[JDBC 라이브러리 구현하기 - 4단계] 무민(박무현) 미션 제출합니다. (#533)

* refactor: generator 삭제

* refactor: UserHistory에도 connection 추가

* docs: READEME 업데이트

* feat: Transaction synchronization 적용

* feat: 트랜잭션 서비스 추상화하기

* refactor: try catch 삭제

* chore: 패키지 이동

* refactor: 생성자 수정

* refactor: executor return 값 생성

* refactor: 필요없는 파라미터 제거

* refactor: null 처리 추가

* refactor: TransactionSynchronizationManager 테스트

README.md

@@ -4,3 +4,6 @@
 - [x] 2단계 - 리팩터링
     - 중복 제거
 - [x] 3단계 - Transaction 적용하기
+- [x] 4단계 - Transaction synchronization 적용하기
+  - [x] Transaction synchronization 적용하기
+  - [x] 트랜잭션 서비스 추상화하기

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

@@ -4,7 +4,6 @@
 import org.springframework.dao.RowMapper;
 import org.springframework.jdbc.core.JdbcTemplate;
 
-import java.sql.Connection;
 import java.util.List;
 
 public class UserDao {
@@ -34,12 +33,6 @@ 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 var sql = "update users SET account = ?, password = ?, email = ? where id = ?";
-
-        jdbcTemplate.update(connection, sql, user.getAccount(), user.getPassword(), user.getEmail(), user.getId());
-    }
-
     public List<User> findAll() {
         final var sql = "select * from users";
 

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 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 +1,36 @@
+package com.techcourse.service;
+
+import com.techcourse.domain.User;
+import org.springframework.transaction.support.TransactionalExecutor;
+
+public class TxUserService implements UserService {
+
+    private final UserService userService;
+    private final TransactionalExecutor transactionalExecutor;
+
+    public TxUserService(final UserService userService, final TransactionalExecutor transactionalExecutor) {
+        this.userService = userService;
+        this.transactionalExecutor = transactionalExecutor;
+    }
+
+    @Override
+    public User findById(final long id) {
+        return userService.findById(id);
+    }
+
+    @Override
+    public void insert(final User user) {
+        userService.insert(user);
+    }
+
+    // override 대상인 메서드는 userService의 메서드를 그대로 위임(delegate)한다.
+    @Override
+    public void changePassword(final long id, final String newPassword, final String createBy) {
+        transactionalExecutor.execute(
+                () -> {
+                    userService.changePassword(id, newPassword, createBy);
+                    return null;
+                }
+        );
+    }
+}

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

@@ -1,52 +1,10 @@
 package com.techcourse.service;
 
-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 javax.sql.DataSource;
-import java.sql.Connection;
-import java.sql.SQLException;
+public interface UserService {
 
-public class UserService {
-
-    private final UserDao userDao;
-    private final UserHistoryDao userHistoryDao;
-    private final DataSource dataSource;
-
-    public UserService(final UserDao userDao, final UserHistoryDao userHistoryDao, final DataSource dataSource) {
-        this.userDao = userDao;
-        this.userHistoryDao = userHistoryDao;
-        this.dataSource = dataSource;
-    }
-
-    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) {
-        try (final Connection connection = dataSource.getConnection())  {
-            try {
-                connection.setAutoCommit(false);
-
-                final var user = findById(id);
-                user.changePassword(newPassword);
-                userDao.update(connection, user);
-                userHistoryDao.log(new UserHistory(user, createBy));
-
-                connection.commit();
-            } catch (Exception e) {
-                connection.rollback();
-                throw new DataAccessException(e);
-            }
-        } catch (SQLException e) {
-            throw new DataAccessException(e);
-        }
-    }
+    User findById(final long id);
+    void insert(final User user);
+    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.TransactionalExecutor;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -31,13 +32,13 @@ void setUp() {
     @Test
     void testChangePassword() {
         final var userHistoryDao = new UserHistoryDao(jdbcTemplate);
-        final var userService = new UserService(userDao, userHistoryDao, DataSourceConfig.getInstance());
+        final var appUserService = new AppUserService(userDao, userHistoryDao);
 
         final var newPassword = "qqqqq";
         final var createBy = "gugu";
-        userService.changePassword(1L, newPassword, createBy);
+        appUserService.changePassword(1L, newPassword, createBy);
 
-        final var actual = userService.findById(1L);
+        final var actual = appUserService.findById(1L);
 
         assertThat(actual.getPassword()).isEqualTo(newPassword);
     }
@@ -46,11 +47,14 @@ void testChangePassword() {
     void testTransactionRollback() {
         // 트랜잭션 롤백 테스트를 위해 mock으로 교체
         final var userHistoryDao = new MockUserHistoryDao(jdbcTemplate);
-        final var userService = new UserService(userDao, userHistoryDao, DataSourceConfig.getInstance());
+        // 애플리케이션 서비스
+        final var appUserService = new AppUserService(userDao, userHistoryDao);
+        // 트랜잭션 서비스 추상화
+        final var userService = new TxUserService(appUserService,
+                new TransactionalExecutor(DataSourceConfig.getInstance()));
 
         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));

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

@@ -5,7 +5,6 @@
 import org.springframework.exception.WrongResultSizeException;
 
 import javax.sql.DataSource;
-import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
@@ -30,15 +29,6 @@ public int update(final String sql, final Object... parameters) {
         );
     }
 
-    public int update(final Connection connection, final String sql, final Object... parameters) {
-        return preparedStatementExecutor.execute(
-                connection,
-                PreparedStatement::executeUpdate,
-                sql,
-                parameters
-        );
-    }
-
     public <T> List<T> query(final RowMapper<T> rowMapper, final String sql, final Object... parameters) {
         return preparedStatementExecutor.execute(
                 preparedStatement -> findQueryResults(rowMapper, preparedStatement),

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

@@ -3,6 +3,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.dao.DataAccessException;
+import org.springframework.jdbc.datasource.DataSourceUtils;
 
 import javax.sql.DataSource;
 import java.sql.Connection;
@@ -24,22 +25,7 @@ public <T> T execute(
             final String sql,
             final Object... parameters
     ) {
-        try (final Connection connection = dataSource.getConnection();
-             final PreparedStatement preparedStatement = generatePreparedStatement(connection, sql, parameters)
-        ) {
-            return preparedStatementProcessor.process(preparedStatement);
-        } catch (final SQLException e) {
-            log.error(e.getMessage(), e);
-            throw new DataAccessException(e);
-        }
-    }
-
-    public <T> T execute(
-            final Connection connection,
-            final PreparedStatementProcessor<T> preparedStatementProcessor,
-            final String sql,
-            final Object... parameters
-    ) {
+        final Connection connection = DataSourceUtils.getConnection(dataSource);
         try (
              final PreparedStatement preparedStatement = generatePreparedStatement(connection, sql, parameters)
         ) {
@@ -54,16 +40,12 @@ private PreparedStatement generatePreparedStatement(
             final Connection connection,
             final String sql,
             final Object... parameters
-    ) {
-        try {
-            log.debug("query : {}", sql);
-            final PreparedStatement preparedStatement = connection.prepareStatement(sql);
+    ) throws SQLException {
+        log.debug("query : {}", sql);
+        final PreparedStatement preparedStatement = connection.prepareStatement(sql);
 
-            setParameters(preparedStatement, parameters);
-            return preparedStatement;
-        } catch (SQLException e) {
-            throw new DataAccessException(e);
-        }
+        setParameters(preparedStatement, parameters);
+        return preparedStatement;
     }
 
     private void setParameters(final PreparedStatement pstmt, final Object[] parameters) throws SQLException {

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

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

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

@@ -2,6 +2,7 @@
 
 import javax.sql.DataSource;
 import java.sql.Connection;
+import java.util.HashMap;
 import java.util.Map;
 
 public abstract class TransactionSynchronizationManager {
@@ -11,13 +12,31 @@ public abstract class TransactionSynchronizationManager {
     private TransactionSynchronizationManager() {}
 
     public static Connection getResource(DataSource key) {
-        return null;
+        if (resources.get() == null) {
+            return null;
+        }
+        if (key == null) {
+            throw new IllegalArgumentException("Key must not be null");
+        }
+        return resources.get().get(key);
     }
 
     public static void bindResource(DataSource key, Connection value) {
+        if (value == null) {
+            throw new IllegalArgumentException("Value must not be null");
+        }
+        if (resources.get() == null) {
+            resources.set(new HashMap<>());
+        }
+        final Map<DataSource, Connection> map = resources.get();
+        map.put(key, value);
     }
 
     public static Connection unbindResource(DataSource key) {
-        return null;
+        if (resources.get() == null) {
+            throw new IllegalStateException("resource is Empty");
+        }
+        final Map<DataSource, Connection> map = resources.get();
+        return map.remove(key);
     }
 }

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

@@ -0,0 +1,41 @@
+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 TransactionalExecutor {
+
+    private final DataSource dataSource;
+
+    public TransactionalExecutor(final DataSource dataSource) {
+        this.dataSource = dataSource;
+    }
+
+    public <T> T execute(BusinessLogicProcessor<T> businessLogicProcessor) {
+        final Connection connection = DataSourceUtils.getConnection(dataSource);
+        try {
+            connection.setAutoCommit(false);
+            final T result = businessLogicProcessor.process();
+            connection.commit();
+            return result;
+        } catch (Exception e) {
+            rollbackAndThrowException(connection);
+            throw new DataAccessException(e);
+        } finally {
+            DataSourceUtils.releaseConnection(connection, dataSource);
+            TransactionSynchronizationManager.unbindResource(dataSource);
+        }
+    }
+
+    private void rollbackAndThrowException(final Connection connection) {
+        try {
+            connection.rollback();
+        } catch (SQLException ex) {
+            throw new DataAccessException(ex);
+        }
+    }
+}