Spring– $ {}在@Value中不起作用

迷南。 2023-02-15 05:14 13阅读 0赞

一个简单的Spring `@PropertySource`示例，用于读取属性文件。

db.properties

db.driver=oracle.jdbc.driver.OracleDriver

AppConfig.java

@Configuration
    @PropertySource("classpath:db.properties")
    public class AppConfig {
     
    	@Value("${db.driver}")
    	private String driver;

但是属性占位符`${}`无法在`@Value`中`@Value` ，如果打印出`driver`变量，它将直接显示字符串`${db.driver}` ，而不是“ oracle.jdbc.driver.OracleDriver”。

## 解 ##

要在Spring `@Value`解析`${}` ，您需要手动声明一个**STATIC** `PropertySourcesPlaceholderConfigurer` bean。 例如 ：

AppConfig.java

import org.springframework.beans.factory.annotation.Value;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.PropertySource;
    import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
    
    @Configuration
    @PropertySource("classpath:db.properties")
    public class AppConfig {
     
    	@Value("${db.driver}")
    	private String driver;
    	
    	@Bean
    	public static PropertySourcesPlaceholderConfigurer propertyConfigInDev() {
    		return new PropertySourcesPlaceholderConfigurer();
    	}
    }

对于XML配置，Spring将帮助您自动注册`PropertySourcesPlaceholderConfigurer` 。

<util:properties location="classpath:db.properties"/>

> **注意**  
> 阅读此SpringJIRA [SPR-8539][]

> **注意**  
> 您可能对此[Spring @PropertySource示例][Spring _PropertySource]感兴趣

标签： [属性][Link 1] [春天][Link 2]

> 翻译自: [https://mkyong.com/spring/spring-is-not-working-in-value/][https_mkyong.com_spring_spring-is-not-working-in-value]

[SPR-8539]: https://jira.spring.io/browse/SPR-8539
[Spring _PropertySource]: http://www.mkyong.com/spring/spring-propertysources-example/
[Link 1]: https://mkyong.com/tag/properties/
[Link 2]: https://mkyong.com/tag/spring/
[https_mkyong.com_spring_spring-is-not-working-in-value]: https://mkyong.com/spring/spring-is-not-working-in-value/