编写转换器

@Configuration
public class DateConver4Jackson extends MappingJackson2HttpMessageConverter {

    /** 默认日期时间格式 */
    public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
    /** 默认日期格式 */
    public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    /** 默认时间格式 */
    public static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";

    public DateConver4Jackson() {
        ObjectMapper objectMapper = new ObjectMapper();

        // 忽略json字符串中不识别的属性
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        // 忽略无法转换的对象
        objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
        // PrettyPrinter 格式化输出
        objectMapper.configure(SerializationFeature.INDENT_OUTPUT, true);
        // NULL不参与序列化
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

        // 指定时区
        objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8:00"));
        // 日期类型字符串处理
        objectMapper.setDateFormat(new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT));

        // java8日期日期处理
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
        javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
        javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
        javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
        javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
        objectMapper.registerModule(javaTimeModule);


        SimpleModule simpleModule = new SimpleModule();
        //JSON Long ==> String 前端Long精度丢失
        simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
        simpleModule.addSerializer(BigInteger.class, ToStringSerializer.instance);
        simpleModule.addSerializer(BigDecimal.class, ToStringSerializer.instance);
        objectMapper.registerModule(simpleModule);


        this.setObjectMapper(objectMapper);
    }

    @Bean
    public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
        return new DateConver4Jackson();
    }

}

注册转换器

去除默认的JackSon的转换器，将自定义的转换器放到第一位。
转换类的是根据converters中的转换器的定义顺序定义的。
所以需要保证自定义的的转换器是第一个才能保证自定义的转换器正常工作。

@Configuration
public class    MyWebMvcConfigurer implements WebMvcConfigurer {
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {

        int index =0;
        for (HttpMessageConverter<?> messageConverter : converters) {
            if (messageConverter instanceof MappingJackson2HttpMessageConverter)
                break;
            index++;

        }
        converters.remove(index);

        converters.add(0,new DateConver4Jackson());

    }
}