解决org.springframework......MethodArgumentTypeMismatchException警告

spring项目中无法访问到对应controller,查看日志,没有报错,只有warnring:

org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.logException Resolved [org.springframework.web.method.annotation.MethodArgumentTypeMismatchException:
 Failed to convert value of type 'java.lang.String' to required type 'java.util.Date'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type 
[@org.springframework.web.bind.annotation.RequestParam java.util.Date] for value '2019-06-21'; nested exception is java.lang.IllegalArgumentException]

直接来说就是字符串无法转为Date类型。

引起原因是大部分人使用Date格式作为controller接口的参数,导致springmvc无法将String转为Date,已知springmvc内置了一系列的转换,不过都是基本类型到包装类以及String到包装类,和List、Set、Map等。但是对类似String转Date还是无能为力的。

种解决办法:

参数改为String类型,在后端处理String到Date的转换,而不是交给SpringMVC来处理。

写转换类实现org.springframework.core.convert.converter.Converter,并在SpringMVC中注册。

该Converter接口较为简单,代码略

 <bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
      <property name="converters">
          <set>
              <bean class="com.l.utils.StringToDateConverter"/>
          </set>
      </property>
  </bean>
  <mvc:annotation-driven conversion-service="conversionService"/>

如果是springboot项目:

   @Bean
   public ConversionService conversionService() {
       FormattingConversionServiceFactoryBean factory = new FormattingConversionServiceFactoryBean();
       DateTimeFormatterRegistrar registrar = new DateTimeFormatterRegistrar();
       registrar.setDateFormatter(DateTimeFormatter.ofPattern("yyyy-MM-dd"));
       factory.setFormatterRegistrars(Collections.singleton(registrar));
       factory.afterPropertiesSet();
       return factory.getObject();
   }

原理:

springmvc默认已经提供了很多自动转换,查看org.springframework.context.support.ConversionServiceFactoryBean源码:


查看Converter接口:

@FunctionalInterface
public interface Converter<S, T> {
 
	/**
	 * Convert the source object of type {@code S} to target type {@code T}.
	 * @param source the source object to convert, which must be an instance of {@code S} (never {@code null})
	 * @return the converted object, which must be an instance of {@code T} (potentially {@code null})
	 * @throws IllegalArgumentException if the source cannot be converted to the desired target type
	 */
	@Nullable
	T convert(S source);
 
}

已经注册了子类

比如,有StringToBooleanConverter,就说明参数String到Boolean(参数以Boolean类型)是没有问题的!


原文:https://blog.csdn.net/mar_ljh/article/details/93190585
作者: 赣江