spring mvc json 问题

applicationContext.xml  

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">  
        <property name="messageConverters">  
            <list>  
               <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">  
                   <property name="supportedMediaTypes">  
                       <list>  
                           <value>text/plain;charset=UTF-8</value>  
                           <value>application/json;charset=UTF-8</value>  
                       </list>  
                   </property>  
                   <property name="objectMapper">  
                       <bean class="com.charmyin.cmstudio.common.utils.ObjectMappingCustomer"></bean>  
                   </property>  
               </bean>     
            </list>  
        </property>  
    </bean>

此处我也尝试了

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"> ...... </bean>

ObjectMappingCustomer.java 

package com.charmyin.cmstudio.common.utils;


import java.io.IOException;

import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;       
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.SerializerProvider;
 
    public class ObjectMappingCustomer extends ObjectMapper  

    {

        /**
         * 
         */
        private static final long serialVersionUID = 1L;  

       

        public ObjectMappingCustomer()  

        {  
//
            super();  

            // 允许单引号  

            this.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);  

            // 字段和值都加引号  

            this.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);  

            // 数字也加引号  

            this.configure(JsonGenerator.Feature.WRITE_NUMBERS_AS_STRINGS, true);  

            this.configure(JsonGenerator.Feature.QUOTE_NON_NUMERIC_NUMBERS, true); 
//
//            // 空值处理为空串  
//
            SerializerProvider sp = (SerializerProvider) this.getSerializerProvider();

            sp.setNullValueSerializer(new JsonSerializer<Object>(){

 

                @Override

                public void serialize(Object value, JsonGenerator jg,

                        SerializerProvider sp) throws IOException,

                        JsonProcessingException {

                     jg.writeString("");  

                }

                 

            });
//
//       
//
        }  

    }

输出的json

{
    "rows": [
        {
            "pageVO": null,
            "praId": "bffa397b245849909a9c2af4e74e007d19a1e6cb",
            "creatorId": 248,
            "creatorName": "stu123",
            "finalReport": null
      }
    ]
}