一、基本使用

1. 创建配置对象
   对象上标注@ConfigurationProperties注解

@ConfigurationProperties(prefix = "spring.datasource")
public class DataSourceProperties implements 
BeanClassLoaderAware, InitializingBean {
private String driverClassName;
     /**
      * JDBC URL of the database.
      */
     private String url;
     /**
      * Login username of the database.
      */
     private String username;
     /**
      * Login password of the database.
      */
     private String password;

}

2. 使用配置对象

• 标注@EnableConfigurationProperties(配置对象类.class)
• 一般用在@Configuration标注的类上

@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(DataSourceProperties.class)
public class EmbeddedDataSourceConfiguration implements BeanClassLoaderAware {

	@Bean(destroyMethod = "shutdown")
	public EmbeddedDatabase dataSource(DataSourceProperties properties) {
		return new EmbeddedDatabaseBuilder().setType(EmbeddedDatabaseConnection.get(this.classLoader).getType())
				.setName(properties.determineDatabaseName()).build();
	}

}

二、关键对象

• ConfigurationPropertiesBindingPostProcessor：实现了BeanPostProcessor
  拦截@ConfigurationProperties标注bean的创建过程，注入值。
• EnableConfigurationPropertiesRegistrar：将ConfigurationPropertiesBindingPostProcessor放入容器；将value属性值（标注@ConfigurationProperties的bean class）放入容器

三、实现流程

1. ConfigurationPropertiesBindingPostProcessor类被加载和解析

2. 拦截@ConfigurationProperties标注bean的创建过程，注入值