Hibernate Validator 6 和 Bean Validation 2.0 需要 Java 8 或更高版本。

2.Hibernate Validator

2.1手动对参数进行校验

import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotEmpty;
import java.util.Iterator;
import java.util.Set;/*** @Author: wangxia* @Date: 2021/10/20 16:30*/
public class TestPerson {public static void main(String[] args) {ValidatorFactory factory = Validation.buildDefaultValidatorFactory();Validator validator = factory.getValidator();TestPerson testPerson = new TestPerson();testPerson.setAge(-5);Set<ConstraintViolation<TestPerson>> validate = validator.validate(testPerson);Iterator<ConstraintViolation<TestPerson>> iterator = validate.iterator();while (iterator.hasNext()) {ConstraintViolation<TestPerson> e=iterator.next();System.out.println(e.getMessage());}}@NotEmpty(message = "用户名不能为空")private String username;@Min(value = 0,message = "年龄不能小于0岁")@Max(value =150,message = "年龄不能大于150岁")private int age;public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}
}

校验结果:

虽然这样能够手动的获取校验结果但是每次想要校验都添加这段校验的代码还是很麻烦的，由此就衍生出里 @Validated,下面就讲下 @Validated是如何实现校验功能的。

3.@Validated生效原理

@Validated生效之所以能生效主要依赖于Spring的Aop和拦截器，在MethodValidationPostProcessor类中通过Aop和拦截器实现@Validated调用参数校验的目的。Aop的主要目的是每次遇到@Validated注解时都执行拦截器中的方法。

public class MethodValidationPostProcessor extends AbstractBeanFactoryAwareAdvisingPostProcessor implements InitializingBean {private Class<? extends Annotation> validatedAnnotationType = Validated.class;@Nullableprivate Validator validator;public MethodValidationPostProcessor() {}public void setValidatedAnnotationType(Class<? extends Annotation> validatedAnnotationType) {Assert.notNull(validatedAnnotationType, "'validatedAnnotationType' must not be null");this.validatedAnnotationType = validatedAnnotationType;}public void setValidator(Validator validator) {if (validator instanceof LocalValidatorFactoryBean) {this.validator = ((LocalValidatorFactoryBean)validator).getValidator();} else if (validator instanceof SpringValidatorAdapter) {this.validator = (Validator)validator.unwrap(Validator.class);} else {this.validator = validator;}}public void setValidatorFactory(ValidatorFactory validatorFactory) {this.validator = validatorFactory.getValidator();}//InitializingBean接口的方法，在类初始化时调用afterPropertiesSet方法public void afterPropertiesSet() {//针对@Validated注解创建切点Pointcut pointcut = new AnnotationMatchingPointcut(this.validatedAnnotationType, true);//整合切点到切面中，每次遇到@Validated切点就执行this.createMethodValidationAdvice(this.validator)方法this.advisor = new DefaultPointcutAdvisor(pointcut, this.createMethodValidationAdvice(this.validator));}protected Advice createMethodValidationAdvice(@Nullable Validator validator) {//创建拦截器return validator != null ? new MethodValidationInterceptor(validator) : new MethodValidationInterceptor();}
}

拦截器简介

参考文档：hibernate-validator

其实目前这个还不是太完善，会尽快把坑填上的。

java中优雅的参数校验方法_WX5991的博客-CSDN博客