[JDBC 라이브러리 구현하기 - 4단계] 가비 미션 제출합니다. (#523)

* refactor: 메서드명 수정

* fix: DataSourceUtil과 TransactionSynchronizationManager를 이용하여 Connection을 사용하도록 변경

* refactor: findById의 반환 타입에서 Optional 제거

* feat: DataSourceUtils 내 TransactionSynchronizationManger 자원 해제 추가

* feat: TransactionManager 구현

* feat: UserService 추상화

* feat: AppUserService, TxUserService 구현

* test: testTransactionRollback() 메서드를 LMS에 있는 내용으로 변경

* fix : jdbctemplate에서 connection 해제하는 부분 제거

* refactor: Connection 선언부를 try-catch 밖으로 분리

* refactor: TranactionManager의 메서드 반환값을 void로 변경

* chore: final 키워드 통일

* fix: TransactionSynchronizationManager.unbindResource(dataSource) 중복 호출 제거

* fix: 불필요한 static 제거

* feat: DatabasePopulatorUtils도 DataSoureUtils를 이용해 connection을 가지고 오도록 변경

* refactor: service에서 TransactionManager를 주입받도록 변경

* refactor: 템플릿 콜백 패턴 적용

* refactor: 함수형 인터페이스 실행 메서드 분리

* refactor: DatasourcePopulatorUtils connection 해제 추가

app/src/main/java/com/techcourse/dao/UserDao.java

@@ -1,6 +1,5 @@
 package com.techcourse.dao;
 
-import java.sql.Connection;
 import java.util.List;
 import java.util.Optional;
 
@@ -42,14 +41,6 @@ public void update(final User user) {
         jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail(), user.getId());
     }
 
-    public void update(final Connection connection, final User user) {
-        final String sql = "update users set account = ?, password = ? , email = ? where id = ?";
-
-        log.debug("query : {}", sql);
-
-        jdbcTemplate.update(connection, sql, user.getAccount(), user.getPassword(), user.getEmail(), user.getId());
-    }
-
     public Optional<User> findById(final Long id) {
         final String sql = "select id, account, password, email from users where id = ?";
 

app/src/main/java/com/techcourse/dao/UserHistoryDao.java

@@ -1,7 +1,5 @@
 package com.techcourse.dao;
 
-import java.sql.Connection;
-
 import com.techcourse.domain.UserHistory;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -32,19 +30,4 @@ public void log(final UserHistory userHistory) {
         log.debug("query : {}", sql);
     }
 
-    public void log(final Connection connection, final UserHistory userHistory) {
-        final var sql = "insert into user_history (user_id, account, password, email, created_at, created_by) values (?, ?, ?, ?, ?, ?)";
-
-        jdbcTemplate.update(connection, sql,
-                userHistory.getUserId(),
-                userHistory.getAccount(),
-                userHistory.getPassword(),
-                userHistory.getEmail(),
-                userHistory.getCreatedAt(),
-                userHistory.getCreateBy()
-        );
-
-        log.debug("query : {}", sql);
-    }
-
 }

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

@@ -0,0 +1,36 @@
+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).orElseThrow();
+    }
+
+    @Override
+    public void insert(final User user) {
+        userDao.insert(user);
+    }
+
+    @Override
+    public void changePassword(final long id, final String newPassword, final String createBy) {
+        final User user = findById(id);
+        user.changePassword(newPassword);
+        userDao.update(user);
+        userHistoryDao.log(new UserHistory(user, createBy));
+    }
+
+}

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

@@ -0,0 +1,31 @@
+package com.techcourse.service;
+
+import com.techcourse.domain.User;
+import org.springframework.transaction.TransactionManager;
+
+public class TxUserService implements UserService {
+
+    private final UserService userService;
+    private final TransactionManager transactionManager;
+
+    public TxUserService(final UserService userService, final TransactionManager transactionManager) {
+        this.userService = userService;
+        this.transactionManager = transactionManager;
+    }
+
+    @Override
+    public User findById(final long id) {
+        return transactionManager.runForObject(() -> userService.findById(id));
+    }
+
+    @Override
+    public void insert(final User user) {
+        transactionManager.run(() -> userService.insert(user));
+    }
+
+    @Override
+    public void changePassword(final long id, final String newPassword, final String createBy) {
+        transactionManager.run(() -> userService.changePassword(id, newPassword, createBy));
+    }
+
+}

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

@@ -1,60 +1,13 @@
 package com.techcourse.service;
 
-import java.sql.Connection;
-import java.sql.SQLException;
-import java.util.Optional;
-
-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;
-
-public class UserService {
-
-    private final UserDao userDao;
-    private final UserHistoryDao userHistoryDao;
-
-    public UserService(final UserDao userDao, final UserHistoryDao userHistoryDao) {
-        this.userDao = userDao;
-        this.userHistoryDao = userHistoryDao;
-    }
-
-    public Optional<User> findById(final long id) {
-        return userDao.findById(id);
-    }
 
-    public void insert(final User user) {
-        userDao.insert(user);
-    }
+public interface UserService {
 
-    public void changePassword(final long id, final String newPassword, final String createBy) {
-        Connection connection = null;
-        try {
-            connection = DataSourceConfig.getInstance().getConnection();
-            connection.setAutoCommit(false);
+    User findById(final long id);
 
-            final User user = findById(id).orElseThrow();
-            user.changePassword(newPassword);
-            userDao.update(connection, user);
-            userHistoryDao.log(connection, new UserHistory(user, createBy));
+    void insert(final User user);
 
-            connection.commit();
-        } catch (final SQLException e) {
-            try {
-                connection.rollback();
-            } catch (final SQLException rollbackException) {
-                throw new DataAccessException(rollbackException);
-            }
-            throw new DataAccessException(e);
-        } finally {
-            try {
-                connection.close();
-            } catch (final SQLException e) {
-                throw new DataAccessException(e);
-            }
-        }
-    }
+    void changePassword(final long id, final String newPassword, final String createBy);
 
 }

app/src/main/java/com/techcourse/support/jdbc/init/DatabasePopulatorUtils.java

@@ -4,6 +4,8 @@
 import org.slf4j.LoggerFactory;
 
 import javax.sql.DataSource;
+import org.springframework.jdbc.datasource.DataSourceUtils;
+
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
@@ -15,8 +17,11 @@ public class DatabasePopulatorUtils {
 
     private static final Logger log = LoggerFactory.getLogger(DatabasePopulatorUtils.class);
 
+    private DatabasePopulatorUtils() {
+    }
+
     public static void execute(final DataSource dataSource) {
-        Connection connection = null;
+        Connection connection = DataSourceUtils.getConnection(dataSource);
         Statement statement = null;
         try {
             final var url = DatabasePopulatorUtils.class.getClassLoader().getResource("schema.sql");
@@ -39,8 +44,7 @@ public static void execute(final DataSource dataSource) {
                     connection.close();
                 }
             } catch (SQLException ignored) {}
+            DataSourceUtils.releaseConnection(connection, dataSource);
         }
     }
-
-    private DatabasePopulatorUtils() {}
 }

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

@@ -14,7 +14,7 @@ public MockUserHistoryDao(final JdbcTemplate jdbcTemplate) {
     }
 
     @Override
-    public void log(final Connection connection, final UserHistory userHistory) {
+    public void log(final UserHistory userHistory) {
         throw new DataAccessException();
     }
 

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

@@ -9,18 +9,21 @@
 import org.junit.jupiter.api.Test;
 import org.springframework.dao.DataAccessException;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.transaction.TransactionManager;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 class UserServiceTest {
 
     private JdbcTemplate jdbcTemplate;
+    private TransactionManager transactionManager;
     private UserDao userDao;
 
     @BeforeEach
     void setUp() {
         this.jdbcTemplate = new JdbcTemplate(DataSourceConfig.getInstance());
+        this.transactionManager = new TransactionManager(DataSourceConfig.getInstance());
         this.userDao = new UserDao(jdbcTemplate);
 
         DatabasePopulatorUtils.execute(DataSourceConfig.getInstance());
@@ -31,31 +34,35 @@ void setUp() {
     @Test
     void testChangePassword() {
         final UserHistoryDao userHistoryDao = new UserHistoryDao(jdbcTemplate);
-        final UserService userService = new UserService(userDao, userHistoryDao);
+        final UserService userService = new AppUserService(userDao, userHistoryDao);
 
         final String newPassword = "qqqqq";
         final String createBy = "gugu";
         userService.changePassword(1L, newPassword, createBy);
 
-        final User actual = userService.findById(1L).orElseThrow();
+        final User actual = userService.findById(1L);
 
         assertThat(actual.getPassword()).isEqualTo(newPassword);
     }
 
     @Test
     void testTransactionRollback() {
         // 트랜잭션 롤백 테스트를 위해 mock으로 교체
-        final UserHistoryDao userHistoryDao = new MockUserHistoryDao(jdbcTemplate);
-        final UserService userService = new UserService(userDao, userHistoryDao);
+        final var userHistoryDao = new MockUserHistoryDao(jdbcTemplate);
+        // 애플리케이션 서비스
+        final UserService appUserService = new AppUserService(userDao, userHistoryDao);
+        // 트랜잭션 서비스 추상화
+        final UserService txUserService = new TxUserService(appUserService, transactionManager);
 
-        final String newPassword = "newPassword";
-        final String createBy = "gugu";
+        final var newPassword = "newPassword";
+        final var createBy = "gugu";
         // 트랜잭션이 정상 동작하는지 확인하기 위해 의도적으로 MockUserHistoryDao에서 예외를 발생시킨다.
         assertThrows(DataAccessException.class,
-                () -> userService.changePassword(1L, newPassword, createBy));
+                () -> txUserService.changePassword(1L, newPassword, createBy));
 
-        final User actual = userService.findById(1L).orElseThrow();
+        final var actual = txUserService.findById(1L);
 
         assertThat(actual.getPassword()).isNotEqualTo(newPassword);
     }
+
 }

jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java

@@ -12,6 +12,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.dao.DataAccessException;
+import org.springframework.jdbc.datasource.DataSourceUtils;
 
 public class JdbcTemplate {
 
@@ -23,26 +24,6 @@ public JdbcTemplate(final DataSource dataSource) {
         this.dataSource = dataSource;
     }
 
-    public void update(final Connection connection, final String sql, final Object... elements) {
-        execute(connection, sql, PreparedStatement::executeUpdate, elements);
-    }
-
-    private <T> T execute(
-            final Connection connection,
-            final String sql,
-            final PreparedStatementExecutor<T> executor,
-            final Object... elements
-    ) {
-        try (final PreparedStatement preparedStatement = connection.prepareStatement(sql)) {
-            setElements(elements, preparedStatement);
-
-            return executor.action(preparedStatement);
-        } catch (final SQLException e) {
-            log.error(e.getMessage(), e);
-            throw new DataAccessException(e);
-        }
-    }
-
     public void update(final String sql, final Object... elements) {
         execute(sql, PreparedStatement::executeUpdate, elements);
     }
@@ -52,9 +33,8 @@ private <T> T execute(
             final PreparedStatementExecutor<T> executor,
             final Object... elements
     ) {
-        try (final Connection connection = dataSource.getConnection();
-             final PreparedStatement preparedStatement = connection.prepareStatement(sql)
-        ) {
+        final Connection connection = DataSourceUtils.getConnection(dataSource);
+        try  (final PreparedStatement preparedStatement = connection.prepareStatement(sql)) {
             setElements(elements, preparedStatement);
 
             return executor.action(preparedStatement);

jdbc/src/main/java/org/springframework/jdbc/datasource/DataSourceUtils.java

@@ -29,6 +29,7 @@ public static Connection getConnection(DataSource dataSource) throws CannotGetJd
 
     public static void releaseConnection(Connection connection, DataSource dataSource) {
         try {
+            TransactionSynchronizationManager.unbindResource(dataSource);
             connection.close();
         } catch (SQLException ex) {
             throw new CannotGetJdbcConnectionException("Failed to close JDBC Connection");