code manipulation : dynamic proxy

code-manipulation/dynamic-proxy/src/main/java/org/example/proxy/BookService.java

@@ -3,4 +3,6 @@ package org.example.proxy;
 public interface BookService {
 
     void rent(Book book);
+
+    void returnBook(Book book);
 }

code-manipulation/dynamic-proxy/src/main/java/org/example/proxy/BookServiceProxy.java

@@ -14,4 +14,9 @@ public class BookServiceProxy implements BookService {
         bookService.rent(book);
         System.out.println("다른기능!!");
     }
+
+    @Override
+    public void returnBook(Book book) {
+
+    }
 }

code-manipulation/dynamic-proxy/src/main/java/org/example/proxy/DefaultBookService.java

@@ -6,4 +6,9 @@ public class DefaultBookService implements BookService{
     public void rent(Book book) {
         System.out.println("rent: " + book.getTitle());
     }
+
+    @Override
+    public void returnBook(Book book) {
+        System.out.println("return: " + book.getTitle());
+    }
 }

code-manipulation/dynamic-proxy/src/test/java/org/example/proxy/BookServiceTest.java

@@ -2,9 +2,28 @@ package org.example.proxy;
 
 import org.junit.Test;
 
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
 public class BookServiceTest {
 
-    BookService bookService = new BookServiceProxy(new DefaultBookService());
+//    BookService bookService = new BookServiceProxy(new DefaultBookService());
+    BookService bookService = (BookService) Proxy.newProxyInstance(
+        BookService.class.getClassLoader(), new Class[]{BookService.class},
+        new InvocationHandler() {
+            BookService bookService = new DefaultBookService();
+            @Override
+            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+                if (method.getName().equals("rent")) {
+                    System.out.println("로깅!!");
+                    Object invoke = method.invoke(bookService, args);
+                    System.out.println("다른기능!!");
+                    return invoke;
+                }
+                return method.invoke(bookService, args);
+            }
+        });
 
     @Test
     public void proxy() {
@@ -13,5 +32,6 @@ public class BookServiceTest {
         book.setTitle("spring");
 
         bookService.rent(book);
+        bookService.returnBook(book);
     }
 }