在项目中日期格式化是最常见的问题，之前涉及的 java.util.Date 和 java.util.Calendar 类易用性差，不支持时区，非线程安全，对日期的计算方式繁琐，而且容易出错，因为月份是从0开始的，从 Calendar 中获取的月份需要加一才能表示当前月份。

在 JDK8 中，一个新的重要特性就是引入了全新的时间和日期API，它被收录在 java.time 包中，借助新的时间和日期API可以以更简洁的方法处理时间和日期。

解决方案

1、注解

（1） @JsonFormat和@DateTimeFormat

@JsonFormat后台到前台的时间格式的转换

@JsonFormat(pattern="yyyy-MM-dd HH:mm:ss",timezone = "GMT+8")

pattern:需要转换的时间日期的格式

timezone：是时间设置为东八区

@DateTimeFormat前后到后台的时间格式的转换

@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")

pattern:需要转换的时间日期的格式

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

（2）Controller

@GetMapping("date")
public Object date(@RequestParam @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") LocalDateTime date) {
    return date;
}

@GetMapping("date2")
public Object date(@RequestParam @DateTimeFormat(pattern = "yyyy-MM-dd") LocalDate date) {
    return date;
}

2、统一配置

配置文件配置

spring:
  jackson:
    date-format: yyyy-MM-dd HH:mm:ss

代码配置

RequestParam|PathVariable参数

Converter

@Configuration
public class DateConfig {
 
    @Bean
    public Converter<String, LocalDate> localDateConverter() {
        return new Converter<>() {
            @Override
            public LocalDate convert(String source) {
                return LocalDate.parse(source, DateTimeFormatter.ofPattern("yyyy-MM-dd"));
            }
        };
    }
 
    @Bean
    public Converter<String, LocalDateTime> localDateTimeConverter() {
        return new Converter<>() {
            @Override
            public LocalDateTime convert(String source) {
                return LocalDateTime.parse(source, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
            }
        };
    }
 
}

使用ControllerAdvice配合initBinder

@ControllerAdvice
public class GlobalExceptionHandler {
 
    @InitBinder
    protected void initBinder(WebDataBinder binder) {
        binder.registerCustomEditor(LocalDate.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) throws IllegalArgumentException {
                setValue(LocalDate.parse(text, DateTimeFormatter.ofPattern("yyyy-MM-dd")));
            }
        });
        binder.registerCustomEditor(LocalDateTime.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) throws IllegalArgumentException {
                setValue(LocalDateTime.parse(text, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
            }
        });
        binder.registerCustomEditor(LocalTime.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) throws IllegalArgumentException {
                setValue(LocalTime.parse(text, DateTimeFormatter.ofPattern("HH:mm:ss")));
            }
        });
    }
}

JSON格式

定义一个配置类，对ObjectMapper对象进行定制，指定日期类对应的序列化与反序列化处理对象

方案一

@Configuration
public class LocalDateTimeFormatConfig {
    private static final String DEFAULT_DATE_TIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
    private static final String DEFAULT_DATE_PATTERN = "yyyy-MM-dd";
    private static final String DEFAULT_TIME_PATTERN = "HH:mm:ss";

    @Bean
    @Primary
    public ObjectMapper objectMapper(){
        ObjectMapper objectMapper = new ObjectMapper();
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN)));
        javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN)));
        javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN)));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN)));
        javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN)));
        javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN)));
        objectMapper.registerModule(javaTimeModule);
        return objectMapper;
    }
}

方案二

@Configuration
public class LocalDateTimeSerializerConfig {

    @Value("${spring.jackson.date-format:yyyy-MM-dd HH:mm:ss}")
    private String pattern;

    @Bean
    @Primary
    public ObjectMapper serializingObjectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer());
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer());
        objectMapper.registerModule(javaTimeModule);
        return objectMapper;
    }

    public class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {
        @Override
        public void serialize(LocalDateTime value, JsonGenerator gen, SerializerProvider serializers)
                throws IOException {
            gen.writeString(value.format(DateTimeFormatter.ofPattern(pattern)));
        }
    }

    public class LocalDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {
        @Override
        public LocalDateTime deserialize(JsonParser p, DeserializationContext deserializationContext)
                throws IOException {
            return LocalDateTime.parse(p.getValueAsString(), DateTimeFormatter.ofPattern(pattern));
        }
    }
}

方案三 

/**
 * @Author ShenTuZhiGang
 * @Version 1.0.0
 * @Date 2020-03-29 19:23
 */
@Configuration
//@EnableWebMvc
public class CustomWebMvcConfigurer implements WebMvcConfigurer {
    private static final String DEFAULT_DATE_TIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
    private static final String DEFAULT_DATE_PATTERN = "yyyy-MM-dd";
    private static final String DEFAULT_TIME_PATTERN = "HH:mm:ss";
    /**
     * 统一输出风格
     * See {@link com.fasterxml.jackson.databind.PropertyNamingStrategy.SnakeCaseStrategy} for details.
     * @param converters
     */
    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        for (int i = 0; i < converters.size(); i++) {
            if (converters.get(i) instanceof MappingJackson2HttpMessageConverter) {
                ObjectMapper objectMapper = new ObjectMapper();
                // 统一返回数据的输出风格
                objectMapper.setPropertyNamingStrategy(new PropertyNamingStrategy.SnakeCaseStrategy());
                objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
                objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
                objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));

                JavaTimeModule javaTimeModule = new JavaTimeModule();
                javaTimeModule.addSerializer(LocalDateTime.class,
                        new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN)));
                javaTimeModule.addSerializer(LocalDate.class,
                        new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN)));
                javaTimeModule.addSerializer(LocalTime.class,
                        new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN)));
                javaTimeModule.addDeserializer(LocalDateTime.class,
                        new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN)));
                javaTimeModule.addDeserializer(LocalDate.class,
                        new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN)));
                javaTimeModule.addDeserializer(LocalTime.class,
                        new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN)));
                objectMapper.registerModule(javaTimeModule);

                MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
                converter.setObjectMapper(objectMapper);
                converters.set(i, converter);

                break;
            }
        }
    }
}

3、自定义配置

自定义一个反序列化类

public class DateDeserializer extends JsonDeserializer<LocalDateTime> {

    @Override
    public LocalDateTime deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException {
    	if (StringUtils.isBlank(jsonParser.getText()))
            return null;
        LocalDate localDate = LocalDate.parse(jsonParser.getText(), DateTimeFormatter.ofPattern("yyyy-MM-dd"));
        return LocalDateTime.of(localDate, LocalTime.MIN);
    }
}

 字段上通过com.fasterxml.jackson.databind.annotation.JsonDeserialize注解指定使用自定义的反序列化类

@JsonDeserialize(using = DateDeserializer.class)
private LocalDateTime updateTime;

4、完整配置

/**
 * @Author ShenTuZhiGang
 * @Version 1.0.0
 * @Date 2020-03-29 19:23
 */
@Configuration
//@EnableWebMvc
public class CustomWebMvcConfigurer implements WebMvcConfigurer {
    private static final String DEFAULT_DATE_TIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
    private static final String DEFAULT_DATE_PATTERN = "yyyy-MM-dd";
    private static final String DEFAULT_TIME_PATTERN = "HH:mm:ss";
    /**
     * 统一输出风格
     * See {@link com.fasterxml.jackson.databind.PropertyNamingStrategy.SnakeCaseStrategy} for details.
     * @param converters
     */
    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        for (int i = 0; i < converters.size(); i++) {
            if (converters.get(i) instanceof MappingJackson2HttpMessageConverter) {
                MappingJackson2HttpMessageConverter converter = (MappingJackson2HttpMessageConverter)converters.get(i);
                ObjectMapper objectMapper = converter.getObjectMapper();
                // 统一返回数据的输出风格
                objectMapper.setPropertyNamingStrategy(new PropertyNamingStrategy.SnakeCaseStrategy());
                objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
                objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
                objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
                break;
            }
        }
    }

    /**
     * LocalDate转换器，用于转换RequestParam和PathVariable参数
     */
    @Bean
    public Converter<String, LocalDate> localDateConverter() {
        return new Converter<String, LocalDate>() {
            @Override
            public LocalDate convert(String source) {
                return  LocalDate.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN));

            }
        };
    }

    /**
     * LocalDateTime转换器，用于转换RequestParam和PathVariable参数
     */
    @Bean
    public Converter<String, LocalDateTime> localDateTimeConverter() {
        return new Converter<String, LocalDateTime>() {
            @Override
            public LocalDateTime convert(String source) {
                return LocalDateTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN));
            }
        };
    }

    /**
     * LocalTime转换器，用于转换RequestParam和PathVariable参数
     */
    @Bean
    public Converter<String, LocalTime> localTimeConverter() {
        return new Converter<String, LocalTime>() {
            @Override
            public LocalTime convert(String source) {
                return LocalTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN));
            }
        };
    }

    /**
     * Date转换器，用于转换RequestParam和PathVariable参数
     */
    @Bean
    public Converter<String, Date> dateConverter() {
        return new Converter<String, Date>() {
            @Override
            public Date convert(String source) {
                SimpleDateFormat format = new SimpleDateFormat(DEFAULT_DATE_TIME_PATTERN);
                try {
                    return format.parse(source);
                } catch (ParseException e) {
                    throw new RuntimeException(e);
                }
            }
        };
    }

    /**
     * Json序列化和反序列化转换器，用于转换POST请求体中的json以及将我们的对象序列化为返回响应的json
     */
    @Bean
    public ObjectMapper objectMapper(){
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        objectMapper.disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);

        //LocalDateTime系列序列化和反序列化模块，继承自jsr310，我们在这里修改了日期格式
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class,
                new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN)));
        javaTimeModule.addSerializer(LocalDate.class,
                new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN)));
        javaTimeModule.addSerializer(LocalTime.class,
                new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN)));
        javaTimeModule.addDeserializer(LocalDateTime.class,
                new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN)));
        javaTimeModule.addDeserializer(LocalDate.class,
                new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN)));
        javaTimeModule.addDeserializer(LocalTime.class,
                new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN)));

        //Date序列化和反序列化
        javaTimeModule.addSerializer(Date.class, new JsonSerializer<Date>() {
            @Override
            public void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
                SimpleDateFormat formatter = new SimpleDateFormat(DEFAULT_DATE_TIME_PATTERN);
                String formattedDate = formatter.format(date);
                jsonGenerator.writeString(formattedDate);
            }
        });
        javaTimeModule.addDeserializer(Date.class, new JsonDeserializer<Date>() {
            @Override
            public Date deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
                SimpleDateFormat format = new SimpleDateFormat(DEFAULT_DATE_TIME_PATTERN);
                String date = jsonParser.getText();
                try {
                    return format.parse(date);
                } catch (ParseException e) {
                    throw new RuntimeException(e);
                }
            }
        });

        objectMapper.registerModule(javaTimeModule);
        return objectMapper;
    }

}

参考文章

LocalDateTime在spring boot中的格式化配置

Spring Boot（十二）：LocalDateTime格式化处理

@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") pattern:需要转换的时间日期的格式

Spring中使用LocalDateTime、LocalDate等参数作为入参数据转换问题

SpringBoot在Controller中接收LocalDate/LocalDateTime

Spring Boot LocalDateTime格式处理

Springboot - 处理LocalDateTime的入参和出参格式