Add ConversionService support for ByteBuffers

Add ByteBufferConverter that is registered by default with the
DefaultConversionService. Allows conversion from/to a ByteBuffer and
byte[] or to any type that can be converted via a byte[].

Issue: SPR-10712

spring-core/src/test/java/org/springframework/core/convert/support/ByteBufferConverterTests.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2002-2013 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
+ *
+ * http://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.core.convert.support;
+
+import java.nio.ByteBuffer;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.core.convert.converter.Converter;
+
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+
+/**
+ * Tests for {@link ByteBufferConverter}.
+ *
+ * @author Phillip Webb
+ */
+public class ByteBufferConverterTests {
+
+	private GenericConversionService conversionService;
+
+	@Before
+	public void setup() {
+		this.conversionService = new GenericConversionService();
+		this.conversionService.addConverter(new ByteBufferConverter(conversionService));
+		this.conversionService.addConverter(new ByteArrayToOtherTypeConverter());
+		this.conversionService.addConverter(new OtherTypeToByteArrayConverter());
+	}
+
+	@Test
+	public void byteArrayToByteBuffer() throws Exception {
+		byte[] bytes = new byte[] { 1, 2, 3 };
+		ByteBuffer convert = this.conversionService.convert(bytes, ByteBuffer.class);
+		assertThat(bytes, not(sameInstance(convert.array())));
+		assertThat(bytes, equalTo(convert.array()));
+	}
+
+	@Test
+	public void byteBufferToByteArray() throws Exception {
+		byte[] bytes = new byte[] { 1, 2, 3 };
+		ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);
+		byte[] convert = this.conversionService.convert(byteBuffer, byte[].class);
+		assertThat(bytes, not(sameInstance(convert)));
+		assertThat(bytes, equalTo(convert));
+	}
+
+	@Test
+	public void byteBufferToOtherType() throws Exception {
+		byte[] bytes = new byte[] { 1, 2, 3 };
+		ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);
+		OtherType convert = this.conversionService.convert(byteBuffer, OtherType.class);
+		assertThat(bytes, not(sameInstance(convert.bytes)));
+		assertThat(bytes, equalTo(convert.bytes));
+	}
+
+	@Test
+	public void otherTypeToByteBuffer() throws Exception {
+		byte[] bytes = new byte[] { 1, 2, 3 };
+		OtherType otherType = new OtherType(bytes);
+		ByteBuffer convert = this.conversionService.convert(otherType, ByteBuffer.class);
+		assertThat(bytes, not(sameInstance(convert.array())));
+		assertThat(bytes, equalTo(convert.array()));
+	}
+
+	private static class OtherType {
+
+		private byte[] bytes;
+
+		public OtherType(byte[] bytes) {
+			this.bytes = bytes;
+		}
+
+	}
+
+	private static class ByteArrayToOtherTypeConverter implements
+			Converter<byte[], OtherType> {
+
+		@Override
+		public OtherType convert(byte[] source) {
+			return new OtherType(source);
+		}
+	}
+
+	private static class OtherTypeToByteArrayConverter implements
+			Converter<OtherType, byte[]> {
+
+		@Override
+		public byte[] convert(OtherType source) {
+			return source.bytes;
+		}
+
+	}
+
+}