原文：http://www.mkyong.com/spring/spring-is-not-working-in-value/
By mkyong | February 4, 2015 | Last Updated : February 12, 2015
A simple Spring @PropertySource example to read a properties file.
db.properties
db.driver=oracle.jdbc.driver.OracleDriver
AppConfig.java
@Configuration
@PropertySource("classpath:db.properties")
public class AppConfig {
@Value("${db.driver}")
private String driver;
But the property placeholder ${} is unable to resolve in @Value, if print out the driver variable, it will display string ${db.driver} directly, instead of “oracle.jdbc.driver.OracleDriver”.
Solution
To resolve ${} in Spring @Value, you need to declare a STATICPropertySourcesPlaceholderConfigurer bean manually. For example :
AppConfig.java
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
@Configuration
@PropertySource("classpath:db.properties")
public class AppConfig {
@Value("${db.driver}")
private String driver;
@Bean
public static PropertySourcesPlaceholderConfigurer propertyConfigInDev() {
return new PropertySourcesPlaceholderConfigurer();
}
}
For XML configuration, Spring will help you to register PropertySourcesPlaceholderConfigurerautomatically.
<util:properties location="classpath:db.properties"/>