@ConfigurationProperties 放在类上和方法上两种应用

@ConfigurationProperties作用首先看一下源码中的解释：* Annotation for externalized configuration. Add this to a class definition or a* {@code @Bean} method in a {@code @Configuration} class if you want to bin...

一首简单的歌-shining

3119人浏览 · 2022-04-10 11:29:00

一首简单的歌-shining · 2022-04-10 11:29:00 发布

@ConfigurationProperties作用

首先看一下源码中的解释：

 * Annotation for externalized configuration. Add this to a class definition or a
 * {@code @Bean} method in a {@code @Configuration} class if you want to bind and validate
 * some external Properties (e.g. from a .properties file).

翻译一下：这是一个(连接)外部配置的注解。我们可以将此注解放在类上，或者放在有@Configuraion注解的类中的方法上(并且方法需要有@Bean注解)，这样就可以绑定外部配置文件(比如.properties或者.yml)的一些属性。

简单来讲，使用此注解可以方便的关联我们在.properties或者.yml中配置的属性。下面应用场景举例：

一、注解放在类上

@Component
@ConfigurationProperties(prefix = "ruoyi")
public class RuoYiConfig
{
    /** 项目名称 */
    private String name;

    /** 版本 */
    private String version;

    /** 版权年份 */
    private String copyrightYear;

    /** 实例演示开关 */
    private boolean demoEnabled;

    /** 上传路径 */
    private static String profile;

    /** 获取地址开关 */
    private static boolean addressEnabled;
...
}

对应的.yml配置文件内容如下：

# 项目相关配置
ruoyi:
  # 名称
  name: RuoYi
  # 版本
  version: 2.2.0
  # 版权年份
  copyrightYear: 2019
  # 实例演示开关
  demoEnabled: true
  # 文件路径 示例( Windows配置D:/ruoyi/uploadPath，Linux配置 /home/ruoyi/uploadPath)
  profile: D:/ruoyi/uploadPath
  # 获取ip地址开关
  addressEnabled: true

二、注解放在方法上(并且方法有@Bean注解，且类上有@Configuration注解)

@Configuration
public class DruidConfig
{
    @Bean
    @ConfigurationProperties("spring.datasource.druid.master")
    public DataSource masterDataSource(DruidProperties druidProperties)
    {
        DruidDataSource dataSource = DruidDataSourceBuilder.create().build();
        return druidProperties.dataSource(dataSource);
    }

    @Bean
    @ConfigurationProperties("spring.datasource.druid.slave")
    @ConditionalOnProperty(prefix = "spring.datasource.druid.slave", name = "enabled", havingValue = "true")
    public DataSource slaveDataSource(DruidProperties druidProperties)
    {
        DruidDataSource dataSource = DruidDataSourceBuilder.create().build();
        return druidProperties.dataSource(dataSource);
    }

    @Bean(name = "dynamicDataSource")
    @Primary
    public DynamicDataSource dataSource(DataSource masterDataSource)
    {
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put(DataSourceType.MASTER.name(), masterDataSource);
        setDataSource(targetDataSources, DataSourceType.SLAVE.name(), "slaveDataSource");
        return new DynamicDataSource(masterDataSource, targetDataSources);
    }
    
    /**
     * 设置数据源
     * 
     * @param targetDataSources 备选数据源集合
     * @param sourceName 数据源名称
     * @param beanName bean名称
     */
    public void setDataSource(Map<Object, Object> targetDataSources, String sourceName, String beanName)
    {
        try
        {
            DataSource dataSource = SpringUtils.getBean(beanName);
            targetDataSources.put(sourceName, dataSource);
        }
        catch (Exception e)
        {
        }
    }

}

相应的@Bean注解注入的类为：

public class DruidDataSource extends DruidAbstractDataSource implements DruidDataSourceMBean, ManagedDataSource, Referenceable, Closeable, Cloneable, ConnectionPoolDataSource, MBeanRegistration {

父类中有如下属性：

public abstract class DruidAbstractDataSource extends WrapperAdapter implements DruidAbstractDataSourceMBean, DataSource, DataSourceProxy, Serializable {

    protected String                                     name;
    protected volatile String                          username;
    protected volatile String                          password;
    protected volatile String                          jdbcUrl;
    protected volatile String                          driverClass;
    ...
}

对应的.yml配置文件内容如下：

# 数据源配置
spring:
    datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        driverClassName: com.mysql.cj.jdbc.Driver
        druid:
            # 主库数据源
            master:
                url: jdbc:mysql://localhost:3306/ry-vue?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
                username: root
                password: password
            # 从库数据源
            slave:
                # 从数据源开关/默认关闭
                enabled: false
                url: 
                username: 
                password: