Added HTTP conversion abstraction for RestTemplate

git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@662 50f2f4bb-b051-0410-bef5-90022cba6387

org.springframework.web/src/main/java/org/springframework/web/converter/AbstractHttpMessageConverter.java

@@ -0,0 +1,144 @@
+/*
+ * Copyright 2002-2009 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.web.converter;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.util.Assert;
+import org.springframework.util.MediaType;
+import org.springframework.web.http.HttpHeaders;
+import org.springframework.web.http.HttpOutputMessage;
+
+/**
+ * Abstract base class for most {@link HttpMessageConverter} implementations.
+ *
+ * <p>This base class adds support for setting supported {@code MediaTypes}, through the {@link
+ * #setSupportedMediaTypes(List) supportedMediaTypes} bean property. It also adds support for {@code Content-Type} and
+ * {@code Content-Length} when writing to output messages.
+ *
+ * @author Arjen Poutsma
+ * @since 3.0
+ */
+public abstract class AbstractHttpMessageConverter<T> implements HttpMessageConverter<T> {
+
+	/**
+	 * Logger available to subclasses.
+	 */
+	protected final Log logger = LogFactory.getLog(getClass());
+
+	private List<MediaType> supportedMediaTypes = Collections.emptyList();
+
+	/**
+	 * Constructs an {@code AbstractHttpMessageConverter} with no supported media types.
+	 *
+	 * @see #setSupportedMediaTypes(List)
+	 */
+	protected AbstractHttpMessageConverter() {
+	}
+
+	/**
+	 * Constructs an {@code AbstractHttpMessageConverter} with one supported media type.
+	 */
+	protected AbstractHttpMessageConverter(MediaType supportedMediaType) {
+		setSupportedMediaTypes(Collections.singletonList(supportedMediaType));
+	}
+
+	/**
+	 * Constructs an {@code AbstractHttpMessageConverter} with multiple supported media type.
+	 */
+	protected AbstractHttpMessageConverter(MediaType... supportedMediaTypes) {
+		setSupportedMediaTypes(Arrays.asList(supportedMediaTypes));
+	}
+
+	public List<MediaType> getSupportedMediaTypes() {
+		return Collections.unmodifiableList(supportedMediaTypes);
+	}
+
+	/**
+	 * Sets the list of {@link MediaType} objects supported by this converter.
+	 */
+	public void setSupportedMediaTypes(List<MediaType> supportedMediaTypes) {
+		Assert.notEmpty(supportedMediaTypes, "'supportedMediaTypes' must not be empty");
+		this.supportedMediaTypes = new ArrayList<MediaType>(supportedMediaTypes);
+	}
+
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>This implementation delegates to {@link #getContentType(Object)} and {@link #getContentLength(Object)}, and sets
+	 * the corresponding headers on the output message. It then calls {@link #writeToInternal(Object, HttpOutputMessage)}.
+	 *
+	 * @throws HttpMessageConversionException in case of conversion errors
+	 */
+	public final void write(T t, HttpOutputMessage outputMessage) throws IOException {
+		HttpHeaders headers = outputMessage.getHeaders();
+		MediaType contentType = getContentType(t);
+		if (contentType != null) {
+			headers.setContentType(contentType);
+		}
+		Long contentLength = getContentLength(t);
+		if (contentLength != null) {
+			headers.setContentLength(contentLength);
+		}
+		writeToInternal(t, outputMessage);
+		outputMessage.getBody().flush();
+	}
+
+	/**
+	 * Returns the content type for the given type.
+	 *
+	 * <p>By default, this returns the first element of the {@link #setSupportedMediaTypes(List) supportedMediaTypes}
+	 * property, if any. Can be overriden in subclasses.
+	 *
+	 * @param t the type to return the content type for
+	 * @return the content type, or <code>null</code> if not known
+	 */
+	protected MediaType getContentType(T t) {
+		List<MediaType> mediaTypes = getSupportedMediaTypes();
+		return !mediaTypes.isEmpty() ? mediaTypes.get(0) : null;
+	}
+
+	/**
+	 * Returns the content length for the given type.
+	 *
+	 * <p>By default, this returns <code>null</code>. Can be overriden in subclasses.
+	 *
+	 * @param t the type to return the content length for
+	 * @return the content length, or <code>null</code> if not known
+	 */
+	protected Long getContentLength(T t) {
+		return null;
+	}
+
+	/**
+	 * Abstract template method that writes the actualy body. Invoked from {@link #write(Object, HttpOutputMessage)}.
+	 *
+	 * @param t			 the object to write to the output message
+	 * @param outputMessage the message to write to
+	 * @throws IOException					in case of I/O errors
+	 * @throws HttpMessageConversionException in case of conversion errors
+	 */
+	protected abstract void writeToInternal(T t, HttpOutputMessage outputMessage) throws IOException;
+
+}

org.springframework.web/src/main/java/org/springframework/web/converter/ByteArrayHttpMessageConverter.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2002-2009 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.web.converter;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+import org.springframework.util.FileCopyUtils;
+import org.springframework.util.MediaType;
+import org.springframework.web.http.HttpInputMessage;
+import org.springframework.web.http.HttpOutputMessage;
+
+/**
+ * Implementation of {@link HttpMessageConverter} that can read and write byte arrays.
+ *
+ * <p>By default, this converter supports all media types (<code>&#42;&#47;&#42;</code>), and writes with a {@code
+ * Content-Type} of {@code application/octet-stream}. This can be overridden by setting the {@link
+ * #setSupportedMediaTypes(java.util.List) supportedMediaTypes} property, and overridding {@link
+ * #getContentType(byte[])}.
+ *
+ * @author Arjen Poutsma
+ * @since 3.0
+ */
+public class ByteArrayHttpMessageConverter extends AbstractHttpMessageConverter<byte[]> {
+
+	/**
+	 * Creates a new instance of the {@code ByteArrayHttpMessageConverter}.
+	 */
+	public ByteArrayHttpMessageConverter() {
+		super(MediaType.ALL);
+	}
+
+	public boolean supports(Class<? extends byte[]> clazz) {
+		return byte[].class == clazz;
+	}
+
+	public byte[] read(Class<byte[]> clazz, HttpInputMessage inputMessage) throws IOException {
+		long contentLength = inputMessage.getHeaders().getContentLength();
+		if (contentLength >= 0) {
+			ByteArrayOutputStream bos = new ByteArrayOutputStream((int) contentLength);
+			FileCopyUtils.copy(inputMessage.getBody(), bos);
+			return bos.toByteArray();
+		}
+		else {
+			return FileCopyUtils.copyToByteArray(inputMessage.getBody());
+		}
+	}
+
+	@Override
+	protected MediaType getContentType(byte[] bytes) {
+		return new MediaType("application", "octet-stream");
+	}
+
+	@Override
+	protected Long getContentLength(byte[] bytes) {
+		return (long) bytes.length;
+	}
+
+	@Override
+	protected void writeToInternal(byte[] bytes, HttpOutputMessage outputMessage) throws IOException {
+		FileCopyUtils.copy(bytes, outputMessage.getBody());
+	}
+
+
+}

org.springframework.web/src/main/java/org/springframework/web/converter/HttpMessageConversionException.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2002-2009 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.web.converter;
+
+import org.springframework.core.NestedRuntimeException;
+
+/**
+ * Thrown by {@link HttpMessageConverter} implementations when the conversion fails.
+ *
+ * @author Arjen Poutsma
+ * @since 3.0
+ */
+public class HttpMessageConversionException extends NestedRuntimeException {
+
+	/**
+	 * Create a new MessageConversionException.
+	 *
+	 * @param msg the detail message
+	 */
+	public HttpMessageConversionException(String msg) {
+		super(msg);
+	}
+
+	/**
+	 * Create a new MessageConversionException.
+	 *
+	 * @param msg   the detail message
+	 * @param cause the root cause (if any)
+	 */
+	public HttpMessageConversionException(String msg, Throwable cause) {
+		super(msg, cause);
+	}
+}

org.springframework.web/src/main/java/org/springframework/web/converter/HttpMessageConverter.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2002-2009 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.web.converter;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.springframework.util.MediaType;
+import org.springframework.web.http.HttpInputMessage;
+import org.springframework.web.http.HttpOutputMessage;
+
+/**
+ * Strategy interface that specifies a converter can convert from and to HTTP request and responses.
+ *
+ * @author Arjen Poutsma
+ * @since 3.0
+ */
+public interface HttpMessageConverter<T> {
+
+	/**
+	 * Indicates whether the given class is supported by this converter.
+	 *
+	 * <p>Typically implemented using an {@code instanceof} check.
+	 *
+	 * @param clazz the class to test for support
+	 * @return <code>true</code> if supported; <code>false</code> otherwise
+	 */
+	boolean supports(Class<? extends T> clazz);
+
+	/**
+	 * Returns the list of {@link MediaType} objects supported by this converter.
+	 */
+	List<MediaType> getSupportedMediaTypes();
+
+	/**
+	 * Reads an object of the given type form the given input message, and returns it.
+	 *
+	 * @param clazz		the type of object to return
+	 * @param inputMessage the HTTP input message to read from
+	 * @return the converted object
+	 * @throws IOException					in case of I/O errors
+	 * @throws HttpMessageConversionException in case of conversion errors
+	 */
+	T read(Class<T> clazz, HttpInputMessage inputMessage) throws IOException;
+
+	/**
+	 * Writes an given object to the given output message.
+	 *
+	 * @param t			 the object to write to the output message
+	 * @param outputMessage the message to write to
+	 * @throws IOException					in case of I/O errors
+	 * @throws HttpMessageConversionException in case of conversion errors
+	 */
+	void write(T t, HttpOutputMessage outputMessage) throws IOException;
+
+}

org.springframework.web/src/main/java/org/springframework/web/converter/StringHttpMessageConverter.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2002-2009 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.web.converter;
+
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.UnsupportedEncodingException;
+import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.util.FileCopyUtils;
+import org.springframework.util.MediaType;
+import org.springframework.web.http.HttpInputMessage;
+import org.springframework.web.http.HttpOutputMessage;
+
+/**
+ * Implementation of {@link HttpMessageConverter} that can read and write strings.
+ *
+ * <p>By default, this converter supports all text media types (<code>text&#47;&#42;</code>), and writes with a {@code
+ * Content-Type} of {@code text/plain}. This can be overridden by setting the {@link
+ * #setSupportedMediaTypes(java.util.List) supportedMediaTypes} property.
+ *
+ * @author Arjen Poutsma
+ * @since 3.0
+ */
+public class StringHttpMessageConverter extends AbstractHttpMessageConverter<String> {
+
+	public static final Charset DEFAULT_CHARSET = Charset.forName("ISO-8859-1");
+
+	private final List<Charset> availableCharsets;
+
+	public StringHttpMessageConverter() {
+		super(new MediaType("text", "plain", DEFAULT_CHARSET), new MediaType("text", "*"));
+		availableCharsets = new ArrayList<Charset>(Charset.availableCharsets().values());
+	}
+
+	public boolean supports(Class<? extends String> clazz) {
+		return String.class.equals(clazz);
+	}
+
+	public String read(Class<String> clazz, HttpInputMessage inputMessage) throws IOException {
+		MediaType contentType = inputMessage.getHeaders().getContentType();
+		Charset charset = contentType.getCharSet() != null ? contentType.getCharSet() : DEFAULT_CHARSET;
+		return FileCopyUtils.copyToString(new InputStreamReader(inputMessage.getBody(), charset));
+	}
+
+	@Override
+	protected Long getContentLength(String s) {
+		Charset charset = getContentType(s).getCharSet();
+		if (charset != null) {
+			try {
+				return (long) s.getBytes(charset.name()).length;
+			}
+			catch (UnsupportedEncodingException ex) {
+				// should not occur
+				throw new InternalError(ex.getMessage());
+			}
+		}
+		else {
+			return null;
+		}
+	}
+
+	@Override
+	protected void writeToInternal(String s, HttpOutputMessage outputMessage) throws IOException {
+		outputMessage.getHeaders().setAcceptCharset(getAcceptedCharsets());
+		MediaType contentType = getContentType(s);
+		Charset charset = contentType.getCharSet() != null ? contentType.getCharSet() : DEFAULT_CHARSET;
+		FileCopyUtils.copy(s, new OutputStreamWriter(outputMessage.getBody(), charset));
+	}
+
+	/**
+	 * Returns the list of supported {@link Charset}.
+	 *
+	 * <p>By default, returns {@link Charset#availableCharsets()}. Can be overridden in subclasses.
+	 *
+	 * @return the list of accepted charsets
+	 */
+	protected List<Charset> getAcceptedCharsets() {
+		return availableCharsets;
+	}
+
+}

org.springframework.web/src/main/java/org/springframework/web/converter/package.html

@@ -0,0 +1,7 @@
+<html>
+<body>
+
+Provides a HttpMessageConverter abstraction to convert between Java objects and HTTP input/output messages.
+
+</body>
+</html>

org.springframework.web/src/main/java/org/springframework/web/http/HttpHeaders.java

@@ -17,12 +17,15 @@
 package org.springframework.web.http;
 
 import java.net.URI;
+import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
+import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
@@ -48,6 +51,8 @@ public final class HttpHeaders implements Map<String, List<String>> {
 
 	private static String ACCEPT = "Accept";
 
+	private static String ACCEPT_CHARSET = "Accept-Charset";
+
 	private static String ALLOW = "Allow";
 
 	private static String CONTENT_LENGTH = "Content-Length";
@@ -59,8 +64,9 @@ public final class HttpHeaders implements Map<String, List<String>> {
 	private Map<String, List<String>> headers = CollectionFactory.createLinkedCaseInsensitiveMapIfPossible(5);
 
 	/**
-	 * Returns the list of acceptable {@link MediaType media types}, as specified by the <code>Accept</code> header. <p/>
+	 * Returns the list of acceptable {@linkplain MediaType media types}, as specified by the <code>Accept</code> header.
-	 * Returns an empty list when the acceptable media types are unspecified.
+	 *
+	 * <p>Returns an empty list when the acceptable media types are unspecified.
 	 *
 	 * @return the acceptable media types
 	 */
@@ -70,7 +76,7 @@ public final class HttpHeaders implements Map<String, List<String>> {
 	}
 
 	/**
-	 * Sets the list of acceptable {@link MediaType media types}, as specified by the <code>Accept</code> header.
+	 * Sets the list of acceptable {@linkplain MediaType media types}, as specified by the <code>Accept</code> header.
 	 *
 	 * @param acceptableMediaTypes the acceptable media types
 	 */
@@ -78,6 +84,47 @@ public final class HttpHeaders implements Map<String, List<String>> {
 		set(ACCEPT, MediaType.toString(acceptableMediaTypes));
 	}
 
+	/**
+	 * Returns the list of acceptable {@linkplain Charset charsets}, as specified by the <code>Accept-Charset</code>
+	 * header.
+	 *
+	 * @return the acceptable charsets
+	 */
+	public List<Charset> getAcceptCharset() {
+		List<Charset> result = new ArrayList<Charset>();
+		String value = getFirst(ACCEPT_CHARSET);
+		if (value != null) {
+			String[] tokens = value.split(",\\s*");
+			for (String token : tokens) {
+				int paramIdx = token.indexOf(';');
+				if (paramIdx == -1) {
+					result.add(Charset.forName(token));
+				}
+				else {
+					result.add(Charset.forName(token.substring(0, paramIdx)));
+				}
+			}
+		}
+		return result;
+	}
+
+	/**
+	 * Sets the list of acceptable {@linkplain Charset charsets}, as specified by the <code>Accept-Charset</code> header.
+	 *
+	 * @param acceptableCharsets the acceptable charsets
+	 */
+	public void setAcceptCharset(List<Charset> acceptableCharsets) {
+		StringBuilder builder = new StringBuilder();
+		for (Iterator<Charset> iterator = acceptableCharsets.iterator(); iterator.hasNext();) {
+			Charset charset = iterator.next();
+			builder.append(charset.name().toLowerCase(Locale.ENGLISH));
+			if (iterator.hasNext()) {
+				builder.append(", ");
+			}
+		}
+		set(ACCEPT_CHARSET, builder.toString());
+	}
+
 	/**
 	 * Returns the set of allowed {@link HttpMethod HTTP methods}, as specified by the <code>Allow</code> header. <p/>
 	 * Returns an empty set when the allowed methods are unspecified.

org.springframework.web/src/test/java/org/springframework/web/converter/ByteArrayHttpMessageConverterTests.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2002-2009 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.web.converter;
+
+import java.io.IOException;
+
+import static org.junit.Assert.*;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.util.MediaType;
+import org.springframework.web.http.MockHttpInputMessage;
+import org.springframework.web.http.MockHttpOutputMessage;
+
+/**
+ * @author Arjen Poutsma
+ */
+public class ByteArrayHttpMessageConverterTests {
+
+	private ByteArrayHttpMessageConverter converter;
+
+	@Before
+	public void setUp() {
+		converter = new ByteArrayHttpMessageConverter();
+	}
+
+	@Test
+	public void read() throws IOException {
+		byte[] body = new byte[]{0x1, 0x2};
+		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body);
+		inputMessage.getHeaders().setContentType(new MediaType("application", "octet-stream"));
+		byte[] result = converter.read(byte[].class, inputMessage);
+		assertArrayEquals("Invalid result", body, result);
+	}
+
+	@Test
+	public void write() throws IOException {
+		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
+		byte[] body = new byte[]{0x1, 0x2};
+		converter.write(body, outputMessage);
+		assertArrayEquals("Invalid result", body, outputMessage.getBodyAsBytes());
+		assertEquals("Invalid content-type", new MediaType("application", "octet-stream"),
+				outputMessage.getHeaders().getContentType());
+		assertEquals("Invalid content-length", 2, outputMessage.getHeaders().getContentLength());
+	}
+
+}

org.springframework.web/src/test/java/org/springframework/web/converter/StringHttpMessageConverterTests.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2002-2009 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.web.converter;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.util.Collections;
+
+import static org.junit.Assert.*;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.util.MediaType;
+import org.springframework.web.http.MockHttpInputMessage;
+import org.springframework.web.http.MockHttpOutputMessage;
+
+/**
+ * @author Arjen Poutsma
+ */
+public class StringHttpMessageConverterTests {
+
+	private StringHttpMessageConverter converter;
+
+	@Before
+	public void setUp() {
+		converter = new StringHttpMessageConverter();
+	}
+
+	@Test
+	public void read() throws IOException {
+		String body = "Hello World";
+		Charset charset = Charset.forName("UTF-8");
+		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body.getBytes(charset));
+		inputMessage.getHeaders().setContentType(new MediaType("text", "plain", charset));
+		String result = converter.read(String.class, inputMessage);
+		assertEquals("Invalid result", body, result);
+	}
+
+	@Test
+	public void write() throws IOException {
+		Charset charset = Charset.forName("UTF-8");
+		converter.setSupportedMediaTypes(Collections.singletonList(new MediaType("text", "plain", charset)));
+		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
+		String body = "HŽllo W¿rld";
+		converter.write(body, outputMessage);
+		assertEquals("Invalid result", body, outputMessage.getBodyAsString(charset));
+		assertEquals("Invalid content-type", new MediaType("text", "plain", charset),
+				outputMessage.getHeaders().getContentType());
+		assertEquals("Invalid content-length", 13, outputMessage.getHeaders().getContentLength());
+		assertFalse("Invalid accept-charset", outputMessage.getHeaders().getAcceptCharset().isEmpty());
+	}
+}

org.springframework.web/src/test/java/org/springframework/web/http/HttpHeadersTests.java

@@ -50,7 +50,19 @@ public class HttpHeadersTests {
 		mediaTypes.add(mediaType2);
 		headers.setAccept(mediaTypes);
 		assertEquals("Invalid Accept header", mediaTypes, headers.getAccept());
-		assertEquals("Invalid Accept header", "text/html,text/plain", headers.getFirst("Accept"));
+		assertEquals("Invalid Accept header", "text/html, text/plain", headers.getFirst("Accept"));
+	}
+
+	@Test
+	public void acceptCharsets() {
+		Charset charset1 = Charset.forName("UTF-8");
+		Charset charset2 = Charset.forName("ISO-8859-1");
+		List<Charset> charsets = new ArrayList<Charset>(2);
+		charsets.add(charset1);
+		charsets.add(charset2);
+		headers.setAcceptCharset(charsets);
+		assertEquals("Invalid Accept header", charsets, headers.getAcceptCharset());
+		assertEquals("Invalid Accept header", "utf-8, iso-8859-1", headers.getFirst("Accept-Charset"));
 	}
 
 	@Test