[3단계 - JDBC 라이브러리 구현하기] 페드로(류형욱) 미션 제출합니다. (#850)

* chore(UserServiceTest): 테스트 코드의 `@Disabled` 삭제

* feat(TransactionManager): 트랜잭션을 관리할 객체 생성

* feat(UserService): 사용자 비밀번호 변경 로직에 트랜잭션 적용

* refactor(JdbcTemplate): 오버로딩된 update() 메서드의 호출 계층 구조 설정

* style(JdbcTemplate): 메서드 순서 변경

* refactor(ThrowingConsumer): 인터페이스 선언 위치 변경

* refactor(JdbcTemplate): update 메서드의 시그니처 추가 지원

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

@@ -3,6 +3,7 @@
 import com.interface21.jdbc.core.JdbcTemplate;
 import com.interface21.jdbc.core.RowMapper;
 import com.techcourse.domain.User;
+import java.sql.Connection;
 import java.util.List;
 import javax.sql.DataSource;
 import org.slf4j.Logger;
@@ -34,6 +35,12 @@ public void insert(User user) {
         jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail());
     }
 
+    public void updateUsingExplicitConnection(User user, Connection connection) {
+        String sql = "UPDATE users SET account = ?, password = ?, email = ? where id = ?";
+        logSql(sql);
+        jdbcTemplate.update(connection, sql, user.getAccount(), user.getPassword(), user.getEmail(), user.getId());
+    }
+
     public void update(final User user) {
         String sql = "UPDATE users SET account = ?, password = ?, email = ? WHERE id = ?";
         logSql(sql);

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

@@ -3,6 +3,7 @@
 import com.interface21.jdbc.core.JdbcTemplate;
 import com.interface21.jdbc.core.RowMapper;
 import com.techcourse.domain.UserHistory;
+import java.sql.Connection;
 import javax.sql.DataSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -31,7 +32,7 @@ public UserHistoryDao(final DataSource dataSource) {
 
     public void log(UserHistory userHistory) {
         String sql = "INSERT INTO user_history (user_id, account, password, email, created_at, created_by) VALUES (?, ?, ?, ?, ?, ?)";
-        log.debug("query : {}", sql);
+        logSql(sql);
 
         jdbcTemplate.update(
                 sql,
@@ -40,9 +41,23 @@ public void log(UserHistory userHistory) {
         );
     }
 
+    public void logUsingExplicitConnection(UserHistory userHistory, Connection connection) {
+        String sql = "INSERT INTO user_history (user_id, account, password, email, created_at, created_by) VALUES (?, ?, ?, ?, ?, ?)";
+        logSql(sql);
+        jdbcTemplate.update(
+                connection, sql,
+                userHistory.getUserId(), userHistory.getAccount(), userHistory.getPassword(),
+                userHistory.getEmail(), userHistory.getCreatedAt(), userHistory.getCreateBy()
+        );
+    }
+
     public UserHistory findById(Long id) {
         String sql = "SELECT id, user_id, account, password, email, created_at, created_by FROM user_history WHERE id = ?";
-        log.debug("query : {}", sql);
+        logSql(sql);
         return jdbcTemplate.queryForObject(sql, ROW_MAPPER, id);
     }
+
+    private void logSql(String sql) {
+        log.debug("query : {}", sql);
+    }
 }

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

@@ -1,32 +1,40 @@
 package com.techcourse.service;
 
+import com.interface21.jdbc.transaction.TransactionManager;
 import com.techcourse.dao.UserDao;
 import com.techcourse.dao.UserHistoryDao;
 import com.techcourse.domain.User;
 import com.techcourse.domain.UserHistory;
+import java.sql.Connection;
 
 public class UserService {
 
+    private final TransactionManager txManager;
     private final UserDao userDao;
     private final UserHistoryDao userHistoryDao;
 
-    public UserService(final UserDao userDao, final UserHistoryDao userHistoryDao) {
+    public UserService(TransactionManager txManager, UserDao userDao, UserHistoryDao userHistoryDao) {
+        this.txManager = txManager;
         this.userDao = userDao;
         this.userHistoryDao = userHistoryDao;
     }
 
-    public User findById(final long id) {
+    public User findById(long id) {
         return userDao.findById(id);
     }
 
-    public void insert(final User user) {
+    public void insert(User user) {
         userDao.insert(user);
     }
 
-    public void changePassword(final long id, final String newPassword, final String createBy) {
+    public void changePassword(long id, String newPassword, String createBy) {
+        txManager.executeTransactionOf(conn -> changePasswordTx(conn, id, newPassword, createBy));
+    }
+
+    private void changePasswordTx(Connection connection, long id, String newPassword, String createBy) {
         final var user = findById(id);
         user.changePassword(newPassword);
-        userDao.update(user);
-        userHistoryDao.log(new UserHistory(user, createBy));
+        userDao.updateUsingExplicitConnection(user, connection);
+        userHistoryDao.logUsingExplicitConnection(new UserHistory(user, createBy), connection);
     }
 }

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

@@ -4,6 +4,7 @@
 import com.techcourse.domain.UserHistory;
 import com.interface21.dao.DataAccessException;
 import com.interface21.jdbc.core.JdbcTemplate;
+import java.sql.Connection;
 
 public class MockUserHistoryDao extends UserHistoryDao {
 
@@ -12,7 +13,7 @@ public MockUserHistoryDao(final JdbcTemplate jdbcTemplate) {
     }
 
     @Override
-    public void log(final UserHistory userHistory) {
+    public void logUsingExplicitConnection(UserHistory userHistory, Connection connection) {
         throw new DataAccessException();
     }
 }

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

@@ -1,39 +1,42 @@
 package com.techcourse.service;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import com.interface21.dao.DataAccessException;
+import com.interface21.jdbc.core.JdbcTemplate;
+import com.interface21.jdbc.transaction.TransactionManager;
 import com.techcourse.config.DataSourceConfig;
 import com.techcourse.dao.UserDao;
 import com.techcourse.dao.UserHistoryDao;
 import com.techcourse.domain.User;
 import com.techcourse.support.jdbc.init.DatabasePopulatorUtils;
-import com.interface21.dao.DataAccessException;
-import com.interface21.jdbc.core.JdbcTemplate;
+import javax.sql.DataSource;
 import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
-import static org.assertj.core.api.Assertions.assertThat;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-
-@Disabled
 class UserServiceTest {
 
+    private TransactionManager txManager;
     private JdbcTemplate jdbcTemplate;
     private UserDao userDao;
 
     @BeforeEach
     void setUp() {
-        this.jdbcTemplate = new JdbcTemplate(DataSourceConfig.getInstance());
-        this.userDao = new UserDao(jdbcTemplate);
+        DataSource dataSource = DataSourceConfig.getInstance();
+        txManager = new TransactionManager(dataSource);
+        jdbcTemplate = new JdbcTemplate(dataSource);
+        userDao = new UserDao(jdbcTemplate);
 
-        DatabasePopulatorUtils.execute(DataSourceConfig.getInstance());
-        final var user = new User("gugu", "password", "[email protected]");
+        DatabasePopulatorUtils.execute(dataSource);
+        User user = new User("gugu", "password", "[email protected]");
         userDao.insert(user);
     }
 
     @Test
     void testChangePassword() {
         final var userHistoryDao = new UserHistoryDao(jdbcTemplate);
-        final var userService = new UserService(userDao, userHistoryDao);
+        final var userService = new UserService(txManager, userDao, userHistoryDao);
 
         final var newPassword = "qqqqq";
         final var createBy = "gugu";
@@ -48,7 +51,7 @@ void testChangePassword() {
     void testTransactionRollback() {
         // 트랜잭션 롤백 테스트를 위해 mock으로 교체
         final var userHistoryDao = new MockUserHistoryDao(jdbcTemplate);
-        final var userService = new UserService(userDao, userHistoryDao);
+        final var userService = new UserService(txManager, userDao, userHistoryDao);
 
         final var newPassword = "newPassword";
         final var createBy = "gugu";

jdbc/src/main/java/com/interface21/jdbc/core/JdbcTemplate.java

@@ -21,11 +21,23 @@ public JdbcTemplate(final DataSource dataSource) {
         this.dataSource = dataSource;
     }
 
+    public int update(QueryConnectionHolder queryConnectionHolder, PreparedStatementSetter preparedStatementSetter) {
+        try {
+            PreparedStatement preparedStatement = queryConnectionHolder.getAsPreparedStatement();
+            preparedStatementSetter.setValues(preparedStatement);
+            return preparedStatement.executeUpdate();
+        } catch (SQLException e) {
+            throw new DataAccessException("Update 실패", e);
+        }
+    }
+
+    public int update(Connection connection, String sql, Object... args) {
+        return update(new QueryConnectionHolder(connection, sql), new PreparedStatementArgumentsSetter(args));
+    }
+
     public int update(String sql, PreparedStatementSetter psSetter) {
-        try (Connection connection = dataSource.getConnection();
-             PreparedStatement ps = connection.prepareStatement(sql)) {
-            psSetter.setValues(ps);
-            return ps.executeUpdate();
+        try (Connection connection = dataSource.getConnection()) {
+             return update(new QueryConnectionHolder(connection, sql), psSetter);
         } catch (SQLException e) {
             throw new DataAccessException("Update 실패", e);
         }
@@ -35,11 +47,6 @@ public int update(String sql, Object... args) {
         return update(sql, new PreparedStatementArgumentsSetter(args));
     }
 
-    public <T> T queryForObject(String sql, RowMapper<T> rowMapper, Object... args) {
-        List<T> query = query(sql, rowMapper, args);
-        return query.isEmpty() ? null : query.getLast();
-    }
-
     public <T> List<T> query(String sql, PreparedStatementSetter psSetter, RowMapper<T> rowMapper) {
         try (Connection connection = dataSource.getConnection();
              PreparedStatement ps = connection.prepareStatement(sql)) {
@@ -54,6 +61,11 @@ public <T> List<T> query(String sql, RowMapper<T> rowMapper, Object... args) {
         return query(sql, new PreparedStatementArgumentsSetter(args), rowMapper);
     }
 
+    public <T> T queryForObject(String sql, RowMapper<T> rowMapper, Object... args) {
+        List<T> query = query(sql, rowMapper, args);
+        return query.isEmpty() ? null : query.getLast();
+    }
+
     private <T> List<T> retrieveRow(RowMapper<T> rowMapper, PreparedStatement ps) throws SQLException {
         List<T> results = new ArrayList<>();
         try (ResultSet rs = ps.executeQuery()) {

jdbc/src/main/java/com/interface21/jdbc/core/QueryConnectionHolder.java

@@ -0,0 +1,26 @@
+package com.interface21.jdbc.core;
+
+import com.interface21.dao.DataAccessException;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+import java.util.Objects;
+
+public class QueryConnectionHolder {
+
+    private final String query;
+    private final Connection connection;
+
+    public QueryConnectionHolder(Connection connection, String query) {
+        this.connection = Objects.requireNonNull(connection);
+        this.query = Objects.requireNonNull(query);
+    }
+
+    public PreparedStatement getAsPreparedStatement() {
+        try {
+            return connection.prepareStatement(query);
+        } catch (SQLException e) {
+            throw new DataAccessException("PreparedStatement 생성 실패", e);
+        }
+    }
+}

jdbc/src/main/java/com/interface21/jdbc/transaction/TransactionManager.java

@@ -0,0 +1,53 @@
+package com.interface21.jdbc.transaction;
+
+import com.interface21.dao.DataAccessException;
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.logging.Logger;
+import javax.sql.DataSource;
+
+public class TransactionManager {
+
+    private static final Logger log = Logger.getLogger(TransactionManager.class.getName());
+
+    private final DataSource dataSource;
+
+    public TransactionManager(DataSource dataSource) {
+        this.dataSource = dataSource;
+    }
+
+    public void executeTransactionOf(TransactionalFunction callback) {
+        Connection connection = null;
+        boolean shouldThrow = false;
+        try {
+            connection = dataSource.getConnection();
+            connection.setAutoCommit(false);
+            callback.execute(connection);
+            connection.commit();
+        } catch (Exception e) {
+            gracefulShutdown(connection, Connection::rollback);
+            shouldThrow = true;
+        } finally {
+            gracefulShutdown(connection, Connection::close);
+        }
+        if (shouldThrow) {
+            throw new DataAccessException("트랜잭션 실행 중 문제가 발생했습니다. 트랜잭션은 롤백됩니다.");
+        }
+    }
+
+    private void gracefulShutdown(Connection connection, ThrowingConsumer<Connection> connectionConsumer) {
+        try {
+            connectionConsumer.accept(connection);
+        } catch (NullPointerException e) {
+            log.warning("Connection을 찾을 수 없습니다.");
+        } catch (SQLException e) {
+            throw new DataAccessException(e.getMessage(), e);
+        }
+    }
+
+    @FunctionalInterface
+    private interface ThrowingConsumer<T> {
+
+        void accept(T connection) throws SQLException;
+    }
+}

jdbc/src/main/java/com/interface21/jdbc/transaction/TransactionalFunction.java

@@ -0,0 +1,10 @@
+package com.interface21.jdbc.transaction;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+
+@FunctionalInterface
+public interface TransactionalFunction {
+
+    void execute(Connection connection) throws SQLException;
+}

jdbc/src/test/java/com/interface21/jdbc/transaction/TransactionManagerTest.java

@@ -0,0 +1,57 @@
+package com.interface21.jdbc.transaction;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
+import com.interface21.dao.DataAccessException;
+import java.sql.Connection;
+import java.sql.SQLException;
+import javax.sql.DataSource;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+class TransactionManagerTest {
+
+    private DataSource dataSource;
+    private Connection connection;
+
+    @BeforeEach
+    void setUp() throws SQLException {
+        dataSource = mock(DataSource.class);
+        connection = mock(Connection.class);
+        given(dataSource.getConnection()).willReturn(connection);
+    }
+
+    @Test
+    @DisplayName("트랜잭션 실행 중 예외가 발생하면 롤백된다.")
+    void rollbackOnException() throws SQLException {
+        // given
+        TransactionManager txManager = new TransactionManager(dataSource);
+        TransactionalFunction txFunction = conn -> {
+            throw new SQLException();
+        };
+
+        // when & then
+        assertThatThrownBy(() -> txManager.executeTransactionOf(txFunction))
+                .isInstanceOf(DataAccessException.class);
+        verify(connection).rollback();
+        verify(connection, never()).commit();
+        verify(connection).close();
+    }
+
+    @Test
+    @DisplayName("예외 없는 트랜잭션은 정상적으로 커밋된다.")
+    void commitOnNoException() throws SQLException {
+        TransactionManager txManager = new TransactionManager(dataSource);
+        TransactionalFunction txFunction = conn -> {};
+        txManager.executeTransactionOf(txFunction);
+
+        verify(connection).commit();
+        verify(connection, never()).rollback();
+        verify(connection).close();
+    }
+}