import javax.validation.Constraint;import javax.validation.Payload;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target({ElementType.METHOD, ElementType.FIELD, ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR, ElementType.PARAMETER})@Retention(RetentionPolicy.RUNTIME)@Constraint(validatedBy = MyValidatorClass.class)public @interface MyValidator {    String message();    Class
      [] groups() default {};    Class
      [] payload() default {};}

import javax.validation.ConstraintValidator;import javax.validation.ConstraintValidatorContext;/** * MyValidator，自定义注解 * String 标注在String类型的字段上，传过来的值是String类型 */public class MyValidatorClass implements ConstraintValidator
      
        {    /**     * 初始化注解时执行的     * @param myValidator     */    @Override    public void initialize(MyValidator myValidator) {    }    /**     * 真正的校验逻辑     * @param o     * @param constraintValidatorContext     * @return     */    @Override    public boolean isValid(String o, ConstraintValidatorContext constraintValidatorContext) {        return false;    }}