注#xff1a;本文基于Springboot2.0测试#xff0c;如果无法生效可能是spring版本较低导致的。

PS但是spring收到参数后总报错为了全局配置时间类型转换尝试了如下3中方法。

注本文基于Springboot2.0测试如果无法生效可能是spring版本较低导致的。

PS如果你的Controller中的LocalDate类型的参数啥注解RequestParam、PathVariable等都没加也是会出错的因为默认情况下解析这种参数使用ModelAttributeMethodProcessor进行处理而这个处理器要通过反射实例化一个对象出来然后再对对象中的各个参数进行convert但是LocalDate类没有构造函数无法反射实例化因此会报错

0x1

当LocalDateTime作为RequestParam或者PathVariable时

这种情况要和时间作为Json字符串时区别对待因为前端json转后端pojo底层使用的是Json序列化Jackson工具HttpMessgeConverter而时间字符串作为普通请求参数传入时转换用的是Converter两者有区别哦。

在这种情况下有如下几种方案

org.springframework.context.annotation.Bean;

import

org.springframework.context.annotation.Configuration;

import

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

import

org.springframework.http.converter.HttpMessageConverter;import

java.time.LocalDate;

java.time.format.DateTimeFormatter;Configuration

public

DateTimeFormatter.ofPattern(yyyy-MM-dd));}};}Beanpublic

ConverterString,

DateTimeFormatter.ofPattern(yyyy-MM-dd

HH:mm:ss));}};}}

mvc的参数解析器好像叫做ParameterConversionService当传入的字符串要转为LocalDateTime类时spring会调用该Converter对这个入参进行转换。

Converter这里遇到了一个坑再这里详细记录下本来想法是为了代码精简将上面匿名内部类的写法精简成lambda表达式的方式

requestMappingHandlerAdapter)public

ConverterString,

DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT));}

Caused

java.lang.IllegalArgumentException:

Unable

[com.example.demo126.config.MappingConverterAdapter$$Lambda$522/817994751];

does

web项目启动注册requestMappingHandlerAdapter的时候会初始化WebBindingInitializer

adapter.setWebBindingInitializer(getConfigurableWebBindingInitializer());

而ConfigurableWebBindingInitializer需要FormattingConversionService,

而FormattingConversionService会将所有的Converter添加进来添加的时候需要获取泛型信息

Override

addFormatters(FormatterRegistry

registry)

getBeansOfType(Converter.class))

{registry.addConverter(converter);}for

(GenericConverter

getBeansOfType(GenericConverter.class))

{registry.addConverter(converter);}for

(Formatter?

getBeansOfType(Formatter.class))

{registry.addFormatter(formatter);}

添加Converter.class

Lambda表达式的接口是Converter并不能得到具体的类型在窥探了SpringMVC源码后才得知原来如此既然指导了原因那解决办法

最简单的方法就是不适用Lambda表达式还是老老实实的使用匿名内部类这样就不会存在上述问题

或者就是等requestMappingHandlerAdapterbean注册完成之后再添加自己的converter就不会注册到FormattingConversionService中

Bean

DateTimeUtils.DEFAULT_FORMATTER);

还可以对前端传递的string进行正则匹配如yyyy-MM-dd

HH:mm:ss、yyyy-MM-dd、

已经写好的解析工具类这里就不重复造轮子了下面的方法同样使用了该工具类想要在自己的项目中使用该工具类也很简单在项目pom文件中引入hutool的依赖就可以了。

ControllerAdvice

{binder.registerCustomEditor(LocalDate.class,

new

{setValue(LocalDate.parse(text,

DateTimeFormatter.ofPattern(yyyy-MM-dd)));}});binder.registerCustomEditor(LocalDateTime.class,

new

{setValue(LocalDateTime.parse(text,

DateTimeFormatter.ofPattern(yyyy-MM-dd

HH:mm:ss)));}});binder.registerCustomEditor(LocalTime.class,

new

{setValue(LocalTime.parse(text,

DateTimeFormatter.ofPattern(HH:mm:ss)));}});}

从名字就可以看出来这是在controller做环切这里面还可以全局异常捕获在参数进入handler之前进行转换转换为相应的对象。

0x2

这种情况下如同上文描述要利用Jackson的json序列化和反序列化来做

Configuration

ObjectMapper();//objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);//objectMapper.disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);JavaTimeModule

javaTimeModule

JavaTimeModule();javaTimeModule.addSerializer(LocalDateTime.class,new

LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));javaTimeModule.addSerializer(LocalDate.class,new

LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));javaTimeModule.addSerializer(LocalTime.class,new

LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));javaTimeModule.addDeserializer(LocalDateTime.class,new

LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));javaTimeModule.addDeserializer(LocalDate.class,new

LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));javaTimeModule.addDeserializer(LocalTime.class,new

LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));objectMapper.registerModule(javaTimeModule).registerModule(new

objectMapper;}}

cn.hutool.core.date.DatePattern;

import

com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;

import

com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;

import

com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;

import

com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;

import

com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;

import

com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;

import

com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;

import

org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;

import

org.springframework.context.annotation.Bean;

import

org.springframework.context.annotation.Configuration;import

java.time.LocalDate;

java.time.format.DateTimeFormatter;

import

java.util.TimeZone;Configuration

public

Jackson2ObjectMapperBuilderCustomizer

customizer()

{builder.locale(Locale.CHINA);builder.timeZone(TimeZone.getTimeZone(GMT8:00));builder.simpleDateFormat(DatePattern.NORM_DATETIME_PATTERN);JavaTimeModule

javaTimeModule

JavaTimeModule();javaTimeModule.addSerializer(LocalDateTime.class,

new

LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DatePattern.NORM_DATETIME_PATTERN)));javaTimeModule.addSerializer(LocalDate.class,

new

LocalDateSerializer(DateTimeFormatter.ofPattern(DatePattern.NORM_DATE_PATTERN)));javaTimeModule.addSerializer(LocalTime.class,

new

LocalTimeSerializer(DateTimeFormatter.ofPattern(DatePattern.NORM_TIME_PATTERN)));javaTimeModule.addDeserializer(LocalDateTime.class,

new

LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DatePattern.NORM_DATETIME_PATTERN)));javaTimeModule.addDeserializer(LocalDate.class,

new

LocalDateDeserializer(DateTimeFormatter.ofPattern(DatePattern.NORM_DATE_PATTERN)));javaTimeModule.addDeserializer(LocalTime.class,

new

LocalTimeDeserializer(DateTimeFormatter.ofPattern(DatePattern.NORM_TIME_PATTERN)));builder.modules(javaTimeModule);};}}

0x4

com.fly.hi.common.config;import

com.fasterxml.jackson.core.JsonGenerator;

import

com.fasterxml.jackson.core.JsonParser;

import

com.fasterxml.jackson.core.JsonProcessingException;

import

com.fasterxml.jackson.databind.*;

import

com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;

import

com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;

import

com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;

import

com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;

import

com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;

import

com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;

import

com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;

import

org.springframework.context.annotation.Bean;

import

org.springframework.context.annotation.Configuration;

import

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

java.io.IOException;

java.time.format.DateTimeFormatter;

import

LocalDate转换器用于转换RequestParam和PathVariable参数*/Beanpublic

ConverterString,

DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT));}};}/***

LocalDateTime转换器用于转换RequestParam和PathVariable参数*/Beanpublic

ConverterString,

DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT));}};}/***

LocalTime转换器用于转换RequestParam和PathVariable参数*/Beanpublic

ConverterString,

DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT));}};}/***

Date转换器用于转换RequestParam和PathVariable参数*/Beanpublic

ConverterString,

SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);try

{return

Json序列化和反序列化转换器用于转换Post请求体中的json以及将我们的对象序列化为返回响应的json*/Beanpublic

ObjectMapper

ObjectMapper();objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);objectMapper.disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);//LocalDateTime系列序列化和反序列化模块继承自jsr310我们在这里修改了日期格式JavaTimeModule

javaTimeModule

JavaTimeModule();javaTimeModule.addSerializer(LocalDateTime.class,new

LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));javaTimeModule.addSerializer(LocalDate.class,new

LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));javaTimeModule.addSerializer(LocalTime.class,new

LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));javaTimeModule.addDeserializer(LocalDateTime.class,new

LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));javaTimeModule.addDeserializer(LocalDate.class,new

LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));javaTimeModule.addDeserializer(LocalTime.class,new

LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));//Date序列化和反序列化javaTimeModule.addSerializer(Date.class,

new

SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);String

formattedDate

formatter.format(date);jsonGenerator.writeString(formattedDate);}});javaTimeModule.addDeserializer(Date.class,

new

SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);String

date

RuntimeException(e);}}});objectMapper.registerModule(javaTimeModule);return

objectMapper;}

{System.out.println(date);System.out.println(dateTime);System.out.println(originalDate);return

LocalDateTime.now();

InvocableHandlerMethod这里的代码是用来拿到实际参数的

Nullable

invokeForRequest(NativeWebRequest

request,

getMethodArgumentValues(request,

mavContainer,

Arrays.toString(args));}//这里开始调用方法return

doInvoke(args);

getMethodArgumentValues(NativeWebRequest

request,

{//获取方法参数数组包含了入参信息比如类型、泛型等等MethodParameter[]

parameters

getMethodParameters();//这个用来存放一会从request

args

parameters[i];parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);//这里看起来没啥卵用providedArgs为空args[i]

resolveProvidedArgument(parameter,

providedArgs);//这里开始获取到方法实际调用的参数步进if

(this.argumentResolvers.supportsParameter(parameter))

this.argumentResolvers.resolveArgument(parameter,

mavContainer,

this.dataBinderFactory);continue;}}return

args;

resolveArgument(MethodParameter

parameter,

{//根据方法入参获取对应的解析器HandlerMethodArgumentResolver

resolver

getArgumentResolver(parameter);//开始解析参数把请求中的parameter转为方法的入参return

resolver.resolveArgument(parameter,

mavContainer,

(methodArgumentResolver.supportsParameter(parameter))

{result

methodArgumentResolver;this.argumentResolverCache.put(parameter,

result);break;}

这里遍历参数解析器查找有没有适合的解析器那么有哪些参数解析器呢(我测试的时候有26个)我列出几个重要的看看是不是很眼熟

{RequestParamMethodArgumentResolver7686}

{PathVariableMethodArgumentResolver8359}

{RequestResponseBodyMethodProcessor8366}

{RequestPartMethodArgumentResolver8367}

进入最常用的一个解析器看看它的supportsParameter方法发现就是通过参数注解来获取相应的解析器的。

public

supportsParameter(MethodParameter

parameter)

{//如果参数拥有注解RequestParam则走这个分支知道为什么上文要对RequestParam和Json两种数据区别对待了把if

(parameter.hasParameterAnnotation(RequestParam.class))

(Map.class.isAssignableFrom(parameter.nestedIfOptional().getNestedParameterType()))

{RequestParam

parameter.getParameterAnnotation(RequestParam.class);return

(requestParam

StringUtils.hasText(requestParam.name()));}else

{return

也就是说对于RequestParam和RequestBody以及PathVariable注解的参数SpringMVC会使用不同的参数解析器进行数据绑定那么这三种解析器分别使用什么Converter解析参数呢分别进入三种解析器看一看首先看下RequestParamMethodArgumentResolver发现内部使用WebDataBinder进行数据绑定底层使用的是ConversionService

WebDataBinder

binderFactory.createBinder(webRequest,

null,

getTypeConverter().convertIfNecessary(value,

requiredType,

this.propertyEditorRegistry.getConversionService();

(editor

TypeDescriptor.forObject(newValue);if

(conversionService.canConvert(sourceTypeDesc,

typeDescriptor))

conversionService.convert(newValue,

sourceTypeDesc,

然后看下RequestResponseBodyMethodProcessor发现使用的转换器是HttpMessageConverter类型的

//resolveArgument方法内部调用下面进行参数解析

Object

readWithMessageConverters(webRequest,

parameter,

parameter.getNestedGenericParameterType());//step

into

readWithMessageConverters()我们看到这里的Converter是HttpMessageConverter

for

converter.getClass();GenericHttpMessageConverter?

genericConverter

genericConverter.canRead(targetType,

contextClass,

getAdvice().beforeBodyRead(message,

parameter,

genericConverter.read(targetType,

contextClass,

getAdvice().afterBodyRead(body,

msgToUse,

getAdvice().handleEmptyBody(null,

message,

最后看下PathVariableMethodArgumentResolver发现

和RequestParam走的执行路径一致二者都是继承自AbstractNamedValueMethodArgumentResolver解析器因此代码就不贴了。

0xFF总结

如果要转换request传来的参数到指定的类型根据入参注解要进行区分

如果是RequestBody那么通过配置ObjectMapper这个玩意儿会注入到Jackson的HttpMessagConverter里面即MappingJackson2HttpMessageConverter中来实现Json格式数据的序列化和反序列化

如果是RequestParam或者PathVariable类型的参数通过配置Converter实现参数转换这些Converter会注入到ConversionService中。