org.springframework.util

## 类 SystemPropertyUtils

- java.lang.Object
- - org.springframework.util.SystemPropertyUtils

-     public abstract class SystemPropertyUtils
      extends Object

  Helper class for resolving placeholders in texts. Usually applied to file paths.

  A text may contain `${...}` placeholders, to be resolved as system properties: e.g. `${user.dir}`. Default values can be supplied using the ":" separator between key and value.

  从以下版本开始:
    1.2.5
  作者:
    Juergen Hoeller, Rob Harrop, Dave Syer
  另请参阅:
    `PLACEHOLDER_PREFIX`, `PLACEHOLDER_SUFFIX`, `System.getProperty(String)`

- - ### 字段概要

    字段
    限定符和类型 | 字段和说明
    --- | ---
    `static String` | `PLACEHOLDER_PREFIX` Prefix for system property placeholders: "${"
    `static String` | `PLACEHOLDER_SUFFIX` Suffix for system property placeholders: "}"
    `static String` | `VALUE_SEPARATOR` Value separator for system property placeholders: ":"

  - ### 构造器概要

    构造器
    构造器和说明
    `SystemPropertyUtils()`

  - ### 方法概要

    所有方法 静态方法 具体方法
    限定符和类型 | 方法和说明
    --- | ---
    `static String` | `resolvePlaceholders(String text)` Resolve `${...}` placeholders in the given text, replacing them with corresponding system property values.
    `static String` | `resolvePlaceholders(String text, boolean ignoreUnresolvablePlaceholders)` Resolve `${...}` placeholders in the given text, replacing them with corresponding system property values.

    - ### 从类继承的方法 java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### 字段详细资料

    - #### PLACEHOLDER_PREFIX

          public static final String PLACEHOLDER_PREFIX

      Prefix for system property placeholders: "${"
      另请参阅:
        常量字段值

    - #### PLACEHOLDER_SUFFIX

          public static final String PLACEHOLDER_SUFFIX

      Suffix for system property placeholders: "}"
      另请参阅:
        常量字段值

    - #### VALUE_SEPARATOR

          public static final String VALUE_SEPARATOR

      Value separator for system property placeholders: ":"
      另请参阅:
        常量字段值

  - ### 构造器详细资料

    - #### SystemPropertyUtils

          public SystemPropertyUtils()

  - ### 方法详细资料

    - #### resolvePlaceholders

          public static String resolvePlaceholders(String text)

      Resolve `${...}` placeholders in the given text, replacing them with corresponding system property values.
      参数:
        `text` - the String to resolve
      返回:
        the resolved String
      抛出:
        `IllegalArgumentException` - if there is an unresolvable placeholder
      另请参阅:
        `PLACEHOLDER_PREFIX`, `PLACEHOLDER_SUFFIX`

    - #### resolvePlaceholders

          public static String resolvePlaceholders(String text,
                                                   boolean ignoreUnresolvablePlaceholders)

      Resolve `${...}` placeholders in the given text, replacing them with corresponding system property values. Unresolvable placeholders with no default value are ignored and passed through unchanged if the flag is set to `true`.
      参数:
        `text` - the String to resolve
        `ignoreUnresolvablePlaceholders` - whether unresolved placeholders are to be ignored
      返回:
        the resolved String
      抛出:
        `IllegalArgumentException` - if there is an unresolvable placeholder and the "ignoreUnresolvablePlaceholders" flag is `false`
      另请参阅:
        `PLACEHOLDER_PREFIX`, `PLACEHOLDER_SUFFIX`