Spring3 MVC使用@ResponseBody产生很大的响应头

Spring3 MVC使用@ResponseBody后会产生很大的响应头(Accept-Charset会达到4K+)，原因在于默认情况下StringHttpMessageConverter.writeInternal()会将所有可用字符集回写到response响应头中：

/**
* Implementation of {@link HttpMessageConverter} that can read and write strings.
*
* <p>By default, this converter supports all media types (<code>*/*</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;

private boolean writeAcceptCharset = true;

public StringHttpMessageConverter() {
super(new MediaType("text", "plain", DEFAULT_CHARSET), MediaType.ALL);
this.availableCharsets = new ArrayList<Charset>(Charset.availableCharsets().values());
}

/**
* Indicates whether the {@code Accept-Charset} should be written to any outgoing request.
* <p>Default is {@code true}.
*/
public void setWriteAcceptCharset(boolean writeAcceptCharset) {
this.writeAcceptCharset = writeAcceptCharset;
}

@Override
public boolean supports(Class<?> clazz) {
return String.class.equals(clazz);
}

@Override
protected String readInternal(Class 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, MediaType contentType) {
if (contentType != null && contentType.getCharSet() != null) {
Charset charset = contentType.getCharSet();
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 writeInternal(String s, HttpOutputMessage outputMessage) throws IOException {
if (writeAcceptCharset) {
outputMessage.getHeaders().setAcceptCharset(getAcceptedCharsets());
}
MediaType contentType = outputMessage.getHeaders().getContentType();
Charset charset = contentType.getCharSet() != null ? contentType.getCharSet() : DEFAULT_CHARSET;
FileCopyUtils.copy(s, new OutputStreamWriter(outputMessage.getBody(), charset));
}

/**
* Return 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 this.availableCharsets;
}

}

解决办法：Spring3 MVC使用@ResponseBody的乱码问题及解决办法