springboot validation 自定义验证注解

Love The Way You Lie 2023-02-26 07:24 2阅读 0赞

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### springboot validation 自定义验证注解 ###

**应用：自定义注解对pojo进行检验**

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**相关类与接口**

**ConstraintValidator：自定义注解对应验证规则**

public interface ConstraintValidator<A extends Annotation, T> {
        default void initialize(A constraintAnnotation) {
        }
    
        boolean isValid(T var1, ConstraintValidatorContext var2);
    }

**第一个参数A表示验证注解，第二个参数T表示注解标注的对象**

**@Length**

@Documented
    @Constraint(
        validatedBy = {}
    )
    @Target({ElementType.METHOD, ElementType.FIELD, ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR, ElementType.PARAMETER, ElementType.TYPE_USE})
    @Retention(RetentionPolicy.RUNTIME)
    @Repeatable(Length.List.class)
    public @interface Length {
        int min() default 0;
    
        int max() default 2147483647;
    
        String message() default "{org.hibernate.validator.constraints.Length.message}";
    
        Class<?>[] groups() default {};
    
        Class<? extends Payload>[] payload() default {};
    
        @Target({ElementType.METHOD, ElementType.FIELD, ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR, ElementType.PARAMETER, ElementType.TYPE_USE})
        @Retention(RetentionPolicy.RUNTIME)
        @Documented
        public @interface List {
            Length[] value();
        }
    }

**LengthValidator：长度验证器**

public class LengthValidator implements ConstraintValidator<Length, CharSequence> {
        private static final Log LOG = LoggerFactory.make(MethodHandles.lookup());
        private int min;
        private int max;
    
        public LengthValidator() {
        }
    
        public void initialize(Length parameters) {
            this.min = parameters.min();
            this.max = parameters.max();
            this.validateParameters();
        }
    
        public boolean isValid(CharSequence value, ConstraintValidatorContext constraintValidatorContext) {
            if (value == null) {
                return true;
            } else {
                int length = value.length();
                return length >= this.min && length <= this.max;
            }
        }
    
        private void validateParameters() {
            if (this.min < 0) {
                throw LOG.getMinCannotBeNegativeException();
            } else if (this.max < 0) {
                throw LOG.getMaxCannotBeNegativeException();
            } else if (this.max < this.min) {
                throw LOG.getLengthCannotBeNegativeException();
            }
        }
    }

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**示例：定义类验证注解，检验price\*amount、totalFee的差值**

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**validation 层**

**@CheckNum**

@Documented
    @Retention(RetentionPolicy.RUNTIME)
    @Constraint(validatedBy = {CustomValidator.class})
    @Target({ElementType.TYPE,ElementType.ANNOTATION_TYPE})
    public @interface CheckNum {
    
        String field();
        String field2();
        String field3();
    
        String message() default "{org.hibernate.validator.constraints.Length.message}";
        Class<?>[] groups() default {};
        Class<? extends Payload>[] payload() default {};
    }

**CustomValidator**

public class CustomValidator implements ConstraintValidator<CheckNum, Object> {
    
        private String field;
        private String field2;
        private String field3;
    
        @Override
        public void initialize(CheckNum constraintAnnotation) {
            this.field=constraintAnnotation.field();
            this.field2=constraintAnnotation.field2();
            this.field3=constraintAnnotation.field3();
        }
    
        @Override
        public boolean isValid(Object o, ConstraintValidatorContext constraintValidatorContext) {
            BeanWrapper beanWrapper=new BeanWrapperImpl(o);
            Double price=Double.parseDouble(Objects.requireNonNull(Objects.requireNonNull(beanWrapper.getPropertyValue(field)).toString()));
            Integer amount=Integer.parseInt(Objects.requireNonNull(Objects.requireNonNull(beanWrapper.getPropertyValue(field2)).toString()));
            double totalFee=Double.parseDouble(Objects.requireNonNull(Objects.requireNonNull(beanWrapper.getPropertyValue(field3)).toString()));
    
            return Math.abs(totalFee-price*amount)<0.01;
        }
    }

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**pojo 层**

**Order**

@Data
    @CheckNum(field = "price",field2 = "amount",field3 = "totalFee",message = "totalFee 与 price*amount数值相差超过0.01")
    public class Order {
    
        private Double price;
        private Integer amount;
        private Double totalFee;
    }

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**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @RequestMapping("/hello")
        public String hello(@Validated Order order, BindingResult result){
            System.out.println(order);
    
            if (result.hasErrors()){
                result.getAllErrors().forEach(error -> {
                    System.out.print("field："+error.getObjectName());
                    System.out.println(" ==> message："+error.getDefaultMessage());
                });
            }
    
            return "success";
        }
    }

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**使用测试**

**localhost:8080/hello?price=2&amount=8&totalFee=8**

2020-07-15 11:53:21.378  INFO 340 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
    2020-07-15 11:53:21.382  INFO 340 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : Completed initialization in 4 ms
    Order(price=2.0, amount=8, totalFee=8.0)
    field：order ==> message：totalFee 与 price*amount数值相差超过0.01