Spring – ${} is not working in @Value--转载

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"/>