spring mvc3 jackson输出null值处理

spring mvc3 jackson输出null值转为空串，找了很久终于找到办法

spring-mvc.xml中配置：

	class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
	
		
			text/html;charset=UTF-8
			application/json;charset=UTF-8
		
		

	
	
		
	



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

objectMapper类：

package com.tyrbl.zy.utils.spring;

import java.io.IOException;

import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonProcessingException;
import org.codehaus.jackson.map.JsonSerializer;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializerProvider;

public class ObjectMappingCustomer extends ObjectMapper {

	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
		this.getSerializerProvider().setNullValueSerializer(
				new JsonSerializer