[week4] 문자열 기반 Bean 생성 및 Controller 어노테이션 추가

.gitignore

@@ -42,3 +42,6 @@ bin/
 
 ### Mac OS ###
 .DS_Store\ntomcat.8080/
+
+## tomcat
+**/tomcat.8080

build.gradle.kts

@@ -26,6 +26,9 @@ dependencies {
     implementation("org.apache.tomcat.embed:tomcat-embed-core:8.5.42")
     implementation("org.apache.tomcat.embed:tomcat-embed-jasper:8.5.42")
 
+    // 리플렉션 의존성 주입
+    implementation("org.reflections:reflections:0.10.2")
+
     implementation(kotlin("stdlib-jdk8"))
 }
 

src/main/java/com/diy/app/Lecture.java

@@ -0,0 +1,29 @@
+package com.diy.app;
+
+import java.math.BigDecimal;
+
+public class Lecture {
+
+    private Long id;
+    private String name;
+    private BigDecimal price;
+
+    public Lecture() {
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+}

src/main/java/com/diy/app/LectureApplication.java

@@ -0,0 +1,23 @@
+package com.diy.app;
+
+import com.diy.framework.context.ApplicationContext;
+import com.diy.framework.web.mvc.Controller;
+import com.diy.framework.web.server.TomcatWebServer;
+import com.diy.framework.web.servlet.DispatcherServlet;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class LectureApplication {
+    public static void main(String[] args) {
+        final Map<String, Controller> controllerMapping = new HashMap<>();
+        controllerMapping.put("/lectures", new LectureController());
+
+        final ApplicationContext ac = new ApplicationContext(LectureApplication.class.getPackageName());
+        ac.initialize();
+
+        final DispatcherServlet servlet = new DispatcherServlet(controllerMapping);
+        final TomcatWebServer tomcatWebServer = new TomcatWebServer(servlet);
+        tomcatWebServer.start();
+    }
+}

src/main/java/com/diy/app/LectureController.java

@@ -0,0 +1,52 @@
+package com.diy.app;
+
+import com.diy.framework.web.mvc.Controller;
+import com.diy.framework.web.mvc.view.ModelAndView;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+
+public class LectureController implements Controller {
+
+    private final Map<Long, Lecture> lectureRepository = new HashMap<>();
+
+    @Override
+    public ModelAndView handleRequest(final HttpServletRequest request, final HttpServletResponse response) throws Exception {
+        if ("POST".equals(request.getMethod())) {
+            return doPost(request, response);
+        } else if ("GET".equals(request.getMethod())) {
+            return doGet(request, response);
+        }
+
+        throw new RuntimeException("404 Not Found");
+    }
+
+    private ModelAndView doPost(final HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException {
+        final byte[] bodyBytes = req.getInputStream().readAllBytes();
+        final String body = new String(bodyBytes, StandardCharsets.UTF_8);
+
+        final Lecture lecture = new ObjectMapper().readValue(body, Lecture.class);
+
+        final long id = lectureRepository.size();
+        lectureRepository.put(id, lecture);
+        lecture.setId(id);
+
+        return new ModelAndView("redirect:/lectures");
+    }
+
+    private ModelAndView doGet(final HttpServletRequest req, final HttpServletResponse resp) throws Exception {
+        final Collection<Lecture> lectures = lectureRepository.values();
+        final Map<String, Object> model = new HashMap<>();
+        final Object lectureModels = lectures.stream().map(lecture -> Map.of("id", lecture.getId(), "name", lecture.getName(), "price", lecture.getPrice())).toList();
+        model.put("lectures", lectureModels);
+
+        return new ModelAndView("lecture-list", model);
+    }
+}

src/main/java/com/diy/framework/beans/factory/BeanScanner.java

@@ -0,0 +1,59 @@
+package com.diy.framework.beans.factory;
+
+import com.diy.framework.context.annotation.Bean;
+import org.reflections.Reflections;
+
+import java.lang.annotation.Annotation;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static java.beans.Introspector.decapitalize;
+
+public class BeanScanner {
+
+    private final Reflections reflections;
+
+    public BeanScanner(final String... basePackages) {
+        reflections = new Reflections(basePackages);
+    }
+
+    public Set<Class<?>> scanClassesTypeAnnotatedWith(final Class<? extends Annotation> annotation) {
+        return reflections.getTypesAnnotatedWith(annotation)
+                .stream()
+                .filter(type -> (!type.isAnnotation() && !type.isInterface()))
+                .collect(Collectors.toSet());
+    }
+
+    /**
+     * @Bean 어노테이션의 문자열 value 값으로 빈 이름-인스턴스 매핑
+     * */
+    public Map<String, Class<?>> scanBeansTypeAnnotatedWithName() {
+        Map<String, Class<?>> container = new HashMap<>();
+        Set<Class<?>> beanClasses = scanClassesTypeAnnotatedWith(Bean.class);
+
+        for(Class<?> clazz: beanClasses) {
+            try {
+                Bean bean = clazz.getAnnotation(Bean.class);
+                // Bean 어노테이션에 등록된 value값 추출
+                String beanName = bean.value();
+
+                //  빈 이름이 없으면 클래스 기본명을 소문자화하여 저장
+                if(beanName.isBlank()) {
+                    beanName = decapitalize(clazz.getSimpleName());
+                }
+
+                // 중복 빈 이름 예외처리하기
+                if(container.containsKey(beanName)){
+                    throw new IllegalArgumentException(beanName + "빈이 이미 등록되어 있습니다!");
+                }
+
+                container.put(beanName, clazz);
+            } catch (Exception e) {
+                throw new RuntimeException(e);
+            }
+        }
+        return container;
+    }
+}

src/main/java/com/diy/framework/context/ApplicationContext.java

@@ -0,0 +1,106 @@
+package com.diy.framework.context;
+
+import com.diy.framework.beans.factory.BeanScanner;
+import com.diy.framework.context.annotation.Autowired;
+import com.diy.framework.context.annotation.Bean;
+import com.diy.framework.context.annotation.Component;
+
+import java.lang.reflect.Constructor;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public class ApplicationContext {
+
+    private final String basePackage;
+    private final Set<Class<?>> beanClasses = new HashSet<>();
+    private final List<Object> beans = new ArrayList<>();
+
+    public ApplicationContext(final String basePackage) {
+        this.basePackage = basePackage;
+    }
+
+    public void initialize() {
+        final BeanScanner beanScanner = new BeanScanner(basePackage);
+        beanClasses.addAll(beanScanner.scanClassesTypeAnnotatedWith(Component.class));
+        beanClasses.addAll(beanScanner.scanBeansTypeAnnotatedWithName().values());
+
+        beanClasses.forEach(clazz -> {
+            if (isBeanInitialized(clazz)) {
+                return;
+            }
+
+            final Object bean = createInstance(clazz);
+            saveBean(bean);
+        });
+
+        // @Bean 어노테이션 코드도 저장
+        beanClasses.forEach(clazz -> {});
+    }
+
+    private Object createInstance(final Class<?> clazz) {
+        final Constructor<?> constructor = findConstructor(clazz);
+
+        try {
+            constructor.setAccessible(true);
+            final Object[] parameters = getConstructorParameters(constructor);
+
+            return constructor.newInstance(parameters);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        } finally {
+            constructor.setAccessible(false);
+        }
+    }
+
+    private Constructor<?> findConstructor(final Class<?> clazz) {
+        final Constructor<?>[] constructors = clazz.getDeclaredConstructors();
+
+        if (constructors.length == 1) {
+            return constructors[0];
+        }
+
+        return findAutowiredConstructor(constructors);
+    }
+
+    private Constructor<?> findAutowiredConstructor(final Constructor<?>[] constructors) {
+        final Constructor<?>[] autowiredConstructors = Arrays.stream(constructors)
+                .filter(constructor -> constructor.isAnnotationPresent(Autowired.class))
+                .toArray(Constructor[]::new);
+
+        if (autowiredConstructors.length != 1) {
+            throw new RuntimeException("Autowired constructor not found");
+        }
+
+        return autowiredConstructors[0];
+    }
+
+    private Object[] getConstructorParameters(final Constructor<?> constructor) {
+        final List<Class<?>> parameterTypes = Arrays.stream(constructor.getParameterTypes()).toList();
+
+        if (!beanClasses.containsAll(parameterTypes)) {
+            throw new RuntimeException("parameter is not bean");
+        }
+
+        return parameterTypes.stream().map(parameterType -> {
+            if (isBeanInitialized(parameterType)) {
+                return beans.stream().findFirst().get();
+            }
+
+            final Object bean = createInstance(parameterType);
+            saveBean(bean);
+
+            return bean;
+        }).toArray();
+    }
+
+    private boolean isBeanInitialized(final Class<?> parameterType) {
+        return beans.stream().anyMatch(bean -> bean.getClass().equals(parameterType));
+    }
+
+    private void saveBean(final Object bean) {
+        beans.add(bean);
+    }
+}

src/main/java/com/diy/framework/context/annotation/Autowired.java

@@ -0,0 +1,11 @@
+package com.diy.framework.context.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.CONSTRUCTOR})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Autowired {
+}

src/main/java/com/diy/framework/context/annotation/Bean.java

@@ -0,0 +1,10 @@
+package com.diy.framework.context.annotation;
+
+import java.lang.annotation.*;
+
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface Bean {
+    String value() default "";
+}

src/main/java/com/diy/framework/context/annotation/Component.java

@@ -0,0 +1,11 @@
+package com.diy.framework.context.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 Component {
+}

src/main/java/com/diy/framework/web/mvc/Controller.java

@@ -0,0 +1,11 @@
+package com.diy.framework.web.mvc;
+
+import com.diy.framework.web.mvc.view.ModelAndView;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+@FunctionalInterface
+public interface Controller {
+    ModelAndView handleRequest(final HttpServletRequest request, final HttpServletResponse response) throws Exception;
+}