step 2 DI 컨테이너 구현하기(힌트)

di/src/main/java/com/interface21/beans/factory/config/BeanDefinitionImpl.java → di/src/main/java/com/interface21/beans/factory/config/DefaultBeanDefinition.java

@@ -1,10 +1,10 @@
 package com.interface21.beans.factory.config;
 
-public class BeanDefinitionImpl implements BeanDefinition {
+public class DefaultBeanDefinition implements BeanDefinition {
     private String beanClassName;
     private Class<?> type;
 
-    public BeanDefinitionImpl(String beanClassName, Class<?> type) {
+    public DefaultBeanDefinition(String beanClassName, Class<?> type) {
         this.beanClassName = beanClassName;
         this.type = type;
     }

di/src/main/java/com/interface21/beans/factory/support/BeanInjector.java

@@ -2,15 +2,18 @@
 
 import com.interface21.beans.BeanUtils;
 import com.interface21.beans.factory.config.BeanDefinition;
-import com.interface21.beans.factory.config.BeanDefinitionImpl;
 import com.interface21.beans.factory.config.MethodBeanDefinitionImpl;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.*;
 
 public class BeanInjector {
+    private final Logger logger = LoggerFactory.getLogger(BeanInjector.class);
+
     private Map<String, BeanDefinition> beanDefinitionMap;
 
     public BeanInjector(Map<String, BeanDefinition> beanDefinitionMap) {
@@ -55,20 +58,7 @@ private void generateBeanFromConstructor(
         // TODO 일단은 생성자가 하나만 있다고 가정하는데 여러개 있는걸 다음스텝으로
         Constructor<?> constructor = BeanFactoryUtils.getInjectedConstructor(targetClass);
         if (constructor == null) {
-            try {
-                objectByClass.put(
-                        targetClass,
-                        targetClass.getDeclaredConstructor().newInstance()
-                );
-            } catch (InstantiationException e) {
-                e.printStackTrace();
-            } catch (IllegalAccessException e) {
-                e.printStackTrace();
-            } catch (InvocationTargetException e) {
-                e.printStackTrace();
-            } catch (NoSuchMethodException e) {
-                e.printStackTrace();
-            }
+            createInstanceWithoutConstructor(targetClass, objectByClass);
             return;
         }
 
@@ -77,12 +67,26 @@ private void generateBeanFromConstructor(
                 instantiateConstructor(
                         constructor,
                         objectByClass,
-                        visited,
-                        beanDefinition
+                        visited
                 )
         );
     }
 
+    private void createInstanceWithoutConstructor(
+            Class<?> targetClass,
+            Map<Class<?>, Object> objectByClass
+    ) {
+        try {
+            objectByClass.put(
+                    targetClass,
+                    targetClass.getDeclaredConstructor().newInstance()
+            );
+        } catch (InstantiationException | IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
+            logger.error(e.getMessage(), e);
+        }
+    }
+
+
     private void generateBeanFromMethod(
             Map<Class<?>, Object> objectByClass,
             BeanDefinition beanDefinition,
@@ -99,11 +103,10 @@ private void generateBeanFromMethod(
     private Object instantiateConstructor(
             Constructor<?> constructor,
             Map<Class<?>, Object> objectByClass,
-            Set<BeanDefinition> visited,
-            BeanDefinition targetBeanDefinition
+            Set<BeanDefinition> visited
     ) {
         Class<?>[] parameterTypes = constructor.getParameterTypes();
-        List<Object> args = new ArrayList();
+        List<Object> args = new ArrayList<>();
         for (Class<?> clazz : parameterTypes) {
             Object object = getBean(clazz, objectByClass);
             if (object == null) {

di/src/main/java/com/interface21/beans/factory/support/BeanScanner.java

@@ -1,7 +1,7 @@
 package com.interface21.beans.factory.support;
 
 import com.interface21.beans.factory.config.BeanDefinition;
-import com.interface21.beans.factory.config.BeanDefinitionImpl;
+import com.interface21.beans.factory.config.DefaultBeanDefinition;
 import com.interface21.beans.factory.config.MethodBeanDefinitionImpl;
 import com.interface21.context.annotation.Bean;
 import com.interface21.context.stereotype.Component;
@@ -53,7 +53,7 @@ private void insertBeanDefinitionFromClass(
     ) {
         for (Class<?> clazz : beanClasses) {
             String name = decapitalize(clazz.getName());
-            BeanDefinition beanDefinition = new BeanDefinitionImpl(
+            BeanDefinition beanDefinition = new DefaultBeanDefinition(
                     clazz.getName(),
                     clazz
             );
@@ -76,13 +76,10 @@ private void insertBeanDefinitionFromMethod(
     }
 
     private String decapitalize(String string) {
-        if (string == null || string.length() == 0) {
+        if (string == null || string.isBlank()) {
             return string;
         }
 
-        char c[] = string.toCharArray();
-        c[0] = Character.toLowerCase(c[0]);
-
-        return new String(c);
+        return Character.toLowerCase(string.charAt(0)) + string.substring(1);
     }
 }