayUtil.isEmpty(bytes)) {
            return null;
        }
        try {
            return OBJECT_MAPPER.readValue(bytes, clazz);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static <T> T parseObject(String text, TypeReference<T> typeReference) {
        if (StrUtils.isBlank(text)) {
            return null;
        }
        try {
            return OBJECT_MAPPER.readValue(text, typeReference);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static Dict parseMap(String text) {
        if (StrUtils.isBlank(text)) {
            return null;
        }
        try {
            return OBJECT_MAPPER.readValue(text, OBJECT_MAPPER.getTypeFactory().constructType(Dict.class));
        } catch (MismatchedInputException e) {
            // 类型不匹配说明不是json
            return null;
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static List<Dict> parseArrayMap(String text) {
        if (StrUtils.isBlank(text)) {
            return null;
        }
        try {
            return OBJECT_MAPPER.readValue(text, OBJECT_MAPPER.getTypeFactory().constructCollectionType(List.class, Dict.class));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static <T> List<T> parseArray(String text, Class<T> clazz) {
        if (StrUtils.isEmpty(text)) {
            return new ArrayList<>();
        }
        try {
            return OBJECT_MAPPER.readValue(text, OBJECT_MAPPER.getTypeFactory().constructCollectionType(List.class, clazz));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

}

对扩展web jackson自动装配修改

/**
 * jackson 配置
 *
 * @author LGC
 */
@Slf4j
@AutoConfiguration(before = JacksonAutoConfiguration.class)
public class JsonAutoConfiguration {

  /**
     * springboot 在构建ObjectMapper时默认使用这个构建器
     *
     * @return
     */
    @Bean
    public Jackson2ObjectMapperBuilderCustomizer customizer() {
        return JsonUtils.CUSTOMIZER;
    }

}

测试

简单创建一个springboot项目，引入common-json 依赖包，创建一个controller

/**
 * @author LGC
 */
@RestController
public class JsonTestController {
    @GetMapping("/testJson")
    public User testJson() {
        User user = new User(999999922222222223L, "lgc", new Date(), LocalDateTime.now());
        System.out.println(JsonUtils.toJsonString(user));
        return user;
    }

}

// 请求后输出都为
{"userId":"999999922222222223","username":"lgc","birthDay":"2023-12-20 15:16:45","birthDay2":"2023-12-20 15:16:45"}

扩展

1. springboot cache redis 缓存修改

   /**
    * Cache 配置类，基于 Redis 实现
    *
    * @author LGC
    */
   @AutoConfiguration
   @EnableConfigurationProperties({CacheProperties.class})
   @EnableCaching
   public class CacheAutoConfiguration {
   
       /**
        * RedisCacheConfiguration Bean
        *
        * @see org.springframework.boot.autoconfigure.cache.RedisCacheConfiguration 的 createConfiguration 方法
        */
       @Bean
       @Primary
       public RedisCacheConfiguration redisCacheConfiguration(CacheProperties cacheProperties) {
           // 设置使用 JSON 序列化方式
           RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig();
   
           config = config.serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(RedisSerializer.string()));
           config = config.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(redisSerializer()));
   
           // 设置 CacheProperties.Redis 的属性
           CacheProperties.Redis redisProperties = cacheProperties.getRedis();
           if (redisProperties.getTimeToLive() != null) {
               config = config.entryTtl(redisProperties.getTimeToLive());
           }
           if (redisProperties.getKeyPrefix() != null) {
               config = config.prefixCacheNameWith(redisProperties.getKeyPrefix());
           }
           if (!redisProperties.isCacheNullValues()) {
               config = config.disableCachingNullValues();
           }
           if (!redisProperties.isUseKeyPrefix()) {
               config = config.disableKeyPrefix();
           }
           return config;
       }
   
   
       /**
        * redis 序列化器
        *
        * @return
        */
       public GenericJackson2JsonRedisSerializer redisSerializer() {
           return new GenericJackson2JsonRedisSerializer(JsonUtils.OBJECT_MAPPER);
       }
   }

   2. RedisTemplate 配置修改

        /**
           * 创建 RedisTemplate 
           */
          @Bean
          public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
              RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
              redisTemplate.setConnectionFactory(factory);
              // 使用 String 序列化方式，序列化 KEY 。
              redisTemplate.setKeySerializer(RedisSerializer.string());
              redisTemplate.setHashKeySerializer(RedisSerializer.string());
              // 值的序列化方式
              redisTemplate.setValueSerializer(redisSerializer());
              redisTemplate.setHashValueSerializer(redisSerializer());
              return redisTemplate;
          }
      
          /**
           * redis 序列化器
           *
           * @return
           */
          public GenericJackson2JsonRedisSerializer redisSerializer() {
               return new GenericJackson2JsonRedisSerializer(JsonUtils.OBJECT_MAPPER);
          }