Can't I @Autowire a Bean which is present in a dependent Library Jar?

Question

I have a Spring Boot application (Y) which relies upon a set of Library files packed as x.jar and mentioned as a dependency in the pom.xml of the application Y.

x.jar has a bean named (User.java) Application Y has a java class named (Department.java)

While i try to Autowire an instance of User.java inside Department.java, i get the following error

Can't I @Autowire a Bean which is present in a dependent Library Jar ?

Could not autowire field: private com.User user; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.User] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

No qualifying bean of type [com.User] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}**

Here is the code in the Spring Boot Application 'Y'

package myapp;

@Component
public class Department {

    @Autowired
    private com.User user;

    //has getter setters for user

}

Here is the code of User.java in the Library x.jar

 package com;

@Component
@ConfigurationProperties(prefix = "test.userproperties")
public class User {

  private String name;
  //has getter setters for name    
}

This is the dependency entry for x.jar in the pom.xml of application Y

      <groupId>com.Lib</groupId>
      <artifactId>x</artifactId>
      <version>001</version>
    </dependency>   

This is the Main class in the Application 'Y'

@Configuration
@EnableAutoConfiguration
@ComponentScan
@EnableZuulProxy
@EnableGemfireSession(maxInactiveIntervalInSeconds=60)
@EnableCircuitBreaker
@EnableHystrixDashboard
@EnableDiscoveryClient
public class ZuulApplication {

    public static void main(String[] args) {
        new SpringApplicationBuilder(ZuulApplication.class).web(true).run(args);
    }
}   

Both Department and User are under different packages.

Solution: I applied the following 2 steps and now the Autowiring is working fine.

Step 1: Added the following class in the jar file

package com
@Configuration
@ComponentScan
public class XConfiguration {

}

Step 2: Imported this Configuration class in the Y project's main class

@Configuration
    @EnableAutoConfiguration
    @ComponentScan
    @EnableZuulProxy
    @EnableGemfireSession(maxInactiveIntervalInSeconds=60)
    @EnableCircuitBreaker
    @EnableHystrixDashboard
    @EnableDiscoveryClient
    @Import(XConfiguration.class) 
    public class ZuulApplication {

        public static void main(String[] args) {
            new SpringApplicationBuilder(ZuulApplication.class).web(true).run(args);
        }
    }

Answer 1

You would need to add the package names of your main class and the User class to be 100% sure, but more then likely, the User class is not in the same package (or a subpackage) of your main class. This means that component scanning will not pick it up.

You can force spring to look at other packages like this:

@ComponentScan(basePackages = {"org.example.main", "package.of.user.class"})