springmvc 1.接受日期类型的参数 2.后台返回json串的格式处理(返回json串null值处理为"")

springmvc中的配置：

<bean id="dateConvert" class="com.iomp.util.DateConvert"/>
    <bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
        <property name="converters">
            <set>
                <ref bean="dateConvert"/>
            </set>
        </property>
    </bean>

    <mvc:annotation-driven conversion-service="conversionService">
        <mvc:message-converters ><!--register-defaults="false"-->
            <bean id="jacksonMessageConverter"
                  class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <!-- 这里顺序不能反，一定先写text/html,不然ie下出现下载提示 -->
                        <value>text/html;charset=UTF-8</value>
                        <value>application/json;charset=UTF-8</value>
                    </list>
                </property>
                <property name="objectMapper"> <!--返回json串null值处理为""-->
                    <bean class="com.iomp.interceptor.ObjectMappingCustomer"></bean>
                </property>

            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

DateConvert类(后台接受日期类型的数据:字符串转日期类型)：

package com.iomp.util;

import org.springframework.core.convert.converter.Converter;

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

public class DateConvert implements Converter<String, Date> {
    @Override
    public Date convert(String stringDate) {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        Date date = null;
        try {
            date = simpleDateFormat.parse(stringDate);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return date;
    }

}

ObjectMappingCustomer 类(返回json串null值处理为“”)：

package com.iomp.interceptor;


import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.DefaultSerializerProvider;

import java.io.IOException;

/**
 * SpringMvc @responseBody 返回json串null值处理为""
 */
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
        DefaultSerializerProvider sp = (DefaultSerializerProvider) this.getSerializerProvider();
        sp.setNullValueSerializer(new JsonSerializer<Object>(){

            @Override
            public void serialize(Object value, JsonGenerator jg,
                                  SerializerProvider sp) throws IOException,
                    JsonProcessingException {
                jg.writeString("");
            }

        });

    }
}