@ConfigurationProperties 作用

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整合大量配置在 application.properties 或 application.yml 的参数。

 

@ConfigurationProperties 基本用法

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以 MybatisProperties 为例： 

首先，在 application.properties 或 application.yml 进行配置：

#mybatis的配置 mybatis: config-location: classpath:/mybatis/mybatis-config.xml mapper-locations: - classpath*:com/jeeplus/modules/**/*Mapper.xml - classpath:/META-INF/admin-mybatis-mappings/*.xml - classpath:/META-INF/modeler-mybatis-mappings/*.xml type-aliases-package: com.jeeplus.modules configuration-properties: prefix: boolValue: TRUE blobType: BLOB

接着，创建 MybatisProperties 类设置属性，提供注解 @ConfigurationProperties，设置注解属性 prefix 为配置的前缀。

@ConfigurationProperties(prefix = MybatisProperties.MYBATIS_PREFIX) public class MybatisProperties { public static final String MYBATIS_PREFIX = "mybatis"; private String configLocation; private String[] mapperLocations; private String typeAliasesPackage; private String typeHandlersPackage; ... }

做了这些仍然不够，如何让属性类真正被 Spring 发现并赋值呢？

1. @Component

@Component @ConfigurationProperties(prefix = "xxx") public class XxxProperties

2. @Configuration + @Bean

@Configuration public class XxxConfiguration { @Bean public YyyProperties yyyProperties { return new YyyProperties(); } }

3. @Configuration + @EnableConfigurationProperties

@org.springframework.context.annotation.Configuration @ConditionalOnClass({ SqlSessionFactory.class, SqlSessionFactoryBean.class }) @ConditionalOnBean(DataSource.class) @EnableConfigurationProperties(MybatisProperties.class) @AutoConfigureAfter(DataSourceAutoConfiguration.class) public class MybatisAutoConfiguration

由此可见，Mybatis 选择的就是第三种方式