From 705a4dcbd33b55a10d98a02157abf4f65eba3a4c Mon Sep 17 00:00:00 2001
From: haerong22 <haerong22@naver.com>
Date: Sat, 20 Feb 2021 23:37:52 +0900
Subject: [PATCH] =?UTF-8?q?code=20manipulation=20:=20reflection(=EA=B0=84?=
 =?UTF-8?q?=EB=8B=A8=ED=95=9C=20DI=20=ED=94=84=EB=A0=88=EC=9E=84=EC=9B=8C?=
 =?UTF-8?q?=ED=81=AC=20=EB=A7=8C=EB=93=A4=EA=B8=B0)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 code-manipulation/di-example/pom.xml          | 36 +++++++++++++++++++
 .../java/org/example/AccountRepository.java   |  8 +++++
 .../main/java/org/example/AccountService.java | 14 ++++++++
 .../src/main/java/org/example/App.java        | 15 ++++++++
 .../src/test/java/org/example/AppTest.java    | 20 +++++++++++
 .../java/org/example/di/ContainerService.java | 30 ++++++++++++++++
 .../src/main/java/org/example/di/Inject.java  |  9 +++++
 .../java/org/example/di/BookRepository.java   |  4 +++
 .../test/java/org/example/di/BookService.java |  7 ++++
 .../org/example/di/ContainerServiceTest.java  | 21 +++++++++++
 10 files changed, 164 insertions(+)
 create mode 100644 code-manipulation/di-example/pom.xml
 create mode 100644 code-manipulation/di-example/src/main/java/org/example/AccountRepository.java
 create mode 100644 code-manipulation/di-example/src/main/java/org/example/AccountService.java
 create mode 100644 code-manipulation/di-example/src/main/java/org/example/App.java
 create mode 100644 code-manipulation/di-example/src/test/java/org/example/AppTest.java
 create mode 100644 code-manipulation/reflection-example/src/main/java/org/example/di/ContainerService.java
 create mode 100644 code-manipulation/reflection-example/src/main/java/org/example/di/Inject.java
 create mode 100644 code-manipulation/reflection-example/src/test/java/org/example/di/BookRepository.java
 create mode 100644 code-manipulation/reflection-example/src/test/java/org/example/di/BookService.java
 create mode 100644 code-manipulation/reflection-example/src/test/java/org/example/di/ContainerServiceTest.java

diff --git a/code-manipulation/di-example/pom.xml b/code-manipulation/di-example/pom.xml
new file mode 100644
index 00000000..8643fce1
--- /dev/null
+++ b/code-manipulation/di-example/pom.xml
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.example</groupId>
+  <artifactId>di-example</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+  <name>di-example</name>
+  <!-- FIXME change it to the project's website -->
+  <url>http://www.example.com</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>11</maven.compiler.target>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.11</version>
+      <scope>test</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>org.example</groupId>
+      <artifactId>reflection-example</artifactId>
+      <version>1.0-SNAPSHOT</version>
+    </dependency>
+  </dependencies>
+
+</project>
diff --git a/code-manipulation/di-example/src/main/java/org/example/AccountRepository.java b/code-manipulation/di-example/src/main/java/org/example/AccountRepository.java
new file mode 100644
index 00000000..91072935
--- /dev/null
+++ b/code-manipulation/di-example/src/main/java/org/example/AccountRepository.java
@@ -0,0 +1,8 @@
+package org.example;
+
+public class AccountRepository {
+
+    public void save() {
+        System.out.println("Repo.save()");
+    }
+}
diff --git a/code-manipulation/di-example/src/main/java/org/example/AccountService.java b/code-manipulation/di-example/src/main/java/org/example/AccountService.java
new file mode 100644
index 00000000..171c2998
--- /dev/null
+++ b/code-manipulation/di-example/src/main/java/org/example/AccountService.java
@@ -0,0 +1,14 @@
+package org.example;
+
+import org.example.di.Inject;
+
+public class AccountService {
+
+    @Inject
+    AccountRepository accountRepository;
+
+    public void join() {
+        System.out.println("Service.join()");
+        accountRepository.save();
+    }
+}
diff --git a/code-manipulation/di-example/src/main/java/org/example/App.java b/code-manipulation/di-example/src/main/java/org/example/App.java
new file mode 100644
index 00000000..cd0e2589
--- /dev/null
+++ b/code-manipulation/di-example/src/main/java/org/example/App.java
@@ -0,0 +1,15 @@
+package org.example;
+
+import org.example.di.ContainerService;
+
+/**
+ * Hello world!
+ *
+ */
+public class App {
+    public static void main( String[] args ) {
+
+        AccountService accountService = ContainerService.getObject(AccountService.class);
+        accountService.join();
+    }
+}
diff --git a/code-manipulation/di-example/src/test/java/org/example/AppTest.java b/code-manipulation/di-example/src/test/java/org/example/AppTest.java
new file mode 100644
index 00000000..6a1d2d79
--- /dev/null
+++ b/code-manipulation/di-example/src/test/java/org/example/AppTest.java
@@ -0,0 +1,20 @@
+package org.example;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+/**
+ * Unit test for simple App.
+ */
+public class AppTest 
+{
+    /**
+     * Rigorous Test :-)
+     */
+    @Test
+    public void shouldAnswerWithTrue()
+    {
+        assertTrue( true );
+    }
+}
diff --git a/code-manipulation/reflection-example/src/main/java/org/example/di/ContainerService.java b/code-manipulation/reflection-example/src/main/java/org/example/di/ContainerService.java
new file mode 100644
index 00000000..a6b8e47c
--- /dev/null
+++ b/code-manipulation/reflection-example/src/main/java/org/example/di/ContainerService.java
@@ -0,0 +1,30 @@
+package org.example.di;
+
+import java.util.Arrays;
+
+public class ContainerService {
+
+    public static <T> T getObject(Class<T> classType) {
+        T instance = createInstance(classType);
+        Arrays.stream(classType.getDeclaredFields()).forEach(field -> {
+            if (field.getAnnotation(Inject.class) != null) {
+                Object fieldInstance = createInstance(field.getType());
+                field.setAccessible(true);
+                try {
+                    field.set(instance, fieldInstance);
+                } catch (IllegalAccessException e) {
+                    throw new RuntimeException();
+                }
+            }
+        });
+        return instance;
+    }
+
+    private static <T> T createInstance(Class<T> classType)  {
+        try {
+            return classType.getConstructor().newInstance();
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+}
diff --git a/code-manipulation/reflection-example/src/main/java/org/example/di/Inject.java b/code-manipulation/reflection-example/src/main/java/org/example/di/Inject.java
new file mode 100644
index 00000000..da5e3603
--- /dev/null
+++ b/code-manipulation/reflection-example/src/main/java/org/example/di/Inject.java
@@ -0,0 +1,9 @@
+package org.example.di;
+
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Inject {
+}
diff --git a/code-manipulation/reflection-example/src/test/java/org/example/di/BookRepository.java b/code-manipulation/reflection-example/src/test/java/org/example/di/BookRepository.java
new file mode 100644
index 00000000..94569f3d
--- /dev/null
+++ b/code-manipulation/reflection-example/src/test/java/org/example/di/BookRepository.java
@@ -0,0 +1,4 @@
+package org.example.di;
+
+public class BookRepository {
+}
diff --git a/code-manipulation/reflection-example/src/test/java/org/example/di/BookService.java b/code-manipulation/reflection-example/src/test/java/org/example/di/BookService.java
new file mode 100644
index 00000000..a251afdb
--- /dev/null
+++ b/code-manipulation/reflection-example/src/test/java/org/example/di/BookService.java
@@ -0,0 +1,7 @@
+package org.example.di;
+
+public class BookService {
+
+    @Inject
+    BookRepository bookRepository;
+}
diff --git a/code-manipulation/reflection-example/src/test/java/org/example/di/ContainerServiceTest.java b/code-manipulation/reflection-example/src/test/java/org/example/di/ContainerServiceTest.java
new file mode 100644
index 00000000..7841cf3b
--- /dev/null
+++ b/code-manipulation/reflection-example/src/test/java/org/example/di/ContainerServiceTest.java
@@ -0,0 +1,21 @@
+package org.example.di;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class ContainerServiceTest {
+
+    @Test
+    public void getObject_BookRepository() {
+        BookRepository bookRepository = ContainerService.getObject(BookRepository.class);
+        assertNotNull(bookRepository);
+    }
+
+    @Test
+    public void getObject_BookService() {
+        BookService bookService = ContainerService.getObject(BookService.class);
+        assertNotNull(bookService);
+        assertNotNull(bookService.bookRepository);
+    }
+}
\ No newline at end of file