Date Formatting Techniques in Spring Boot Applications

In Spring Boot development, formatting the date returned by APIs is essential for data readability and maintainability across different systems, especially in front‑end/back‑end separated projects where inconsistent date formats can cause display and processing issues.

Typical use cases include front‑end/back‑end data exchange, database storage and queries, and log recording, all of which benefit from a unified date format.

Spring Boot provides several approaches to achieve date formatting, such as configuration‑file settings, annotations, and global formatters, allowing developers to choose the method that best fits their needs.

Front‑end Date Formatting

function dateFormat(fmt, date) {
    let ret;
    const opt = {
        "Y+": date.getFullYear().toString(),
        "m+": (date.getMonth() + 1).toString(),
        "d+": date.getDate().toString(),
        "H+": date.getHours().toString(),
        "M+": date.getMinutes().toString(),
        "S+": date.getSeconds().toString()
    };
    for (let k in opt) {
        ret = new RegExp("(" + k + ")").exec(fmt);
        if (ret) {
            fmt = fmt.replace(ret[1], (ret[1].length == 1) ? (opt[k]) : (opt[k].padStart(ret[1].length, "0")));
        };
    };
    return fmt;
}
let date = new Date();
dateFormat("YYYY-mm-dd HH:MM:SS", date);
// >>> 2021-07-25 21:45:12

SimpleDateFormat Formatting (pre‑JDK 8)

// Define formatter
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
// Format a Date object
String date = dateFormat.format(new Date());

In a Spring controller, you can format fields of a list of entities as follows:

@RequestMapping("/list")
public List
getList() {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    List
list = userMapper.getList();
    list.forEach(item -> {
        item.setCtime(dateFormat.format(item.getCreatetime()));
        item.setUtime(dateFormat.format(item.getUpdatetime()));
    });
    return list;
}

DateTimeFormatter Formatting (JDK 8+)

@RequestMapping("/list")
public List
getList() {
    DateTimeFormatter dateFormat = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    List
list = userMapper.getList();
    list.forEach(item -> {
        item.setCtime(dateFormat.format(item.getCreatetime()));
        item.setUtime(dateFormat.format(item.getUpdatetime()));
    });
    return list;
}

DateTimeFormatter is thread‑safe and works with the new java.time types such as LocalDateTime, whereas SimpleDateFormat works with the legacy Date class.

Global Date Formatting via Configuration Files

# application.properties
spring.jackson.date-format=yyyy-MM-dd HH:mm:ss
spring.jackson.time-zone=GMT+8

Jackson automatically applies this format to all date fields when serializing JSON responses, providing a uniform output without additional code.

Partial Field Formatting with @JsonFormat

import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.Data;
import java.util.Date;

@Data
public class UserInfo {
    private int id;
    private String username;
    @JsonFormat(pattern = "yyyy-MM-dd hh:mm:ss", timezone = "GMT+8")
    private Date createtime;
    private Date updatetime;
}

Custom Parameter Converters

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

When using lambda expressions, ensure the target type is correctly inferred; otherwise, prefer anonymous inner classes or register the converters after RequestMappingHandlerAdapter is initialized.

Spring Annotation @DateTimeFormat

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

The pattern must match the incoming string format, otherwise a conversion exception will be thrown.

ControllerAdvice with initBinder

@ControllerAdvice
public class InitBinderDateController {
    @InitBinder("date")
    public void initBinder(WebDataBinder binder) {
        binder.registerCustomEditor(LocalDateTime.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) {
                if (!StringUtils.isEmpty(text)) {
                    setValue(LocalDateTime.parse(text, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
                }
            }
        });
    }
}

Backend Global Settings via Beans

@Configuration
public class LocalDateTimeSerializerConfig {
    private static final String PATTERN = "yyyy-MM-dd HH:mm:ss";
    @Bean
    public LocalDateTimeSerializer localDateTimeSerializer() {
        return new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(PATTERN));
    }
    @Bean
    public LocalDateTimeDeserializer localDateTimeDeserializer() {
        return new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(PATTERN));
    }
    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {
        return builder -> {
            builder.serializerByType(LocalDateTime.class, localDateTimeSerializer());
            builder.deserializerByType(LocalDateTime.class, localDateTimeDeserializer());
        };
    }
}

Returning Dates as Timestamps

# application.properties
spring.mvc.format.date=unix

Example controller:

@RestController
public class MyController {
    @GetMapping("/entity")
    public MyEntity getEntity() {
        MyEntity entity = new MyEntity();
        entity.setDate(new Date());
        return entity;
    }
}

The response will contain the date field as a Unix timestamp, e.g., { "date": 1678912345678 }.