Introduce ObjectUtils.nullSafeConciseToString()

ObjectUtils.nullSafeToString(Object) exists for generating a string
representation of various objects in a "null-safe" manner, including
support for object graphs, collections, etc.

However, there are times when we would like to generate a "concise",
null-safe string representation that does not include an entire object
graph (or potentially a collection of object graphs).

This commit introduces ObjectUtils.nullSafeConciseToString(Object) to
address this need and makes use of the new feature in FieldError and
ConversionFailedException.

Closes gh-30286

spring-context/src/main/java/org/springframework/validation/FieldError.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * 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.
@@ -125,7 +125,7 @@ public class FieldError extends ObjectError {
 	@Override
 	public String toString() {
 		return "Field error in object '" + getObjectName() + "' on field '" + this.field +
-				"': rejected value [" + ObjectUtils.nullSafeToString(this.rejectedValue) + "]; " +
+				"': rejected value [" + ObjectUtils.nullSafeConciseToString(this.rejectedValue) + "]; " +
 				resolvableToString();
 	}
 

spring-context/src/test/java/org/springframework/format/datetime/DateFormattingTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * 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.
@@ -133,7 +133,7 @@ public class DateFormattingTests {
 		assertThat(exception)
 			.hasMessageContaining("for property 'styleDate'")
 			.hasCauseInstanceOf(ConversionFailedException.class).cause()
-				.hasMessageContaining("for value '99/01/01'")
+				.hasMessageContaining("for value [99/01/01]")
 				.hasCauseInstanceOf(IllegalArgumentException.class).cause()
 					.hasMessageContaining("Parse attempt failed for value [99/01/01]")
 					.hasCauseInstanceOf(ParseException.class).cause()
@@ -353,7 +353,7 @@ public class DateFormattingTests {
 			assertThat(fieldError.unwrap(TypeMismatchException.class))
 				.hasMessageContaining("for property 'patternDateWithFallbackPatterns'")
 				.hasCauseInstanceOf(ConversionFailedException.class).cause()
-					.hasMessageContaining("for value '210302'")
+					.hasMessageContaining("for value [210302]")
 					.hasCauseInstanceOf(IllegalArgumentException.class).cause()
 						.hasMessageContaining("Parse attempt failed for value [210302]")
 						.hasCauseInstanceOf(ParseException.class).cause()

spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java

@@ -368,7 +368,7 @@ class DateTimeFormattingTests {
 		assertThat(fieldError.unwrap(TypeMismatchException.class))
 			.hasMessageContaining("for property 'isoLocalDate'")
 			.hasCauseInstanceOf(ConversionFailedException.class).cause()
-				.hasMessageContaining("for value '2009-31-10'")
+				.hasMessageContaining("for value [2009-31-10]")
 				.hasCauseInstanceOf(IllegalArgumentException.class).cause()
 					.hasMessageContaining("Parse attempt failed for value [2009-31-10]")
 					.hasCauseInstanceOf(DateTimeParseException.class).cause()
@@ -606,7 +606,7 @@ class DateTimeFormattingTests {
 			assertThat(fieldError.unwrap(TypeMismatchException.class))
 				.hasMessageContaining("for property 'patternLocalDateWithFallbackPatterns'")
 				.hasCauseInstanceOf(ConversionFailedException.class).cause()
-					.hasMessageContaining("for value '210302'")
+					.hasMessageContaining("for value [210302]")
 					.hasCauseInstanceOf(IllegalArgumentException.class).cause()
 						.hasMessageContaining("Parse attempt failed for value [210302]")
 						.hasCauseInstanceOf(DateTimeParseException.class).cause()

spring-core/src/main/java/org/springframework/core/convert/ConversionFailedException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * 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.
@@ -49,7 +49,7 @@ public class ConversionFailedException extends ConversionException {
 			@Nullable Object value, Throwable cause) {
 
 		super("Failed to convert from type [" + sourceType + "] to type [" + targetType +
-				"] for value '" + ObjectUtils.nullSafeToString(value) + "'", cause);
+				"] for value [" + ObjectUtils.nullSafeConciseToString(value) + "]", cause);
 		this.sourceType = sourceType;
 		this.targetType = targetType;
 		this.value = value;

spring-core/src/main/java/org/springframework/util/ObjectUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * 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.
@@ -17,8 +17,13 @@
 package org.springframework.util;
 
 import java.lang.reflect.Array;
+import java.net.URI;
+import java.net.URL;
+import java.time.temporal.Temporal;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Date;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.StringJoiner;
@@ -630,6 +635,7 @@ public abstract class ObjectUtils {
 	 * Returns a {@code "null"} String if {@code obj} is {@code null}.
 	 * @param obj the object to build a String representation for
 	 * @return a String representation of {@code obj}
+	 * @see #nullSafeConciseToString(Object)
 	 */
 	public static String nullSafeToString(@Nullable Object obj) {
 		if (obj == null) {
@@ -885,4 +891,73 @@ public abstract class ObjectUtils {
 		return stringJoiner.toString();
 	}
 
+	/**
+	 * Generate a null-safe, concise string representation of the supplied object
+	 * as described below.
+	 * <p>Favor this method over {@link #nullSafeToString(Object)} when you need
+	 * the length of the generated string to be limited.
+	 * <p>Returns:
+	 * <ul>
+	 * <li>{@code "null"} if {@code obj} is {@code null}</li>
+	 * <li>{@linkplain Class#getName() Class name} if {@code obj} is a {@link Class}</li>
+	 * <li>Potentially {@linkplain StringUtils#truncate(CharSequence) truncated string}
+	 * if {@code obj} is a {@link String} or {@link CharSequence}</li>
+	 * <li>Potentially {@linkplain StringUtils#truncate(CharSequence) truncated string}
+	 * if {@code obj} is a <em>simple type</em> whose {@code toString()} method returns
+	 * a non-null value.</li>
+	 * <li>Otherwise, a string representation of the object's type name concatenated
+	 * with {@code @} and a hex string form of the object's identity hash code</li>
+	 * </ul>
+	 * <p>In the context of this method, a <em>simple type</em> is any of the following:
+	 * a primitive or primitive wrapper (excluding {@code Void} and {@code void}),
+	 * an enum, a Number, a Date, a Temporal, a URI, a URL, or a Locale.
+	 * @param obj the object to build a string representation for
+	 * @return a concise string representation of the supplied object
+	 * @since 5.3.27
+	 * @see #nullSafeToString(Object)
+	 * @see StringUtils#truncate(CharSequence)
+	 */
+	public static String nullSafeConciseToString(@Nullable Object obj) {
+		if (obj == null) {
+			return "null";
+		}
+		if (obj instanceof Class<?> clazz) {
+			return clazz.getName();
+		}
+		if (obj instanceof CharSequence charSequence) {
+			return StringUtils.truncate(charSequence);
+		}
+		Class<?> type = obj.getClass();
+		if (isSimpleValueType(type)) {
+			String str = obj.toString();
+			if (str != null) {
+				return StringUtils.truncate(str);
+			}
+		}
+		return type.getTypeName() + "@" + getIdentityHexString(obj);
+	}
+
+	/**
+	 * Copy of {@link org.springframework.beans.BeanUtils#isSimpleValueType(Class)}.
+	 * <p>Check if the given type represents a "simple" value type: a primitive or
+	 * primitive wrapper, an enum, a String or other CharSequence, a Number, a
+	 * Date, a Temporal, a URI, a URL, a Locale, or a Class.
+	 * <p>{@code Void} and {@code void} are not considered simple value types.
+	 * @param type the type to check
+	 * @return whether the given type represents a "simple" value type
+	 */
+	private static boolean isSimpleValueType(Class<?> type) {
+		return (Void.class != type && void.class != type &&
+				(ClassUtils.isPrimitiveOrWrapper(type) ||
+				Enum.class.isAssignableFrom(type) ||
+				CharSequence.class.isAssignableFrom(type) ||
+				Number.class.isAssignableFrom(type) ||
+				Date.class.isAssignableFrom(type) ||
+				Temporal.class.isAssignableFrom(type) ||
+				URI.class == type ||
+				URL.class == type ||
+				Locale.class == type ||
+				Class.class == type));
+	}
+
 }

spring-core/src/test/java/org/springframework/util/ObjectUtilsTests.java

@@ -17,15 +17,24 @@
 package org.springframework.util;
 
 import java.io.IOException;
+import java.net.URI;
+import java.net.URL;
 import java.sql.SQLException;
+import java.time.LocalDate;
+import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.springframework.util.ObjectUtils.isEmpty;
 
@@ -791,7 +800,135 @@ class ObjectUtilsTests {
 			.withMessage("Constant [bogus] does not exist in enum type org.springframework.util.ObjectUtilsTests$Tropes");
 	}
 
-	private void assertEqualHashCodes(int expected, Object array) {
+	@Nested
+	class NullSafeConciseToStringTests {
+
+		private static final String truncated = " (truncated)...";
+		private static final int truncatedLength = 100 + truncated.length();
+
+		@Test
+		void nullSafeConciseToStringForNull() {
+			assertThat(ObjectUtils.nullSafeConciseToString(null)).isEqualTo("null");
+		}
+
+		@Test
+		void nullSafeConciseToStringForClass() {
+			assertThat(ObjectUtils.nullSafeConciseToString(String.class)).isEqualTo("java.lang.String");
+		}
+
+		@Test
+		void nullSafeConciseToStringForStrings() {
+			String repeat100 = "X".repeat(100);
+			String repeat101 = "X".repeat(101);
+
+			assertThat(ObjectUtils.nullSafeConciseToString("foo")).isEqualTo("foo");
+			assertThat(ObjectUtils.nullSafeConciseToString(repeat100)).isEqualTo(repeat100);
+			assertThat(ObjectUtils.nullSafeConciseToString(repeat101)).hasSize(truncatedLength).endsWith(truncated);
+		}
+
+		@Test
+		void nullSafeConciseToStringForStringBuilders() {
+			String repeat100 = "X".repeat(100);
+			String repeat101 = "X".repeat(101);
+
+			assertThat(ObjectUtils.nullSafeConciseToString(new StringBuilder("foo"))).isEqualTo("foo");
+			assertThat(ObjectUtils.nullSafeConciseToString(new StringBuilder(repeat100))).isEqualTo(repeat100);
+			assertThat(ObjectUtils.nullSafeConciseToString(new StringBuilder(repeat101))).hasSize(truncatedLength).endsWith(truncated);
+		}
+
+		@Test
+		void nullSafeConciseToStringForEnum() {
+			assertThat(ObjectUtils.nullSafeConciseToString(Tropes.FOO)).isEqualTo("FOO");
+		}
+
+		@Test
+		void nullSafeConciseToStringForNumber() {
+			assertThat(ObjectUtils.nullSafeConciseToString(42L)).isEqualTo("42");
+			assertThat(ObjectUtils.nullSafeConciseToString(99.1234D)).isEqualTo("99.1234");
+		}
+
+		@Test
+		void nullSafeConciseToStringForDate() {
+			Date date = new Date();
+			assertThat(ObjectUtils.nullSafeConciseToString(date)).isEqualTo(date.toString());
+		}
+
+		@Test
+		void nullSafeConciseToStringForTemporal() {
+			LocalDate localDate = LocalDate.now();
+			assertThat(ObjectUtils.nullSafeConciseToString(localDate)).isEqualTo(localDate.toString());
+		}
+
+		@Test
+		void nullSafeConciseToStringForUri() {
+			String uri = "https://www.example.com/?foo=1&bar=2&baz=3";
+			assertThat(ObjectUtils.nullSafeConciseToString(URI.create(uri))).isEqualTo(uri);
+
+			uri += "&qux=" + "4".repeat(60);
+			assertThat(ObjectUtils.nullSafeConciseToString(URI.create(uri)))
+					.hasSize(truncatedLength)
+					.startsWith(uri.subSequence(0, 100))
+					.endsWith(truncated);
+		}
+
+		@Test
+		void nullSafeConciseToStringForUrl() throws Exception {
+			String url = "https://www.example.com/?foo=1&bar=2&baz=3";
+			assertThat(ObjectUtils.nullSafeConciseToString(new URL(url))).isEqualTo(url);
+
+			url += "&qux=" + "4".repeat(60);
+			assertThat(ObjectUtils.nullSafeConciseToString(new URL(url)))
+					.hasSize(truncatedLength)
+					.startsWith(url.subSequence(0, 100))
+					.endsWith(truncated);
+		}
+
+		@Test
+		void nullSafeConciseToStringForLocale() {
+			assertThat(ObjectUtils.nullSafeConciseToString(Locale.GERMANY)).isEqualTo("de_DE");
+		}
+
+		@Test
+		void nullSafeConciseToStringForArraysAndCollections() {
+			List<String> list = List.of("a", "b", "c");
+			assertThat(ObjectUtils.nullSafeConciseToString(new int[][] {{1, 2}, {3, 4}})).startsWith(prefix(int[][].class));
+			assertThat(ObjectUtils.nullSafeConciseToString(list.toArray())).startsWith(prefix(Object[].class));
+			assertThat(ObjectUtils.nullSafeConciseToString(list.toArray(String[]::new))).startsWith(prefix(String[].class));
+			assertThat(ObjectUtils.nullSafeConciseToString(new ArrayList<>(list))).startsWith(prefix(ArrayList.class));
+			assertThat(ObjectUtils.nullSafeConciseToString(new HashSet<>(list))).startsWith(prefix(HashSet.class));
+		}
+
+		@Test
+		void nullSafeConciseToStringForCustomTypes() {
+			class ExplosiveType {
+				@Override
+				public String toString() {
+					throw new UnsupportedOperationException("no-go");
+				}
+			}
+			ExplosiveType explosiveType = new ExplosiveType();
+			assertThatExceptionOfType(UnsupportedOperationException.class).isThrownBy(explosiveType::toString);
+			assertThat(ObjectUtils.nullSafeConciseToString(explosiveType)).startsWith(prefix(ExplosiveType.class));
+
+			class WordyType {
+				@Override
+				public String toString() {
+					return "blah blah".repeat(20);
+				}
+			}
+			WordyType wordyType = new WordyType();
+			assertThat(wordyType).asString().hasSizeGreaterThanOrEqualTo(180 /* 9x20 */);
+			assertThat(ObjectUtils.nullSafeConciseToString(wordyType)).startsWith(prefix(WordyType.class));
+		}
+
+		private static String prefix(Class<?> clazz) {
+			return clazz.getTypeName() + "@";
+		}
+
+	}
+
+
+	private static void assertEqualHashCodes(int expected, Object array) {
 		int actual = ObjectUtils.nullSafeHashCode(array);
 		assertThat(actual).isEqualTo(expected);
 		assertThat(array.hashCode()).isNotEqualTo(actual);