3장: 변하는 것과 변하지 않는 것 - 템플릿 메소드 패턴 적용

상속을 통해 확장해서 사용해보자.
하지만, 컴파일 시점에 관계가 결정되기 때문에 굉장히 유연하지 못한 구조가 된다.

src/main/java/com/toby/tobyspring/user/dao/DaoFactory.java

@@ -10,7 +10,7 @@
 public class DaoFactory {
     @Bean
     public UserDao userDao() {
-        UserDao userDao = new UserDao();
+        UserDao userDao = new UserDaoDeleteAll();
         userDao.setDataSource(dataSource());
         return userDao;
     }

src/main/java/com/toby/tobyspring/user/dao/UserDao.java

@@ -9,7 +9,7 @@
 import java.sql.ResultSet;
 import java.sql.SQLException;
 
-public class UserDao {
+public abstract class UserDao {
     private DataSource dataSource;
 
     public void setDataSource(DataSource dataSource) {
@@ -100,7 +100,7 @@ public void deleteAll() throws SQLException {
 
         try {
             connection = dataSource.getConnection();
-            preparedStatement = connection.prepareStatement("delete from users");
+            preparedStatement = this.makeStatement(connection);
             preparedStatement.executeUpdate();
         } catch (SQLException e) {
             throw e;
@@ -119,4 +119,6 @@ public void deleteAll() throws SQLException {
             }
         }
     }
+
+    protected abstract PreparedStatement makeStatement(Connection connection) throws SQLException;
 }

src/main/java/com/toby/tobyspring/user/dao/UserDaoDeleteAll.java

@@ -0,0 +1,12 @@
+package com.toby.tobyspring.user.dao;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+
+public class UserDaoDeleteAll extends UserDao {
+    @Override
+    protected PreparedStatement makeStatement(Connection connection) throws SQLException {
+        return connection.prepareStatement("delete from users");
+    }
+}

src/test/java/com/toby/tobyspring/user/dao/UserDaoTest.java

@@ -5,15 +5,8 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.extension.ExtendWith;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.context.ApplicationContext;
-import org.springframework.context.support.GenericXmlApplicationContext;
 import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.jdbc.datasource.SingleConnectionDataSource;
-import org.springframework.test.annotation.DirtiesContext;
-import org.springframework.test.context.ContextConfiguration;
-import org.springframework.test.context.junit.jupiter.SpringExtension;
 
 import javax.sql.DataSource;
 import java.sql.SQLException;
@@ -33,7 +26,7 @@ public class UserDaoTest {
 
     @BeforeEach
     public void setup() {
-        userDao = new UserDao();
+        userDao = new UserDaoDeleteAll();
         DataSource dataSource = new SingleConnectionDataSource("jdbc:oracle:thin:@localhost:1521:orcl", "dahye", "test", true);
         userDao.setDataSource(dataSource);