Type Conversion

See equivalent in the Reactive stack

By default, formatters for various number and date types are installed, along with support for customization via @NumberFormat and @DateTimeFormat on fields.

To register custom formatters and converters in Java config, use the following:

Java
Kotlin

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

	@Override
	public void addFormatters(FormatterRegistry registry) {
		// ...
	}
}

@Configuration
@EnableWebMvc
class WebConfig : WebMvcConfigurer {

	override fun addFormatters(registry: FormatterRegistry) {
		// ...
	}
}

To do the same in XML config, use the following:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans
		https://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/mvc
		https://www.springframework.org/schema/mvc/spring-mvc.xsd">

	<mvc:annotation-driven conversion-service="conversionService"/>

	<bean id="conversionService"
			class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
		<property name="converters">
			<set>
				<bean class="org.example.MyConverter"/>
			</set>
		</property>
		<property name="formatters">
			<set>
				<bean class="org.example.MyFormatter"/>
				<bean class="org.example.MyAnnotationFormatterFactory"/>
			</set>
		</property>
		<property name="formatterRegistrars">
			<set>
				<bean class="org.example.MyFormatterRegistrar"/>
			</set>
		</property>
	</bean>

</beans>

By default Spring MVC considers the request Locale when parsing and formatting date values. This works for forms where dates are represented as Strings with "input" form fields. For "date" and "time" form fields, however, browsers use a fixed format defined in the HTML spec. For such cases date and time formatting can be customized as follows:

Java
Kotlin

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

	@Override
	public void addFormatters(FormatterRegistry registry) {
		DateTimeFormatterRegistrar registrar = new DateTimeFormatterRegistrar();
		registrar.setUseIsoFormat(true);
		registrar.registerFormatters(registry);
     	}
}

@Configuration
@EnableWebMvc
class WebConfig : WebMvcConfigurer {

	override fun addFormatters(registry: FormatterRegistry) {
		val registrar = DateTimeFormatterRegistrar()
		registrar.setUseIsoFormat(true)
		registrar.registerFormatters(registry)
	}
}

See the FormatterRegistrar SPI and the FormattingConversionServiceFactoryBean for more information on when to use FormatterRegistrar implementations.