网络营销个人网站,微博广告,wordpress 律师,网页设计制作图片页面0x0 背景 项目中使用LocalDateTime系列作为dto中时间的类型#xff0c;但是spring收到参数后总报错#xff0c;为了全局配置时间类型转换#xff0c;尝试了如下3中方法。
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
1. 使用Converter
import 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;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;Configuration
public class DateConfig {Beanpublic ConverterString, LocalDate localDateConverter() {return new Converter() {Overridepublic LocalDate convert(String source) {return LocalDate.parse(source, DateTimeFormatter.ofPattern(yyyy-MM-dd));}};}Beanpublic ConverterString, LocalDateTime localDateTimeConverter() {return new Converter() {Overridepublic LocalDateTime convert(String source) {return LocalDateTime.parse(source, DateTimeFormatter.ofPattern(yyyy-MM-dd HH:mm:ss));}};}}
以上两个bean会注入到spring 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。
注意关于自定义的参数转换器 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 BeanConditionalOnBean(name requestMappingHandlerAdapter)public ConverterString, LocalDate localDateConverter() {return source - LocalDate.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT));}
当我再次启动项目时却出现了异常
Caused by: java.lang.IllegalArgumentException: Unable to determine source type S and target type T for your Converter [com.example.demo126.config.MappingConverterAdapter$$Lambda$522/817994751]; does the class parameterize those types? 百思不得其解在查阅了资料才得知一二。
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
public void addFormatters(FormatterRegistry registry) {for (Converter?, ? converter : getBeansOfType(Converter.class)) {registry.addConverter(converter);}for (GenericConverter converter : getBeansOfType(GenericConverter.class)) {registry.addConverter(converter);}for (Formatter? formatter : getBeansOfType(Formatter.class)) {registry.addFormatter(formatter);}
}
添加Converter.class 一般是通过接口获取两个泛型的具体类型
public ResolvableType as(Class? type) {if (this NONE) {return NONE;}Class? resolved resolve();if (resolved null || resolved type) {return this;}for (ResolvableType interfaceType : getInterfaces()) {ResolvableType interfaceAsType interfaceType.as(type);if (interfaceAsType ! NONE) {return interfaceAsType;}}return getSuperType().as(type);
} 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
ConditionalOnBean(name requestMappingHandlerAdapter)
public ConverterString, LocalDateTime localDateTimeConverter() {return source - LocalDateTime.parse(source, 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、 HH:mm:ss等进行匹配。以适应多种场景。
Component
public class DateConverter implements ConverterString, Date {Overridepublic Date convert(String value) {/*** 可对value进行正则匹配支持日期、时间等多种类型转换* 这里我偷个懒在匹配Date日期格式时直接使用了 hutool 为我们已经写好的解析工具类这里就不重复造轮子了* cn.hutool.core.date.DateUtil* param value* return*/return DateUtil.parse(value.trim());}
} 注这里偷个懒在匹配Date日期格式时直接使用了 hutool 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。
2. 使用ControllerAdvice配合initBinder
ControllerAdvice
public class GlobalExceptionHandler {InitBinderprotected void initBinder(WebDataBinder binder) {binder.registerCustomEditor(LocalDate.class, new PropertyEditorSupport() {Overridepublic void setAsText(String text) throws IllegalArgumentException {setValue(LocalDate.parse(text, DateTimeFormatter.ofPattern(yyyy-MM-dd)));}});binder.registerCustomEditor(LocalDateTime.class, new PropertyEditorSupport() {Overridepublic void setAsText(String text) throws IllegalArgumentException {setValue(LocalDateTime.parse(text, DateTimeFormatter.ofPattern(yyyy-MM-dd HH:mm:ss)));}});binder.registerCustomEditor(LocalTime.class, new PropertyEditorSupport() {Overridepublic void setAsText(String text) throws IllegalArgumentException {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 当LocalDateTime作为Json形式传入 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
public class JacksonConfig {/** 默认日期时间格式 */public static final String DEFAULT_DATE_TIME_FORMAT yyyy-MM-dd HH:mm:ss;/** 默认日期格式 */public static final String DEFAULT_DATE_FORMAT yyyy-MM-dd;/** 默认时间格式 */public static final String DEFAULT_TIME_FORMAT HH:mm:ss;Beanpublic ObjectMapper objectMapper(){ObjectMapper objectMapper new ObjectMapper();//objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);//objectMapper.disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);JavaTimeModule javaTimeModule new 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 ParameterNamesModule());return objectMapper;}} 0x3 当LocalDateTime作为Json形式传入 import 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;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
import java.util.TimeZone;Configuration
public class DateConfig {Beanpublic Jackson2ObjectMapperBuilderCustomizer customizer() {return builder - {builder.locale(Locale.CHINA);builder.timeZone(TimeZone.getTimeZone(GMT8:00));builder.simpleDateFormat(DatePattern.NORM_DATETIME_PATTERN);JavaTimeModule javaTimeModule new 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 来个完整的配置 package 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;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.Date;Configuration
public class DateConfig {/** 默认日期时间格式 */public static final String DEFAULT_DATE_TIME_FORMAT yyyy-MM-dd HH:mm:ss;/** 默认日期格式 */public static final String DEFAULT_DATE_FORMAT yyyy-MM-dd;/** 默认时间格式 */public static final String DEFAULT_TIME_FORMAT HH:mm:ss;/*** LocalDate转换器用于转换RequestParam和PathVariable参数*/Beanpublic ConverterString, LocalDate localDateConverter() {return new Converter() {Overridepublic LocalDate convert(String source) {return LocalDate.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT));}};}/*** LocalDateTime转换器用于转换RequestParam和PathVariable参数*/Beanpublic ConverterString, LocalDateTime localDateTimeConverter() {return new Converter() {Overridepublic LocalDateTime convert(String source) {return LocalDateTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT));}};}/*** LocalTime转换器用于转换RequestParam和PathVariable参数*/Beanpublic ConverterString, LocalTime localTimeConverter() {return new Converter() {Overridepublic LocalTime convert(String source) {return LocalTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT));}};}/*** Date转换器用于转换RequestParam和PathVariable参数*/Beanpublic ConverterString, Date dateConverter() {return new Converter() {Overridepublic Date convert(String source) {SimpleDateFormat format new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);try {return format.parse(source);} catch (ParseException e) {throw new RuntimeException(e);}}};}/*** 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 objectMapper new 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 new 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 JsonSerializer() {Overridepublic void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {SimpleDateFormat formatter new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);String formattedDate formatter.format(date);jsonGenerator.writeString(formattedDate);}});javaTimeModule.addDeserializer(Date.class, new JsonDeserializer() {Overridepublic Date deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException {SimpleDateFormat format new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);String date jsonParser.getText();try {return format.parse(date);} catch (ParseException e) {throw new RuntimeException(e);}}});objectMapper.registerModule(javaTimeModule);return objectMapper;}
} 0x5 深入研究SpringMVC数据绑定过程 写一个简单controller下个断点看看方法调用栈
GetMapping(/getDate)
public LocalDateTime getDate(RequestParam LocalDate date,RequestParam LocalDateTime dateTime,RequestParam Date originalDate) {System.out.println(date);System.out.println(dateTime);System.out.println(originalDate);return LocalDateTime.now();
}
断住以后看下方法调用栈中一些关键方法
//进入DispatcherServlet
doService:942, DispatcherServlet
//处理请求
doDispatch:1038, DispatcherServlet
//生成调用链前处理、实际调用方法、后处理
handle:87, AbstractHandlerMethodAdapter
//反射获取到实际调用方法准备开始调用
invokeHandlerMethod:895, RequestMappingHandlerAdapter
invokeAndHandle:102, ServletInvocableHandlerMethod
//这里是关键参数从这里开始获取到
invokeForRequest:142, InvocableHandlerMethod
doInvoke:215, InvocableHandlerMethod
//这个是Java reflect调用因此一定是在这之前获取到的参数
invoke:566, Method
根据上述分析发现invokeForRequest:142, InvocableHandlerMethod这里的代码是用来拿到实际参数的
Nullable
public Object invokeForRequest(NativeWebRequest request, Nullable ModelAndViewContainer mavContainer,Object... providedArgs) throws Exception {//这个方法是获取参数的在这里下个断Object[] args getMethodArgumentValues(request, mavContainer, providedArgs);if (logger.isTraceEnabled()) {logger.trace(Arguments: Arrays.toString(args));}//这里开始调用方法return doInvoke(args);
}
进入这个方法看看是什么操作
protected Object[] getMethodArgumentValues(NativeWebRequest request, Nullable ModelAndViewContainer mavContainer,Object... providedArgs) throws Exception {//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 parameter转换的参数Object[] args new Object[parameters.length];for (int i 0; i parameters.length; i) {MethodParameter parameter 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)) {//从名字就看出来参数解析器解析参数args[i] this.argumentResolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);continue;}}return args;
}
进入resolveArgument看看
public Object resolveArgument(MethodParameter parameter, Nullable ModelAndViewContainer mavContainer,NativeWebRequest webRequest, Nullable WebDataBinderFactory binderFactory) throws Exception {//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, webRequest, binderFactory);
}
这里根据参数获取相应的参数解析器看看内部如何获取的
//遍历调用supportParameter方法跟进看看
for (HandlerMethodArgumentResolver methodArgumentResolver : this.argumentResolvers) {if (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 boolean 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)) {//这个似乎是对Optional类型的参数进行处理的if (Map.class.isAssignableFrom(parameter.nestedIfOptional().getNestedParameterType())) {RequestParam requestParam parameter.getParameterAnnotation(RequestParam.class);return (requestParam ! null StringUtils.hasText(requestParam.name()));}else {return true;}}//......
}
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 也就是Converter注入的地方
WebDataBinder binder binderFactory.createBinder(webRequest, null, namedValueInfo.name);
//通过DataBinder进行数据绑定的
arg binder.convertIfNecessary(arg, parameter.getParameterType(), parameter);
//跟进convertIfNecessary()
public T T convertIfNecessary(Nullable Object value, Nullable ClassT requiredType,Nullable MethodParameter methodParam) throws TypeMismatchException {return getTypeConverter().convertIfNecessary(value, requiredType, methodParam);
}
//继续跟进看到了把
ConversionService conversionService this.propertyEditorRegistry.getConversionService();
if (editor null conversionService ! null newValue ! null typeDescriptor ! null) {TypeDescriptor sourceTypeDesc TypeDescriptor.forObject(newValue);if (conversionService.canConvert(sourceTypeDesc, typeDescriptor)) {try {return (T) conversionService.convert(newValue, sourceTypeDesc, typeDescriptor);}catch (ConversionFailedException ex) {// fallback to default conversion logic belowconversionAttemptEx ex;}}
}
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 arg readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType());//step into readWithMessageConverters()我们看到这里的Converter是HttpMessageConverter
for (HttpMessageConverter? converter : this.messageConverters) {ClassHttpMessageConverter? converterType (ClassHttpMessageConverter?) converter.getClass();GenericHttpMessageConverter? genericConverter (converter instanceof GenericHttpMessageConverter ? (GenericHttpMessageConverter?) converter : null);if (genericConverter ! null ? genericConverter.canRead(targetType, contextClass, contentType) :(targetClass ! null converter.canRead(targetClass, contentType))) {if (message.hasBody()) {HttpInputMessage msgToUse getAdvice().beforeBodyRead(message, parameter, targetType, converterType);body (genericConverter ! null ? genericConverter.read(targetType, contextClass, msgToUse) :((HttpMessageConverterT) converter).read(targetClass, msgToUse));body getAdvice().afterBodyRead(body, msgToUse, parameter, targetType, converterType);}else {body getAdvice().handleEmptyBody(null, message, parameter, targetType, converterType);}break;}
}
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。
