### Dependency Injection { #dependency-injection }

FastAPI includes an extremely easy to use, but extremely powerful <dfn title='also known as "components", "resources", "services", "providers"'><strong>Dependency Injection</strong></dfn> system.

* Even dependencies can have dependencies, creating a hierarchy or **"graph" of dependencies**.

/**
 * A factory to create model builder instances when no dependency injection is available. Note: This class is
 * only meant as a utility for developers that want to employ the model builder outside of the Maven build system, Maven
 * plugins should always acquire model builder instances via dependency injection. Developers might want to subclass

        "InjectOnConstructorOfAbstractClass", // We use abstract injection as a pattern
        "InlineMeSuggester", // Only suppression seems to actually "fix" this, so make it global
        "JavaUtilDate", // We are fine with using Date
        "JavaxInjectOnAbstractMethod", // We use abstract injection as a pattern
        "MissingSummary", // We have another mechanism to check Javadocs on public API

# /---------------------------------------------------------------------------
# dependencyInjectionMap: (NotRequired - Default map:{})
#
# The various settings about dependency injection(DI Container). 
#
# {Java} Spring Only:
# o dbfluteBeansPackageName (NotRequired - Default '../resources')
# o dbfluteBeansFileName: (NotRequired - Default 'dbfluteBeans.xml')
# o dbfluteBeansDataSourceName: (NotRequired - Default 'dataSource')

import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Meta-annotation that marks other annotations as scope annotations.
 * <p>
 * Scopes define the lifecycle and visibility of objects in the dependency injection
 * system. Custom scope annotations should be annotated with {@code @Scope}.
 * <p>
 * Built-in scopes include:
 * <ul>
 *   <li>{@link Singleton} - One instance per container</li>

package org.apache.maven.model.management;

import org.apache.maven.model.Model;
import org.apache.maven.model.building.ModelBuildingRequest;
import org.apache.maven.model.building.ModelProblemCollector;

/**
 * Handles injection of dependency management into the model.
 *
 * @deprecated use {@code org.apache.maven.api.services.ModelBuilder} instead
 */
@Deprecated(since = "4.0.0")
public interface DependencyManagementInjector {

    /**

package org.apache.maven.model.management;

import org.apache.maven.model.Model;
import org.apache.maven.model.building.ModelBuildingRequest;
import org.apache.maven.model.building.ModelProblemCollector;

/**
 * Handles injection of plugin management into the model.
 *
 * @deprecated use {@code org.apache.maven.api.services.ModelBuilder} instead
 */
@Deprecated(since = "4.0.0")
public interface PluginManagementInjector {

    /**

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.exception;

/**
 * Exception thrown when a dependency injection container or component is not available.
 * This exception indicates that the required container or a specific component within it cannot be accessed.
 */
public class ContainerNotAvailableException extends FessSystemException {

    }

    /**
     * Registers this creator with the dictionary manager upon initialization.
     * This method is annotated with {@link PostConstruct} to be executed after
     * dependency injection is complete.
     */
    @PostConstruct
    public void register() {
        if (logger.isInfoEnabled()) {
            logger.info("Loaded {}", this.getClass().getSimpleName());
        }

    }

    /**
     * Registers this creator with the dictionary manager upon initialization.
     * This method is annotated with {@link PostConstruct} to be executed after
     * dependency injection is complete.
     */
    @PostConstruct
    public void register() {
        if (logger.isInfoEnabled()) {
            logger.info("Loaded {}", this.getClass().getSimpleName());
        }