Deprecate Base64Utils in favor of Java's Base64

Originally, `Base64Utils` was providing base64 encoding and decoding
utilities, bridging to commons-codecs or Java 8, if available. Since
then, only the Java 8 variant remains and Spring Framework 6 requires
now Java 17. This utility class doesn't provide additional checks or
syntactic sugar over what's in Java already.

As a result, this commit deprecates this class in favor of `Base64` and
schedules the removal of this class completely.

Closes gh-28434

spring-core/src/main/java/org/springframework/util/Base64Utils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 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.
@@ -27,7 +27,9 @@ import java.util.Base64;
  * @author Gary Russell
  * @since 4.1
  * @see java.util.Base64
+ * @deprecated as of Spring Framework 6.0.5 in favor of {@link Base64}.
  */
+@Deprecated(since = "6.0.5", forRemoval = true)
 public abstract class Base64Utils {
 
 	/**

spring-core/src/test/java/org/springframework/util/Base64UtilsTests.java

@@ -1,101 +0,0 @@
-/*
- * Copyright 2002-2019 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.util;
-
-import jakarta.xml.bind.DatatypeConverter;
-import org.junit.jupiter.api.Test;
-
-import static java.nio.charset.StandardCharsets.UTF_8;
-import static org.assertj.core.api.Assertions.assertThat;
-
-/**
- * @author Juergen Hoeller
- * @since 4.2
- */
-class Base64UtilsTests {
-
-
-	@Test
-	void encode() {
-		byte[] bytes = new byte[]
-				{-0x4f, 0xa, -0x73, -0x4f, 0x64, -0x20, 0x75, 0x41, 0x5, -0x49, -0x57, -0x65, -0x19, 0x2e, 0x3f, -0x1b};
-		assertThat(Base64Utils.decode(Base64Utils.encode(bytes))).isEqualTo(bytes);
-
-		bytes = "Hello World".getBytes(UTF_8);
-		assertThat(Base64Utils.decode(Base64Utils.encode(bytes))).isEqualTo(bytes);
-
-		bytes = "Hello World\r\nSecond Line".getBytes(UTF_8);
-		assertThat(Base64Utils.decode(Base64Utils.encode(bytes))).isEqualTo(bytes);
-
-		bytes = "Hello World\r\nSecond Line\r\n".getBytes(UTF_8);
-		assertThat(Base64Utils.decode(Base64Utils.encode(bytes))).isEqualTo(bytes);
-
-		bytes = new byte[] { (byte) 0xfb, (byte) 0xf0 };
-		assertThat(Base64Utils.encode(bytes)).isEqualTo("+/A=".getBytes());
-		assertThat(Base64Utils.decode(Base64Utils.encode(bytes))).isEqualTo(bytes);
-
-		assertThat(Base64Utils.encodeUrlSafe(bytes)).isEqualTo("-_A=".getBytes());
-		assertThat(Base64Utils.decodeUrlSafe(Base64Utils.encodeUrlSafe(bytes))).isEqualTo(bytes);
-	}
-
-	@Test
-	void encodeToStringWithJdk8VsJaxb() {
-		byte[] bytes = new byte[]
-				{-0x4f, 0xa, -0x73, -0x4f, 0x64, -0x20, 0x75, 0x41, 0x5, -0x49, -0x57, -0x65, -0x19, 0x2e, 0x3f, -0x1b};
-		assertThat(DatatypeConverter.printBase64Binary(bytes)).isEqualTo(Base64Utils.encodeToString(bytes));
-		assertThat(Base64Utils.decodeFromString(Base64Utils.encodeToString(bytes))).isEqualTo(bytes);
-		assertThat(DatatypeConverter.parseBase64Binary(DatatypeConverter.printBase64Binary(bytes))).isEqualTo(bytes);
-
-		bytes = "Hello World".getBytes(UTF_8);
-		assertThat(DatatypeConverter.printBase64Binary(bytes)).isEqualTo(Base64Utils.encodeToString(bytes));
-		assertThat(Base64Utils.decodeFromString(Base64Utils.encodeToString(bytes))).isEqualTo(bytes);
-		assertThat(DatatypeConverter.parseBase64Binary(DatatypeConverter.printBase64Binary(bytes))).isEqualTo(bytes);
-
-		bytes = "Hello World\r\nSecond Line".getBytes(UTF_8);
-		assertThat(DatatypeConverter.printBase64Binary(bytes)).isEqualTo(Base64Utils.encodeToString(bytes));
-		assertThat(Base64Utils.decodeFromString(Base64Utils.encodeToString(bytes))).isEqualTo(bytes);
-		assertThat(DatatypeConverter.parseBase64Binary(DatatypeConverter.printBase64Binary(bytes))).isEqualTo(bytes);
-
-		bytes = "Hello World\r\nSecond Line\r\n".getBytes(UTF_8);
-		assertThat(DatatypeConverter.printBase64Binary(bytes)).isEqualTo(Base64Utils.encodeToString(bytes));
-		assertThat(Base64Utils.decodeFromString(Base64Utils.encodeToString(bytes))).isEqualTo(bytes);
-		assertThat(DatatypeConverter.parseBase64Binary(DatatypeConverter.printBase64Binary(bytes))).isEqualTo(bytes);
-	}
-
-	@Test
-	void encodeDecodeUrlSafe() {
-		byte[] bytes = new byte[] { (byte) 0xfb, (byte) 0xf0 };
-		assertThat(Base64Utils.encodeUrlSafe(bytes)).isEqualTo("-_A=".getBytes());
-		assertThat(Base64Utils.decodeUrlSafe(Base64Utils.encodeUrlSafe(bytes))).isEqualTo(bytes);
-
-		assertThat(Base64Utils.encodeToUrlSafeString(bytes)).isEqualTo("-_A=");
-		assertThat(Base64Utils.decodeFromUrlSafeString(Base64Utils.encodeToUrlSafeString(bytes))).isEqualTo(bytes);
-	}
-	@Test
-	void emptyInputs() {
-		assertThat(Base64Utils.encode(new byte[0])).isEmpty();
-		assertThat(Base64Utils.encodeToString(new byte[0])).isEmpty();
-		assertThat(Base64Utils.encodeUrlSafe(new byte[0])).isEmpty();
-		assertThat(Base64Utils.encodeToUrlSafeString(new byte[0])).isEmpty();
-
-		assertThat(Base64Utils.decode(new byte[0])).isEmpty();
-		assertThat(Base64Utils.decodeFromString("")).isEmpty();
-		assertThat(Base64Utils.decodeUrlSafe(new byte[0])).isEmpty();
-		assertThat(Base64Utils.decodeFromUrlSafeString("")).isEmpty();
-	}
-
-}

spring-web/src/main/java/org/springframework/http/converter/json/GsonBuilderUtils.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.
@@ -17,6 +17,7 @@
 package org.springframework.http.converter.json;
 
 import java.lang.reflect.Type;
+import java.util.Base64;
 
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonDeserializationContext;
@@ -26,7 +27,6 @@ import com.google.gson.JsonPrimitive;
 import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 
-import org.springframework.util.Base64Utils;
 
 /**
  * A simple utility class for obtaining a Google Gson 2.x {@link GsonBuilder}
@@ -36,7 +36,6 @@ import org.springframework.util.Base64Utils;
  * @author Roy Clarkson
  * @since 4.1
  * @see GsonFactoryBean#setBase64EncodeByteArrays
- * @see org.springframework.util.Base64Utils
  */
 public abstract class GsonBuilderUtils {
 
@@ -59,12 +58,12 @@ public abstract class GsonBuilderUtils {
 
 		@Override
 		public JsonElement serialize(byte[] src, Type typeOfSrc, JsonSerializationContext context) {
-			return new JsonPrimitive(Base64Utils.encodeToString(src));
+			return new JsonPrimitive(Base64.getEncoder().encodeToString(src));
 		}
 
 		@Override
 		public byte[] deserialize(JsonElement json, Type type, JsonDeserializationContext cxt) {
-			return Base64Utils.decodeFromString(json.getAsString());
+			return Base64.getDecoder().decode(json.getAsString());
 		}
 	}