java 用于验证字段的@Size 注释

@Size annotation to validate a field

提问by Andy

I need to validate a field - secPhoneNumber (secondary phone #). I need to satisfy below conditions using JSR validation

我需要验证一个字段 - secPhoneNumber（辅助电话号码）。我需要使用 JSR 验证满足以下条件

• The field can be empty/null
• Otherwise, the data must be of length 10.

• 该字段可以为空/null
• 否则，数据长度必须为 10。

I tried the code below. The field is always getting validated on form submission. How do I validate the field to be of length 10 only when it is not empty?

我尝试了下面的代码。该字段总是在表单提交时得到验证。仅当字段不为空时，如何验证字段的长度为 10？

Spring Form:

弹簧形式：

<form:label path="secPhoneNumber">
Secondary phone number <form:errors path="secPhoneNumber" cssClass="error" />
</form:label>
<form:input path="secPhoneNumber" />

Bean

豆角，扁豆

@Size(max=10,min=10)
    private String secPhoneNumber;

回答by Andy

Following patterns work

以下模式有效

1. @Pattern(regexp="^(\s*|[a-zA-Z0-9]{10})$")
2. @Pattern(regexp="^(\s*|\d{10})$")

1. @Pattern(regexp="^(\s*|[a-zA-Z0-9]{10})$")
2. @Pattern(regexp="^(\s*|\d{10})$")

// ^             # Start of the line
// \s*           # A whitespace character, Zero or more times
// \d{10}        # A digit: [0-9], exactly 10 times
//[a-zA-Z0-9]{10}    # a-z,A-Z,0-9, exactly 10 times
// $             # End of the line

Reference: Validate only if the field is not Null

参考：仅当字段不为空时才验证

回答by cralfaro

I think for readability and to use in future times i would create my custom validation class, you only should follow this steps:

我认为为了可读性和将来使用我会创建我的自定义验证类，您只应该按照以下步骤操作：

1. Add your new custom annotation to your field

   @notEmptyMinSize(size=10)
   private String secPhoneNumber;
   

2. Create the custom validation classes

   @Documented
   @Constraint(validatedBy = notEmptyMinSize.class)
   @Target( { ElementType.METHOD, ElementType.FIELD })
   @Retention(RetentionPolicy.RUNTIME)
   public @interface notEmptyMinSize {
   
   
       int size() default 10;
   
       Class<?>[] groups() default {};
   
       Class<? extends Payload>[] payload() default {};
   
   }
   

3. Add your business logic to your validation

   public class NotEmptyConstraintValidator implements      ConstraintValidator<notEmptyMinSize, String> {
   
        private NotEmptyMinSize notEmptyMinSize;
   
        @Override
        public void initialize(notEmptyMinSize notEmptyMinSize) { 
            this.notEmptyMinSize = notEmptyMinSize
        }
   
        @Override
        public boolean isValid(String notEmptyField, ConstraintValidatorContext cxt) {
           if(notEmptyField == null) {
                return true;
           }
           return notEmptyField.length() == notEmptyMinSize.size();
       }
   
   }
   

1. 将您的新自定义注释添加到您的字段

   @notEmptyMinSize(size=10)
   private String secPhoneNumber;
   

2. 创建自定义验证类

   @Documented
   @Constraint(validatedBy = notEmptyMinSize.class)
   @Target( { ElementType.METHOD, ElementType.FIELD })
   @Retention(RetentionPolicy.RUNTIME)
   public @interface notEmptyMinSize {
   
   
       int size() default 10;
   
       Class<?>[] groups() default {};
   
       Class<? extends Payload>[] payload() default {};
   
   }
   

3. 将您的业务逻辑添加到您的验证中

   public class NotEmptyConstraintValidator implements      ConstraintValidator<notEmptyMinSize, String> {
   
        private NotEmptyMinSize notEmptyMinSize;
   
        @Override
        public void initialize(notEmptyMinSize notEmptyMinSize) { 
            this.notEmptyMinSize = notEmptyMinSize
        }
   
        @Override
        public boolean isValid(String notEmptyField, ConstraintValidatorContext cxt) {
           if(notEmptyField == null) {
                return true;
           }
           return notEmptyField.length() == notEmptyMinSize.size();
       }
   
   }
   

And now you could use this validation in several fields with different sizes.

现在您可以在多个不同大小的字段中使用此验证。

Here another example you can follow example

这里是另一个例子，你可以按照例子