[JDBC 라이브러리 구현하기 - 1단계] 로지(윤가영) 미션 제출합니다.

README.md

@@ -1 +1,10 @@
 # JDBC 라이브러리 구현하기
+
+개발자는 SQL 쿼리 작성, 쿼리에 전달할 인자, SELECT 구문일 경우
+조회 결과를 추출하는 것만 집중할 수 있도록 라이브러리를 만들자.
+
+## 힌트
+
+- 리팩터링은 UserDaoTest를 활용해 진행한다.
+- 중복을 제거하기 위한 라이브러리는 JdbcTemplate 클래스에 구현한다.
+- DataSource는 DataSourceConfig 클래스의 getInstance() 메서드를 호출하면 된다.

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

@@ -1,6 +1,8 @@
 package com.techcourse.dao;
 
+import com.techcourse.config.DataSourceConfig;
 import com.techcourse.domain.User;
+import java.util.ArrayList;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -11,111 +13,50 @@
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.List;
+import org.springframework.jdbc.core.RowMapper;
 
 public class UserDao {
 
     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;
-    }
 
     public UserDao(final JdbcTemplate jdbcTemplate) {
-        this.dataSource = null;
+        this.jdbcTemplate = new JdbcTemplate(DataSourceConfig.getInstance());
     }
 
     public void insert(final User user) {
         final var sql = "insert into users (account, password, email) values (?, ?, ?)";
-
-        Connection conn = null;
-        PreparedStatement pstmt = null;
-        try {
-            conn = dataSource.getConnection();
-            pstmt = conn.prepareStatement(sql);
-
-            log.debug("query : {}", sql);
-
-            pstmt.setString(1, user.getAccount());
-            pstmt.setString(2, user.getPassword());
-            pstmt.setString(3, user.getEmail());
-            pstmt.executeUpdate();
-        } catch (SQLException e) {
-            log.error(e.getMessage(), e);
-            throw new RuntimeException(e);
-        } finally {
-            try {
-                if (pstmt != null) {
-                    pstmt.close();
-                }
-            } catch (SQLException ignored) {}
-
-            try {
-                if (conn != null) {
-                    conn.close();
-                }
-            } catch (SQLException ignored) {}
-        }
+        jdbcTemplate.execute(sql, user.getAccount(), user.getPassword(), user.getEmail());
     }
 
     public void update(final User user) {
-        // todo
+        final var sql = "update users set password = ?, email = ?, account = ? where id = ?";
+        jdbcTemplate.execute(sql, user.getPassword(), user.getEmail(), user.getAccount(), user.getId());
     }
 
     public List<User> findAll() {
-        // todo
-        return null;
+        final var sql = "select id, account, password, email from users";
+        return jdbcTemplate.query(sql, (rs, rowNum) -> new User(rs.getLong("id"),
+                rs.getString("account"),
+                rs.getString("password"),
+                rs.getString("email")));
     }
 
     public User findById(final Long id) {
         final var sql = "select id, account, password, email from users where id = ?";
-
-        Connection conn = null;
-        PreparedStatement pstmt = null;
-        ResultSet rs = null;
-        try {
-            conn = dataSource.getConnection();
-            pstmt = conn.prepareStatement(sql);
-            pstmt.setLong(1, id);
-            rs = pstmt.executeQuery();
-
-            log.debug("query : {}", sql);
-
-            if (rs.next()) {
-                return new User(
-                        rs.getLong(1),
-                        rs.getString(2),
-                        rs.getString(3),
-                        rs.getString(4));
-            }
-            return null;
-        } catch (SQLException e) {
-            log.error(e.getMessage(), e);
-            throw new RuntimeException(e);
-        } finally {
-            try {
-                if (rs != null) {
-                    rs.close();
-                }
-            } catch (SQLException ignored) {}
-
-            try {
-                if (pstmt != null) {
-                    pstmt.close();
-                }
-            } catch (SQLException ignored) {}
-
-            try {
-                if (conn != null) {
-                    conn.close();
-                }
-            } catch (SQLException ignored) {}
-        }
+        return jdbcTemplate.queryForObject(sql, (rs, rowNum) -> new User(rs.getLong("id"),
+                rs.getString("account"),
+                rs.getString("password"),
+                rs.getString("email")), id);
     }
 
     public User findByAccount(final String account) {
-        // todo
-        return null;
+        final var sql = "select id, account, password, email from users where account = ?";
+        return jdbcTemplate.queryForObject(sql, (rs, rowNum) -> new User(rs.getLong("id"),
+                rs.getString("account"),
+                rs.getString("password"),
+                rs.getString("email")), account);
     }
 }

app/src/test/java/com/techcourse/dao/UserDaoTest.java

@@ -3,24 +3,32 @@
 import com.techcourse.config.DataSourceConfig;
 import com.techcourse.domain.User;
 import com.techcourse.support.jdbc.init.DatabasePopulatorUtils;
+import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.springframework.jdbc.core.JdbcTemplate;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 class UserDaoTest {
 
     private UserDao userDao;
+    private JdbcTemplate jdbcTemplate;
 
     @BeforeEach
     void setup() {
         DatabasePopulatorUtils.execute(DataSourceConfig.getInstance());
-
-        userDao = new UserDao(DataSourceConfig.getInstance());
+        jdbcTemplate = new JdbcTemplate(DataSourceConfig.getInstance());
+        userDao = new UserDao(jdbcTemplate);
         final var user = new User("gugu", "password", "[email protected]");
         userDao.insert(user);
     }
 
+    @AfterEach
+    void tearDown() {
+        jdbcTemplate.execute("truncate table users restart identity");
+    }
+
     @Test
     void findAll() {
         final var users = userDao.findAll();
@@ -66,4 +74,5 @@ void update() {
 
         assertThat(actual.getPassword()).isEqualTo(newPassword);
     }
+
 }

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

@@ -1,5 +1,11 @@
 package org.springframework.jdbc.core;
 
+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 org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -14,4 +20,53 @@ public class JdbcTemplate {
     public JdbcTemplate(final DataSource dataSource) {
         this.dataSource = dataSource;
     }
+
+    public void execute(String sql, Object... parameters) {
+        try (final Connection conn = dataSource.getConnection();
+             final PreparedStatement pstmt = conn.prepareStatement(sql)) {
+            log.debug("query : {}", sql);
+
+            for (int i = 0; i < parameters.length; i++) {
+                pstmt.setObject(i + 1, parameters[i]);
+            }
+
+            pstmt.executeUpdate();
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw new RuntimeException(e);
+        }
+    }
+
+    public <T> T queryForObject(String sql, RowMapper<T> rowMapper, Object... params) {
+        List<T> results = query(sql, rowMapper, params);
+        if (results.size() > 1) {
+            throw new RuntimeException("too many result. expected 1 but was " + results.size());
+        }
+        if (results.isEmpty()) {
+            throw new RuntimeException("no result");
+        }
+        return results.get(0);
+    }
+
+    public <T> List<T> query(String sql, RowMapper<T> rowMapper, Object... parameters) {
+        try (final Connection conn = dataSource.getConnection();
+             final PreparedStatement pstmt = conn.prepareStatement(sql)) {
+            for (int i = 0; i < parameters.length; i++) {
+                pstmt.setObject(i + 1, parameters[i]);
+            }
+            ResultSet rs = pstmt.executeQuery();
+
+            log.debug("query : {}", sql);
+
+            final List<T> results = new ArrayList<>();
+            while (rs.next()) {
+                results.add(rowMapper.mapRow(rs, rs.getRow()));
+            }
+            return results;
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw new RuntimeException(e);
+        }
+    }
+
 }

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

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.jdbc.core;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+/**
+ * An interface used by {@link JdbcTemplate} for mapping rows of a
+ * {@link ResultSet} on a per-row basis. Implementations of this
+ * interface perform the actual work of mapping each row to a result object,
+ * but don't need to worry about exception handling.
+ * {@link SQLException SQLExceptions} will be caught and handled
+ * by the calling JdbcTemplate.
+ *
+ * <p>Typically used either for {@link JdbcTemplate}'s query methods
+ * or for out parameters of stored procedures. RowMapper objects are
+ * typically stateless and thus reusable; they are an ideal choice for
+ * implementing row-mapping logic in a single place.
+ *
+ * <p>Alternatively, consider subclassing
+ * {@code jdbc.object} package: Instead of working with separate
+ * JdbcTemplate and RowMapper objects, you can build executable query
+ * objects (containing row-mapping logic) in that style.
+ *
+ * @author Thomas Risberg
+ * @author Juergen Hoeller
+ * @param <T> the result type
+ * @see JdbcTemplate
+ */
+@FunctionalInterface
+public interface RowMapper<T> {
+
+	/**
+	 * Implementations must implement this method to map each row of data
+	 * in the ResultSet. This method should not call {@code next()} on
+	 * the ResultSet; it is only supposed to map values of the current row.
+	 * @param rs the ResultSet to map (pre-initialized for the current row)
+	 * @param rowNum the number of the current row
+	 * @return the result object for the current row (maybe {@code null})
+	 * @throws SQLException if an SQLException is encountered getting
+	 * column values (that is, there's no need to catch SQLException)
+	 */
+	T mapRow(ResultSet rs, int rowNum) throws SQLException;
+
+}