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implemented an injector using annotations.
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package mate.academy.lib; | ||
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public @interface Component { | ||
import java.lang.annotation.ElementType; | ||
import java.lang.annotation.Retention; | ||
import java.lang.annotation.RetentionPolicy; | ||
import java.lang.annotation.Target; | ||
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@Target(ElementType.TYPE) | ||
@Retention(RetentionPolicy.RUNTIME) | ||
public @interface Component { | ||
} |
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@@ -1,5 +1,11 @@ | ||
package mate.academy.lib; | ||
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public @interface Inject { | ||
import java.lang.annotation.ElementType; | ||
import java.lang.annotation.Retention; | ||
import java.lang.annotation.RetentionPolicy; | ||
import java.lang.annotation.Target; | ||
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@Retention(RetentionPolicy.RUNTIME) | ||
@Target(ElementType.FIELD) | ||
public @interface Inject { | ||
} |
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@@ -1,13 +1,80 @@ | ||
package mate.academy.lib; | ||
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import java.lang.reflect.Constructor; | ||
import java.lang.reflect.Field; | ||
import java.lang.reflect.InvocationTargetException; | ||
import java.util.HashMap; | ||
import java.util.Map; | ||
import mate.academy.service.FileReaderService; | ||
import mate.academy.service.ProductParser; | ||
import mate.academy.service.ProductService; | ||
import mate.academy.service.impl.FileReaderServiceImpl; | ||
import mate.academy.service.impl.ProductParserImpl; | ||
import mate.academy.service.impl.ProductServiceImpl; | ||
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public class Injector { | ||
private static final Injector injector = new Injector(); | ||
private final Map<Class<?>, Object> instances = new HashMap<>(); | ||
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public static Injector getInjector() { | ||
return injector; | ||
} | ||
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public Object getInstance(Class<?> interfaceClazz) { | ||
return null; | ||
Class<?> clazz = findImplementation(interfaceClazz); | ||
isClassValid(clazz); | ||
Object clazzImplementationInstance = null; | ||
Field[] declaredFields = interfaceClazz.getDeclaredFields(); | ||
for (Field field : declaredFields) { | ||
if (field.isAnnotationPresent(Inject.class)) { | ||
Object fieldInstance = getInstance(field.getType()); | ||
clazzImplementationInstance = createNewInstance(clazz); | ||
try { | ||
field.setAccessible(true); | ||
field.set(clazzImplementationInstance, fieldInstance); | ||
} catch (IllegalAccessException e) { | ||
throw new RuntimeException("Can't initialize field value. Class: " | ||
+ clazz.getName() + ". Field: " + field.getName()); | ||
} | ||
} | ||
} | ||
if (clazzImplementationInstance == null) { | ||
clazzImplementationInstance = createNewInstance(clazz); | ||
} | ||
return clazzImplementationInstance; | ||
} | ||
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private void isClassValid(Class<?> clazz) { | ||
if (!clazz.isAnnotationPresent(Component.class)) { | ||
throw new RuntimeException("Class: " + clazz.getName() | ||
+ " isn't valid, because isn't declared as @Component"); | ||
} | ||
} | ||
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private Object createNewInstance(Class<?> clazz) { | ||
if (instances.containsKey(clazz)) { | ||
return instances.get(clazz); | ||
} | ||
try { | ||
Constructor<?> constructor = clazz.getConstructor(); | ||
Object instance = constructor.newInstance(); | ||
instances.put(clazz, instance); | ||
return instance; | ||
} catch (NoSuchMethodException | InvocationTargetException | ||
| InstantiationException | IllegalAccessException e) { | ||
throw new RuntimeException("Can't create new instance of " + clazz.getName()); | ||
} | ||
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} | ||
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private Class<?> findImplementation(Class<?> interfaceClazz) { | ||
Map<Class<?>, Class<?>> interfaceImplementation = new HashMap<>(); | ||
interfaceImplementation.put(ProductService.class, ProductServiceImpl.class); | ||
interfaceImplementation.put(ProductParser.class, ProductParserImpl.class); | ||
interfaceImplementation.put(FileReaderService.class, FileReaderServiceImpl.class); | ||
if (interfaceClazz.isInterface()) { | ||
return interfaceImplementation.get(interfaceClazz); | ||
} | ||
return interfaceClazz; | ||
} | ||
} |
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src/main/java/mate.academy/service/impl/ProductParserImpl.java
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