#22 mvc: reflection - annotation scan

my-framework/mvc-practice/src/main/java/org/example/Main.java

@@ -0,0 +1,4 @@
+package org.example;
+
+public class Main {
+}

my-framework/mvc-practice/src/main/java/org/example/annotation/Controller.java

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+package org.example.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Controller {
+}

my-framework/mvc-practice/src/main/java/org/example/annotation/RequestMapping.java

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+package org.example.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.TYPE, ElementType.METHOD})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface RequestMapping {
+
+    String value() default "";
+
+    RequestMethod[] method() default {};
+}

my-framework/mvc-practice/src/main/java/org/example/annotation/RequestMethod.java

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+package org.example.annotation;
+
+public enum RequestMethod {
+    GET, POST, PUT, PATCH, DELETE
+}

my-framework/mvc-practice/src/main/java/org/example/controller/HealthCheckController.java

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+package org.example.controller;
+
+import org.example.annotation.Controller;
+import org.example.annotation.RequestMapping;
+import org.example.annotation.RequestMethod;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+@Controller
+public class HealthCheckController {
+
+    @RequestMapping(value = "/", method = RequestMethod.GET)
+    public String health(HttpServletRequest request, HttpServletResponse response) {
+        return "ok";
+    }
+}

my-framework/mvc-practice/src/main/java/org/example/controller/HomeController.java

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+package org.example.controller;
+
+import org.example.annotation.Controller;
+import org.example.annotation.RequestMapping;
+import org.example.annotation.RequestMethod;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+@Controller
+public class HomeController {
+
+    @RequestMapping(value = "/", method = RequestMethod.GET)
+    public String home(HttpServletRequest request, HttpServletResponse response) {
+        return "home";
+    }
+}

my-framework/mvc-practice/src/test/java/org/example/ReflectionTest.java

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+package org.example;
+
+import org.example.annotation.Controller;
+import org.junit.jupiter.api.Test;
+import org.reflections.Reflections;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class ReflectionTest {
+
+    private static final Logger logger = LoggerFactory.getLogger(ReflectionTest.class);
+
+    @Test
+    void controllerScan() {
+        Reflections reflections = new Reflections("org.example");
+
+        Set<Class<?>> beans = new HashSet<>();
+        beans.addAll(reflections.getTypesAnnotatedWith(Controller.class));
+
+        logger.debug("beans: [{}]", beans);
+    }
+}