Enable Spring Dependency Injection for New Objects with @Configurable

1. Introduction

Spring's AnnotationBeanConfigurerAspect in spring-aspects.jar allows dependency injection for objects that are not managed by the Spring container, such as domain objects instantiated with new or returned from ORM queries.

<code>public class Account {
  private Long id;
  private String name;
  @Resource
  private BaseService baseService;
}</code>

The Account class above is a plain domain object; @Resource injection will not work without additional configuration.

2. Practical Example

2.1 Environment Preparation

<code>&lt;dependency&gt;
  &lt;groupId&gt;org.springframework&lt;/groupId&gt;
  &lt;artifactId&gt;spring-aspects&lt;/artifactId&gt;
  &lt;version&gt;${spring.version}&lt;/version&gt;
&lt;/dependency&gt;</code>

Define a service to be injected:

<code>@Component
public class BaseService {
  public void save() {
    System.out.println("BaseService save...");
  }
}</code>

2.2 Enable Configuration

<code>@Configuration
// Enable @Configurable processing
@EnableSpringConfigured
public class AppConfig {
}</code>

The @EnableSpringConfigured annotation registers the AnnotationBeanConfigurerAspect with the container.

2.3 Define Configurable Class

<code>@Configurable
public class Account {
  @Resource
  private BaseService baseService;

  public void s() {
    this.baseService.save();
  }
}</code>

Although Account is not a Spring bean, the @Configurable annotation triggers AspectJ to enhance the class at compile time, enabling injection.

2.4 Configure AspectJ Maven Plugin

<code>&lt;plugin&gt;
  &lt;groupId&gt;org.codehaus.mojo&lt;/groupId&gt;
  &lt;artifactId&gt;aspectj-maven-plugin&lt;/artifactId&gt;
  &lt;version&gt;1.15.0&lt;/version&gt;
  &lt;configuration&gt;
    &lt;complianceLevel&gt;1.8&lt;/complianceLevel&gt;
    &lt;source&gt;1.8&lt;/source&gt;
    &lt;target&gt;1.8&lt;/target&gt;
    &lt;outxml&gt;true&lt;/outxml&gt;
    &lt;verbose&gt;true&lt;/verbose&gt;
    &lt;showWeaveInfo&gt;true&lt;/showWeaveInfo&gt;
    &lt;aspectLibraries&gt;
      &lt;aspectLibrary&gt;
        &lt;groupId&gt;org.springframework&lt;/groupId&gt;
        &lt;artifactId&gt;spring-aspects&lt;/artifactId&gt;
      &lt;/aspectLibrary&gt;
    &lt;/aspectLibraries&gt;
  &lt;/configuration&gt;
  &lt;executions&gt;
    &lt;execution&gt;
      &lt;phase&gt;process-classes&lt;/phase&gt;
      &lt;goals&gt;
        &lt;goal&gt;compile&lt;/goal&gt;
      &lt;/goals&gt;
    &lt;/execution&gt;
  &lt;/executions&gt;
&lt;/plugin&gt;</code>

If weaving does not take effect, recompile the project.

2.5 Test

<code>try (AnnotationConfigApplicationContext context =
     new AnnotationConfigApplicationContext("com.pack.aop.configurable")) {
  Account account = new Account();
  account.s();
}</code>

Output:

<code>BaseService save...</code>

The Account instance created with new works correctly, and the generated Account.class shows the applied enhancement.

2.6 Additional Configurations

Autowiring You can specify the autowire mode on @Configurable : <code>@Configurable(autowire = Autowire.BY_TYPE) public class Account { private BaseService baseService; public void setBaseService(BaseService baseService) { this.baseService = baseService; } public void s() { this.baseService.save(); } }</code>

Constructor Injection By default, dependencies are not available in the constructor. Enable them with preConstruction = true : <code>@Configurable(autowire = Autowire.BY_TYPE, preConstruction = true) public class Account { @Resource private BaseService baseService; public Account() { System.out.println(this.baseService); } }</code>

Dependency Check Set dependencyCheck = true to enforce that required beans exist, otherwise an exception is thrown. <code>@Configurable(autowire = Autowire.BY_TYPE, preConstruction = true, dependencyCheck = true) public class Account {}</code>

2.7 Load‑time Weaving (optional)

Alternatively, enable weaving at runtime by adding the Spring Instrument agent:

<code>-javaagent:D:/java/maven/org/springframework/spring-instrument/6.1.7/spring-instrument-6.1.7.jar</code>

Feel free to experiment with the above configurations.