[JDBC 라이브러리 구현하기 - 1단계] 도치(김동흠) 미션 제출합니다.

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

@@ -1,121 +1,65 @@
 package com.techcourse.dao;
 
 import com.techcourse.domain.User;
-import org.springframework.jdbc.core.JdbcTemplate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.jdbc.core.RowMapper;
 
 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 java.util.Optional;
+
 
 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;
+        this.jdbcTemplate = new JdbcTemplate(dataSource);
     }
 
     public UserDao(final JdbcTemplate jdbcTemplate) {
-        this.dataSource = null;
+        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) {}
-        }
+        final String sql = "insert into users (account, password, email) values (?, ?, ?)";
+
+        jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail());
     }
 
     public void update(final User user) {
-        // todo
+        final String sql = "update users set account = ?, password = ?, email = ? where users.id = ?";
+
+        jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail(), user.getId());
     }
 
     public List<User> findAll() {
-        // todo
-        return null;
+        final String sql = "select id, account, password, email from users";
+
+        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) {}
-        }
+    private final RowMapper<User> rowMapper = rs -> (
+            new User(
+                    rs.getLong("id"),
+                    rs.getString("account"),
+                    rs.getString("password"),
+                    rs.getString("email")
+            )
+    );
+
+    public Optional<User> findById(final Long id) {
+        final String sql = "select id, account, password, email from users where id = ?";
+
+        return jdbcTemplate.queryForObject(sql, rowMapper, id);
     }
 
-    public User findByAccount(final String account) {
-        // todo
-        return null;
+    public Optional<User> findByAccount(final String account) {
+        final String sql = "select id, account, password, email from users where users.account = ?";
+
+        return jdbcTemplate.queryForObject(sql, rowMapper, account);
     }
 }

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

@@ -16,7 +16,8 @@ public UserService(final UserDao userDao, final UserHistoryDao userHistoryDao) {
     }
 
     public User findById(final long id) {
-        return userDao.findById(id);
+        return userDao.findById(id)
+                .orElseThrow(() -> new IllegalArgumentException("해당 아이디의 회원이 존재하지 않습니다."));
     }
 
     public void insert(final User user) {

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

@@ -30,15 +30,15 @@ void findAll() {
 
     @Test
     void findById() {
-        final var user = userDao.findById(1L);
+        final var user = userDao.findById(1L).get();
 
         assertThat(user.getAccount()).isEqualTo("gugu");
     }
 
     @Test
     void findByAccount() {
         final var account = "gugu";
-        final var user = userDao.findByAccount(account);
+        final var user = userDao.findByAccount(account).get();
 
         assertThat(user.getAccount()).isEqualTo(account);
     }
@@ -49,20 +49,21 @@ void insert() {
         final var user = new User(account, "password", "[email protected]");
         userDao.insert(user);
 
-        final var actual = userDao.findById(2L);
+        final var actual = userDao.findById(2L).get();
 
         assertThat(actual.getAccount()).isEqualTo(account);
+        assertThat(actual.getEmail()).isEqualTo("[email protected]");
     }
 
     @Test
     void update() {
         final var newPassword = "password99";
-        final var user = userDao.findById(1L);
+        final var user = userDao.findById(1L).get();
         user.changePassword(newPassword);
 
         userDao.update(user);
 
-        final var actual = userDao.findById(1L);
+        final var actual = userDao.findById(1L).get();
 
         assertThat(actual.getPassword()).isEqualTo(newPassword);
     }

jdbc/build.gradle

@@ -14,6 +14,7 @@ dependencies {
     implementation "org.reflections:reflections:0.10.2"
     implementation "org.apache.commons:commons-lang3:3.13.0"
     implementation "ch.qos.logback:logback-classic:1.2.12"
+    implementation "com.h2database:h2:2.2.220"
 
     testImplementation "org.assertj:assertj-core:3.24.2"
     testImplementation "org.junit.jupiter:junit-jupiter-api:5.7.2"

jdbc/src/main/java/org/springframework/jdbc/BadGrammarJdbcException.java

@@ -0,0 +1,13 @@
+package org.springframework.jdbc;
+
+import java.sql.SQLException;
+
+public class BadGrammarJdbcException extends JdbcException {
+    public BadGrammarJdbcException(String msg) {
+        super(msg);
+    }
+
+    public BadGrammarJdbcException(String msg, SQLException ex) {
+        super(msg, ex);
+    }
+}

jdbc/src/main/java/org/springframework/jdbc/CannotGetJdbcConnectionException.java

@@ -2,7 +2,7 @@
 
 import java.sql.SQLException;
 
-public class CannotGetJdbcConnectionException extends RuntimeException {
+public class CannotGetJdbcConnectionException extends JdbcException {
 
     public CannotGetJdbcConnectionException(String msg) {
         super(msg);

jdbc/src/main/java/org/springframework/jdbc/JdbcException.java

@@ -0,0 +1,11 @@
+package org.springframework.jdbc;
+
+public class JdbcException extends RuntimeException {
+    public JdbcException(String message) {
+        super(message);
+    }
+
+    public JdbcException(String message, Throwable cause) {
+        super(message);
+    }
+}

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

@@ -2,16 +2,114 @@
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.jdbc.BadGrammarJdbcException;
+import org.springframework.jdbc.CannotGetJdbcConnectionException;
+import org.springframework.jdbc.JdbcException;
 
 import javax.sql.DataSource;
+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.Optional;
+import java.util.Set;
 
 public class JdbcTemplate {
 
     private static final Logger log = LoggerFactory.getLogger(JdbcTemplate.class);
 
     private final DataSource dataSource;
+    private final SqlExceptionTranslator sqlExceptionTranslator = new SqlExceptionTranslator();
 
     public JdbcTemplate(final DataSource dataSource) {
         this.dataSource = dataSource;
     }
+
+    public int update(String sql, Object... arguments) {
+        try (
+                Connection conn = dataSource.getConnection();
+                PreparedStatement pstmt = StatementCreator.createStatement(conn, sql, arguments)
+        ) {
+            log.debug("query : {}", sql);
+
+            return pstmt.executeUpdate();
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw sqlExceptionTranslator.translateException(e);
+        }
+    }
+
+    public <T> Optional<T> queryForObject(String sql, RowMapper<T> rowMapper, Object... arguments) {
+        try (
+                Connection conn = dataSource.getConnection();
+                PreparedStatement pstmt = StatementCreator.createStatement(conn, sql, arguments);
+                ResultSet rs = pstmt.executeQuery()
+        ) {
+            log.debug("query : {}", sql);
+
+            if (rs.next()) {
+                return Optional.of(rowMapper.mapRow(rs));
+            }
+
+            return Optional.empty();
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw sqlExceptionTranslator.translateException(e);
+        }
+    }
+
+
+    public <T> List<T> query(String sql, RowMapper<T> rowMapper, Object... arguments) {
+        try (
+                Connection conn = dataSource.getConnection();
+                PreparedStatement pstmt = StatementCreator.createStatement(conn, sql, arguments);
+                ResultSet rs = pstmt.executeQuery()
+        ) {
+            log.debug("query : {}", sql);
+
+            List<T> result = new ArrayList<>();
+            while (rs.next()) {
+                result.add(rowMapper.mapRow(rs));
+            }
+
+            return result;
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw sqlExceptionTranslator.translateException(e);
+        }
+    }
+
+    private class SqlExceptionTranslator {
+        private final Set<String> BAD_SQL_GRAMMAR_CODES = Set.of(
+                "07",  // Dynamic SQL error
+                "21",  // Cardinality violation
+                "2A",  // Syntax error direct SQL
+                "37",  // Syntax error dynamic SQL
+                "42",  // General SQL syntax error
+                "65"   // Oracle: unknown identifier
+        );
+
+        private final Set<String> DATA_ACCESS_RESOURCE_FAILURE_CODES = Set.of(
+                "08",  // Connection exception
+                "53",  // PostgreSQL: insufficient resources (e.g. disk full)
+                "54",  // PostgreSQL: program limit exceeded (e.g. statement too complex)
+                "57",  // DB2: out-of-memory exception / database not started
+                "58"   // DB2: unexpected system error
+        );
+
+        private JdbcException translateException(SQLException e) {
+            String sqlState = e.getSQLState();
+            String classCode = sqlState.substring(0, 2);
+            if (DATA_ACCESS_RESOURCE_FAILURE_CODES.contains(classCode)) {
+                throw new CannotGetJdbcConnectionException(e.getMessage(), e);
+            }
+            if (BAD_SQL_GRAMMAR_CODES.contains(classCode)) {
+                throw new BadGrammarJdbcException(e.getMessage(), e);
+            }
+
+            throw new JdbcException(e.getMessage(), e);
+        }
+    }
 }

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

@@ -0,0 +1,9 @@
+package org.springframework.jdbc.core;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+@FunctionalInterface
+public interface RowMapper<T> {
+    T mapRow(ResultSet rs) throws SQLException;
+}