org.springframework.format.annotation

## 注释类型 NumberFormat

-     @Documented
       @Retention(value=RUNTIME)
       @Target(value={METHOD,FIELD,PARAMETER,ANNOTATION_TYPE})
      public @interface NumberFormat

  Declares that a field or method parameter should be formatted as a number.

  Supports formatting by style or custom pattern string. Can be applied to any JDK `Number` type such as `Double` and `Long`.

  For style-based formatting, set the `style()` attribute to be the desired `NumberFormat.Style`. For custom formatting, set the `pattern()` attribute to be the number pattern, such as `#, ###.##`.

  Each attribute is mutually exclusive, so only set one attribute per annotation instance (the one most convenient one for your formatting needs). When the `pattern()` attribute is specified, it takes precedence over the `style()` attribute. When no annotation attributes are specified, the default format applied is style-based for either number of currency, depending on the annotated field or method parameter type.

  从以下版本开始:
    3.0
  作者:
    Keith Donald, Juergen Hoeller
  另请参阅:
    `NumberFormat`

- - ### 可选元素概要

    可选元素
    限定符和类型 | 可选元素和说明
    --- | ---
    `String` | `pattern` The custom pattern to use to format the field.
    `NumberFormat.Style` | `style` The style pattern to use to format the field.

- - ### 元素详细资料

    - #### style

          public abstract NumberFormat.Style style

      The style pattern to use to format the field.

      Defaults to `NumberFormat.Style.DEFAULT` for general-purpose number formatting for most annotated types, except for money types which default to currency formatting. Set this attribute when you wish to format your field in accordance with a common style other than the default style.

      默认值:
        org.springframework.format.annotation.NumberFormat.Style.DEFAULT

  - - #### pattern

          public abstract String pattern

      The custom pattern to use to format the field.

      Defaults to empty String, indicating no custom pattern String has been specified. Set this attribute when you wish to format your field in accordance with a custom number pattern not represented by a style.

      默认值:
        ""