feat: userService 에서 커넥션 관리를 하지 않도록 TransactionTemplate을 만들음

app/src/main/java/com/techcourse/service/AppUserService.java

@@ -0,0 +1,35 @@
+package com.techcourse.service;
+
+import com.techcourse.dao.UserDao;
+import com.techcourse.dao.UserHistoryDao;
+import com.techcourse.domain.User;
+import com.techcourse.domain.UserHistory;
+
+public class AppUserService implements UserService {
+
+    private final UserDao userDao;
+    private final UserHistoryDao userHistoryDao;
+
+    public AppUserService(final UserDao userDao, final UserHistoryDao userHistoryDao) {
+        this.userDao = userDao;
+        this.userHistoryDao = userHistoryDao;
+    }
+
+    @Override
+    public User findById(final long id) {
+        return userDao.findById(id);
+    }
+
+    @Override
+    public void insert(final User user) {
+        userDao.insert(user);
+    }
+
+    @Override
+    public void changePassword(final long id, final String newPassword, final String createBy) {
+        final var findUser = findById(id);
+        findUser.changePassword(newPassword);
+        userDao.update(findUser);
+        userHistoryDao.log(new UserHistory(findUser, createBy));
+    }
+}

app/src/main/java/com/techcourse/service/TxUserService.java

@@ -0,0 +1,37 @@
+package com.techcourse.service;
+
+import com.techcourse.domain.User;
+import org.springframework.transaction.support.TransactionTemplate;
+
+public class TxUserService implements UserService {
+
+    private final AppUserService userService;
+
+    private final TransactionTemplate transactionTemplate;
+
+    public TxUserService(final AppUserService userService, final TransactionTemplate transactionTemplate) {
+        this.userService = userService;
+        this.transactionTemplate = transactionTemplate;
+    }
+
+    @Override
+    public User findById(final long id) {
+        return userService.findById(id);
+    }
+
+    @Override
+    public void insert(final User user) {
+        transactionTemplate.execute(() -> {
+            userService.insert(user);
+            return null;
+        });
+    }
+
+    @Override
+    public void changePassword(final long id, final String newPassword, final String createBy) {
+        transactionTemplate.execute(() -> {
+            userService.changePassword(id, newPassword, createBy);
+            return null;
+        });
+    }
+}

app/src/main/java/com/techcourse/service/UserService.java

@@ -1,56 +1,11 @@
 package com.techcourse.service;
 
-import com.techcourse.config.DataSourceConfig;
-import com.techcourse.dao.UserDao;
-import com.techcourse.dao.UserHistoryDao;
 import com.techcourse.domain.User;
-import com.techcourse.domain.UserHistory;
-import org.springframework.dao.DataAccessException;
-import org.springframework.jdbc.datasource.DataSourceUtils;
-import org.springframework.transaction.support.TransactionSynchronizationManager;
 
-import javax.sql.DataSource;
-import java.sql.SQLException;
+public interface UserService {
+    User findById(final long id);
 
-public class UserService {
+    void insert(final User user);
 
-    private final UserDao userDao;
-    private final UserHistoryDao userHistoryDao;
-
-    public UserService(final UserDao userDao, final UserHistoryDao userHistoryDao) {
-        this.userDao = userDao;
-        this.userHistoryDao = userHistoryDao;
-    }
-
-    public User findById(final long id) {
-        return userDao.findById(id);
-    }
-
-    public void insert(final User user) {
-        userDao.insert(user);
-    }
-
-    public void changePassword(final long id, final String newPassword, final String createBy) {
-        final var findUser = findById(id);
-
-        final DataSource dataSource = DataSourceConfig.getInstance();
-        final var connection = DataSourceUtils.getConnection(dataSource);
-        try {
-            connection.setAutoCommit(false);
-            findUser.changePassword(newPassword);
-            userDao.update(findUser);
-            userHistoryDao.log(new UserHistory(findUser, createBy));
-            connection.commit();
-        } catch (SQLException e) {
-            try {
-                connection.rollback();
-            } catch (SQLException ex) {
-                throw new DataAccessException(ex);
-            }
-            throw new DataAccessException(e);
-        } finally {
-            DataSourceUtils.releaseConnection(connection, dataSource);
-            TransactionSynchronizationManager.unbindResource(dataSource);
-        }
-    }
+    void changePassword(final long id, final String newPassword, final String createBy);
 }

app/src/test/java/com/techcourse/service/UserServiceTest.java

@@ -9,6 +9,7 @@
 import org.junit.jupiter.api.Test;
 import org.springframework.dao.DataAccessException;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.transaction.support.TransactionTemplate;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -31,7 +32,7 @@ void setUp() {
     @Test
     void testChangePassword() {
         final var userHistoryDao = new UserHistoryDao(jdbcTemplate);
-        final var userService = new UserService(userDao, userHistoryDao);
+        final var userService = new AppUserService(userDao, userHistoryDao);
 
         final var newPassword = "qqqqq";
         final var createBy = "gugu";
@@ -46,7 +47,10 @@ void testChangePassword() {
     void testTransactionRollback() {
         // 트랜잭션 롤백 테스트를 위해 mock으로 교체
         final var userHistoryDao = new MockUserHistoryDao(jdbcTemplate);
-        final var userService = new UserService(userDao, userHistoryDao);
+        // 애플리케이션 서비스
+        final var appUserService = new AppUserService(userDao, userHistoryDao);
+        // 트랜잭션 서비스 추상화
+        final var userService = new TxUserService(appUserService, new TransactionTemplate(DataSourceConfig.getInstance()));
 
         final var newPassword = "newPassword";
         final var createBy = "gugu";

jdbc/src/main/java/org/springframework/transaction/support/TransactionExecutor.java

@@ -0,0 +1,7 @@
+package org.springframework.transaction.support;
+
+@FunctionalInterface
+public interface TransactionExecutor<T> {
+
+    T execute();
+}

jdbc/src/main/java/org/springframework/transaction/support/TransactionTemplate.java

@@ -0,0 +1,58 @@
+package org.springframework.transaction.support;
+
+import org.springframework.dao.DataAccessException;
+import org.springframework.jdbc.datasource.DataSourceUtils;
+
+import javax.sql.DataSource;
+import java.sql.Connection;
+import java.sql.SQLException;
+
+public class TransactionTemplate {
+
+    private final DataSource dataSource;
+
+    public TransactionTemplate(final DataSource dataSource) {
+        this.dataSource = dataSource;
+    }
+
+    public <T> T execute(final TransactionExecutor<T> transactionExecutor) {
+        final var connection = DataSourceUtils.getConnection(dataSource);
+        try {
+            connection.setAutoCommit(false);
+            final T result = transactionExecutor.execute();
+            commit(connection);
+            return result;
+        } catch (SQLException e) {
+            rollback(connection);
+            throw new DataAccessException(e);
+        } finally {
+            turnOnAutoCommit(connection);
+            DataSourceUtils.releaseConnection(connection, dataSource);
+            TransactionSynchronizationManager.unbindResource(dataSource);
+        }
+    }
+
+    private void commit(final Connection connection) {
+        try {
+            connection.commit();
+        } catch (SQLException e) {
+            throw new DataAccessException(e);
+        }
+    }
+
+    private void rollback(final Connection connection) {
+        try {
+            connection.rollback();
+        } catch (SQLException ex) {
+            throw new DataAccessException(ex);
+        }
+    }
+
+    private void turnOnAutoCommit(final Connection connection) {
+        try {
+            connection.commit();
+        } catch (SQLException e) {
+            throw new DataAccessException(e);
+        }
+    }
+}