校验类注解的区别 @NotNull、@NotEmpty、@NotBlank
使用场景
- @NotEmpty用在集合类
- @NotBlank 用在String
- @NotNull 用在基本类型
注解的探究
@NotEmpty
/**
* The annotated element must not be {@code null} nor empty.
* <p>
* Supported types are:
* <ul>
* <li>{@code CharSequence} (length of character sequence is evaluated)</li>
* <li>{@code Collection} (collection size is evaluated)</li>
* <li>{@code Map} (map size is evaluated)</li>
* <li>Array (array length is evaluated)</li>
* </ul>
*
* @author Emmanuel Bernard
* @author Hardy Ferentschik
*
* @since 2.0
*/
@Documented
@Constraint(validatedBy = { })
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
public @interface NotEmpty {
String message() default "{javax.validation.constraints.NotEmpty.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@code @NotEmpty} constraints on the same element.
*
* @see NotEmpty
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
public @interface List {
NotEmpty[] value();
}
}
@NotEmpty的String类、Collection、Map、数组，是不能为null并且长度必须大于0的（String、Collection、Map的isEmpty()方法）。
@NotBlank
/**
* The annotated element must not be {@code null} and must contain at least one
* non-whitespace character. Accepts {@code CharSequence}.
*
* @author Hardy Ferentschik
* @since 2.0
*
* @see Character#isWhitespace(char)
*/
@Documented
@Constraint(validatedBy = { })
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
public @interface NotBlank {
String message() default "{javax.validation.constraints.NotBlank.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@code @NotBlank} constraints on the same element.
*
* @see NotBlank
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
public @interface List {
NotBlank[] value();
}
}
@NotBlank用于String，只能作用在String上，不能为null，而且调用trim()后，长度必须大于0。
@NotNull
/**
* The annotated element must not be {@code null}.
* Accepts any type.
*
* @author Emmanuel Bernard
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Repeatable(List.class)
@Documented
@Constraint(validatedBy = { })
public @interface NotNull {
String message() default "{javax.validation.constraints.NotNull.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
/**
* Defines several {@link NotNull} annotations on the same element.
*
* @see javax.validation.constraints.NotNull
*/
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@interface List {
NotNull[] value();
}
}
接受任何类型，要求非空
常用注解示例
String
@NotBlank(message = "姓名不能为空！")
@Length(min = 2, max = 10, message = "姓名的长度只能在{min}到{max}之间！")
@Pattern(regexp = "^(((13[0-9])|(14[579])|(15([0-3]|[5-9]))|(16[6])|(17[0135678])|(18[0-9])|(19[89]))\\d{8})$", message = "手机号格式不正确")
CLC
