去除Spring @ResponseBody产生的大量Accept-Charset

Spring 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：

去除这些信息我们可以这样,定义一个拦截器:

package cn.krun.cup.pojo;
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.http.HttpInputMessage;

import org.springframework.http.HttpOutputMessage;

import org.springframework.http.MediaType;

import org.springframework.http.converter.AbstractHttpMessageConverter;

import org.springframework.util.FileCopyUtils;
public class UTF8StringHttpMessageConverter extends

AbstractHttpMessageConverter<String> {
public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");

private final List&lt;Charset&gt; availableCharsets;

private boolean writeAcceptCharset = true;

public UTF8StringHttpMessageConverter() {
	super(new MediaType("text", "plain", DEFAULT_CHARSET), MediaType.ALL);
	this.availableCharsets = new ArrayList&lt;Charset&gt;(Charset
			.availableCharsets().values());
}

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

@Override
public boolean supports(Class&lt;?&gt; clazz) {
	return String.class.equals(clazz);
}

@SuppressWarnings("rawtypes")
@Override
protected String readInternal(Class clazz, HttpInputMessage inputMessage)
		throws IOException {
	Charset charset = getContentTypeCharset(inputMessage.getHeaders()
			.getContentType());
	return FileCopyUtils.copyToString(new InputStreamReader(inputMessage
			.getBody(), charset));
}

@Override
protected Long getContentLength(String s, MediaType contentType) {
	Charset charset = getContentTypeCharset(contentType);
	try {
		return (long) s.getBytes(charset.name()).length;
	} catch (UnsupportedEncodingException ex) {
		// should not occur
		throw new InternalError(ex.getMessage());
	}
}

@Override
protected void writeInternal(String s, HttpOutputMessage outputMessage)
		throws IOException {
	if (writeAcceptCharset) {
		outputMessage.getHeaders().setAcceptCharset(getAcceptedCharsets());
	}
	Charset charset = getContentTypeCharset(outputMessage.getHeaders()
			.getContentType());
	FileCopyUtils.copy(s, new OutputStreamWriter(outputMessage.getBody(),
			charset));
}

/**
 * Return the list of supported {@link Charset}.
 * &lt;p&gt;
 * By default, returns {@link Charset#availableCharsets()}. Can be
 * overridden in subclasses.
 * 
 * @return the list of accepted charsets
 */
protected List&lt;Charset&gt; getAcceptedCharsets() {
	return this.availableCharsets;
}

private Charset getContentTypeCharset(MediaType contentType) {
	if (contentType != null &amp;&amp; contentType.getCharSet() != null) {
		return contentType.getCharSet();
	} else {
		return DEFAULT_CHARSET;
	}
}
​
}

然后在spring中配置

	<mvc:annotation-driven>
		<mvc:message-converters>
			<bean class="cn.krun.cup.pojo.UTF8StringHttpMessageConverter">
				<property name="writeAcceptCharset" value="false">
				</property>
			</bean>
		</mvc:message-converters>
	</mvc:annotation-driven>

Done!