spring mvc3.1 @ResponseBody注解生成大量Accept-Charset

Spring3 MVC使用@ResponseBody后会产生非常大的响应头(Accept-Charset会达到4K+)。原因在于默认情况下StringHttpMessageConverter.writeInternal()会将全部可用字符集回写到response响应头中：问题来了

解决方案：

一般我们都会重写springs mvc的HttpMessageConverter。改为utf-8编码：

package com.goldpalm.core.spring.mvc;

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;

/**
 * 重写SpringMVC的字符串转换器。使用UTF-8编码
 * @since 2012-7-5 下午2:28:19
 * @author Jesse Lu
 */
public class UTF8StringHttpMessageConverter extends AbstractHttpMessageConverter<String> {
    
    public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
    
    private final List<Charset> availableCharsets;
    
    private boolean writeAcceptCharset = true;
    
    public UTF8StringHttpMessageConverter() {
        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);
    }
    
    @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}.
     * <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;
    }
    
    private Charset getContentTypeCharset(MediaType contentType) {
        if (contentType != null && contentType.getCharSet() != null) {
            return contentType.getCharSet();
        } else {
            return DEFAULT_CHARSET;
        }
    }
    
}

在xm中配置：注意红色圈起来的配置

<mvc:annotation-driven>
		<mvc:message-converters>
			<bean class="com.goldpalm.core.spring.mvc.UTF8StringHttpMessageConverter">
				<property name="writeAcceptCharset" value="false" />
			</bean>
		</mvc:message-