0023SpringMVC自定义类型转换器

页面录入的字符串：2019/12/05可以映射到实体的日期属性上，但是如果是录入2019-12-05就会报错400 bad request，想要以2019-12-05日期格式的方式映射到实体的日期属性上，需要自定义类型转换器，主要步骤如下：

1、  自定义类实现Convertro<S,T>接口

2、Springmvc.xml中配置ConversionServiceFactoryBean，其属性上配置我们自定义的转换器

3、欲使配置的转换器生效，需要将springmvc.xml的<mvc:annotation-driven />改为

<mvc:annotation-driven conversion-service="conversionServiceFactoryBean"/>

1、  自定义类实现Convertro<S,T>接口

package com.example.util;

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

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

public class StingToDateConvertr implements Converter<String, Date> {
    @Override
    public Date convert(String s) {
        if(StringUtils.isEmpty(s)){
            throw new RuntimeException("日期字符串不能为空！");
        }
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        try {
            return df.parse(s);
        } catch (ParseException e) {
            throw new RuntimeException("类型转换出错！");
        }
    }
}

2、Springmvc.xml中配置ConversionServiceFactoryBean，其属性上配置我们自定义的转换器

<!--配置自定义类型转换器-->
<bean id="conversionServiceFactoryBean" class="org.springframework.context.support.ConversionServiceFactoryBean">
    <property name="converters">
        <set>
            <bean class="com.example.util.StingToDateConvertr" />
        </set>
    </property>
</bean>

3、欲使配置的转换器生效，需要将springmvc.xml的<mvc:annotation-driven />改为

<mvc:annotation-driven conversion-service="conversionServiceFactoryBean"/>

springmvc.xml的完整配置如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:c="http://www.springframework.org/schema/c"
       xmlns:cache="http://www.springframework.org/schema/cache"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:jdbc="http://www.springframework.org/schema/jdbc"
       xmlns:jee="http://www.springframework.org/schema/jee"
       xmlns:lang="http://www.springframework.org/schema/lang"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:task="http://www.springframework.org/schema/task"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:util="http://www.springframework.org/schema/util"
       xsi:schemaLocation="http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.3.xsd
      http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
      http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
      http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
      http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd
      http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.3.xsd
      http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-4.3.xsd
      http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.3.xsd
      http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-4.3.xsd
      http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd ">
    <!--开启注解扫描-->
    <context:component-scan base-package="com.example" />
    <!--视图解析器，根据Controller返回的字符串找对应的文件-->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--文件路径-->
        <property name="prefix" value="/WEB-INF/pages/" />
        <!--文件后缀-->
        <property name="suffix" value=".jsp" />
    </bean>
    <!--配置自定义类型转换器-->
    <bean id="conversionServiceFactoryBean" class="org.springframework.context.support.ConversionServiceFactoryBean">
        <property name="converters">
            <set>
                <bean class="com.example.util.StingToDateConvertr" />
            </set>
        </property>
    </bean>

    <!--1、开启springmvc框架注解的支持-->
    <!--2、欲使配置的自定义类型转换器生效，需加上conversion-service属性-->
    <mvc:annotation-driven conversion-service="conversionServiceFactoryBean"/>

</beans>

注意：自定义的类型转换器生效之后，日期格式就只能使用yyyy-MM-dd的格式了，若再使用原有的yyyy/MM/dd格式就会报错！

如有理解不到之处，望指正！