beans instanciated, and inserted into container

Author: JavaEEPRO

src/main/java/si/inspirited/Main.java

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+package main.java.si.inspirited;
+
+import org.springframework.beans.factory.BeanFactory;
+
+public class Main {
+    public static void main(String[] args) {
+
+        BeanFactory beanFactory = new BeanFactory();
+        beanFactory.instantiate("main.java.si.inspirited");
+    }
+}

src/main/java/si/inspirited/ProductService.java

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+package main.java.si.inspirited;
+
+import org.springframework.beans.factory.stereotype.Component;
+
+@Component
+public class ProductService {
+
+    private PromotionsService promotionsService;
+
+    public PromotionsService getPromotionsService() {
+        return promotionsService;
+    }
+
+    public void setPromotionsService(PromotionsService promotionsService) {
+        this.promotionsService = promotionsService;
+    }
+}

src/main/java/si/inspirited/PromotionsService.java

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+package main.java.si.inspirited;
+
+import org.springframework.beans.factory.stereotype.Component;
+
+@Component
+public class PromotionsService {
+
+}

src/org/springframework/beans/factory/BeanFactory.java

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+package org.springframework.beans.factory;
+
+import org.springframework.beans.factory.stereotype.Component;
+
+import java.io.File;
+import java.net.URL;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.Map;
+
+public class BeanFactory {
+
+    private Map<String, Object> singletons = new HashMap();
+
+    public Object getBean(String beanName){
+        return singletons.get(beanName);
+    }
+
+    public void instantiate(String basePackage) {
+        try {
+            ClassLoader classLoader = ClassLoader.getSystemClassLoader();
+            String path = basePackage.replace('.', '/'); //"main.java.si.inspirited" -> "main/java/si/inspirited"
+            Enumeration<URL> resources = classLoader.getResources(path);
+
+            while (resources.hasMoreElements()) {
+                URL resource = resources.nextElement();
+
+                File file = new File(resource.toURI());
+                for (File classFile : file.listFiles()) {
+                    String fileName = classFile.getName();//ProductService.class
+
+                    if (fileName.endsWith(".class")) {
+                        String className = fileName.substring(0, fileName.lastIndexOf("."));
+                        Class classObject = Class.forName(basePackage + "." + className);
+
+                        if (classObject.isAnnotationPresent(Component.class)) {
+                            System.out.println("Component: " + classObject);
+                        }
+                        Object instance = classObject.getDeclaredConstructor().newInstance();//=new CustomClass()
+                        String beanName = className.substring(0, 1).toLowerCase() + className.substring(1);
+                        singletons.put(beanName, instance);
+                    }
+                }
+            }
+        }catch (Exception e) {e.printStackTrace();}
+        System.out.println(singletons);
+    }
+}

src/org/springframework/beans/factory/stereotype/Component.java

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+package org.springframework.beans.factory.stereotype;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Component {
+
+}