JAVA中json日期格式问题的办法

package cn.jbit.BookSys.util;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import net.sf.json.JsonConfig;
import net.sf.json.processors.JsonValueProcessor;

public class JsonDateValueProcessor implements JsonValueProcessor{
     private String format ="yyyy-MM-dd";  

        public JsonDateValueProcessor() {
            super();
        }  

        public JsonDateValueProcessor(String format) {
            super();
            this.format = format;
        }  

        @Override
        public Object processArrayValue(Object value, JsonConfig jsonConfig) {
            // TODO Auto-generated method stub
             String[] obj = {};
                if (value instanceof Date[])
                {
                    SimpleDateFormat sf = new SimpleDateFormat(format);
                    Date[] dates = (Date[]) value;
                    obj = new String[dates.length];
                    for (int i = 0; i < dates.length; i++)
                    {
                        obj[i] = sf.format(dates[i]);
                    }
                }
                return obj;
        }

        @Override
        public Object processObjectValue(String key, Object value, JsonConfig jsonConfig) {
            // TODO Auto-generated method stub
            if (value instanceof Date)
            {
                String str = new SimpleDateFormat(format).format((Date) value);
                return str;
            }
            return value;
        }
         public String getFormat()
            {
                return format;
            }  

            public void setFormat(String format)
            {
                this.format = format;
            }  

}