feat: userDao의 조회쿼리 부분 JdbcTemplate으로 리팩터링

README.md

@@ -9,9 +9,9 @@
     - [ ] JdbcTemplate 구현하기
         - [x] 조회기능 구현
         - [x] 쓰기기능 구현
-- [ ] UserDao를 JdbcTemplate을 사용하도록 리팩터링
-    - [ ] findByAccount
-    - [ ] findById
-    - [ ] findAll
+- [x] UserDao를 JdbcTemplate을 사용하도록 리팩터링
+    - [x] findByAccount
+    - [x] findById
+    - [x] findAll
     - [x] update
     - [x] insert

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

@@ -1,32 +1,31 @@
 package com.techcourse.dao;
 
-import com.techcourse.config.DataSourceConfig;
 import com.techcourse.domain.User;
-import java.sql.Connection;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
 import javax.sql.DataSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.jdbc.core.Mapper;
 
 public class UserDao {
 
+    private static final Mapper<User> USER_MAPPER = (rs) -> new User(
+        rs.getLong(1),
+        rs.getString(2),
+        rs.getString(3),
+        rs.getString(4)
+    );
     private static final Logger log = LoggerFactory.getLogger(UserDao.class);
 
-    private final DataSource dataSource;
     private final JdbcTemplate jdbcTemplate;
 
     public UserDao(final DataSource dataSource) {
-        this.dataSource = dataSource;
         this.jdbcTemplate = new JdbcTemplate(dataSource);
     }
 
     public UserDao(final JdbcTemplate jdbcTemplate) {
-        this.dataSource = DataSourceConfig.getInstance();
         this.jdbcTemplate = jdbcTemplate;
     }
 
@@ -44,70 +43,24 @@ public void update(final User user) {
 
     public List<User> findAll() {
         final var sql = "select id, account, password, email from users";
-
-        try (final Connection connection = dataSource.getConnection();
-            final PreparedStatement pstmt = connection.prepareStatement(sql)) {
-            final ResultSet rs = pstmt.executeQuery();
-
-            log.debug("query : {}", sql);
+        return jdbcTemplate.executeQuery(sql, (rs) -> {
             final List<User> users = new ArrayList<>();
-            if (rs.next()) {
-                final User user = extractUser(rs);
-                users.add(user);
+            while (rs.next()) {
+                users.add(USER_MAPPER.map(rs));
             }
             return users;
-        } catch (SQLException e) {
-            log.error(e.getMessage(), e);
-            throw new RuntimeException(e);
-        }
+        });
     }
 
     public User findById(final Long id) {
         final var sql = "select id, account, password, email from users where id = ?";
 
-        try (final Connection connection = dataSource.getConnection();
-            final PreparedStatement pstmt = connection.prepareStatement(sql)) {
-            pstmt.setLong(1, id);
-            final ResultSet rs = pstmt.executeQuery();
-
-            log.debug("query : {}", sql);
-
-            if (rs.next()) {
-                return extractUser(rs);
-            }
-            return null;
-        } catch (SQLException e) {
-            log.error(e.getMessage(), e);
-            throw new RuntimeException(e);
-        }
+        return jdbcTemplate.executeQuery(sql, USER_MAPPER, id);
     }
 
     public User findByAccount(final String account) {
         final var sql = "select id, account, password, email from users where account = ?";
 
-        try (final Connection connection = dataSource.getConnection();
-            final PreparedStatement pstmt = connection.prepareStatement(sql)) {
-            pstmt.setString(1, account);
-            final ResultSet rs = pstmt.executeQuery();
-
-            log.debug("query : {}", sql);
-
-            if (rs.next()) {
-                return extractUser(rs);
-            }
-            return null;
-        } catch (SQLException e) {
-            log.error(e.getMessage(), e);
-            throw new RuntimeException(e);
-        }
-    }
-
-    private static User extractUser(final ResultSet rs) throws SQLException {
-        return new User(
-            rs.getLong(1),
-            rs.getString(2),
-            rs.getString(3),
-            rs.getString(4)
-        );
+        return jdbcTemplate.executeQuery(sql, USER_MAPPER, account);
     }
 }