import lombok.Data;  import javax.validation.constraints.NotNull;  @Data public class IDDTO {      @NotNull     private Long id; } 

@Slf4j @Controller @RequestMapping("/example") public class ExampleController {      @POSTMapping(value = "/valid")     public BaseResponseVO valid(@Valid IDDTO idDTO, BindingResult bindingResult){         if(bindingResult.hasErrors()){             log.error("what fuck");         }         return BaseResponseVO.success();     }  } 

看起来像不像会打印what fuck，实际上居然不会。实际上是因为Valid Property 会在json序列化构建Java Bean的时候，所以这里的Post请求还必须是application/json 即：

    @POSTMapping(value = "/valid")     public BaseResponseVO valid(@Valid @RequestBody IDDTO idDTO, BindingResult bindingResult){         if(bindingResult.hasErrors()){             log.error("what fuck");         }         return BaseResponseVO.success();     } 

如果有其他情况发现@Valid不生效，提供一个手动检查的方案

import org.apache.commons.collections.CollectionUtils;  import javax.validation.ConstraintViolation; import javax.validation.Validation; import javax.validation.Validator; import java.util.HashMap; import java.util.Map; import java.util.Set;  public class ValidateUtil {     private static Validator validator = Validation.buildDefaultValidatorFactory()             .getValidator();      public static void beanValidate(Object obj) {         Map<String, String> validatedMsg = new HashMap<>();         Set<ConstraintViolation<Object>> constraintViolations = validator.validate(obj);         for (ConstraintViolation<Object> c : constraintViolations) {             validatedMsg.put(c.getPropertyPath().toString(), c.getMessage());         }         if (CollectionUtils.isNotEmpty(constraintViolations)) {             throw new Exception(validatedMsg);         }      }  } 

即：

@Slf4j @Controller @RequestMapping("/example") public class ExampleController {      @POSTMapping(value = "/valid")     public BaseResponseVO valid(IDDTO idDTO){         ValidateUtil.beanValidate(idDTO);         return BaseResponseVO.success();     }  } 

笔者在开发过程中发现有如下一段日志，应该可以定位为什么@Valid不生效，笔者暂时比较忙，稍后再补充分析。如果有同学有兴趣，可以先自行分析。

2020-07-11 11:44:20,468 [main] DEBUG (OptionalValidatorFactoryBean:43) - Failed to set up a Bean Validation provider javax.validation.ValidationException: Unable to create a Configuration, because no Bean Validation provider could be found. Add a provider like Hibernate Validator (RI) to your classpath. 	at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:271) ~[validation-api-1.1.0.Final.jar:?] 	at org.springframework.validation.beanvalidation.LocalValidatorFactoryBean.afterPropertiesSet(LocalValidatorFactoryBean.java:255) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean.afterPropertiesSet(OptionalValidatorFactoryBean.java:40) [spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1692) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1630) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) [spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) [spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) [spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:668) [spring-webmvc-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:634) [spring-webmvc-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:682) [spring-webmvc-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:553) [spring-webmvc-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:494) [spring-webmvc-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:171) [spring-webmvc-4.3.17.RELEASE.jar:4.3.17.RELEASE] 	at javax.servlet.GenericServlet.init(GenericServlet.java:244) [javax.servlet-3.0.0.v201112011016.jar:?]