Support multiple style of parsing/printing Durations

framework-docs/modules/ROOT/pages/core/validation/format.adoc

@@ -74,7 +74,8 @@ The `format` subpackages provide several `Formatter` implementations as a conven
 The `number` package provides `NumberStyleFormatter`, `CurrencyStyleFormatter`, and
 `PercentStyleFormatter` to format `Number` objects that use a `java.text.NumberFormat`.
 The `datetime` package provides a `DateFormatter` to format `java.util.Date` objects with
-a `java.text.DateFormat`.
+a `java.text.DateFormat`, as well as a `DurationFormatter` to format `Duration` objects
+in different styles defined in the `@DurationFormat.Style` enum (see <<format-annotations-api>>).
 
 The following `DateFormatter` is an example `Formatter` implementation:
 
@@ -280,7 +281,8 @@ Kotlin::
 
 A portable format annotation API exists in the `org.springframework.format.annotation`
 package. You can use `@NumberFormat` to format `Number` fields such as `Double` and
-`Long`, and `@DateTimeFormat` to format `java.util.Date`, `java.util.Calendar`, `Long`
+`Long`, `@DurationFormat` to format `Duration` fields in ISO8601 and simplified styles,
+and `@DateTimeFormat` to format `java.util.Date`, `java.util.Calendar`, `Long`
 (for millisecond timestamps) as well as JSR-310 `java.time`.
 
 The following example uses `@DateTimeFormat` to format a `java.util.Date` as an ISO Date

framework-docs/modules/ROOT/pages/web/webflux/config.adoc

@@ -91,7 +91,7 @@ class WebConfig : WebFluxConfigurer {
 [.small]#xref:web/webmvc/mvc-config/conversion.adoc[See equivalent in the Servlet stack]#
 
 By default, formatters for various number and date types are installed, along with support
-for customization via `@NumberFormat` and `@DateTimeFormat` on fields.
+for customization via `@NumberFormat`, `@DurationFormat` and `@DateTimeFormat` on fields.
 
 To register custom formatters and converters in Java config, use the following:
 

framework-docs/modules/ROOT/pages/web/webmvc/mvc-config/conversion.adoc

@@ -4,7 +4,7 @@
 [.small]#xref:web/webflux/config.adoc#webflux-config-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.
+for customization via `@NumberFormat`, `@DurationFormat` and `@DateTimeFormat` on fields.
 
 To register custom formatters and converters in Java config, use the following:
 

spring-context/src/main/java/org/springframework/format/annotation/DurationFormat.java

@@ -0,0 +1,213 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.format.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.time.Duration;
+import java.time.temporal.ChronoUnit;
+import java.util.function.Function;
+
+import org.springframework.lang.Nullable;
+
+/**
+ * Declares that a field or method parameter should be formatted as a {@link java.time.Duration},
+ * according to the specified {@code style}.
+ *
+ * @author Simon Baslé
+ * @since 6.1
+ */
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER, ElementType.ANNOTATION_TYPE})
+public @interface DurationFormat {
+
+	/**
+	 * Which {@code Style} to use for parsing and printing a {@code Duration}. Defaults to
+	 * the JDK style ({@link Style#ISO8601}).
+	 */
+	Style style() default Style.ISO8601;
+
+	/**
+	 * Define which {@link Unit} to fall back to in case the {@code style()}
+	 * needs a unit for either parsing or printing, and none is explicitly provided in
+	 * the input ({@code Unit.MILLIS} if unspecified).
+	 */
+	Unit defaultUnit() default Unit.MILLIS;
+
+	/**
+	 * Duration format styles.
+	 */
+	enum Style {
+
+		/**
+		 * Simple formatting based on a short suffix, for example '1s'.
+		 * Supported unit suffixes are: {@code ns, us, ms, s, m, h, d}.
+		 * This corresponds to nanoseconds, microseconds, milliseconds, seconds,
+		 * minutes, hours and days respectively.
+		 * <p>Note that when printing a {@code Duration}, this style can be lossy if the
+		 * selected unit is bigger than the resolution of the duration. For example,
+		 * {@code Duration.ofMillis(5).plusNanos(1234)} would get truncated to {@code "5ms"}
+		 * when printing using {@code ChronoUnit.MILLIS}.
+		 */
+		SIMPLE,
+
+		/**
+		 * ISO-8601 formatting.
+		 * <p>This is what the JDK uses in {@link java.time.Duration#parse(CharSequence)}
+		 * and {@link Duration#toString()}.
+		 */
+		ISO8601;
+	}
+
+	/**
+	 * Duration format unit, which mirrors a subset of {@link ChronoUnit} and allows conversion to and from
+	 * supported {@code ChronoUnit} as well as converting durations to longs.
+	 * The enum includes its corresponding suffix in the {@link Style#SIMPLE simple} Duration format style.
+	 */
+	enum Unit {
+		/**
+		 * Nanoseconds ({@code "ns"}).
+		 */
+		NANOS(ChronoUnit.NANOS, "ns", Duration::toNanos),
+
+		/**
+		 * Microseconds ({@code "us"}).
+		 */
+		MICROS(ChronoUnit.MICROS, "us", duration -> duration.toNanos() / 1000L),
+
+		/**
+		 * Milliseconds ({@code "ms"}).
+		 */
+		MILLIS(ChronoUnit.MILLIS, "ms", Duration::toMillis),
+
+		/**
+		 * Seconds ({@code "s"}).
+		 */
+		SECONDS(ChronoUnit.SECONDS, "s", Duration::getSeconds),
+
+		/**
+		 * Minutes ({@code "m"}).
+		 */
+		MINUTES(ChronoUnit.MINUTES, "m", Duration::toMinutes),
+
+		/**
+		 * Hours ({@code "h"}).
+		 */
+		HOURS(ChronoUnit.HOURS, "h", Duration::toHours),
+
+		/**
+		 * Days ({@code "d"}).
+		 */
+		DAYS(ChronoUnit.DAYS, "d", Duration::toDays);
+
+		private final ChronoUnit chronoUnit;
+
+		private final String suffix;
+
+		private final Function<Duration, Long> longValue;
+
+		Unit(ChronoUnit chronoUnit, String suffix, Function<Duration, Long> toUnit) {
+			this.chronoUnit = chronoUnit;
+			this.suffix = suffix;
+			this.longValue = toUnit;
+		}
+
+		/**
+		 * Convert this {@code DurationFormat.Unit} to its {@link ChronoUnit} equivalent.
+		 */
+		public ChronoUnit asChronoUnit() {
+			return this.chronoUnit;
+		}
+
+		/**
+		 * Convert this {@code DurationFormat.Unit} to a simple {@code String} suffix,
+		 * suitable for the {@link Style#SIMPLE} style.
+		 */
+		public String asSuffix() {
+			return this.suffix;
+		}
+
+		/**
+		 * Parse a {@code long} from a {@code String} and interpret it to be a {@code Duration}
+		 * in the current unit.
+		 * @param value the String representation of the long
+		 * @return the corresponding {@code Duration}
+		 */
+		public Duration parse(String value) {
+			return Duration.of(Long.parseLong(value), asChronoUnit());
+		}
+
+		/**
+		 * Print a {@code Duration} as a {@code String}, converting it to a long value
+		 * using this unit's precision via {@link #longValue(Duration)} and appending
+		 * this unit's simple {@link #asSuffix() suffix}.
+		 * @param value the {@code Duration} to convert to String
+		 * @return the String representation of the {@code Duration} in the {@link Style#SIMPLE SIMPLE style}
+		 */
+		public String print(Duration value) {
+			return longValue(value) + asSuffix();
+		}
+
+		/**
+		 * Convert the given {@code Duration} to a long value in the resolution of this
+		 * unit. Note that this can be lossy if the current unit is bigger than the
+		 * actual resolution of the duration.
+		 * <p>For example, {@code Duration.ofMillis(5).plusNanos(1234)} would get truncated
+		 * to {@code 5} for unit {@code MILLIS}.
+		 * @param value the {@code Duration} to convert to long
+		 * @return the long value for the Duration in this Unit
+		 */
+		public long longValue(Duration value) {
+			return this.longValue.apply(value);
+		}
+
+		/**
+		 * Get the {@code Unit} corresponding to the given {@code ChronoUnit}.
+		 * @throws IllegalArgumentException if that particular ChronoUnit isn't supported
+		 */
+		public static Unit fromChronoUnit(@Nullable ChronoUnit chronoUnit) {
+			if (chronoUnit == null) {
+				return Unit.MILLIS;
+			}
+			for (Unit candidate : values()) {
+				if (candidate.chronoUnit == chronoUnit) {
+					return candidate;
+				}
+			}
+			throw new IllegalArgumentException("No matching Unit for ChronoUnit." + chronoUnit.name());
+		}
+
+		/**
+		 * Get the {@code Unit} corresponding to the given {@code String} suffix.
+		 * @throws IllegalArgumentException if that particular suffix is unknown
+		 */
+		public static Unit fromSuffix(String suffix) {
+			for (Unit candidate : values()) {
+				if (candidate.suffix.equalsIgnoreCase(suffix)) {
+					return candidate;
+				}
+			}
+			throw new IllegalArgumentException("'" + suffix + "' is not a valid simple duration Unit");
+		}
+
+	}
+
+}

spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterRegistrar.java

@@ -197,6 +197,7 @@ public void registerFormatters(FormatterRegistry registry) {
 		registry.addFormatterForFieldType(MonthDay.class, new MonthDayFormatter());
 
 		registry.addFormatterForFieldAnnotation(new Jsr310DateTimeFormatAnnotationFormatterFactory());
+		registry.addFormatterForFieldAnnotation(new DurationFormatAnnotationFormatterFactory());
 	}
 
 	private DateTimeFormatter getFormatter(Type type) {

spring-context/src/main/java/org/springframework/format/datetime/standard/DurationFormatAnnotationFormatterFactory.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.format.datetime.standard;
+
+import java.time.Duration;
+import java.util.Set;
+
+import org.springframework.context.support.EmbeddedValueResolutionSupport;
+import org.springframework.format.AnnotationFormatterFactory;
+import org.springframework.format.Parser;
+import org.springframework.format.Printer;
+import org.springframework.format.annotation.DurationFormat;
+
+/**
+ * Formats fields annotated with the {@link DurationFormat} annotation using the
+ * selected style for parsing and printing JSR-310 {@code Duration}.
+ *
+ * @author Simon Baslé
+ * @since 6.1
+ * @see DurationFormat
+ * @see DurationFormatter
+ */
+public class DurationFormatAnnotationFormatterFactory extends EmbeddedValueResolutionSupport
+		implements AnnotationFormatterFactory<DurationFormat> {
+
+	// Create the set of field types that may be annotated with @DurationFormat.
+	private static final Set<Class<?>> FIELD_TYPES = Set.of(Duration.class);
+
+	@Override
+	public final Set<Class<?>> getFieldTypes() {
+		return FIELD_TYPES;
+	}
+
+	@Override
+	public Printer<?> getPrinter(DurationFormat annotation, Class<?> fieldType) {
+		return new DurationFormatter(annotation.style(), annotation.defaultUnit());
+	}
+
+	@Override
+	public Parser<?> getParser(DurationFormat annotation, Class<?> fieldType) {
+		return new DurationFormatter(annotation.style(), annotation.defaultUnit());
+	}
+}