springboot日期及BigDecimal处理

springboot jackson日期和BigDecimal处理

• 概述
• • jackson简单使用
  • springboot使用
• 自定义序列化属性
• 序列化

概述

jackson简单使用

springboot是使用jackson来序列化和反序列化json数据，而jackson主要用到的是ObjectMapper类,
如以下简单实例

package com.test.jacson;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

public class Test {

    @Data
    @AllArgsConstructor
    @NoArgsConstructor
    static class User {
        private String name;

        private Integer age;
    }

    public static void main(String[] args) throws JsonProcessingException {
        User user = new User("abc", 12);
        ObjectMapper objectMapper = new ObjectMapper();
        String value = objectMapper.writeValueAsString(user);
        System.out.println(value);

        User user1 = objectMapper.readValue(value, User.class);
        System.out.println(user1);
    }
}

springboot使用

配置类，如下，可以看出自动配置了ObjectMapper，需要Jackson2ObjectMapperBuilder设置属性，比如对日期的序列化和反序列化。

@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(Jackson2ObjectMapperBuilder.class)
	static class JacksonObjectMapperConfiguration {

		@Bean
		@Primary
		@ConditionalOnMissingBean
		ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
			return builder.createXmlMapper(false).build();
		}

	}

Jackson2ObjectMapperBuilder对象的配置，从List customizers这里可以看出，只需把Jackson2ObjectMapperBuilderCustomizer放到spring容器，即可对jackson的一些特性做自定义配置。

@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(Jackson2ObjectMapperBuilder.class)
	static class JacksonObjectMapperBuilderConfiguration {

		@Bean
		@Scope("prototype")
		@ConditionalOnMissingBean
		Jackson2ObjectMapperBuilder jacksonObjectMapperBuilder(ApplicationContext applicationContext,
				List<Jackson2ObjectMapperBuilderCustomizer> customizers) {
			Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
			builder.applicationContext(applicationContext);
			customize(builder, customizers);
			return builder;
		}

		private void customize(Jackson2ObjectMapperBuilder builder,
				List<Jackson2ObjectMapperBuilderCustomizer> customizers) {
			for (Jackson2ObjectMapperBuilderCustomizer customizer : customizers) {
				customizer.customize(builder);
			}
		}

	}

自定义序列化属性

如下代码，主要配置了一些序列化的属性，Date类型转化为yyyy-MM-dd HH:mm:ss格式，LocalDateTime也是为该格式，并且对返回给前端的BigDecimal类型不返回科学计数法。

package com.ax.config;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;
import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import org.springframework.stereotype.Component;

import java.io.IOException;
import java.math.BigDecimal;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

@Component
public class CustomizerJackson2ObjectMapperBuilder implements Jackson2ObjectMapperBuilderCustomizer {

    @Override
    public void customize(Jackson2ObjectMapperBuilder builder) {

        builder.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);
        builder.dateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        builder.modules(javaTimeModule, new Jdk8Module(), new ParameterNamesModule());
        builder.serializerByType(BigDecimal.class, new JsonSerializer<BigDecimal>() {
            @Override
            public void serialize(BigDecimal value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
                gen.writeString(value.stripTrailingZeros().toPlainString());
            }
        });
    }
}

以上配置方式是统一处理，也可以对日期单独处理，使用@JsonFormat注解

序列化

从前端可能会传过来类似于yyyy-MM-dd HH:mm:ss这种格式，后端希望以Date或LocalDateTime来接收，可以使用@DateTimeFormat来标注，如下

    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private LocalDateTime time;

    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date date;