Question

read this article on SO, and had some clarifying questions.

I put my config.properties under src/main/resources

In spring-servlet.xml config file

I added the following:

<context:property-placeholder location="classpath:config.properties"/>

In my business layer, I am trying to access it via

@Value("${upload.file.path}")
private String uploadFilePath;

Eclipse shows error:

The attribute value is undefined for the annotation type Value

Can i not access the property in the business layer or are property files only read in the controller?

UPDATE::
src/main/java/com.companyname.controllers/homecontroller.java

public String home(Locale locale, Model model) {
    MyServiceObject myObj = new MyServiceObject();
    System.out.println("Property from my service object: = " + myObj.PropertyValue());

    if(myObj.PerformService())
    {
      ///
    }
}

src/main/java/com.companyname.services/MyService.java

public class MyServiceObject {

    @Value("${db.server.ip}")
    private String _dbServerIP;


    public String PropertyValue() {

        return _dbServerIPaseURL;
    }



}

Another site where I found the explanation

Answer 1

Please check that you import Value from org.springframework.beans.factory.annotation package:

import org.springframework.beans.factory.annotation.Value;

also the property placeholder must be declared in the respective context configuration file, in case of controller it’s likely Spring dispatcher servlet configuration file.

update You are confusing property-placeholder that post processes bean values, that contain dollar symbol ${<property name>} with Spring expression language container extension that process values containing a hash symbol #{<Spring expression language expression>}, in the link you have shown the latter approach is used.

regarding the instantiation of MyServiceObject myObj
If you want the object to be managed by Spring you should delegate its creation to the container:

• if MyServiceObject is a stateless service then it’s a singleton with the singleton bean scope, you should register it in your application context, for example with the following xml configuration:

  <bean class="my.package.MyServiceObject"/>
  

  and inject it to your controller:

  private MyServiceObject myServiceObject;
  @Autowired 
  public void setMyServiceObject(MyServiceObject myServiceObject){
     this.myServiceObject = myServiceObject;
  }
  

• if many instances of MyServiceObject are required, you can declare it as a bean with some other (non-singleton) bean scope (prototype, or request, for example).
  However, as there’s only one instance of the controller, you can’t merely let the Spring container to autowire MyServiceObject instance to the controller field, because there will be only one field and many instances of MyServiceObject class. You can read about the different approaches(for the different bean scopes) for resolving this issue in the respective section of the documentation.