[JDBC 라이브러리 구현하기 - 4단계] 테오(최우성) 미션 제출합니다.

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

@@ -5,7 +5,6 @@
 import org.springframework.jdbc.core.RowMapper;
 
 import javax.sql.DataSource;
-import java.sql.Connection;
 import java.util.List;
 
 public class UserDao {
@@ -32,11 +31,6 @@ public void insert(final User user) {
         jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail());
     }
 
-    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 void update(final User user) {
         final var sql = "update users set account = ?, password = ?, email = ? where id = ?";
         jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail(), user.getId());

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

@@ -5,8 +5,6 @@
 import org.slf4j.LoggerFactory;
 import org.springframework.jdbc.core.JdbcTemplate;
 
-import java.sql.Connection;
-
 public class UserHistoryDao {
 
     private static final Logger log = LoggerFactory.getLogger(UserHistoryDao.class);
@@ -17,12 +15,12 @@ public UserHistoryDao(final JdbcTemplate jdbcTemplate) {
         this.jdbcTemplate = jdbcTemplate;
     }
 
-    public void log(final Connection connection, final UserHistory userHistory) {
+    public void log(final UserHistory userHistory) {
         final var sql = "insert into user_history (user_id, account, password, email, created_at, created_by)" +
                 " values (?, ?, ?, ?, ?, ?)";
         log.debug("query = {}", sql);
 
-        jdbcTemplate.update(connection, sql, userHistory.getUserId(), userHistory.getAccount(), userHistory.getPassword(),
+        jdbcTemplate.update(sql, userHistory.getUserId(), userHistory.getAccount(), userHistory.getPassword(),
                 userHistory.getEmail(), userHistory.getCreatedAt(), userHistory.getCreateBy());
     }
 }

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/Transaction.java

@@ -0,0 +1,54 @@
+package com.techcourse.service;
+
+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 Transaction implements AutoCloseable {
+
+    private final DataSource dataSource;
+    private final Connection connection;
+
+    private Transaction(final DataSource dataSource, final Connection connection) {
+        this.dataSource = dataSource;
+        this.connection = connection;
+    }
+
+    public static Transaction start(final DataSource dataSource) {
+        try {
+            Connection connection = DataSourceUtils.getConnection(dataSource);
+            connection.setAutoCommit(false);
+            return new Transaction(dataSource, connection);
+        } catch (SQLException e) {
+            throw new DataAccessException(e);
+        }
+    }
+
+    public void commit() throws SQLException {
+        connection.commit();
+    }
+
+    public void rollback() {
+        try {
+            connection.rollback();
+        } catch (SQLException e) {
+            throw new DataAccessException(e);
+        }
+    }
+
+    public void setReadOnly(final boolean readOnly) {
+        try {
+            connection.setReadOnly(readOnly);
+        } catch (SQLException e) {
+            throw new DataAccessException(e);
+        }
+    }
+
+    @Override
+    public void close() {
+        DataSourceUtils.releaseConnection(dataSource);
+    }
+}

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

@@ -0,0 +1,79 @@
+package com.techcourse.service;
+
+import com.techcourse.domain.User;
+import org.springframework.dao.DataAccessException;
+
+import javax.sql.DataSource;
+import java.sql.SQLException;
+import java.util.function.Supplier;
+
+public class TransactionUserService implements UserService {
+
+    private final AppUserService appUserService;
+    private final DataSource dataSource;
+
+    public TransactionUserService(final AppUserService appUserService, final DataSource dataSource) {
+        this.appUserService = appUserService;
+        this.dataSource = dataSource;
+    }
+
+    @Override
+    public User findById(final long id) {
+        return new TransactionExecutor()
+                .setDataSource(dataSource)
+                .setReadOnlyTrue()
+                .executeTransactionWithSupplier(() -> appUserService.findById(id));
+    }
+
+    @Override
+    public void insert(final User user) {
+        new TransactionExecutor()
+                .setDataSource(dataSource)
+                .executeTransactionWithRunnable(() -> appUserService.insert(user));
+    }
+
+    @Override
+    public void changePassword(final long id, final String newPassword, final String createBy) {
+        new TransactionExecutor()
+                .setDataSource(dataSource)
+                .executeTransactionWithRunnable(() -> appUserService.changePassword(id, newPassword, createBy));
+    }
+
+    private static class TransactionExecutor {
+
+        private DataSource dataSource;
+        private boolean readOnly = false;
+
+        private TransactionExecutor setReadOnlyTrue() {
+            this.readOnly = true;
+            return this;
+        }
+
+        private TransactionExecutor setDataSource(final DataSource dataSource) {
+            this.dataSource = dataSource;
+            return this;
+        }
+
+        private void executeTransactionWithRunnable(final Runnable runnable) {
+            executeTransactionWithSupplier(() -> {
+                runnable.run();
+                return null;
+            });
+        }
+
+        private <T> T executeTransactionWithSupplier(final Supplier<T> supplier) {
+            Transaction transaction = Transaction.start(dataSource);
+            transaction.setReadOnly(readOnly);
+            try {
+                T result = supplier.get();
+                transaction.commit();
+                return result;
+            } catch (SQLException | RuntimeException e) {
+                transaction.rollback();
+                throw new DataAccessException(e);
+            } finally {
+                transaction.close();
+            }
+        }
+    }
+}

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

@@ -1,73 +1,12 @@
 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 {
+    User findById(final long id);
 
-    private final UserDao userDao;
-    private final UserHistoryDao userHistoryDao;
+    void insert(final User user);
 
-    private final DataSource dataSource;
-
-    public UserService(UserDao userDao, UserHistoryDao userHistoryDao, 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) {
-        Connection connection = null;
-        try {
-            connection = dataSource.getConnection();
-            connection.setAutoCommit(false);
-
-            final var user = findById(id);
-            user.changePassword(newPassword);
-            userDao.update(connection, user);
-            userHistoryDao.log(connection, new UserHistory(user, createBy));
-
-            connection.commit();
-        } catch (SQLException | RuntimeException e) {
-            tryRollback(connection);
-            throw new DataAccessException(e);
-        } finally {
-            tryCloseConnection(connection);
-        }
-    }
-
-    private void tryRollback(Connection connection) {
-        try {
-            if (connection != null) {
-                connection.rollback();
-            }
-        } catch (SQLException ex) {
-            throw new DataAccessException(ex);
-        }
-    }
-
-    private void tryCloseConnection(Connection connection) {
-        try {
-            if (connection != null) {
-                connection.close();
-            }
-        } catch (SQLException e) {
-            throw new DataAccessException(e);
-        }
-    }
+    void changePassword(final long id, final String newPassword, final String createdBy);
 }

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

@@ -5,16 +5,14 @@
 import org.springframework.dao.DataAccessException;
 import org.springframework.jdbc.core.JdbcTemplate;
 
-import java.sql.Connection;
-
 public class MockUserHistoryDao extends UserHistoryDao {
 
     public MockUserHistoryDao(final JdbcTemplate jdbcTemplate) {
         super(jdbcTemplate);
     }
 
     @Override
-    public void log(final Connection connection, final UserHistory userHistory) {
+    public void log(UserHistory userHistory) {
         throw new DataAccessException();
     }
 }

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

@@ -35,7 +35,8 @@ void setUp() {
     @Test
     void testChangePassword() {
         final var userHistoryDao = new UserHistoryDao(jdbcTemplate);
-        final var userService = new UserService(userDao, userHistoryDao, dataSource);
+        final var appUserService = new AppUserService(userDao, userHistoryDao);
+        final var userService = new TransactionUserService(appUserService, dataSource);
 
         final var newPassword = "qqqqq";
         final var createBy = "gugu";
@@ -50,7 +51,8 @@ void testChangePassword() {
     void testTransactionRollback() {
         // 트랜잭션 롤백 테스트를 위해 mock으로 교체
         final var userHistoryDao = new MockUserHistoryDao(jdbcTemplate);
-        final var userService = new UserService(userDao, userHistoryDao, dataSource);
+        final var appUserService = new AppUserService(userDao, userHistoryDao);
+        final var userService = new TransactionUserService(appUserService, dataSource);
 
         final var newPassword = "newPassword";
         final var createBy = "gugu";

docs/README.md

@@ -5,3 +5,15 @@
   - ThreadLocal을 통해 커넥션 객체 자체를 스레드 변수로 등록하고, 필요한 곳에서 사용하는 방법은 어떨까?
     - 문제는 해결되겠지만 그럼에도 Service에 트랜잭션 관련 코드가 남아 있다.
     - AOP를 사용해야 할 시점이 아닐까?
+
+
+### step 4 기록
+- 트랜잭션 동기화 매니져는 왜 Map 형태로 구현이 되어 있을까?
+  - ThreadLocal의 경우 하나의 스레드에 대한 지역변수처럼 작동한다.
+  - 그렇다면 Map을 사용하는 이유는 하나의 서비스에서 여러 DataSource를 사용할 일을 대비하기 위함이 아닐까?
+
+- 스프링을 사용하지 않는 환경에서 Spring AOP 같은 기능은 어떻게 만들 수 있을까?
+  - 동적으로 런타임에 프록시를 만들고 싶다.
+  - 스프링의 경우 Context로 빈들을 관리하기 때문에 런타임 주입 시 프록시 객체로 주입할 수 있다.
+  - 하지만 스프링을 사용하지 않는 경우에는 `new 객체();` 처럼 선언을 하니 런타임에 프록시로 구현체를 갈아끼울 수 없다.
+  - 객체간 의존관계를 스프링이 설정한다는 점 덕분에 Spring AOP가 가능한게 아닐까?

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

@@ -1,7 +1,6 @@
 package org.springframework.jdbc.core;
 
 import javax.sql.DataSource;
-import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.util.ArrayList;
@@ -16,11 +15,6 @@ public JdbcTemplate(final DataSource dataSource) {
         this.statementAgent = new StatementAgent(dataSource);
     }
 
-    public int update(final Connection connection, final String sql, final Object... args) {
-        StatementCallback<Integer> callback = PreparedStatement::executeUpdate;
-        return statementAgent.service(connection, sql, callback, args);
-    }
-
     public int update(final String sql, final Object... args) {
         StatementCallback<Integer> callback = PreparedStatement::executeUpdate;
         return statementAgent.service(sql, callback, args);