Add toByteBuffer to BinaryData (Azure#19795)

Add toByteBuffer to BinaryData

Author: alzimmermsft

sdk/core/azure-core/src/main/java/com/azure/core/util/BinaryData.java

@@ -17,6 +17,7 @@
 import java.io.InputStream;
 import java.io.UncheckedIOException;
 import java.nio.ByteBuffer;
+import java.nio.ReadOnlyBufferException;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
@@ -593,6 +594,21 @@ public InputStream toStream() {
         return new ByteArrayInputStream(this.data);
     }
 
+    /**
+     * Returns a read-only {@link ByteBuffer} representation of this {@link BinaryData}.
+     * <p>
+     * Attempting to mutate the returned {@link ByteBuffer} will throw a {@link ReadOnlyBufferException}.
+     *
+     * <p><strong>Get a read-only ByteBuffer from the BinaryData</strong></p>
+     *
+     * {@codesnippet com.azure.util.BinaryData.toByteBuffer}
+     *
+     * @return A read-only {@link ByteBuffer} representing the {@link BinaryData}.
+     */
+    public ByteBuffer toByteBuffer() {
+        return ByteBuffer.wrap(this.data).asReadOnlyBuffer();
+    }
+
     /* This will ensure lazy instantiation to avoid hard dependency on Json Serializer. */
     private static JsonSerializer getDefaultSerializer() {
         if (defaultJsonSerializer == null) {

sdk/core/azure-core/src/samples/java/com/azure/core/util/BinaryDataJavaDocCodeSnippet.java

@@ -656,6 +656,19 @@ public void toStream() throws IOException {
         // END: com.azure.core.util.BinaryData.toStream
     }
 
+    /**
+     * Codesnippets for {@link BinaryData#toByteBuffer()}.
+     */
+    public void toReadOnlyByteBuffer() {
+        // BEGIN: com.azure.util.BinaryData.toByteBuffer
+        final byte[] data = "Some Data".getBytes(StandardCharsets.UTF_8);
+        BinaryData binaryData = BinaryData.fromBytes(data);
+        final byte[] bytes = new byte[data.length];
+        binaryData.toByteBuffer().get(bytes, 0, data.length);
+        System.out.println(new String(bytes));
+        // END: com.azure.util.BinaryData.toByteBuffer
+    }
+
     public static class MyJsonSerializer implements JsonSerializer {
         private final ClientLogger logger = new ClientLogger(BinaryDataTest.MyJsonSerializer.class);
         private final ObjectMapper mapper;

sdk/core/azure-core/src/test/java/com/azure/core/util/BinaryDataTest.java

@@ -21,12 +21,14 @@
 import java.io.OutputStream;
 import java.io.UncheckedIOException;
 import java.nio.ByteBuffer;
+import java.nio.ReadOnlyBufferException;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
 
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 /**
  * Test class for {@link BinaryData}.
@@ -289,6 +291,13 @@ public void createFromNullByte() {
         assertEquals("", data.toString());
     }
 
+    @Test
+    public void toReadOnlyByteBufferThrowsOnMutation() {
+        BinaryData binaryData = BinaryData.fromString("Hello");
+
+        assertThrows(ReadOnlyBufferException.class, () -> binaryData.toByteBuffer().put((byte) 0));
+    }
+
     public static class MyJsonSerializer implements JsonSerializer {
         private final ClientLogger logger = new ClientLogger(MyJsonSerializer.class);
         private final ObjectMapper mapper;