@Value not resolved when using @PropertySource ann

问题:

I have following configuration class:

@Configuration
@PropertySource(name = "props", value = "classpath:/app-config.properties")
@ComponentScan("service")
public class AppConfig {

and I have service with property:

@Component 
public class SomeService {
    @Value("#{props['some.property']}") private String someProperty;

I receive error when I want to test the AppConfig configuration class with

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'someService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.lang.String service.SomeService.someProperty; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 0): Field or property 'props' cannot be found on object of type 'org.springframework.beans.factory.config.BeanExpressionContext' 

The issue is documented in SPR-8539

but anyway I cannot figure out how to configure PropertySourcesPlaceholderConfigurer to get it work.

Edit 1

This approach works well with xml configuration

<util:properties id="props" location="classpath:/app-config.properties" />

but I want to use java for configuration.

回答1:

If you use @PropertySource, properties have to be retrieved with:

@Autowired
Environment env;
// ...
String subject = env.getProperty("mail.subject");

If you want to retrieve with @Value("${mail.subject}"), you have to register the prop placeholder by xml.

Reason: https://jira.springsource.org/browse/SPR-8539

回答2:

as @cwash said;

@Configuration
@PropertySource("classpath:/test-config.properties")
public class TestConfig {

     @Value("${name}")
     public String name;


     //You need this
     @Bean
     public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
     }

}

回答3:

I found the reason @value was not working for me is, @value requires PropertySourcesPlaceholderConfigurer instead of a PropertyPlaceholderConfigurer. I did the same changes and it worked for me, I am using spring 4.0.3 release. I configured this using below code in my configuration file.

@Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
   return new PropertySourcesPlaceholderConfigurer();
}

回答4:

Don't you need a method on your @Configuration class that returns PropertySourcesPlaceholderConfigurer, annotated @Bean and is static, to register any @PropertySource with Spring?

http://www.baeldung.com/2012/02/06/properties-with-spring/#java

https://jira.springsource.org/browse/SPR-8539

回答5:

I had the very same problem. @PropertySource is not playing well with @Value. A quick workaround is to have an XML configuration which you'll refer to it from your Spring Java Configuration using @ImportResource as usual and that XML configuration file will include a single entry: <context:property-placeholder /> (of course with the needed namespace ceremony). Without any other change @Value will inject properties in your @Configuration pojo.

回答6:

This can also be configured in java this way

@Bean
public static PropertySourcesPlaceholderConfigurer properties() {
    PropertySourcesPlaceholderConfigurer configurer = new PropertySourcesPlaceholderConfigurer();
    configurer.setIgnoreUnresolvablePlaceholders(true);
    configurer.setIgnoreResourceNotFound(true);
    return configurer;
}

回答7:

That looks mighty complicated, can't you just do

 <context:property-placeholder location="classpath:some.properties" ignore-unresolvable="true"/>

then in code reference:

@Value("${myProperty}")
private String myString;

@Value("${myProperty.two}")
private String myStringTwo;

where some.properties looks something like this

myProperty = whatever
myProperty.two = something else\
that consists of multiline string

For java based config you can do this

@Configuration
@PropertySource(value="classpath:some.properties")
public class SomeService {

And then just inject using @value as before

回答8:

The thing is: as far as I get it, <util:propertes id="id" location="loc"/>, is just a shorthand for

<bean id="id" class="org.springframework.beans.factory.config.PropertiesFactoryBean">
  <property name="location" value="loc"/>
</bean>

(see documentation of util:properties). Thus, when you use util:properties, a standalone bean is created.

@PropertySource, on the other hand, as documentation says is an

annotation providing a convenient and declarative mechanism for adding a PropertySource to Spring's Environment'.

(see @PropertySource doc). So it doesn't create any bean.

Then "#{a['something']}" is a SpEL expression (see SpEL), that means "get something from bean 'a'". When util:properties is used, the bean exists and the expression is meaningful, but when @PropertySource is used, there is no actual bean and the expression is meaningless.

You can workaround this either by using XML (which is the best way, I think) or by issuing a PropertiesFactoryBean by yourself, declaring it as a normal @Bean.

回答9:

Another thing that may be happening: ensure your @Value annotated values are not static.

回答10:

Since Spring 4.3 RC2 using PropertySourcesPlaceholderConfigurer or <context:property-placeholder> is not needed anymore. We can use directly @PropertySource with @Value. See this Spring framework ticket

I have created a test application with Spring 5.1.3.RELEASE. The application.properties contains two pairs:

app.name=My application
app.version=1.1

The AppConfig loads the properties via @PropertySource.

package com.zetcode.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
@PropertySource(value = "application.properties", ignoreResourceNotFound = true)
public class AppConfig {

}

The Application injects the properties via @Value and uses them.

package com.zetcode;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;

@ComponentScan(basePackages = "com.zetcode")
public class Application {

    private static final Logger logger = LoggerFactory.getLogger(Application.class);

    @Value("${app.name}")
    private String appName;

    @Value("${app.version}")
    private String appVersion;

    public static void main(String[] args) {

        var ctx = new AnnotationConfigApplicationContext(Application.class);
        var app = ctx.getBean(Application.class);

        app.run();

        ctx.close();
    }

    public void run() {

        logger.info("Application name: {}", appName);
        logger.info("Application version: {}", appVersion);
    }
}

The output is:

$ mvn -q exec:java
22:20:10.894 [com.zetcode.Application.main()] INFO  com.zetcode.Application - Application name: My application
22:20:10.894 [com.zetcode.Application.main()] INFO  com.zetcode.Application - Application version: 1.1