關(guān)于Springboot日期時(shí)間格式化處理方式總結(jié)

@JsonFormat(pattern = "yyyy-MM-dd", timezone="GMT+8")
private Date releaseDate;

/**
 * 日期序列化
 */
public class DateJsonSerializer extends JsonSerializer<Date> {
  @Override
  public void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws
      IOException {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
    jsonGenerator.writeString(dateFormat.format(date));
  }
}

/**
 * 日期反序列化
 */
public class DateJsonDeserializer extends JsonDeserializer<Date> {

  @Override
  public Date deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
    try {
      SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
      return dateFormat.parse(jsonParser.getText());
    } catch (ParseException e) {
      throw new RuntimeException(e);
    }
  }
}

/**
 * 使用方式
 */
@JsonSerialize(using = DateJsonSerializer.class)
@JsonDeserialize(using = DateJsonDeserializer.class)
private Date releaseDate;

@Configuration
public class DateHandlerConfig {

  /** 默認(rèn)日期時(shí)間格式 */
  public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
  /** 默認(rèn)日期格式 */
  public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
  /** 默認(rèn)時(shí)間格式 */
  public static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";

  /**
   * LocalDate轉(zhuǎn)換器，用于轉(zhuǎn)換RequestParam和PathVariable參數(shù)
   */
  @Bean
  public Converter<String, LocalDate> localDateConverter() {
    return new Converter<>() {
      @Override
      public LocalDate convert(String source) {
        return LocalDate.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT));
      }
    };
  }

  /**
   * LocalDateTime轉(zhuǎn)換器，用于轉(zhuǎn)換RequestParam和PathVariable參數(shù)
   */
  @Bean
  public Converter<String, LocalDateTime> localDateTimeConverter() {
    return new Converter<>() {
      @Override
      public LocalDateTime convert(String source) {
        return LocalDateTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT));
      }
    };
  }

  /**
   * LocalTime轉(zhuǎn)換器，用于轉(zhuǎn)換RequestParam和PathVariable參數(shù)
   */
  @Bean
  public Converter<String, LocalTime> localTimeConverter() {
    return new Converter<>() {
      @Override
      public LocalTime convert(String source) {
        return LocalTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT));
      }
    };
  }

  /**
   * Date轉(zhuǎn)換器，用于轉(zhuǎn)換RequestParam和PathVariable參數(shù)
   */
  @Bean
  public Converter<String, Date> dateConverter() {
    return new Converter<>() {
      @Override
      public 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序列化和反序列化轉(zhuǎn)換器，用于轉(zhuǎn)換Post請(qǐng)求體中的json以及將我們的對(duì)象序列化為返回響應(yīng)的json
   */
  @Bean
  public 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塊，繼承自jsr310，我們?cè)谶@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<>() {
      @Override
      public 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<>() {
      @Override
      public 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;
  }
}

  @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();
  }

//進(jìn)入DispatcherServlet
doService:942, DispatcherServlet
//處理請(qǐng)求
doDispatch:1038, DispatcherServlet
//生成調(diào)用鏈（前處理、實(shí)際調(diào)用方法、后處理）
handle:87, AbstractHandlerMethodAdapter
//反射獲取到實(shí)際調(diào)用方法，準(zhǔn)備開(kāi)始調(diào)用
invokeHandlerMethod:895, RequestMappingHandlerAdapter
invokeAndHandle:102, ServletInvocableHandlerMethod
//這里是關(guān)鍵，參數(shù)從這里開(kāi)始獲取到
invokeForRequest:142, InvocableHandlerMethod
doInvoke:215, InvocableHandlerMethod
//這個(gè)是Java reflect調(diào)用，因此一定是在這之前獲取到的參數(shù)
invoke:566, Method

  @Nullable
  public Object invokeForRequest(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
      Object... providedArgs) throws Exception {
    //這個(gè)方法是獲取參數(shù)的，在這里下個(gè)斷
    Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
    if (logger.isTraceEnabled()) {
      logger.trace("Arguments: " + Arrays.toString(args));
    }
    //這里開(kāi)始調(diào)用方法
    return doInvoke(args);
  }

protected Object[] getMethodArgumentValues(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {
  //獲取方法參數(shù)數(shù)組，包含了入?yún)⑿畔?，比如?lèi)型、泛型等等
  MethodParameter[] parameters = getMethodParameters();
  //這個(gè)用來(lái)存放一會(huì)從request parameter轉(zhuǎn)換的參數(shù)
  Object[] args = new Object[parameters.length];
  for (int i = 0; i < parameters.length; i++) {
   MethodParameter parameter = parameters[i];
   parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);
   //這里看起來(lái)沒(méi)啥卵用（providedArgs為空）
   args[i] = resolveProvidedArgument(parameter, providedArgs);
   //這里開(kāi)始獲取到方法實(shí)際調(diào)用的參數(shù)，步進(jìn)
   if (this.argumentResolvers.supportsParameter(parameter)) {
    //從名字就看出來(lái)：參數(shù)解析器解析參數(shù)
    args[i] = this.argumentResolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);
    continue;
   }
  }
  return args;
}

public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
               NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
 //根據(jù)方法入?yún)ⅲ@取對(duì)應(yīng)的解析器
 HandlerMethodArgumentResolver resolver = getArgumentResolver(parameter);
 //開(kāi)始解析參數(shù)（把請(qǐng)求中的parameter轉(zhuǎn)為方法的入?yún)ⅲ? return resolver.resolveArgument(parameter, mavContainer, webRequest, binderFactory);
}

//遍歷，調(diào)用supportParameter方法，跟進(jìn)看看
for (HandlerMethodArgumentResolver methodArgumentResolver : this.argumentResolvers) {
 if (methodArgumentResolver.supportsParameter(parameter)) {
  result = methodArgumentResolver;
  this.argumentResolverCache.put(parameter, result);
  break;
 }
}

{RequestParamMethodArgumentResolver@7686} 
{PathVariableMethodArgumentResolver@8359} 
{RequestResponseBodyMethodProcessor@8366} 
{RequestPartMethodArgumentResolver@8367} 

  public boolean supportsParameter(MethodParameter parameter) {
    //如果參數(shù)擁有注解@RequestParam，則走這個(gè)分支（知道為什么上文要對(duì)RequestParam和Json兩種數(shù)據(jù)區(qū)別對(duì)待了把）
    if (parameter.hasParameterAnnotation(RequestParam.class)) {
      //這個(gè)似乎是對(duì)Optional類(lèi)型的參數(shù)進(jìn)行處理的
      if (Map.class.isAssignableFrom(parameter.nestedIfOptional().getNestedParameterType())) {
        RequestParam requestParam = parameter.getParameterAnnotation(RequestParam.class);
        return (requestParam != null && StringUtils.hasText(requestParam.name()));
      }
      else {
        return true;
      }
    }
    //......
  }

WebDataBinder binder = binderFactory.createBinder(webRequest, null, namedValueInfo.name);
//通過(guò)DataBinder進(jìn)行數(shù)據(jù)綁定的
arg = binder.convertIfNecessary(arg, parameter.getParameterType(), parameter);

//跟進(jìn)convertIfNecessary()
public <T> T convertIfNecessary(@Nullable Object value, @Nullable Class<T> requiredType,
                @Nullable MethodParameter methodParam) throws TypeMismatchException {

 return getTypeConverter().convertIfNecessary(value, requiredType, methodParam);
}

//繼續(xù)跟進(jìn)，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 below
   conversionAttemptEx = ex;
  }
 }
}

//resolveArgument方法內(nèi)部調(diào)用下面進(jìn)行參數(shù)解析
Object arg = readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType());

//step into readWithMessageConverters()，我們看到這里的Converter是HttpMessageConverter
for (HttpMessageConverter<?> converter : this.messageConverters) {
 Class<HttpMessageConverter<?>> converterType = (Class<HttpMessageConverter<?>>) 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) :
       ((HttpMessageConverter<T>) converter).read(targetClass, msgToUse));
   body = getAdvice().afterBodyRead(body, msgToUse, parameter, targetType, converterType);
  }
  else {
   body = getAdvice().handleEmptyBody(null, message, parameter, targetType, converterType);
  }
  break;
 }
}