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Spring ConfigurationMetaData

时间：2018/9/25 11:45:17

参考：

  1. Appendix B. Configuration Metadata

Spring 配置元数据#

简介#

通过 Json 定义配置参数对应的类。Json文件由三部分组成，配置信息实体类需要添加 @ConfigurationProperties 注解。（结合 @ConditionalOnProperty 使用效果更好）

  • groups: 定义一个分组， 如 server。
    • name: 分组的名称，必须有。
    • type：属性的类型，可以省略。
    • description：分组的描述，可以省略。
    • sourceType：提供配置类的名字，可以省略。
    • sourceMethod：方法的全名，可以省略。
  • properties: 定义分组下的字段的类型和默认值等信息。
    • name：属性名。
    • type：数据类型。
    • description：描述。
    • sourceType：类名。
    • defaultValue：默认值。
    • deprecation：不推荐使用。
  • hits: 指定字段的可选值。
    • name：属性名。
    • values:可选值列表。
    • providers: 属性值来源。

Json定义： 

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{
  "groups": [
    {
      "name": "server",
      "type": "org.springframework.boot.autoconfigure.web.ServerProperties",
      "sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties"
    },
    {
      "name": "spring.jpa.hibernate",
      "type": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties$Hibernate",
      "sourceType": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties",
      "sourceMethod": "getHibernate()"
    }
    ...
  ],
  "properties": [
    {
      "name": "server.port",
      "type": "java.lang.Integer",
      "sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties"
    },
    {
      "name": "server.servlet.path",
      "type": "java.lang.String",
      "sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties",
      "defaultValue": "/"
    },
    {
      "name": "spring.jpa.hibernate.ddl-auto",
      "type": "java.lang.String",
      "description": "DDL mode. This is actually a shortcut for the \"hibernate.hbm2ddl.auto\" property.",
      "sourceType": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties$Hibernate"
    }
    ...
  ],
  "hints": [
    {
      "name": "spring.jpa.hibernate.ddl-auto",
      "values": [
        {
          "value": "none",
          "description": "Disable DDL handling."
        },
        {
          "value": "validate",
          "description": "Validate the schema, make no changes to the database."
        },
        {
          "value": "update",
          "description": "Update the schema if necessary."
        },
        {
          "value": "create",
          "description": "Create the schema and destroy previous data."
        },
        {
          "value": "create-drop",
          "description": "Create and then destroy the schema at the end of the session."
        }
      ]
    }
  ]
}

具体类：

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@ConfigurationProperties(prefix = "server", ignoreUnknownFields = true)
public class ServerProperties {

    private Integer port;

    public void setPort(Integer port) {
        this.port = port;
    }
}

其它#

@ConfigurationProperties 源码：

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@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ConfigurationProperties {

    /**
     * The name prefix of the properties that are valid to bind to this object. Synonym
     * for {@link #prefix()}.
     * @return the name prefix of the properties to bind
     */
    @AliasFor("prefix")
    String value() default "";

    /**
     * The name prefix of the properties that are valid to bind to this object. Synonym
     * for {@link #value()}.
     * @return the name prefix of the properties to bind
     */
    @AliasFor("value")
    String prefix() default "";

    /**
     * Flag to indicate that when binding to this object invalid fields should be ignored.
     * Invalid means invalid according to the binder that is used, and usually this means
     * fields of the wrong type (or that cannot be coerced into the correct type).
     * @return the flag value (default false)
     */
    boolean ignoreInvalidFields() default false;

    /**
     * Flag to indicate that when binding to this object unknown fields should be ignored.
     * An unknown field could be a sign of a mistake in the Properties.
     * @return the flag value (default true)
     */
    boolean ignoreUnknownFields() default true;

}