[3주차] 관심사 분리 1 - 신재희

build.gradle.kts

@@ -1,3 +1,5 @@
+import org.gradle.internal.impldep.org.junit.Assert.assertThat
+
 plugins {
     id("java")
     kotlin("jvm")
@@ -24,11 +26,16 @@ dependencies {
 
     implementation(group = "org.json", name = "json", version = "20160810")
 
+    // aop
+    implementation("org.reflections:reflections:0.10.2")
+
     // 톰캣
     implementation("org.apache.tomcat.embed:tomcat-embed-core:8.5.42")
     implementation("org.apache.tomcat.embed:tomcat-embed-jasper:8.5.42")
 
     implementation(kotlin("stdlib-jdk8"))
+
+    implementation("org.assertj:assertj-core:3.24.2")
 }
 
 tasks.test {

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

@@ -1,9 +1,12 @@
 package com.diy.app;
 
+import com.diy.app.business.repository.LectureRepository;
+import com.diy.framework.beans.factory.BeanStorage;
 import com.diy.framework.web.server.TomcatWebServer;
 
 public class Main {
     public static void main(String[] args) {
+        BeanStorage beanStorage = BeanStorage.getInstance();
         TomcatWebServer tomcatWebServer = new TomcatWebServer();
         tomcatWebServer.start();
     }

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

@@ -5,22 +5,30 @@
 import com.diy.app.infra.dto.ModelAndView;
 import com.diy.app.infra.httpSpec.HttpMethod;
 import com.diy.app.infra.port.Controller;
+import com.diy.framework.beans.annotations.Autowired;
+import com.diy.framework.beans.annotations.Component;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.util.Map;
 
+@Component
 public class LectureController implements Controller {
 
+    @Autowired
     private LectureService service;
-    private ObjectMapper objectMapper;
+    private final ObjectMapper objectMapper;
 
-    public LectureController(LectureService service) {
-        this.service = service;
-        this.objectMapper = new ObjectMapper();
+    public LectureController() {
+        objectMapper = new ObjectMapper();
     }
 
+    //    public LectureController(LectureService service) {
+//        this.service = service;
+//        this.objectMapper = new ObjectMapper();
+//    }
+
     @Override
     public ModelAndView handleRequest(HttpServletRequest req, HttpServletResponse resp) throws Exception {
         String uri = req.getRequestURI();

src/main/java/com/diy/app/business/repository/LectureRepository.java

@@ -1,15 +1,16 @@
 package com.diy.app.business.repository;
 
 import com.diy.app.business.domain.Lecture;
+import com.diy.framework.beans.annotations.Component;
 
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicLong;
 
+@Component
 public class LectureRepository {
-    static LectureRepository instance;
 
     AtomicLong nextId;
     Map<Long, Lecture> lectureDB;
@@ -19,10 +20,6 @@ private LectureRepository() {
         lectureDB = new ConcurrentHashMap<>();
     }
 
-    public static LectureRepository getInstance() {
-        return instance == null ? instance = new LectureRepository() : instance;
-    }
-
     public List<Lecture> getAll() {
         return lectureDB.values().stream().toList();
     }

src/main/java/com/diy/app/business/service/LectureService.java

@@ -2,21 +2,16 @@
 
 import com.diy.app.business.domain.Lecture;
 import com.diy.app.business.repository.LectureRepository;
+import com.diy.framework.beans.annotations.Autowired;
+import com.diy.framework.beans.annotations.Component;
 
 import java.util.List;
 
+@Component
 public class LectureService {
-    private static LectureService instance = null;
 
-    private static LectureRepository repository = null;
-
-    private LectureService(LectureRepository repository) {
-        this.repository = repository;
-    }
-
-    public static LectureService getInstance() {
-        return instance == null ? instance = new LectureService(LectureRepository.getInstance()) : instance;
-    }
+    @Autowired
+    private static LectureRepository repository;
 
     public List<Lecture> getAllLectures() {
         return repository.getAll();

src/main/java/com/diy/app/infra/servlet/UrlControllerMapper.java

@@ -4,6 +4,7 @@
 import com.diy.app.business.service.LectureService;
 import com.diy.app.infra.port.Controller;
 import com.diy.app.infra.viewRender.ViewResolver;
+import com.diy.framework.beans.factory.BeanStorage;
 
 import java.util.Comparator;
 import java.util.Map;
@@ -14,7 +15,7 @@ public class UrlControllerMapper {
     private static UrlControllerMapper instance;
 
     public UrlControllerMapper() {
-        uriToController.put("/lectures", new LectureController(LectureService.getInstance()));
+        uriToController.put("/lectures", BeanStorage.getInstance().getBeans(LectureController.class).getFirst());
     }
 
     public Controller findController(String uri) {

src/main/java/com/diy/app/infra/viewRender/JspView.java

@@ -24,6 +24,9 @@ public void render(final HttpServletRequest req, final HttpServletResponse resp,
                 .getFile().split("resources/")[1];
 
         final RequestDispatcher requestDispatcher = req.getRequestDispatcher(filePath);
+        for (String key : modelAndView.getModel().keySet()) {
+            req.setAttribute(key, modelAndView.getModel().get(key));
+        }
         requestDispatcher.forward(req, resp);
     }
 

src/main/java/com/diy/framework/beans/annotations/Autowired.java

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

src/main/java/com/diy/framework/beans/annotations/Component.java

@@ -0,0 +1,11 @@
+package com.diy.framework.beans.annotations;
+
+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/beans/factory/BeanScanner.java

@@ -0,0 +1,32 @@
+package com.diy.framework.beans.factory;
+
+import com.diy.framework.beans.annotations.Autowired;
+import org.reflections.Reflections;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Field;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+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());
+    }
+
+    public Set<Field> scanField(final Class<?> clazz) {
+        return Arrays.stream(clazz.getDeclaredFields()).filter(field -> Objects.nonNull(field.getDeclaredAnnotation(Autowired.class))).collect(Collectors.toSet());
+    }
+}

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

@@ -0,0 +1,123 @@
+package com.diy.framework.beans.factory;
+
+import com.diy.framework.beans.annotations.Component;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.util.*;
+
+public class BeanStorage {
+
+    private static BeanStorage instance;
+
+    private final List<Object> beans;
+    private final BeanScanner bc = new BeanScanner("com.diy.app");
+
+    private BeanStorage() {
+        Set<Class<?>> classes = bc.scanClassesTypeAnnotatedWith(Component.class);
+        Map<Class<?>, Set<Field>> classToFields = getFields(classes);
+        List<Class<?>> sortedClasses = topologicalSort(classToFields);
+        beans = makeBeans(sortedClasses, classToFields);
+    }
+
+    public static BeanStorage getInstance() {
+        if (Objects.isNull(instance)) instance = new BeanStorage();
+        return instance;
+    }
+
+    private static List<Object> makeBeans(List<Class<?>> classes, Map<Class<?>, Set<Field>> classToFields) {
+        List<Object> results = new ArrayList<>();
+
+        for (Class<?> clazz : classes) {
+            Constructor<?> constructor = null;
+            try {
+                constructor = clazz.getDeclaredConstructor();
+                constructor.setAccessible(true);
+                Object bean = constructor.newInstance();
+                setFields(bean, results, classToFields);
+                results.add(bean);
+            } catch (InstantiationException | IllegalAccessException | InvocationTargetException |
+                     NoSuchMethodException e) {
+                throw new RuntimeException(e);
+            } finally {
+                if (constructor != null) {
+                    constructor.setAccessible(false);
+                }
+            }
+        }
+
+        return results;
+    }
+
+    public <T> List<T> getBeans(final Class<T> classType) {
+        return beans.stream()
+                .filter(classType::isInstance)
+                .map(classType::cast)
+                .toList();
+    }
+
+    public Map<Class<?>, Set<Field>> getFields(Set<Class<?>> classes) {
+        Map<Class<?>, Set<Field>> classToField = new HashMap<>();
+        for (Class<?> clazz : classes) {
+            classToField.put(clazz, bc.scanField(clazz));
+        }
+        return classToField;
+    }
+
+    public static void setFields(Object target, List<Object> nowBeanList, Map<Class<?>, Set<Field>> classToFields) {
+        for (Field field : classToFields.get(target.getClass())) {
+            Object fieldTarget = null;
+            for (Object targetBean : nowBeanList) {
+                if (!field.getType().isInstance(targetBean)) continue;
+                if (Objects.nonNull(fieldTarget)) throw new IllegalArgumentException("2개 이상의 빈이 존재 : " + field.getType().getName());
+                fieldTarget = targetBean;
+            }
+            if (Objects.isNull(fieldTarget)) throw new IllegalArgumentException("존재하지 않는 빈 : " + field.getType().getName());
+            try {
+                field.setAccessible(true);
+                field.set(target, fieldTarget);
+            } catch (IllegalAccessException e) {
+                throw new RuntimeException(e);
+            } finally {
+                field.setAccessible(false);
+            }
+        }
+    }
+
+    public List<Class<?>> topologicalSort(Map<Class<?>, Set<Field>> classMap) {
+        Map<Class<?>, Set<Class<?>>> map = copyMap(classMap);
+
+        List<Class<?>> result = new ArrayList<>();
+        Set<Class<?>> visited = new HashSet<>();
+
+        while (visited.size() < map.size()) {
+            List<Class<?>> canMake = new ArrayList<>();
+            for (Map.Entry<Class<?>, Set<Class<?>>> entry : map.entrySet()) {
+                if (visited.contains(entry.getKey())) continue;
+                if (visited.containsAll(entry.getValue())) {
+                    canMake.add(entry.getKey());
+                }
+            }
+            if (canMake.isEmpty()) {
+                throw new IllegalArgumentException("순환 참조 혹은 존재하지 않는 빈을 필드로하는 것이 존재합니다");
+            }
+            visited.addAll(canMake);
+            result.addAll(canMake);
+        }
+
+        return result;
+    }
+
+    private static Map<Class<?>, Set<Class<?>>> copyMap(Map<Class<?>, Set<Field>> classMap) {
+        Map<Class<?>, Set<Class<?>>> map = new HashMap<>();
+        for (Map.Entry<Class<?>, Set<Field>> entry : classMap.entrySet()) {
+            Set<Class<?>> fieldTypes = new HashSet<>();
+            for (Field field : entry.getValue()) {
+                fieldTypes.add(field.getType());
+            }
+            map.put(entry.getKey(), fieldTypes);
+        }
+        return map;
+    }
+}

src/test/java/study/reflection/Car.java

@@ -0,0 +1,37 @@
+package study.reflection;
+
+public class Car {
+
+    private String name;
+    private int price;
+
+    public String getName() {
+        return name;
+    }
+
+    public int getPrice() {
+        return price;
+    }
+
+    public Car() {
+
+    }
+
+    public Car(String name, int price) {
+        this.name = name;
+        this.price = price;
+    }
+
+    @PrintView
+    public void printView() {
+        System.out.println("자동차 정보를 출력 합니다.");
+    }
+
+    public String testGetName() {
+        return "test : " + name;
+    }
+
+    public String testGetPrice() {
+        return "test : " + price;
+    }
+}

src/test/java/study/reflection/PrintView.java

@@ -0,0 +1,8 @@
+package study.reflection;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+public @interface PrintView {
+}