Spring Validation参数校验没那么简单，原理深度剖析！
本文会详细介绍 Spring Validation 各种场景下的最佳实践及其实现原理，死磕到底！
且看Spring Validation参数校验没那么简单，原理深度剖析！
简单使用
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<dependency> <groupId>org.hibernategroupId> <artifactId>hibernate-validatorartifactId> <version>6.0.1.Finalversion> dependency>requestBody 参数校验
public class UserDTO { private Long userId; private String userName; private String account; private String password;} public Result saveUser( UserDTO userDTO) { // 校验通过，才会执行业务逻辑处理 return Result.ok(); }requestParam/PathVariable 参数校验 class UserController { // 路径变量 @GetMapping("{userId}") public Result detail(@PathVariable("userId") @Min(10000000000000000L) Long userId) { // 校验通过，才会执行业务逻辑处理 UserDTO userDTO = new UserDTO(); userDTO.setUserId(userId); userDTO.setAccount("11111111111111111"); userDTO.setUserName("xixi"); userDTO.setAccount("11111111111111111"); return Result.ok(userDTO); } // 查询参数 @GetMapping("getByAccount") public Result getByAccount(@Length(min = 6, max = 20) @NotNull String account) { // 校验通过，才会执行业务逻辑处理 UserDTO userDTO = new UserDTO(); userDTO.setUserId(10000000000000003L); userDTO.setAccount(account); userDTO.setUserName("xixi"); userDTO.setAccount("11111111111111111"); return Result.ok(userDTO); }}public class CommonExceptionHandler { public Result handleMethodArgumentNotValidException(MethodArgumentNotValidException ex) { BindingResult bindingResult = ex.getBindingResult(); StringBuilder sb = new StringBuilder("校验失败:"); for (FieldError fieldError : bindingResult.getFieldErrors()) { sb.append(fieldError.getField()).append("：").append(fieldError.getDefaultMessage()).append(", "); } String msg = sb.toString(); return Result.fail(BusinessCode.参数校验失败, msg); } public Result handleConstraintViolationException(ConstraintViolationException ex) { return Result.fail(BusinessCode.参数校验失败, ex.getMessage()); }}进阶使用 分组效验
@Datapublic class UserDTO { @Min(value = 10000000000000000L, groups = Update.class) private Long userId; @NotNull(groups = {Save.class, Update.class}) @Length(min = 2, max = 10, groups = {Save.class, Update.class}) private String userName; @NotNull(groups = {Save.class, Update.class}) @Length(min = 6, max = 20, groups = {Save.class, Update.class}) private String account; @NotNull(groups = {Save.class, Update.class}) @Length(min = 6, max = 20, groups = {Save.class, Update.class}) private String password; /** * 保存的时候校验分组 */ public interface Save { } /** * 更新的时候校验分组 */ public interface Update { }}public Result saveUser( UserDTO userDTO) { // 校验通过，才会执行业务逻辑处理 return Result.ok();}
public Result updateUser( UserDTO userDTO) { // 校验通过，才会执行业务逻辑处理 return Result.ok();}嵌套校验
@Datapublic class UserDTO { @Min(value = 10000000000000000L, groups = Update.class) private Long userId; @NotNull(groups = {Save.class, Update.class}) @Length(min = 2, max = 10, groups = {Save.class, Update.class}) private String userName; @NotNull(groups = {Save.class, Update.class}) @Length(min = 6, max = 20, groups = {Save.class, Update.class}) private String account; @NotNull(groups = {Save.class, Update.class}) @Length(min = 6, max = 20, groups = {Save.class, Update.class}) private String password;
@NotNull(groups = {Save.class, Update.class}) @Valid private Job job;
@Data public static class Job {
@Min(value = 1, groups = Update.class) private Long jobId;
@NotNull(groups = {Save.class, Update.class}) @Length(min = 2, max = 10, groups = {Save.class, Update.class}) private String jobName;
@NotNull(groups = {Save.class, Update.class}) @Length(min = 2, max = 10, groups = {Save.class, Update.class}) private String position; }
/** * 保存的时候校验分组 */ public interface Save { }
/** * 更新的时候校验分组 */ public interface Update { }}public class ValidationList<E> implements List<E> {
// @Delegate是lombok注解 // 一定要加@Valid注解 public List list = new ArrayList<>();
// 一定要记得重写toString方法 public String toString() { return list.toString(); }}public Result saveList( ValidationList userList) { // 校验通过，才会执行业务逻辑处理 return Result.ok();}public EncryptId {
// 默认错误消息 String message() default "加密id格式错误";
// 分组 Class[] groups() default {};
// 负载 Class[] payload() default {};}public class EncryptIdValidator implements ConstraintValidator<EncryptId, String> {
private static final Pattern PATTERN = Pattern.compile("^[a-f\\d]{32,256}$");
public boolean isValid(String value, ConstraintValidatorContext context) { // 不为null才进行校验 if (value != null) { Matcher matcher = PATTERN.matcher(value); return matcher.find(); } return true; }}编程式校验
private javax.validation.Validator globalValidator;
// 编程式校验public Result saveWithCodingValidate( UserDTO userDTO) { Set<constraintviolation> validate = globalValidator.validate(userDTO, UserDTO.Save.class); // 如果校验通过，validate为空；否则，validate包含未校验通过项 if (validate.isEmpty()) { // 校验通过，才会执行业务逻辑处理
} else { for (ConstraintViolation userDTOConstraintViolation : validate) { // 校验失败，做其它逻辑 System.out.println(userDTOConstraintViolation); } } return Result.ok();}快速失败(Fail Fast)
public Validator validator() { ValidatorFactory validatorFactory = Validation.byProvider(HibernateValidator.class) .configure() // 快速失败模式 .failFast(true) .buildValidatorFactory(); return validatorFactory.getValidator();}@Valid 和 @Validated 区别
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实现原理
requestBody参数校验实现原理
public class RequestResponseBodyMethodProcessor extends AbstractMessageConverterMethodProcessor { public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception { parameter = parameter.nestedIfOptional(); //将请求数据封装到DTO对象中 Object arg = readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType()); String name = Conventions.getVariableNameForParameter(parameter); if (binderFactory != null) { WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name); if (arg != null) { // 执行数据校验 validateIfApplicable(binder, parameter); if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) { throw new MethodArgumentNotValidException(parameter, binder.getBindingResult()); } } if (mavContainer != null) { mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult()); } } return adaptArgumentIfNecessary(arg, parameter); }}protected void validateIfApplicable(WebDataBinder binder, MethodParameter parameter) { // 获取参数注解，比如@RequestBody、@Valid、@Validated Annotation[] annotations = parameter.getParameterAnnotations(); for (Annotation ann : annotations) { // 先尝试获取@Validated注解 Validated validatedAnn = AnnotationUtils.getAnnotation(ann, Validated.class); //如果直接标注了@Validated，那么直接开启校验。 //如果没有，那么判断参数前是否有Valid起头的注解。 if (validatedAnn != null || ann.annotationType().getSimpleName().startsWith("Valid")) { Object hints = (validatedAnn != null ? validatedAnn.value() : AnnotationUtils.getValue(ann)); Object[] validationHints = (hints instanceof Object[] ?(Object[]) hints : new Object[] {hints}); //执行校验 binder.validate(validationHints); break; } }}public void validate(Object target, Errors errors, Object... validationHints) { if (this.targetValidator != null) { processConstraintViolations( //此处调用Hibernate Validator执行真正的校验 this.targetValidator.validate(target, asValidationGroups(validationHints)), errors); }}方法级别的参数校验实现原理
public class MethodValidationPostProcessor extends AbstractBeanFactoryAwareAdvisingPostProcessorimplements InitializingBean { public void afterPropertiesSet() { //为所有`@Validated`标注的Bean创建切面 Pointcut pointcut = new AnnotationMatchingPointcut(this.validatedAnnotationType, true); //创建Advisor进行增强 this.advisor = new DefaultPointcutAdvisor(pointcut, createMethodValidationAdvice(this.validator)); } //创建Advice，本质就是一个方法拦截器 protected Advice createMethodValidationAdvice(@Nullable Validator validator) { return (validator != null ? new MethodValidationInterceptor(validator) : new MethodValidationInterceptor()); }}public class MethodValidationInterceptor implements MethodInterceptor { public Object invoke(MethodInvocation invocation) throws Throwable { //无需增强的方法，直接跳过 if (isFactoryBeanMetadataMethod(invocation.getMethod())) { return invocation.proceed(); } //获取分组信息 Class[] groups = determineValidationGroups(invocation); ExecutableValidator execVal = this.validator.forExecutables(); Method methodToValidate = invocation.getMethod(); Set<constraintviolation> result; try { //方法入参校验，最终还是委托给Hibernate Validator来校验 result = execVal.validateParameters( invocation.getThis(), methodToValidate, invocation.getArguments(), groups); } catch (IllegalArgumentException ex) { ... } //有异常直接抛出 if (!result.isEmpty()) { throw new ConstraintViolationException(result); } //真正的方法调用 Object returnValue = invocation.proceed(); //对返回值做校验，最终还是委托给Hibernate Validator来校验 result = execVal.validateReturnValue(invocation.getThis(), methodToValidate, returnValue, groups); //有异常直接抛出 if (!result.isEmpty()) { throw new ConstraintViolationException(result); } return returnValue; }}下是我们校区的地址和联系方式：
北大青鸟贵州大数据学院白云校区
贵阳市白云区白云南路895号
北大青鸟高新大学生实训校区
贵阳市观山湖区长岭南路33号国家大数据（贵州）综合试验区四楼
