springMvc与fastJson 集成时日期格式的问题

package com.jjs.util;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Date;

import org.springframework.http.HttpOutputMessage;
import org.springframework.http.converter.HttpMessageNotWritableException;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializeConfig;
import com.alibaba.fastjson.serializer.SimpleDateFormatSerializer;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;

/**
* 自定义fastJson日期转换格式
* 将默认的"yyyy-MM-dd HH:mm:ss"格式改为 "yyyy-MM-dd"格式
* @author jjs
*
*/
public class JsonHttpMessageConverter extends FastJsonHttpMessageConverter{

private static SerializeConfig mapping = new SerializeConfig();
private static String dateFormat;
static {
dateFormat = "yyyy-MM-dd";
mapping.put(Date.class, new SimpleDateFormatSerializer(dateFormat));
}

@Override
protected void writeInternal(Object obj, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
// TODO Auto-generated method stub

OutputStream out = outputMessage.getBody();
String text = JSON.toJSONString(obj, mapping, this.getFeatures());
byte[] bytes = text.getBytes(this.getCharset());
out.write(bytes);
}

}

package com.jjs.util;

import java.io.IOException;

import org.springframework.http.HttpOutputMessage;
import org.springframework.http.converter.HttpMessageNotWritableException;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;

public class JsonHttpMessageConverter extends FastJsonHttpMessageConverter {

@Override
protected void writeInternal(Object obj, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
// TODO Auto-generated method stub
JSON.DEFFAULT_DATE_FORMAT = "yyyy-MM-dd HH";
JSON.toJSONString(obj, SerializerFeature.WriteDateUseDateFormat);
super.writeInternal(obj, outputMessage);

}

}

<mvc:annotation-driven>
<mvc:message-converters register-defaults="true">
<!-- <bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter"> -->
            <bean class="com.jjs.util.JsonHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/html;charset=UTF-8</value>
<value>application/json</value>
</list>
</property>
<property name="features">
<list>
<value>WriteDateUseDateFormat</value>
<value>WriteMapNullValue</value>
<value>QuoteFieldNames</value>
</list>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>