From 0454fcee2bca991f99526813159b34d31a084931 Mon Sep 17 00:00:00 2001 From: Pavlo Melnyk Date: Mon, 28 Oct 2024 09:23:16 +0000 Subject: [PATCH] feat: implemented dependency injection mechanism using @Component and @Inject annotations --- src/main/java/mate.academy/Main.java | 3 +- src/main/java/mate.academy/lib/Component.java | 5 +- src/main/java/mate.academy/lib/Inject.java | 5 +- src/main/java/mate.academy/lib/Injector.java | 51 ++++++++++++++++++- .../service/impl/FileReaderServiceImpl.java | 2 + .../service/impl/ProductParserImpl.java | 2 + .../service/impl/ProductServiceImpl.java | 5 ++ 7 files changed, 68 insertions(+), 5 deletions(-) diff --git a/src/main/java/mate.academy/Main.java b/src/main/java/mate.academy/Main.java index 9be740020..4afee2f36 100644 --- a/src/main/java/mate.academy/Main.java +++ b/src/main/java/mate.academy/Main.java @@ -8,9 +8,8 @@ public class Main { public static void main(String[] args) { - // Please test your Injector here. Feel free to push this class as a part of your solution Injector injector = Injector.getInjector(); - ProductService productService = null; + ProductService productService = (ProductService) injector.getInstance(ProductService.class); List products = productService.getAllFromFile("products.txt"); products.forEach(System.out::println); } diff --git a/src/main/java/mate.academy/lib/Component.java b/src/main/java/mate.academy/lib/Component.java index c7e830420..563153122 100644 --- a/src/main/java/mate.academy/lib/Component.java +++ b/src/main/java/mate.academy/lib/Component.java @@ -1,5 +1,8 @@ package mate.academy.lib; -public @interface Component { +import java.lang.annotation.Retention; +import java.lang.annotation.RetentionPolicy; +@Retention(RetentionPolicy.RUNTIME) +public @interface Component { } diff --git a/src/main/java/mate.academy/lib/Inject.java b/src/main/java/mate.academy/lib/Inject.java index 1741f9df9..dfd2a0486 100644 --- a/src/main/java/mate.academy/lib/Inject.java +++ b/src/main/java/mate.academy/lib/Inject.java @@ -1,5 +1,8 @@ package mate.academy.lib; -public @interface Inject { +import java.lang.annotation.Retention; +import java.lang.annotation.RetentionPolicy; +@Retention(RetentionPolicy.RUNTIME) +public @interface Inject { } diff --git a/src/main/java/mate.academy/lib/Injector.java b/src/main/java/mate.academy/lib/Injector.java index e87b914ad..4e3833799 100644 --- a/src/main/java/mate.academy/lib/Injector.java +++ b/src/main/java/mate.academy/lib/Injector.java @@ -1,13 +1,62 @@ package mate.academy.lib; +import java.lang.reflect.Constructor; +import java.lang.reflect.Field; +import java.util.HashMap; +import java.util.Map; +import mate.academy.service.FileReaderService; +import mate.academy.service.ProductParser; +import mate.academy.service.ProductService; + public class Injector { private static final Injector injector = new Injector(); + private final Map, Object> instances = new HashMap<>(); public static Injector getInjector() { return injector; } public Object getInstance(Class interfaceClazz) { - return null; + if (instances.containsKey(interfaceClazz)) { + return instances.get(interfaceClazz); + } + Class clazz = findImplementation(interfaceClazz); + if (clazz == null || !clazz.isAnnotationPresent(Component.class)) { + throw new RuntimeException("No implementation found for: " + interfaceClazz.getName()); + } + Object instance = createInstance(clazz); + instances.put(interfaceClazz, instance); + return instance; + } + + private Class findImplementation(Class interfaceClazz) { + if (interfaceClazz.isInterface()) { + if (interfaceClazz.equals(FileReaderService.class)) { + return mate.academy.service.impl.FileReaderServiceImpl.class; + } else if (interfaceClazz.equals(ProductParser.class)) { + return mate.academy.service.impl.ProductParserImpl.class; + } else if (interfaceClazz.equals(ProductService.class)) { + return mate.academy.service.impl.ProductServiceImpl.class; + } + } + return interfaceClazz; + } + + private Object createInstance(Class clazz) { + Constructor constructor; + try { + constructor = clazz.getDeclaredConstructor(); + Object instance = constructor.newInstance(); + for (Field field : clazz.getDeclaredFields()) { + if (field.isAnnotationPresent(Inject.class)) { + field.setAccessible(true); + Object fieldInstance = getInstance(field.getType()); + field.set(instance, fieldInstance); + } + } + return instance; + } catch (Exception e) { + throw new RuntimeException("Can't create instance of class: " + clazz.getName(), e); + } } } diff --git a/src/main/java/mate.academy/service/impl/FileReaderServiceImpl.java b/src/main/java/mate.academy/service/impl/FileReaderServiceImpl.java index 58540d301..752474e0d 100644 --- a/src/main/java/mate.academy/service/impl/FileReaderServiceImpl.java +++ b/src/main/java/mate.academy/service/impl/FileReaderServiceImpl.java @@ -4,8 +4,10 @@ import java.io.IOException; import java.nio.file.Files; import java.util.List; +import mate.academy.lib.Component; import mate.academy.service.FileReaderService; +@Component public class FileReaderServiceImpl implements FileReaderService { @Override public List readFile(String fileName) { diff --git a/src/main/java/mate.academy/service/impl/ProductParserImpl.java b/src/main/java/mate.academy/service/impl/ProductParserImpl.java index 00837f28d..03ea21a56 100644 --- a/src/main/java/mate.academy/service/impl/ProductParserImpl.java +++ b/src/main/java/mate.academy/service/impl/ProductParserImpl.java @@ -1,9 +1,11 @@ package mate.academy.service.impl; import java.math.BigDecimal; +import mate.academy.lib.Component; import mate.academy.model.Product; import mate.academy.service.ProductParser; +@Component public class ProductParserImpl implements ProductParser { public static final int ID_POSITION = 0; public static final int NAME_POSITION = 1; diff --git a/src/main/java/mate.academy/service/impl/ProductServiceImpl.java b/src/main/java/mate.academy/service/impl/ProductServiceImpl.java index 755304777..425ca5552 100644 --- a/src/main/java/mate.academy/service/impl/ProductServiceImpl.java +++ b/src/main/java/mate.academy/service/impl/ProductServiceImpl.java @@ -2,13 +2,18 @@ import java.util.List; import java.util.stream.Collectors; +import mate.academy.lib.Component; +import mate.academy.lib.Inject; import mate.academy.model.Product; import mate.academy.service.FileReaderService; import mate.academy.service.ProductParser; import mate.academy.service.ProductService; +@Component public class ProductServiceImpl implements ProductService { + @Inject private ProductParser productParser; + @Inject private FileReaderService fileReaderService; @Override