- @NotEmpty :用于集合类,不能为null,且size>0
- @NotNull:不能为null,但可以为empty,没有size的约束
- @NotBlank:只用于String,不能为null,且trim()之后size>0
@NotEmpty
/** * Asserts that the annotated string, collection, map or array is not {@code null} or empty. * * @author Emmanuel Bernard * @author Hardy Ferentschik */
@NotNull
/** * The annotated element must not be {@code null}. * Accepts any type. * * @author Emmanuel Bernard */
@NotBlank
/** * Validate that the annotated string is not {@code null} or empty. * The difference to {@code NotEmpty} is that trailing whitespaces are getting ignored. * * @author Hardy Ferentschik */
和{@code NotEmpty}不同的是,尾部空格被忽略,也就是说,纯空格的String也是不符合规则的。所以才会说@NotBlank用于String。
3. 示例:1.String name = null; @NotNull: false @NotEmpty:false @NotBlank:false
2.String name = ""; @NotNull:true @NotEmpty: false @NotBlank: false
3.String name = " "; @NotNull: true @NotEmpty: true @NotBlank: false
4.String name = "Great answer!"; @NotNull: true @NotEmpty:true @NotBlank:true