Reactor StringEncoder into CharSequenceEncoder

This commit refactors the StringEncoder to a CharSequenceEncoder, in
order to support StringBuilders, Groovy GStrings, etc.

Issue: https://github.com/spring-projects/spring-reactive/issues/120

spring-core/src/main/java/org/springframework/core/codec/CharSequenceEncoder.java

@@ -16,6 +16,8 @@
 
 package org.springframework.core.codec;
 
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 
@@ -28,18 +30,19 @@ import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.util.MimeType;
 
 /**
- * Encode from a String stream to a bytes stream.
+ * Encode from a CharSequence stream to a bytes stream.
  *
  * @author Sebastien Deleuze
+ * @author Arjen Poutsma
  * @since 5.0
  * @see StringDecoder
  */
-public class StringEncoder extends AbstractEncoder<String> {
+public class CharSequenceEncoder extends AbstractEncoder<CharSequence> {
 
 	public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
 
 
-	public StringEncoder() {
+	public CharSequenceEncoder() {
 		super(new MimeType("text", "plain", DEFAULT_CHARSET));
 	}
 
@@ -47,11 +50,11 @@ public class StringEncoder extends AbstractEncoder<String> {
 	@Override
 	public boolean canEncode(ResolvableType elementType, MimeType mimeType, Object... hints) {
 		Class<?> clazz = elementType.getRawClass();
-		return (super.canEncode(elementType, mimeType, hints) && String.class.equals(clazz));
+		return (super.canEncode(elementType, mimeType, hints) && CharSequence.class.isAssignableFrom(clazz));
 	}
 
 	@Override
-	public Flux<DataBuffer> encode(Publisher<? extends String> inputStream,
+	public Flux<DataBuffer> encode(Publisher<? extends CharSequence> inputStream,
 			DataBufferFactory bufferFactory, ResolvableType elementType,
 			MimeType mimeType, Object... hints) {
 
@@ -62,11 +65,10 @@ public class StringEncoder extends AbstractEncoder<String> {
 		else {
 			 charset = DEFAULT_CHARSET;
 		}
-		return Flux.from(inputStream).map(s -> {
-			byte[] bytes = s.getBytes(charset);
-			DataBuffer dataBuffer = bufferFactory.allocateBuffer(bytes.length);
-			dataBuffer.write(bytes);
-			return dataBuffer;
+		return Flux.from(inputStream).map(charSequence -> {
+			CharBuffer charBuffer = CharBuffer.wrap(charSequence);
+			ByteBuffer byteBuffer = charset.encode(charBuffer);
+			return bufferFactory.wrap(byteBuffer);
 		});
 	}
 

spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java

@@ -45,7 +45,7 @@ import org.springframework.util.MimeTypeUtils;
  * @author Arjen Poutsma
  * @author Mark Paluch
  * @since 5.0
- * @see StringEncoder
+ * @see CharSequenceEncoder
  */
 public class StringDecoder extends AbstractDecoder<String> {
 

spring-core/src/test/java/org/springframework/core/codec/CharSequenceEncoderTests.java

@@ -27,6 +27,7 @@ import reactor.test.TestSubscriber;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
+import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.support.DataBufferUtils;
 import org.springframework.util.MimeTypeUtils;
 
@@ -37,35 +38,46 @@ import static org.junit.Assert.assertTrue;
  * @author Sebastien Deleuze
  */
 @RunWith(Parameterized.class)
-public class StringEncoderTests extends AbstractDataBufferAllocatingTestCase {
+public class CharSequenceEncoderTests extends AbstractDataBufferAllocatingTestCase {
 
-	private StringEncoder encoder;
+	private CharSequenceEncoder encoder;
 
 	@Before
 	public void createEncoder() {
-		this.encoder = new StringEncoder();
+		this.encoder = new CharSequenceEncoder();
 	}
 
 	@Test
 	public void canWrite() {
 		assertTrue(this.encoder.canEncode(ResolvableType.forClass(String.class), MimeTypeUtils.TEXT_PLAIN));
+		assertTrue(this.encoder.canEncode(ResolvableType.forClass(StringBuilder.class), MimeTypeUtils.TEXT_PLAIN));
+		assertTrue(this.encoder.canEncode(ResolvableType.forClass(StringBuffer.class), MimeTypeUtils.TEXT_PLAIN));
 		assertFalse(this.encoder.canEncode(ResolvableType.forClass(Integer.class), MimeTypeUtils.TEXT_PLAIN));
 		assertFalse(this.encoder.canEncode(ResolvableType.forClass(String.class), MimeTypeUtils.APPLICATION_JSON));
 	}
 
 	@Test
-	public void write() throws InterruptedException {
-		Flux<String> output = Flux.from(
-				this.encoder.encode(Flux.just("foo"), this.bufferFactory, null, null))
-						.map(chunk -> {
-							byte[] b = new byte[chunk.readableByteCount()];
-							chunk.read(b);
-							DataBufferUtils.release(chunk);
-							return new String(b, StandardCharsets.UTF_8);
-		});
+	public void writeString() throws InterruptedException {
+		Flux<String> stringFlux = Flux.just("foo");
+		Flux<DataBuffer> output = Flux.from(
+				this.encoder.encode(stringFlux, this.bufferFactory, null, null));
 		TestSubscriber
 				.subscribe(output)
-				.assertValues("foo");
+				.assertNoError()
+				.assertComplete()
+				.assertValuesWith(stringConsumer("foo"));
+	}
+
+	@Test
+	public void writeStringBuilder() throws InterruptedException {
+		Flux<StringBuilder> stringBuilderFlux = Flux.just(new StringBuilder("foo"));
+		Flux<DataBuffer> output = Flux.from(
+				this.encoder.encode(stringBuilderFlux, this.bufferFactory, null, null));
+		TestSubscriber
+				.subscribe(output)
+				.assertNoError()
+				.assertComplete()
+				.assertValuesWith(stringConsumer("foo"));
 	}
 
 }

spring-web-reactive/src/main/java/org/springframework/web/reactive/config/WebReactiveConfiguration.java

@@ -29,10 +29,10 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.codec.ByteBufferDecoder;
 import org.springframework.core.codec.ByteBufferEncoder;
+import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.codec.Encoder;
 import org.springframework.core.codec.ResourceDecoder;
 import org.springframework.core.codec.StringDecoder;
-import org.springframework.core.codec.StringEncoder;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.format.Formatter;
 import org.springframework.format.FormatterRegistry;
@@ -368,7 +368,7 @@ public class WebReactiveConfiguration implements ApplicationContextAware {
 	protected final void addDefaultHttpMessageWriters(List<HttpMessageWriter<?>> writers) {
 		List<Encoder<?>> sseDataEncoders = new ArrayList<>();
 		writers.add(new EncoderHttpMessageWriter<>(new ByteBufferEncoder()));
-		writers.add(new EncoderHttpMessageWriter<>(new StringEncoder()));
+		writers.add(new EncoderHttpMessageWriter<>(new CharSequenceEncoder()));
 		writers.add(new ResourceHttpMessageWriter());
 		if (jaxb2Present) {
 			writers.add(new EncoderHttpMessageWriter<>(new Jaxb2Encoder()));

spring-web-reactive/src/test/java/org/springframework/web/reactive/DispatcherHandlerErrorTests.java

@@ -29,7 +29,7 @@ import reactor.test.TestSubscriber;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.core.codec.StringEncoder;
+import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DefaultDataBufferFactory;
 import org.springframework.http.HttpMethod;
@@ -61,6 +61,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertThat;
 
+
 /**
  * Test the effect of exceptions at different stages of request processing by
  * checking the error signals on the completion publisher.
@@ -197,7 +198,7 @@ public class DispatcherHandlerErrorTests {
 		@Bean
 		public ResponseBodyResultHandler resultHandler() {
 			return new ResponseBodyResultHandler(
-					Collections.singletonList(new EncoderHttpMessageWriter<>(new StringEncoder())),
+					Collections.singletonList(new EncoderHttpMessageWriter<>(new CharSequenceEncoder())),
 					new HeaderContentTypeResolver());
 		}
 

spring-web-reactive/src/test/java/org/springframework/web/reactive/config/WebReactiveConfigurationTests.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.reactive.config;
 
 import java.net.URI;
@@ -34,8 +35,8 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
 import org.springframework.core.ResolvableType;
+import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.codec.StringDecoder;
-import org.springframework.core.codec.StringEncoder;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.io.Resource;
 import org.springframework.http.HttpMethod;
@@ -68,16 +69,8 @@ import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.adapter.DefaultServerWebExchange;
 import org.springframework.web.server.session.MockWebSessionManager;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
-import static org.springframework.http.MediaType.APPLICATION_JSON;
-import static org.springframework.http.MediaType.APPLICATION_OCTET_STREAM;
-import static org.springframework.http.MediaType.APPLICATION_XML;
-import static org.springframework.http.MediaType.IMAGE_PNG;
-import static org.springframework.http.MediaType.TEXT_PLAIN;
+import static org.junit.Assert.*;
+import static org.springframework.http.MediaType.*;
 
 /**
  * Unit tests for {@link WebReactiveConfiguration}.
@@ -307,7 +300,7 @@ public class WebReactiveConfigurationTests {
 
 		@Override
 		protected void configureMessageWriters(List<HttpMessageWriter<?>> messageWriters) {
-			messageWriters.add(new EncoderHttpMessageWriter<>(new StringEncoder()));
+			messageWriters.add(new EncoderHttpMessageWriter<>(new CharSequenceEncoder()));
 		}
 
 		@Override

spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/annotation/MessageWriterResultHandlerTests.java

@@ -30,7 +30,6 @@ import java.util.List;
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import org.junit.Before;
-import org.junit.Ignore;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -40,7 +39,7 @@ import rx.Observable;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.codec.ByteBufferEncoder;
-import org.springframework.core.codec.StringEncoder;
+import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.buffer.support.DataBufferTestUtils;
@@ -176,7 +175,7 @@ public class MessageWriterResultHandlerTests {
 		if (ObjectUtils.isEmpty(writers)) {
 			writerList = new ArrayList<>();
 			writerList.add(new EncoderHttpMessageWriter<>(new ByteBufferEncoder()));
-			writerList.add(new EncoderHttpMessageWriter<>(new StringEncoder()));
+			writerList.add(new EncoderHttpMessageWriter<>(new CharSequenceEncoder()));
 			writerList.add(new ResourceHttpMessageWriter());
 			writerList.add(new EncoderHttpMessageWriter<>(new Jaxb2Encoder()));
 			writerList.add(new EncoderHttpMessageWriter<>(new JacksonJsonEncoder()));

spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseBodyResultHandlerTests.java

@@ -26,7 +26,7 @@ import org.junit.Test;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.codec.ByteBufferEncoder;
-import org.springframework.core.codec.StringEncoder;
+import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.codec.json.JacksonJsonEncoder;
@@ -86,7 +86,7 @@ public class ResponseBodyResultHandlerTests {
 		if (ObjectUtils.isEmpty(writers)) {
 			writerList = new ArrayList<>();
 			writerList.add(new EncoderHttpMessageWriter<>(new ByteBufferEncoder()));
-			writerList.add(new EncoderHttpMessageWriter<>(new StringEncoder()));
+			writerList.add(new EncoderHttpMessageWriter<>(new CharSequenceEncoder()));
 			writerList.add(new ResourceHttpMessageWriter());
 			writerList.add(new EncoderHttpMessageWriter<>(new Jaxb2Encoder()));
 			writerList.add(new EncoderHttpMessageWriter<>(new JacksonJsonEncoder()));

spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandlerTests.java

@@ -33,7 +33,7 @@ import rx.Single;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.codec.ByteBufferEncoder;
-import org.springframework.core.codec.StringEncoder;
+import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.io.buffer.support.DataBufferTestUtils;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
@@ -91,7 +91,7 @@ public class ResponseEntityResultHandlerTests {
 		if (ObjectUtils.isEmpty(writers)) {
 			writerList = new ArrayList<>();
 			writerList.add(new EncoderHttpMessageWriter<>(new ByteBufferEncoder()));
-			writerList.add(new EncoderHttpMessageWriter<>(new StringEncoder()));
+			writerList.add(new EncoderHttpMessageWriter<>(new CharSequenceEncoder()));
 			writerList.add(new ResourceHttpMessageWriter());
 			writerList.add(new EncoderHttpMessageWriter<>(new Jaxb2Encoder()));
 			writerList.add(new EncoderHttpMessageWriter<>(new JacksonJsonEncoder()));

spring-web-reactive/src/test/java/org/springframework/web/reactive/result/view/HttpMessageWriterViewTests.java

@@ -13,11 +13,10 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.web.reactive.result.view;
 
+package org.springframework.web.reactive.result.view;
 
 import java.net.URI;
-import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.Collections;
@@ -32,7 +31,7 @@ import org.junit.Test;
 import reactor.test.TestSubscriber;
 
 import org.springframework.core.MethodParameter;
-import org.springframework.core.codec.StringEncoder;
+import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.io.buffer.support.DataBufferTestUtils;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
@@ -51,10 +50,7 @@ import org.springframework.web.server.session.DefaultWebSessionManager;
 import org.springframework.web.server.session.WebSessionManager;
 
 import static junit.framework.TestCase.assertTrue;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 
 
 /**
@@ -123,7 +119,7 @@ public class HttpMessageWriterViewTests {
 
 	@Test
 	public void extractObjectMultipleMatchesNotSupported() throws Exception {
-		HttpMessageWriterView view = new HttpMessageWriterView(new StringEncoder());
+		HttpMessageWriterView view = new HttpMessageWriterView(new CharSequenceEncoder());
 		view.setModelKeys(new HashSet<>(Arrays.asList("foo1", "foo2")));
 		this.model.addAttribute("foo1", "bar1");
 		this.model.addAttribute("foo2", "bar2");

spring-web/src/main/java/org/springframework/web/client/reactive/WebClient.java

@@ -30,9 +30,9 @@ import reactor.core.publisher.Mono;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.codec.ByteBufferDecoder;
 import org.springframework.core.codec.ByteBufferEncoder;
+import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.codec.ResourceDecoder;
 import org.springframework.core.codec.StringDecoder;
-import org.springframework.core.codec.StringEncoder;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.client.reactive.ClientHttpConnector;
@@ -105,7 +105,7 @@ public final class WebClient {
 	 * Register by default the following Encoders and Decoders:
 	 * <ul>
 	 * <li>{@link ByteBufferEncoder} / {@link ByteBufferDecoder}</li>
-	 * <li>{@link StringEncoder} / {@link StringDecoder}</li>
+	 * <li>{@link CharSequenceEncoder} / {@link StringDecoder}</li>
 	 * <li>{@link Jaxb2Encoder} / {@link Jaxb2Decoder}</li>
 	 * <li>{@link JacksonJsonEncoder} / {@link JacksonJsonDecoder}</li>
 	 * </ul>
@@ -138,7 +138,7 @@ public final class WebClient {
 	 */
 	protected final void addDefaultHttpMessageWriters(List<HttpMessageWriter<?>> messageWriters) {
 		messageWriters.add(new EncoderHttpMessageWriter<>(new ByteBufferEncoder()));
-		messageWriters.add(new EncoderHttpMessageWriter<>(new StringEncoder()));
+		messageWriters.add(new EncoderHttpMessageWriter<>(new CharSequenceEncoder()));
 		messageWriters.add(new ResourceHttpMessageWriter());
 		if (jaxb2Present) {
 			messageWriters.add(new EncoderHttpMessageWriter<>(new Jaxb2Encoder()));