Merge pull request #21136 from Grubhart

* pr/21136:
  Polish 'Add Period converter support'
  Add Period converter support

Closes gh-21136

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -1450,6 +1450,26 @@ Doing so gives a transparent upgrade path while supporting a much richer format.
 
 
 
+[[boot-features-external-config-conversion-period]]
+===== Converting periods
+In addition to durations, Spring Boot can also work with `java.time.Period` type.
+The following formats can be used in application properties:
+
+* An regular `int` representation (using days as the default unit unless a `@PeriodUnit` has been specified)
+* The standard ISO-8601 format {java-api}/java/time/Period.html#parse-java.lang.CharSequence-[used by `java.time.Period`]
+* A simpler format where the value and the unit pairs are coupled (e.g. `1y3d` means 1 year and 3 days)
+
+The following units are supported with the simple format:
+
+* `y` for years
+* `m` for months
+* `w` for weeks
+* `d` for days
+
+NOTE: The `java.time.Period` type never actually stores the number of weeks, it is simply a shortcut that means "`7 days`".
+
+
+
 [[boot-features-external-config-conversion-datasize]]
 ===== Converting Data Sizes
 Spring Framework has a `DataSize` value type that expresses a size in bytes.

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/fieldvalues/javac/JavaCompilerFieldValuesParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -116,6 +116,19 @@ public class JavaCompilerFieldValuesParser implements FieldValuesParser {
 			DURATION_SUFFIX = Collections.unmodifiableMap(values);
 		}
 
+		private static final String PERIOD_OF = "Period.of";
+
+		private static final Map<String, String> PERIOD_SUFFIX;
+
+		static {
+			Map<String, String> values = new HashMap<>();
+			values.put("Days", "d");
+			values.put("Weeks", "w");
+			values.put("Months", "m");
+			values.put("Years", "y");
+			PERIOD_SUFFIX = Collections.unmodifiableMap(values);
+		}
+
 		private static final String DATA_SIZE_OF = "DataSize.of";
 
 		private static final Map<String, String> DATA_SIZE_SUFFIX;
@@ -194,6 +207,10 @@ public class JavaCompilerFieldValuesParser implements FieldValuesParser {
 			if (dataSizeValue != null) {
 				return dataSizeValue;
 			}
+			Object periodValue = getFactoryValue(expression, factoryValue, PERIOD_OF, PERIOD_SUFFIX);
+			if (periodValue != null) {
+				return periodValue;
+			}
 			return factoryValue;
 		}
 

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/fieldvalues/AbstractFieldValuesProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -100,6 +100,11 @@ public abstract class AbstractFieldValuesProcessorTests {
 		assertThat(values.get("dataSizeMegabytes")).isEqualTo("20MB");
 		assertThat(values.get("dataSizeGigabytes")).isEqualTo("30GB");
 		assertThat(values.get("dataSizeTerabytes")).isEqualTo("40TB");
+		assertThat(values.get("periodNone")).isNull();
+		assertThat(values.get("periodDays")).isEqualTo("3d");
+		assertThat(values.get("periodWeeks")).isEqualTo("2w");
+		assertThat(values.get("periodMonths")).isEqualTo("10m");
+		assertThat(values.get("periodYears")).isEqualTo("15y");
 	}
 
 	@SupportedAnnotationTypes({ "org.springframework.boot.configurationsample.ConfigurationProperties" })

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/fieldvalues/FieldValues.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -19,6 +19,7 @@ package org.springframework.boot.configurationsample.fieldvalues;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.time.Duration;
+import java.time.Period;
 
 import org.springframework.boot.configurationsample.ConfigurationProperties;
 import org.springframework.util.MimeType;
@@ -136,4 +137,14 @@ public class FieldValues {
 
 	private DataSize dataSizeTerabytes = DataSize.ofTerabytes(40);
 
+	private Period periodNone;
+
+	private Period periodDays = Period.ofDays(3);
+
+	private Period periodWeeks = Period.ofWeeks(2);
+
+	private Period periodMonths = Period.ofMonths(10);
+
+	private Period periodYears = Period.ofYears(15);
+
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/ApplicationConversionService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -113,6 +113,9 @@ public class ApplicationConversionService extends FormattingConversionService {
 		registry.addConverter(new DurationToStringConverter());
 		registry.addConverter(new NumberToDurationConverter());
 		registry.addConverter(new DurationToNumberConverter());
+		registry.addConverter(new StringToPeriodConverter());
+		registry.addConverter(new PeriodToStringConverter());
+		registry.addConverter(new NumberToPeriodConverter());
 		registry.addConverter(new StringToDataSizeConverter());
 		registry.addConverter(new NumberToDataSizeConverter());
 		registry.addConverter(new StringToFileConverter());

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/NumberToPeriodConverter.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+import java.time.Period;
+import java.util.Collections;
+import java.util.Set;
+
+import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.convert.converter.GenericConverter;
+
+/**
+ * {@link Converter} to convert from a {@link Number} to a {@link Period}. Supports
+ * {@link Period#parse(CharSequence)} as well a more readable {@code 10m} form.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ * @see PeriodFormat
+ * @see PeriodUnit
+ */
+final class NumberToPeriodConverter implements GenericConverter {
+
+	private final StringToPeriodConverter delegate = new StringToPeriodConverter();
+
+	@Override
+	public Set<ConvertiblePair> getConvertibleTypes() {
+		return Collections.singleton(new ConvertiblePair(Number.class, Period.class));
+	}
+
+	@Override
+	public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+		return this.delegate.convert((source != null) ? source.toString() : null, TypeDescriptor.valueOf(String.class),
+				targetType);
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/PeriodFormat.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+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.Period;
+
+/**
+ * Annotation that can be used to indicate the format to use when converting a
+ * {@link Period}.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ * @since 2.3.0
+ */
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface PeriodFormat {
+
+	/**
+	 * The {@link Period} format style.
+	 * @return the period format style.
+	 */
+	PeriodStyle value();
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/PeriodStyle.java

@@ -0,0 +1,276 @@
+/*
+ * Copyright 2002-2020 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.boot.convert;
+
+import java.time.Period;
+import java.time.temporal.ChronoUnit;
+import java.util.function.Function;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.springframework.util.Assert;
+
+/**
+ * A standard set of {@link Period} units.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ * @since 2.3.0
+ * @see Period
+ */
+public enum PeriodStyle {
+
+	/**
+	 * Simple formatting, for example '1d'.
+	 */
+	SIMPLE("^" + "(?:([-+]?[0-9]+)Y)?" + "(?:([-+]?[0-9]+)M)?" + "(?:([-+]?[0-9]+)W)?" + "(?:([-+]?[0-9]+)D)?" + "$",
+			Pattern.CASE_INSENSITIVE) {
+
+		@Override
+		public Period parse(String value, ChronoUnit unit) {
+			try {
+				if (NUMERIC.matcher(value).matches()) {
+					return Unit.fromChronoUnit(unit).parse(value);
+				}
+				Matcher matcher = matcher(value);
+				Assert.state(matcher.matches(), "Does not match simple period pattern");
+				Assert.isTrue(hasAtLeastOneGroupValue(matcher), "'" + value + "' is not a valid simple period");
+				int years = parseInt(matcher, 1);
+				int months = parseInt(matcher, 2);
+				int weeks = parseInt(matcher, 3);
+				int days = parseInt(matcher, 4);
+				return Period.of(years, months, Math.addExact(Math.multiplyExact(weeks, 7), days));
+			}
+			catch (Exception ex) {
+				throw new IllegalArgumentException("'" + value + "' is not a valid simple period", ex);
+			}
+		}
+
+		boolean hasAtLeastOneGroupValue(Matcher matcher) {
+			for (int i = 0; i < matcher.groupCount(); i++) {
+				if (matcher.group(i + 1) != null) {
+					return true;
+				}
+			}
+			return false;
+		}
+
+		private int parseInt(Matcher matcher, int group) {
+			String value = matcher.group(group);
+			return (value != null) ? Integer.parseInt(value) : 0;
+		}
+
+		@Override
+		protected boolean matches(String value) {
+			return NUMERIC.matcher(value).matches() || matcher(value).matches();
+		}
+
+		@Override
+		public String print(Period value, ChronoUnit unit) {
+			if (value.isZero()) {
+				return Unit.fromChronoUnit(unit).print(value);
+			}
+			StringBuilder result = new StringBuilder();
+			append(result, value, Unit.YEARS);
+			append(result, value, Unit.MONTHS);
+			append(result, value, Unit.DAYS);
+			return result.toString();
+		}
+
+		private void append(StringBuilder result, Period value, Unit unit) {
+			if (!unit.isZero(value)) {
+				result.append(unit.print(value));
+			}
+		}
+
+	},
+
+	/**
+	 * ISO-8601 formatting.
+	 */
+	ISO8601("^[\\+\\-]?P.*$", 0) {
+
+		@Override
+		public Period parse(String value, ChronoUnit unit) {
+			try {
+				return Period.parse(value);
+			}
+			catch (Exception ex) {
+				throw new IllegalArgumentException("'" + value + "' is not a valid ISO-8601 period", ex);
+			}
+		}
+
+		@Override
+		public String print(Period value, ChronoUnit unit) {
+			return value.toString();
+		}
+
+	};
+
+	private static final Pattern NUMERIC = Pattern.compile("^[-+]?[0-9]+$");
+
+	private final Pattern pattern;
+
+	PeriodStyle(String pattern, int flags) {
+		this.pattern = Pattern.compile(pattern, flags);
+	}
+
+	protected boolean matches(String value) {
+		return this.pattern.matcher(value).matches();
+	}
+
+	protected final Matcher matcher(String value) {
+		return this.pattern.matcher(value);
+	}
+
+	/**
+	 * Parse the given value to a Period.
+	 * @param value the value to parse
+	 * @return a period
+	 */
+	public Period parse(String value) {
+		return parse(value, null);
+	}
+
+	/**
+	 * Parse the given value to a period.
+	 * @param value the value to parse
+	 * @param unit the period unit to use if the value doesn't specify one ({@code null}
+	 * will default to d)
+	 * @return a period
+	 */
+	public abstract Period parse(String value, ChronoUnit unit);
+
+	/**
+	 * Print the specified period.
+	 * @param value the value to print
+	 * @return the printed result
+	 */
+	public String print(Period value) {
+		return print(value, null);
+	}
+
+	/**
+	 * Print the specified period using the given unit.
+	 * @param value the value to print
+	 * @param unit the value to use for printing
+	 * @return the printed result
+	 */
+	public abstract String print(Period value, ChronoUnit unit);
+
+	/**
+	 * Detect the style then parse the value to return a period.
+	 * @param value the value to parse
+	 * @return the parsed period
+	 * @throws IllegalStateException if the value is not a known style or cannot be parsed
+	 */
+	public static Period detectAndParse(String value) {
+		return detectAndParse(value, null);
+	}
+
+	/**
+	 * Detect the style then parse the value to return a period.
+	 * @param value the value to parse
+	 * @param unit the period unit to use if the value doesn't specify one ({@code null}
+	 * will default to ms)
+	 * @return the parsed period
+	 * @throws IllegalStateException if the value is not a known style or cannot be parsed
+	 */
+	public static Period detectAndParse(String value, ChronoUnit unit) {
+		return detect(value).parse(value, unit);
+	}
+
+	/**
+	 * Detect the style from the given source value.
+	 * @param value the source value
+	 * @return the period style
+	 * @throws IllegalStateException if the value is not a known style
+	 */
+	public static PeriodStyle detect(String value) {
+		Assert.notNull(value, "Value must not be null");
+		for (PeriodStyle candidate : values()) {
+			if (candidate.matches(value)) {
+				return candidate;
+			}
+		}
+		throw new IllegalArgumentException("'" + value + "' is not a valid period");
+	}
+
+	enum Unit {
+
+		/**
+		 * Days, represented by suffix {@code d}.
+		 */
+		DAYS(ChronoUnit.DAYS, "d", Period::getDays, Period::ofDays),
+
+		/**
+		 * Months, represented by suffix {@code m}.
+		 */
+		MONTHS(ChronoUnit.MONTHS, "m", Period::getMonths, Period::ofMonths),
+
+		/**
+		 * Years, represented by suffix {@code y}.
+		 */
+		YEARS(ChronoUnit.YEARS, "y", Period::getYears, Period::ofYears);
+
+		private final ChronoUnit chronoUnit;
+
+		private final String suffix;
+
+		private final Function<Period, Integer> intValue;
+
+		private final Function<Integer, Period> factory;
+
+		Unit(ChronoUnit chronoUnit, String suffix, Function<Period, Integer> intValue,
+				Function<Integer, Period> factory) {
+			this.chronoUnit = chronoUnit;
+			this.suffix = suffix;
+			this.intValue = intValue;
+			this.factory = factory;
+		}
+
+		private Period parse(String value) {
+			return this.factory.apply(Integer.parseInt(value));
+		}
+
+		private String print(Period value) {
+			return intValue(value) + this.suffix;
+		}
+
+		public boolean isZero(Period value) {
+			return intValue(value) == 0;
+		}
+
+		public int intValue(Period value) {
+			return this.intValue.apply(value);
+		}
+
+		public static Unit fromChronoUnit(ChronoUnit chronoUnit) {
+			if (chronoUnit == null) {
+				return Unit.DAYS;
+			}
+			for (Unit candidate : values()) {
+				if (candidate.chronoUnit == chronoUnit) {
+					return candidate;
+				}
+			}
+			throw new IllegalArgumentException("Unsupported unit " + chronoUnit);
+		}
+
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/PeriodToStringConverter.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2002-2020 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.boot.convert;
+
+import java.time.Period;
+import java.time.temporal.ChronoUnit;
+import java.util.Collections;
+import java.util.Set;
+
+import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.convert.converter.GenericConverter;
+import org.springframework.util.ObjectUtils;
+
+/**
+ * {@link Converter} to convert from a {@link Period} to a {@link String}.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ * @since 2.3.0
+ * @see Period
+ */
+public class PeriodToStringConverter implements GenericConverter {
+
+	@Override
+	public Set<ConvertiblePair> getConvertibleTypes() {
+		return Collections.singleton(new ConvertiblePair(Period.class, String.class));
+	}
+
+	@Override
+	public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+		if (ObjectUtils.isEmpty(source)) {
+			return null;
+		}
+		return convert((Period) source, getPeriodStyle(sourceType), getPeriodUnit(sourceType));
+	}
+
+	private PeriodStyle getPeriodStyle(TypeDescriptor sourceType) {
+		PeriodFormat annotation = sourceType.getAnnotation(PeriodFormat.class);
+		return (annotation != null) ? annotation.value() : null;
+	}
+
+	private String convert(Period source, PeriodStyle style, ChronoUnit unit) {
+		style = (style != null) ? style : PeriodStyle.ISO8601;
+		return style.print(source, unit);
+	}
+
+	private ChronoUnit getPeriodUnit(TypeDescriptor sourceType) {
+		PeriodUnit annotation = sourceType.getAnnotation(PeriodUnit.class);
+		return (annotation != null) ? annotation.value() : null;
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/PeriodUnit.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+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.Period;
+import java.time.temporal.ChronoUnit;
+
+/**
+ * Annotation that can be used to change the default unit used when converting a
+ * {@link Period}.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ * @since 2.3.0
+ */
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface PeriodUnit {
+
+	/**
+	 * The Period unit to use if one is not specified.
+	 * @return the Period unit
+	 */
+	ChronoUnit value();
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/StringToPeriodConverter.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+import java.time.Period;
+import java.time.temporal.ChronoUnit;
+import java.util.Collections;
+import java.util.Set;
+
+import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.convert.converter.GenericConverter;
+import org.springframework.util.ObjectUtils;
+
+/**
+ * {@link Converter} to convert from a {@link String} to a {@link Period}. Supports
+ * {@link Period#parse(CharSequence)} as well a more readable form.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ * @since 2.3.0
+ * @see PeriodUnit
+ */
+public class StringToPeriodConverter implements GenericConverter {
+
+	@Override
+	public Set<GenericConverter.ConvertiblePair> getConvertibleTypes() {
+		return Collections.singleton(new GenericConverter.ConvertiblePair(String.class, Period.class));
+	}
+
+	@Override
+	public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+		if (ObjectUtils.isEmpty(source)) {
+			return null;
+		}
+		return convert(source.toString(), getStyle(targetType), getPeriodUnit(targetType));
+	}
+
+	private PeriodStyle getStyle(TypeDescriptor targetType) {
+		PeriodFormat annotation = targetType.getAnnotation(PeriodFormat.class);
+		return (annotation != null) ? annotation.value() : null;
+	}
+
+	private ChronoUnit getPeriodUnit(TypeDescriptor targetType) {
+		PeriodUnit annotation = targetType.getAnnotation(PeriodUnit.class);
+		return (annotation != null) ? annotation.value() : null;
+	}
+
+	private Period convert(String source, PeriodStyle style, ChronoUnit unit) {
+		style = (style != null) ? style : PeriodStyle.detect(source);
+		return style.parse(source, unit);
+	}
+
+}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/convert/MockPeriodTypeDescriptor.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+import java.time.Period;
+import java.time.temporal.ChronoUnit;
+import java.util.Collections;
+
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.convert.TypeDescriptor;
+
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Create a mock {@link TypeDescriptor} with optional {@link PeriodUnit @PeriodUnit} and
+ * {@link PeriodFormat @PeriodFormat} annotations.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ */
+public final class MockPeriodTypeDescriptor {
+
+	private MockPeriodTypeDescriptor() {
+	}
+
+	@SuppressWarnings({ "rawtypes", "unchecked" })
+	public static TypeDescriptor get(ChronoUnit unit, PeriodStyle style) {
+		TypeDescriptor descriptor = mock(TypeDescriptor.class);
+		if (unit != null) {
+			PeriodUnit unitAnnotation = AnnotationUtils.synthesizeAnnotation(Collections.singletonMap("value", unit),
+					PeriodUnit.class, null);
+			given(descriptor.getAnnotation(PeriodUnit.class)).willReturn(unitAnnotation);
+		}
+		if (style != null) {
+			PeriodFormat formatAnnotation = AnnotationUtils
+					.synthesizeAnnotation(Collections.singletonMap("value", style), PeriodFormat.class, null);
+			given(descriptor.getAnnotation(PeriodFormat.class)).willReturn(formatAnnotation);
+		}
+		given(descriptor.getType()).willReturn((Class) Period.class);
+		given(descriptor.getObjectType()).willReturn((Class) Period.class);
+		return descriptor;
+	}
+
+}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/convert/NumberToPeriodConverterTests.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+import java.time.Period;
+import java.time.temporal.ChronoUnit;
+import java.util.Collections;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.params.provider.Arguments;
+
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.TypeDescriptor;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link NumberToPeriodConverter}.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ */
+class NumberToPeriodConverterTests {
+
+	@ConversionServiceTest
+	void convertWhenSimpleWithoutSuffixShouldReturnPeriod(ConversionService conversionService) {
+		assertThat(convert(conversionService, 10)).isEqualTo(Period.ofDays(10));
+		assertThat(convert(conversionService, +10)).isEqualTo(Period.ofDays(10));
+		assertThat(convert(conversionService, -10)).isEqualTo(Period.ofDays(-10));
+	}
+
+	@ConversionServiceTest
+	void convertWhenSimpleWithoutSuffixButWithAnnotationShouldReturnPeriod(ConversionService conversionService) {
+		assertThat(convert(conversionService, 10, ChronoUnit.MONTHS)).isEqualTo(Period.ofMonths(10));
+		assertThat(convert(conversionService, +10, ChronoUnit.MONTHS)).isEqualTo(Period.ofMonths(10));
+		assertThat(convert(conversionService, -10, ChronoUnit.MONTHS)).isEqualTo(Period.ofMonths(-10));
+	}
+
+	private Period convert(ConversionService conversionService, Integer source) {
+		return conversionService.convert(source, Period.class);
+	}
+
+	@SuppressWarnings({ "rawtypes", "unchecked" })
+	private Period convert(ConversionService conversionService, Integer source, ChronoUnit defaultUnit) {
+		TypeDescriptor targetType = mock(TypeDescriptor.class);
+		if (defaultUnit != null) {
+			PeriodUnit unitAnnotation = AnnotationUtils
+					.synthesizeAnnotation(Collections.singletonMap("value", defaultUnit), PeriodUnit.class, null);
+			given(targetType.getAnnotation(PeriodUnit.class)).willReturn(unitAnnotation);
+		}
+		given(targetType.getType()).willReturn((Class) Period.class);
+		return (Period) conversionService.convert(source, TypeDescriptor.forObject(source), targetType);
+	}
+
+	static Stream<? extends Arguments> conversionServices() {
+		return ConversionServiceArguments.with(new NumberToPeriodConverter());
+	}
+
+}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/convert/PeriodStyleTests.java

@@ -0,0 +1,222 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+import java.time.Period;
+import java.time.temporal.ChronoUnit;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
+/**
+ * Tests for {@link PeriodStyle}.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ */
+class PeriodStyleTests {
+
+	@Test
+	void detectAndParseWhenValueIsNullShouldThrowException() {
+		assertThatIllegalArgumentException().isThrownBy(() -> PeriodStyle.detectAndParse(null))
+				.withMessageContaining("Value must not be null");
+	}
+
+	@Test
+	void detectAndParseWhenIso8601ShouldReturnPeriod() {
+		assertThat(PeriodStyle.detectAndParse("P15M")).isEqualTo(Period.parse("P15M"));
+		assertThat(PeriodStyle.detectAndParse("-P15M")).isEqualTo(Period.parse("P-15M"));
+		assertThat(PeriodStyle.detectAndParse("+P15M")).isEqualTo(Period.parse("P15M"));
+		assertThat(PeriodStyle.detectAndParse("P2D")).isEqualTo(Period.parse("P2D"));
+		assertThat(PeriodStyle.detectAndParse("-P20Y")).isEqualTo(Period.parse("P-20Y"));
+
+	}
+
+	@Test
+	void detectAndParseWhenSimpleDaysShouldReturnPeriod() {
+		assertThat(PeriodStyle.detectAndParse("10d")).isEqualTo(Period.ofDays(10));
+		assertThat(PeriodStyle.detectAndParse("10D")).isEqualTo(Period.ofDays(10));
+		assertThat(PeriodStyle.detectAndParse("+10d")).isEqualTo(Period.ofDays(10));
+		assertThat(PeriodStyle.detectAndParse("-10D")).isEqualTo(Period.ofDays(-10));
+	}
+
+	@Test
+	void detectAndParseWhenSimpleWeeksShouldReturnPeriod() {
+		assertThat(PeriodStyle.detectAndParse("10w")).isEqualTo(Period.ofWeeks(10));
+		assertThat(PeriodStyle.detectAndParse("10W")).isEqualTo(Period.ofWeeks(10));
+		assertThat(PeriodStyle.detectAndParse("+10w")).isEqualTo(Period.ofWeeks(10));
+		assertThat(PeriodStyle.detectAndParse("-10W")).isEqualTo(Period.ofWeeks(-10));
+	}
+
+	@Test
+	void detectAndParseWhenSimpleMonthsShouldReturnPeriod() {
+		assertThat(PeriodStyle.detectAndParse("10m")).isEqualTo(Period.ofMonths(10));
+		assertThat(PeriodStyle.detectAndParse("10M")).isEqualTo(Period.ofMonths(10));
+		assertThat(PeriodStyle.detectAndParse("+10m")).isEqualTo(Period.ofMonths(10));
+		assertThat(PeriodStyle.detectAndParse("-10M")).isEqualTo(Period.ofMonths(-10));
+	}
+
+	@Test
+	void detectAndParseWhenSimpleYearsShouldReturnPeriod() {
+		assertThat(PeriodStyle.detectAndParse("10y")).isEqualTo(Period.ofYears(10));
+		assertThat(PeriodStyle.detectAndParse("10Y")).isEqualTo(Period.ofYears(10));
+		assertThat(PeriodStyle.detectAndParse("+10y")).isEqualTo(Period.ofYears(10));
+		assertThat(PeriodStyle.detectAndParse("-10Y")).isEqualTo(Period.ofYears(-10));
+	}
+
+	@Test
+	void detectAndParseWhenSimpleWithoutSuffixShouldReturnPeriod() {
+		assertThat(PeriodStyle.detectAndParse("10")).isEqualTo(Period.ofDays(10));
+		assertThat(PeriodStyle.detectAndParse("+10")).isEqualTo(Period.ofDays(10));
+		assertThat(PeriodStyle.detectAndParse("-10")).isEqualTo(Period.ofDays(-10));
+	}
+
+	@Test
+	void detectAndParseWhenSimpleWithoutSuffixButWithChronoUnitShouldReturnPeriod() {
+		assertThat(PeriodStyle.detectAndParse("10", ChronoUnit.MONTHS)).isEqualTo(Period.ofMonths(10));
+		assertThat(PeriodStyle.detectAndParse("+10", ChronoUnit.MONTHS)).isEqualTo(Period.ofMonths(10));
+		assertThat(PeriodStyle.detectAndParse("-10", ChronoUnit.MONTHS)).isEqualTo(Period.ofMonths(-10));
+	}
+
+	@Test
+	void detectAndParseWhenComplexShouldReturnPeriod() {
+		assertThat(PeriodStyle.detectAndParse("1y2m")).isEqualTo(Period.of(1, 2, 0));
+		assertThat(PeriodStyle.detectAndParse("1y2m3d")).isEqualTo(Period.of(1, 2, 3));
+		assertThat(PeriodStyle.detectAndParse("2m3d")).isEqualTo(Period.of(0, 2, 3));
+		assertThat(PeriodStyle.detectAndParse("1y3d")).isEqualTo(Period.of(1, 0, 3));
+		assertThat(PeriodStyle.detectAndParse("-1y3d")).isEqualTo(Period.of(-1, 0, 3));
+		assertThat(PeriodStyle.detectAndParse("-1y-3d")).isEqualTo(Period.of(-1, 0, -3));
+	}
+
+	@Test
+	void detectAndParseWhenBadFormatShouldThrowException() {
+		assertThatIllegalArgumentException().isThrownBy(() -> PeriodStyle.detectAndParse("10foo"))
+				.withMessageContaining("'10foo' is not a valid period");
+	}
+
+	@Test
+	void detectWhenSimpleShouldReturnSimple() {
+		assertThat(PeriodStyle.detect("10")).isEqualTo(PeriodStyle.SIMPLE);
+		assertThat(PeriodStyle.detect("+10")).isEqualTo(PeriodStyle.SIMPLE);
+		assertThat(PeriodStyle.detect("-10")).isEqualTo(PeriodStyle.SIMPLE);
+		assertThat(PeriodStyle.detect("10m")).isEqualTo(PeriodStyle.SIMPLE);
+		assertThat(PeriodStyle.detect("10y")).isEqualTo(PeriodStyle.SIMPLE);
+		assertThat(PeriodStyle.detect("10d")).isEqualTo(PeriodStyle.SIMPLE);
+		assertThat(PeriodStyle.detect("10D")).isEqualTo(PeriodStyle.SIMPLE);
+	}
+
+	@Test
+	void detectWhenIso8601ShouldReturnIso8601() {
+		assertThat(PeriodStyle.detect("P20")).isEqualTo(PeriodStyle.ISO8601);
+		assertThat(PeriodStyle.detect("-P15M")).isEqualTo(PeriodStyle.ISO8601);
+		assertThat(PeriodStyle.detect("+P15M")).isEqualTo(PeriodStyle.ISO8601);
+		assertThat(PeriodStyle.detect("P10Y")).isEqualTo(PeriodStyle.ISO8601);
+		assertThat(PeriodStyle.detect("P2D")).isEqualTo(PeriodStyle.ISO8601);
+		assertThat(PeriodStyle.detect("-P6")).isEqualTo(PeriodStyle.ISO8601);
+		assertThat(PeriodStyle.detect("-P-6M")).isEqualTo(PeriodStyle.ISO8601);
+	}
+
+	@Test
+	void detectWhenUnknownShouldThrowException() {
+		assertThatIllegalArgumentException().isThrownBy(() -> PeriodStyle.detect("bad"))
+				.withMessageContaining("'bad' is not a valid period");
+	}
+
+	@Test
+	void parseIso8601ShouldParse() {
+		assertThat(PeriodStyle.ISO8601.parse("P20D")).isEqualTo(Period.parse("P20D"));
+		assertThat(PeriodStyle.ISO8601.parse("P15M")).isEqualTo(Period.parse("P15M"));
+		assertThat(PeriodStyle.ISO8601.parse("+P15M")).isEqualTo(Period.parse("P15M"));
+		assertThat(PeriodStyle.ISO8601.parse("P10Y")).isEqualTo(Period.parse("P10Y"));
+		assertThat(PeriodStyle.ISO8601.parse("P2D")).isEqualTo(Period.parse("P2D"));
+		assertThat(PeriodStyle.ISO8601.parse("-P6D")).isEqualTo(Period.parse("-P6D"));
+		assertThat(PeriodStyle.ISO8601.parse("-P-6Y+3M")).isEqualTo(Period.parse("-P-6Y+3M"));
+	}
+
+	@Test
+	void parseIso8601WithUnitShouldIgnoreUnit() {
+		assertThat(PeriodStyle.ISO8601.parse("P20D", ChronoUnit.SECONDS)).isEqualTo(Period.parse("P20D"));
+		assertThat(PeriodStyle.ISO8601.parse("P15M", ChronoUnit.SECONDS)).isEqualTo(Period.parse("P15M"));
+		assertThat(PeriodStyle.ISO8601.parse("+P15M", ChronoUnit.SECONDS)).isEqualTo(Period.parse("P15M"));
+		assertThat(PeriodStyle.ISO8601.parse("P10Y", ChronoUnit.SECONDS)).isEqualTo(Period.parse("P10Y"));
+		assertThat(PeriodStyle.ISO8601.parse("P2D", ChronoUnit.SECONDS)).isEqualTo(Period.parse("P2D"));
+		assertThat(PeriodStyle.ISO8601.parse("-P6D", ChronoUnit.SECONDS)).isEqualTo(Period.parse("-P6D"));
+		assertThat(PeriodStyle.ISO8601.parse("-P-6Y+3M", ChronoUnit.SECONDS)).isEqualTo(Period.parse("-P-6Y+3M"));
+	}
+
+	@Test
+	void parseIso8601WhenSimpleShouldThrowException() {
+		assertThatIllegalArgumentException().isThrownBy(() -> PeriodStyle.ISO8601.parse("10d"))
+				.withMessageContaining("'10d' is not a valid ISO-8601 period");
+	}
+
+	@Test
+	void parseSimpleShouldParse() {
+		assertThat(PeriodStyle.SIMPLE.parse("10m")).isEqualTo(Period.ofMonths(10));
+	}
+
+	@Test
+	void parseSimpleWithUnitShouldUseUnitAsFallback() {
+		assertThat(PeriodStyle.SIMPLE.parse("10m", ChronoUnit.DAYS)).isEqualTo(Period.ofMonths(10));
+		assertThat(PeriodStyle.SIMPLE.parse("10", ChronoUnit.MONTHS)).isEqualTo(Period.ofMonths(10));
+	}
+
+	@Test
+	void parseSimpleWhenUnknownUnitShouldThrowException() {
+		assertThatIllegalArgumentException().isThrownBy(() -> PeriodStyle.SIMPLE.parse("10x")).satisfies(
+				(ex) -> assertThat(ex.getCause().getMessage()).isEqualTo("Does not match simple period pattern"));
+	}
+
+	@Test
+	void parseSimpleWhenIso8601ShouldThrowException() {
+		assertThatIllegalArgumentException().isThrownBy(() -> PeriodStyle.SIMPLE.parse("PT10H"))
+				.withMessageContaining("'PT10H' is not a valid simple period");
+	}
+
+	@Test
+	void printIso8601ShouldPrint() {
+		Period period = Period.parse("-P-6M+3D");
+		assertThat(PeriodStyle.ISO8601.print(period)).isEqualTo("P6M-3D");
+	}
+
+	@Test
+	void printIso8601ShouldIgnoreUnit() {
+		Period period = Period.parse("-P3Y");
+		assertThat(PeriodStyle.ISO8601.print(period, ChronoUnit.DAYS)).isEqualTo("P-3Y");
+	}
+
+	@Test
+	void printSimpleWhenZeroWithoutUnitShouldPrintInDays() {
+		Period period = Period.ofMonths(0);
+		assertThat(PeriodStyle.SIMPLE.print(period)).isEqualTo("0d");
+	}
+
+	@Test
+	void printSimpleWhenZeroWithUnitShouldPrintInUnit() {
+		Period period = Period.ofYears(0);
+		assertThat(PeriodStyle.SIMPLE.print(period, ChronoUnit.YEARS)).isEqualTo("0y");
+	}
+
+	@Test
+	void printSimpleWhenNonZeroShouldIgnoreUnit() {
+		Period period = Period.of(1, 2, 3);
+		assertThat(PeriodStyle.SIMPLE.print(period, ChronoUnit.YEARS)).isEqualTo("1y2m3d");
+	}
+
+}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/convert/PeriodToStringConverterTests.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+import java.time.Period;
+import java.time.temporal.ChronoUnit;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.params.provider.Arguments;
+
+import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.TypeDescriptor;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link PeriodToStringConverter}.
+ *
+ * @author Eddú Melendez
+ * @author Edson Chávez
+ */
+class PeriodToStringConverterTests {
+
+	@ConversionServiceTest
+	void convertWithoutStyleShouldReturnIso8601(ConversionService conversionService) {
+		String converted = conversionService.convert(Period.ofDays(1), String.class);
+		assertThat(converted).isEqualTo(Period.ofDays(1).toString());
+	}
+
+	@ConversionServiceTest
+	void convertWithFormatWhenZeroShouldUseFormatAndDays(ConversionService conversionService) {
+		String converted = (String) conversionService.convert(Period.ofMonths(0),
+				MockPeriodTypeDescriptor.get(null, PeriodStyle.SIMPLE), TypeDescriptor.valueOf(String.class));
+		assertThat(converted).isEqualTo("0d");
+	}
+
+	@ConversionServiceTest
+	void convertWithFormatShouldUseFormat(ConversionService conversionService) {
+		String converted = (String) conversionService.convert(Period.of(1, 2, 3),
+				MockPeriodTypeDescriptor.get(null, PeriodStyle.SIMPLE), TypeDescriptor.valueOf(String.class));
+		assertThat(converted).isEqualTo("1y2m3d");
+	}
+
+	@ConversionServiceTest
+	void convertWithFormatAndUnitWhenZeroShouldUseFormatAndUnit(ConversionService conversionService) {
+		String converted = (String) conversionService.convert(Period.ofYears(0),
+				MockPeriodTypeDescriptor.get(ChronoUnit.YEARS, PeriodStyle.SIMPLE),
+				TypeDescriptor.valueOf(String.class));
+		assertThat(converted).isEqualTo("0y");
+	}
+
+	@ConversionServiceTest
+	void convertWithFormatAndUnitWhenNonZeroShouldUseFormatAndIgnoreUnit(ConversionService conversionService) {
+		String converted = (String) conversionService.convert(Period.of(1, 0, 3),
+				MockPeriodTypeDescriptor.get(ChronoUnit.YEARS, PeriodStyle.SIMPLE),
+				TypeDescriptor.valueOf(String.class));
+		assertThat(converted).isEqualTo("1y3d");
+	}
+
+	static Stream<? extends Arguments> conversionServices() throws Exception {
+		return ConversionServiceArguments.with(new PeriodToStringConverter());
+	}
+
+}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/convert/StringToPeriodConverterTest.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2012-2020 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.boot.convert;
+
+import java.time.Period;
+import java.time.temporal.ChronoUnit;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.params.provider.Arguments;
+
+import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.TypeDescriptor;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link StringToPeriodConverter}.
+ *
+ * @author Eddú Meléndez
+ * @author Edson Chávez
+ */
+public class StringToPeriodConverterTest {
+
+	@ConversionServiceTest
+	void convertWhenIso8601ShouldReturnPeriod(ConversionService conversionService) {
+		assertThat(convert(conversionService, "P2Y")).isEqualTo(Period.parse("P2Y"));
+		assertThat(convert(conversionService, "P3M")).isEqualTo(Period.parse("P3M"));
+		assertThat(convert(conversionService, "P4W")).isEqualTo(Period.parse("P4W"));
+		assertThat(convert(conversionService, "P5D")).isEqualTo(Period.parse("P5D"));
+		assertThat(convert(conversionService, "P1Y2M3D")).isEqualTo(Period.parse("P1Y2M3D"));
+		assertThat(convert(conversionService, "P1Y2M3W4D")).isEqualTo(Period.parse("P1Y2M3W4D"));
+		assertThat(convert(conversionService, "P-1Y2M")).isEqualTo(Period.parse("P-1Y2M"));
+		assertThat(convert(conversionService, "-P1Y2M")).isEqualTo(Period.parse("-P1Y2M"));
+	}
+
+	@ConversionServiceTest
+	void convertWhenSimpleDaysShouldReturnPeriod(ConversionService conversionService) {
+		assertThat(convert(conversionService, "10d")).isEqualTo(Period.ofDays(10));
+		assertThat(convert(conversionService, "10D")).isEqualTo(Period.ofDays(10));
+		assertThat(convert(conversionService, "+10d")).isEqualTo(Period.ofDays(10));
+		assertThat(convert(conversionService, "-10D")).isEqualTo(Period.ofDays(-10));
+	}
+
+	@ConversionServiceTest
+	void convertWhenSimpleMonthsShouldReturnPeriod(ConversionService conversionService) {
+		assertThat(convert(conversionService, "10m")).isEqualTo(Period.ofMonths(10));
+		assertThat(convert(conversionService, "10M")).isEqualTo(Period.ofMonths(10));
+		assertThat(convert(conversionService, "+10m")).isEqualTo(Period.ofMonths(10));
+		assertThat(convert(conversionService, "-10M")).isEqualTo(Period.ofMonths(-10));
+	}
+
+	@ConversionServiceTest
+	void convertWhenSimpleYearsShouldReturnPeriod(ConversionService conversionService) {
+		assertThat(convert(conversionService, "10y")).isEqualTo(Period.ofYears(10));
+		assertThat(convert(conversionService, "10Y")).isEqualTo(Period.ofYears(10));
+		assertThat(convert(conversionService, "+10y")).isEqualTo(Period.ofYears(10));
+		assertThat(convert(conversionService, "-10Y")).isEqualTo(Period.ofYears(-10));
+	}
+
+	@ConversionServiceTest
+	void convertWhenSimpleWithoutSuffixShouldReturnPeriod(ConversionService conversionService) {
+		assertThat(convert(conversionService, "10")).isEqualTo(Period.ofDays(10));
+		assertThat(convert(conversionService, "+10")).isEqualTo(Period.ofDays(10));
+		assertThat(convert(conversionService, "-10")).isEqualTo(Period.ofDays(-10));
+	}
+
+	@ConversionServiceTest
+	void convertWhenSimpleWithoutSuffixButWithAnnotationShouldReturnPeriod(ConversionService conversionService) {
+		assertThat(convert(conversionService, "10", ChronoUnit.MONTHS, null)).isEqualTo(Period.ofMonths(10));
+		assertThat(convert(conversionService, "+10", ChronoUnit.MONTHS, null)).isEqualTo(Period.ofMonths(10));
+		assertThat(convert(conversionService, "-10", ChronoUnit.MONTHS, null)).isEqualTo(Period.ofMonths(-10));
+	}
+
+	private Period convert(ConversionService conversionService, String source) {
+		return conversionService.convert(source, Period.class);
+	}
+
+	private Period convert(ConversionService conversionService, String source, ChronoUnit unit, PeriodStyle style) {
+		return (Period) conversionService.convert(source, TypeDescriptor.forObject(source),
+				MockPeriodTypeDescriptor.get(unit, style));
+	}
+
+	static Stream<? extends Arguments> conversionServices() {
+		return ConversionServiceArguments.with(new StringToPeriodConverter());
+	}
+
+}