问题描述
项目中使用Springboot，在Controller中配置了@NotNull和@Valid，@Notnull不生效，@Valid生效，返回http status为400。
1 2 3 4 5 6 7 8 9 10 11 | @RestController@RequestMapping("/demo")public class DemoController { @Override @PostMapping("/user") public CreateUserRsp createUser( @NotNull @Size(min = 1, max = 64) @RequestHeader(value = "token") String token, @NotNull @Valid @RequestBody CreateUserReq createUserReq) { // 业务逻辑 }} |
原因分析
controller接收到请求，首先会进行参数解析，解析相关的类：
为什么@RequestBody中的@Valid生效了？
参数中@RequestBody注解是使用RequestResponseBodyMethodProcessor解析的，下面重点看下这个。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer, NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception { parameter = parameter.nestedIfOptional(); Object arg = this.readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType()); String name = Conventions.getVariableNameForParameter(parameter); if (binderFactory != null) { WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name); if (arg != null) { // 重点 this.validateIfApplicable(binder, parameter); if (binder.getBindingResult().hasErrors() && this.isBindExceptionRequired(binder, parameter)) { throw new MethodArgumentNotValidException(parameter, binder.getBindingResult()); } } if (mavContainer != null) { mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult()); } } return this.adaptArgumentIfNecessary(arg, parameter);} |
1 2 3 4 5 6 | protected void validateIfApplicable(WebDataBinder binder, MethodParameter parameter) { Annotation[] annotations = parameter.getParameterAnnotations(); Annotation[] var4 = annotations; int var5 = annotations.length; for(int var6 = 0; var6 |
可以看出，@Valid和@Validated注解都可以解析到：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | public static Object[] determineValidationHints(Annotation ann) { if (ann instanceof Validated) { return ((Validated)ann).value(); } else { Class extends Annotation> annotationType = ann.annotationType(); if ("javax.validation.Valid".equals(annotationType.getName())) { return EMPTY_OBJECT_ARRAY; } else { Validated validatedAnn = (Validated)AnnotationUtils.getAnnotation(ann, Validated.class); if (validatedAnn != null) { return validatedAnn.value(); } else { return annotationType.getSimpleName().startsWith("Valid") ? convertValidationHints(AnnotationUtils.getValue(ann)) : null; } } }} |
为什么@RequestHeader中的@NotNull没有生效？
按照上面的思路，我们看下RequestHeaderMapMethodArgumentResolver，里面并没有调用validate相关的代码。
怎么样才能生效？
在类上加@Validated。并且加maven依赖
1 | org.springframework.bootspring-boot-starter-validation |
@Validated生效原理
后处理器MethodValidationPostProcessor中给使用了@Validated注解的类创建了个切面。实际执行切面逻辑的是MethodValidationInterceptor
1 2 3 4 5 6 7 8 9 10 11 | public class MethodValidationPostProcessor extends AbstractBeanFactoryAwareAdvisingPostProcessor implements InitializingBean { private Class extends Annotation> validatedAnnotationType = Validated.class; public void afterPropertiesSet() { Pointcut pointcut = new AnnotationMatchingPointcut(this.validatedAnnotationType, true); this.advisor = new DefaultPointcutAdvisor(pointcut, this.createMethodValidationAdvice(this.validator)); } protected Advice createMethodValidationAdvice(@Nullable Validator validator) { return validator != null ? new MethodValidationInterceptor(validator) : new MethodValidationInterceptor(); }} |
请求执行时，MethodValidationInterceptor中先判断方法和类上有没有@Validated，
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 | public Object invoke(MethodInvocation invocation) throws Throwable { if (this.isFactoryBeanMetadataMethod(invocation.getMethod())) { return invocation.proceed(); } else { // 方法和类上有没有@Validated Class>[] groups = this.determineValidationGroups(invocation); ExecutableValidator execVal = this.validator.forExecutables(); Method methodToValidate = invocation.getMethod(); Object target = invocation.getThis(); Assert.state(target != null, "Target must not be null"); Set result; try { // 校验 result = execVal.validateParameters(target, methodToValidate, invocation.getArguments(), groups); } catch (IllegalArgumentException var8) { methodToValidate = BridgeMethodResolver.findBridgedMethod(ClassUtils.getMostSpecificMethod(invocation.getMethod(), target.getClass())); result = execVal.validateParameters(target, methodToValidate, invocation.getArguments(), groups); } if (!result.isEmpty()) { // 校验失败的异常 throw new ConstraintViolationException(result); } else { Object returnValue = invocation.proceed(); result = execVal.validateReturnValue(target, methodToValidate, returnValue, groups); if (!result.isEmpty()) { throw new ConstraintViolationException(result); } else { return returnValue; } } }} |
实际校验的类是ValidatorImpl。代码一直跟下去，能找到最终执行校验的地方。—注意，ValidatorImpl已经是hibernate-validator提供的了。
1 2 3 4 5 6 7 8 9 10 11 12 | private void validateMetaConstraints(BaseBeanValidationContext> validationContext, ValueContext, Object> valueContext, Object parent, Iterable> constraints) { Iterator var5 = constraints.iterator(); while(var5.hasNext()) { MetaConstraint> metaConstraint = (MetaConstraint)var5.next(); this.validateMetaConstraint(validationContext, valueContext, parent, metaConstraint); if (this.shouldFailFast(validationContext)) { break; } }} |
总结
controller中requestBody中直接可以用@Valid或@Validated校验，如果想校验方法中单个参数，需要在方法或类上加@Validated，这样会开启方法校验的切面，切面中会拿到方法签名中每个字段的注解然后进行校验。
以上就是Spring controller校验入参的方法详解的详细内容，更多关于Spring controller校验入参的资料请关注IT俱乐部其它相关文章！
