[JDBC 라이브러리 구현하기 - 1단계] 쥬니(전정준) 미션 제출합니다.

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

@@ -1,121 +1,72 @@
 package com.techcourse.dao;
 
 import com.techcourse.domain.User;
-import org.springframework.jdbc.core.JdbcTemplate;
+import java.util.List;
+import javax.sql.DataSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
-import javax.sql.DataSource;
-import java.sql.Connection;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-import java.util.List;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.jdbc.core.RowMapper;
 
 public class UserDao {
 
     private static final Logger log = LoggerFactory.getLogger(UserDao.class);
-
-    private final DataSource dataSource;
-
-    public UserDao(final DataSource dataSource) {
-        this.dataSource = dataSource;
+    private static final RowMapper<User> rowMapper =
+            rs -> new User(
+                    rs.getLong("id"),
+                    rs.getString("account"),
+                    rs.getString("password"),
+                    rs.getString("email")
+            );
+
+    private final JdbcTemplate jdbcTemplate;
+
+    public UserDao(DataSource dataSource) {
+        this.jdbcTemplate = new JdbcTemplate(dataSource);
     }
 
-    public UserDao(final JdbcTemplate jdbcTemplate) {
-        this.dataSource = null;
+    public UserDao(JdbcTemplate jdbcTemplate) {
+        this.jdbcTemplate = jdbcTemplate;
     }
 
-    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) {}
-        }
+    public void insert(User user) {
+        String sql = "insert into users (account, password, email) values (?, ?, ?)";
+
+        log.debug("query : {}", sql);
+
+        jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail());
     }
 
-    public void update(final User user) {
-        // todo
+    public void update(User user) {
+        String sql = "UPDATE users SET account = ?, password = ?, email = ? WHERE id = ?";
+
+        log.debug("query : {}", sql);
+
+        jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail(), user.getId());
     }
 
     public List<User> findAll() {
-        // todo
-        return null;
+        String sql = "SELECT * from users";
+
+        log.debug("query : {}", sql);
+
+        return jdbcTemplate.query(sql, rowMapper);
     }
 
-    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) {}
-        }
+    public User findById(Long id) {
+        String sql = "select * from users where id = ?";
+
+        log.debug("query : {}", sql);
+
+        return jdbcTemplate.queryForObject(sql, rowMapper, id);
     }
 
-    public User findByAccount(final String account) {
-        // todo
-        return null;
+    public User findByAccount(String account) {
+        String sql = "select * from users where account = ?";
+
+        log.debug("query : {}", sql);
+
+        return jdbcTemplate.queryForObject(sql, rowMapper, account);
     }
+
 }

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

@@ -1,68 +1,74 @@
 package com.techcourse.dao;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 import com.techcourse.config.DataSourceConfig;
 import com.techcourse.domain.User;
 import com.techcourse.support.jdbc.init.DatabasePopulatorUtils;
+import java.util.List;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-
-import static org.assertj.core.api.Assertions.assertThat;
+import org.springframework.jdbc.core.JdbcTemplate;
 
 class UserDaoTest {
 
+    private final JdbcTemplate jdbcTemplate = new JdbcTemplate(DataSourceConfig.getInstance());
     private UserDao userDao;
 
     @BeforeEach
     void setup() {
         DatabasePopulatorUtils.execute(DataSourceConfig.getInstance());
 
+        jdbcTemplate.update("TRUNCATE TABLE users RESTART IDENTITY");
         userDao = new UserDao(DataSourceConfig.getInstance());
-        final var user = new User("gugu", "password", "[email protected]");
+
+        User user = new User("gugu", "password", "[email protected]");
         userDao.insert(user);
     }
 
     @Test
     void findAll() {
-        final var users = userDao.findAll();
+        List<User> users = userDao.findAll();
 
         assertThat(users).isNotEmpty();
     }
 
     @Test
     void findById() {
-        final var user = userDao.findById(1L);
+        userDao.insert(new User("gugu", "password", "[email protected]"));
+        User user = userDao.findById(1L);
 
         assertThat(user.getAccount()).isEqualTo("gugu");
     }
 
     @Test
     void findByAccount() {
-        final var account = "gugu";
-        final var user = userDao.findByAccount(account);
+        String account = "gugu";
+        User user = userDao.findByAccount(account);
 
         assertThat(user.getAccount()).isEqualTo(account);
     }
 
     @Test
     void insert() {
-        final var account = "insert-gugu";
-        final var user = new User(account, "password", "[email protected]");
+        String account = "insert-gugu";
+        User user = new User(account, "password", "[email protected]");
         userDao.insert(user);
 
-        final var actual = userDao.findById(2L);
+        User actual = userDao.findById(2L);
 
         assertThat(actual.getAccount()).isEqualTo(account);
     }
 
     @Test
     void update() {
-        final var newPassword = "password99";
-        final var user = userDao.findById(1L);
+        String newPassword = "password99";
+        User user = userDao.findById(1L);
         user.changePassword(newPassword);
 
         userDao.update(user);
 
-        final var actual = userDao.findById(1L);
+        User actual = userDao.findById(1L);
 
         assertThat(actual.getPassword()).isEqualTo(newPassword);
     }

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

@@ -1,17 +1,93 @@
 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 java.util.NoSuchElementException;
+import javax.sql.DataSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import javax.sql.DataSource;
-
 public class JdbcTemplate {
 
     private static final Logger log = LoggerFactory.getLogger(JdbcTemplate.class);
 
     private final DataSource dataSource;
 
-    public JdbcTemplate(final DataSource dataSource) {
+    public JdbcTemplate(DataSource dataSource) {
         this.dataSource = dataSource;
     }
+
+    public void update(String sql, Object... args) {
+        try (Connection conn = dataSource.getConnection();
+                PreparedStatement pstmt = conn.prepareStatement(sql)) {
+
+            initializePstmtArgs(pstmt, args);
+
+            pstmt.executeUpdate();
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw new RuntimeException(e);
+        }
+    }
+
+    private void initializePstmtArgs(PreparedStatement pstmt, Object... args) throws SQLException {
+        for (int i = 0; i < args.length; i++) {
+            pstmt.setObject(i + 1, args[i]);
+        }
+    }
+
+    public <T> List<T> query(String sql, RowMapper<T> rowMapper) {
+        try (Connection conn = dataSource.getConnection();
+                PreparedStatement pstmt = conn.prepareStatement(sql);
+                ResultSet rs = pstmt.executeQuery()) {
+
+            List<T> results = new ArrayList<>();
+
+            while (rs.next()) {
+                T result = rowMapper.mapRow(rs);
+
+                results.add(result);
+            }
+
+            return results;
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw new RuntimeException(e);
+        }
+    }
+
+    public <T> T queryForObject(String sql, RowMapper<T> rowMapper, Object... args) {
+        try (Connection conn = dataSource.getConnection();
+                PreparedStatement pstmt = getQueryPstmtForObject(sql, conn, args);
+                ResultSet rs = pstmt.executeQuery()) {
+
+            if (rs.next()) {
+                T result = rowMapper.mapRow(rs);
+
+                if (rs.next()) {
+                    throw new IllegalArgumentException("Incorrect Result Size ! Result  must be one");
+                }
+
+                return result;
+            }
+
+            throw new NoSuchElementException("Incorrect Result Size ! Result is null");
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw new RuntimeException(e);
+        }
+    }
+
+    private PreparedStatement getQueryPstmtForObject(String sql, Connection conn, Object... args) throws SQLException {
+        PreparedStatement pstmt = conn.prepareStatement(sql);
+
+        initializePstmtArgs(pstmt, args);
+
+        return pstmt;
+    }
+
 }

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

@@ -0,0 +1,11 @@
+package org.springframework.jdbc.core;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+@FunctionalInterface
+public interface RowMapper<T> {
+
+    T mapRow(ResultSet resultSet) throws SQLException;
+
+}