在Spring 3中注册带注释的转换器和converterFactories

6 回答

• 9

  @Ralph概述的方法很整洁，我的答案是1 . 我还建议使用 @Configuration support的替代方法 - 本质上是一种使用Java而不是xml配置Spring bean的方法 . 使用这种方法，可以通过以下方式注册消息转换器：

  @Configuration
   @EnableWebMvc
   @ComponentScan(...)
   public class CustomConfig extends WebMvcConfigurerAdapter {
  
  
      @Override
      public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
          converters.add(new EnumConverter());
                  converters.add(new FooConverter());
                  ...
      }
  
   }
  

  回复于 2024-04-26T02:06:14+08:00
• 6

  Spring没有对转换器的注释支持，但您可以构建自己的 .

  您只需要一个自定义限定符注释（让我们称之为 @AutoRegistered ）和某种类型的Converter / Formatter注册器（实现FormatterRegistrar），它使用此 @AutoRegistered 注释注册所有Spring Bean（以及一些xml来注册此注册服务） .

  然后你需要用这个注释（和一些其他的注释使它成为一个 spring beans ）来注释你的对流器，这就是全部 .

  @AutoRegistered 注释：

  @Target({ ElementType.FIELD, ElementType.PARAMETER, ElementType.TYPE })
  @Retention(RetentionPolicy.RUNTIME)
  @Qualifier
  public @interface AutoRegistered {}
  

  报名服务：

  import java.util.List;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.core.convert.converter.Converter;
  import org.springframework.format.FormatterRegistrar;
  import org.springframework.format.FormatterRegistry;
  
  public class AutoregisterFormatterRegistrar implements FormatterRegistrar {
  
      /**
       * All {@link Converter} Beans with {@link AutoRegistered} annotation.
       * If spring does not find any matching bean, then the List is {@code null}!.
       */
      @Autowired(required = false)
      @AutoRegistered
      private List<Converter<?, ?>> autoRegisteredConverters;
  
  
      @Override
      public void registerFormatters(final FormatterRegistry registry) {
          if (this.autoRegisteredConverters != null) {
              for (Converter<?, ?> converter : this.autoRegisteredConverters) {
                  registry.addConverter(converter);
              }
          }
      }
  }
  

  注册商的XML配置：

  <bean id="applicationConversionService"
      class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
      <property name="formatterRegistrars">
          <set>
              <bean
                  class="AutoregisterFormatterRegistrar"
                  autowire="byType" />
          </set>
      </property>
  </bean>
  

  BTW为您的枚举转换器，您不需要 ConversionFactory - 一个简单的转换器就足够了：

  @AutoRegistered
  @Component
  public class EnumConverter implements Converter<Enum<?>, String> {
  
      /** Use the same immutable value instead of creating an new array every time. */
      private static final Object[] NO_PARAM = new Object[0];
  
      /** The prefix of all message codes. */
      private static final String PREFIX = "label_";
  
      /** The separator in the message code, between different packages
          as well as between package can class. */
      private static final String PACKAGE_SEPARATOR = "_";
  
      /** The separator in the message code, between the class name
          and the enum case name. */
      private static final String ENUM_CASE_SEPARATOR = "_";
  
      /** The message source. */
      private MessageSource messageSource;
  
      @Autowired
      public EnumConverter(final MessageSource messageSource) {
          if (messageSource == null) {
              throw new RuntimeException("messageSource must not be null");
          }
  
          this.messageSource = messageSource;
      }
  
      @Override
      public String convert(final Enum<?> source) {
          if (source != null) {
              String enumValueName = source.name();
              String code = PREFIX + source.getClass().getName().toLowerCase().
                    replace(".", PACKAGE_SEPARATOR)
              + ENUM_CASE_SEPARATOR + enumValueName.toLowerCase();
  
              String message = messageSource.getMessage(code, NO_PARAM, enumValueName,
                                                    LocaleContextHolder.getLocale());
  
               return message;
           } else {
              return "";
           }
       }   
  }
  

  回复于 2024-04-26T02:06:14+08:00
• 5

  使用Spring MVC 3.2，您可以创建一个扩展DefaultFormattingConversionService的转换服务类，例如

  ApplicationConversionService.java

  import org.springframework.format.support.DefaultFormattingConversionService;
  import org.springframework.stereotype.Component;
  
  @Component("conversionService")
  public class ApplicationConversionService extends DefaultFormattingConversionService  { 
  
      public ApplicationConversionService(){
          //DefaultFormattingConversionService's default constructor
          //creates default formatters and converters
          super(); //no need for explicit super()?
  
          //add custom formatters and converters
          addConverter(new MyConverter());
      }
  
  }
  

  并在spring配置中指定它，例如

  dispatcher-servlet.xml

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

  回复于 2024-04-26T02:06:14+08:00
• 6

  首先，您必须定义注释：TypeConverter

  @Target({ElementType.TYPE})
  @Retention(RetentionPolicy.RUNTIME)
  @Documented
  @Component
  public @interface TypeConverter {
  }
  

  然后，您必须注册转换服务并添加具有注释的所有bean . 这将使用以下后处理器完成：

  public class ConverterRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor {
  
  public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
      registry.registerBeanDefinition("conversionService", BeanDefinitionBuilder.rootBeanDefinition(ConversionServiceFactoryBean.class).getBeanDefinition());
  }
  
  public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
      Map<String, Object> beansWithAnnotation = beanFactory.getBeansWithAnnotation(TypeConverter.class);
      Collection converters = beansWithAnnotation.values();
      DefaultConversionService conversionService = (DefaultConversionService) beanFactory.getBean("conversionService");
      for (Object converter : converters) {
          conversionService.addConverter((Converter<?, ?>) converter);
      }
  }
  }
  

  如果您需要更多详细信息，请查看blog entry

  回复于 2024-04-26T02:06:14+08:00
• 1

  我不确定这是否适用于Spring 3，但这是Spring 4的解决方案：

  @Configuration
  @EnableWebMvc
  class WebMvcContext extends WebMvcConfigurerAdapter {
  
      @Override
      public void addFormatters(FormatterRegistry registry) {
          registry.addConverter(new DateConverter("yyyy-MM-dd HH:mm:ss"));
          //registry.addConverter(anotherConverter);
      }
  }
  

  DateConverter是一个自定义转换器：

  public class DateConverter implements Converter<String, Date>{
      private static final Logger LOGGER = LoggerFactory.getLogger(DateConverter.class);
      private final String dateFormat;
      private final SimpleDateFormat formatter;
      public DateConverter(String dateFormatPattern) {
          this.dateFormat = dateFormatPattern;
          this.formatter = new SimpleDateFormat(dateFormatPattern);
      }
  
      @Override
      public Date convert(String source) {
          Date date = null;
          try {
              date = formatter.parse(source);
          } catch (ParseException e) {
              e.printStackTrace();
          }
          return date;
      }
  }
  

  回复于 2024-04-26T02:06:14+08:00
• 0

  当@EnableAutoConfiguration打开时，Spring Boot也会自动注册Converter Bean - 请参阅Spring Boot features . 似乎没有额外的注释（除了将每个转换器bean标记为 @Component 之外） .

  回复于 2024-04-26T02:06:14+08:00