Spring-style DI: a @Component service constructor-injected into a @Controller, plus the Beans facade

README.md

@@ -29,3 +29,11 @@ controller routes:
 
 The OpenAPI fragment for the controller is published automatically at
 `/services/openapi`.
+
+## Dependency injection styles
+
+- **Field injection** — `CountryController` uses `@Inject CountryRepository` (still supported).
+- **Constructor injection (preferred)** — `GreetingController` receives a `@Component GreetingService` through its constructor; more testable.
+- **Programmatic lookup** — `Beans.get(...)` for when an injection point isn't convenient.
+
+See the [Develop guide](https://www.dirigible.io/help/develop/dependency-injection/) and the [Java SDK](https://www.dirigible.io/sdk/).

demo/GreetingController.java

@@ -0,0 +1,31 @@
+package demo;
+
+import org.eclipse.dirigible.sdk.component.Beans;
+import org.eclipse.dirigible.sdk.http.Controller;
+import org.eclipse.dirigible.sdk.http.Get;
+import org.eclipse.dirigible.sdk.http.PathParam;
+
+/**
+ * Constructor injection (preferred, testable). Also shows the Beans facade for programmatic lookup
+ * when an injection point isn't convenient.
+ */
+@Controller
+public class GreetingController {
+
+    private final GreetingService greetings;
+
+    public GreetingController(GreetingService greetings) {
+        this.greetings = greetings;
+    }
+
+    @Get("/greet/{name}")
+    public String greet(@PathParam("name") String name) {
+        return greetings.greet(name);
+    }
+
+    @Get("/greet-via-beans/{name}")
+    public String greetViaBeans(@PathParam("name") String name) {
+        return Beans.get(GreetingService.class)
+                    .greet(name);
+    }
+}

demo/GreetingService.java

@@ -0,0 +1,15 @@
+package demo;
+
+import org.eclipse.dirigible.sdk.component.Component;
+
+/**
+ * A plain @Component service injected into a controller by constructor — the Spring-style DI the
+ * client-Java model now supports.
+ */
+@Component
+public class GreetingService {
+
+    public String greet(String name) {
+        return "Hello, " + name + "!";
+    }
+}