[JDBC 라이브러리 구현하기 - 2단계] 바론(이소민) 미션 제출합니다.

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

@@ -1,13 +1,15 @@
 package com.techcourse.dao;
 
+import com.techcourse.dao.exception.UserNotExistException;
 import com.techcourse.domain.User;
 import java.util.List;
+import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.core.RowMapper;
 
 public class UserDao {
 
-    private static final RowMapper<User> ROW_MAPPER = (rs, count) ->
+    private static final RowMapper<User> ROW_MAPPER = rs ->
         new User(
             rs.getLong("id"),
             rs.getString("account"),
@@ -42,12 +44,20 @@ public List<User> findAll() {
     public User findById(final Long id) {
         final String sql = "select id, account, password, email from users where id = ?";
 
-        return jdbcTemplate.queryForObject(sql, ROW_MAPPER, id);
+        try {
+            return jdbcTemplate.queryForObject(sql, ROW_MAPPER, id);
+        } catch (EmptyResultDataAccessException e) {
+            throw new UserNotExistException();
+        }
     }
 
     public User findByAccount(final String account) {
         final String sql = "select id, account, password, email from users where account = ?";
 
-        return jdbcTemplate.queryForObject(sql, ROW_MAPPER, account);
+        try {
+            return jdbcTemplate.queryForObject(sql, ROW_MAPPER, account);
+        } catch (EmptyResultDataAccessException e) {
+            throw new UserNotExistException();
+        }
     }
 }

app/src/main/java/com/techcourse/dao/exception/UserNotExistException.java

@@ -0,0 +1,8 @@
+package com.techcourse.dao.exception;
+
+public class UserNotExistException extends RuntimeException {
+
+    public UserNotExistException() {
+        super("존재하지 않는 사용자입니다.");
+    }
+}

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

@@ -1,14 +1,15 @@
 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 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;
@@ -22,6 +23,12 @@ void setup() {
         userDao.insert(user);
     }
 
+    @AfterEach
+    void tearDown() {
+        final JdbcTemplate jdbcTemplate = new JdbcTemplate(DataSourceConfig.getInstance());
+        jdbcTemplate.update("TRUNCATE TABLE `users` RESTART IDENTITY");
+    }
+
     @Test
     void findAll() {
         final var users = userDao.findAll();

jdbc/src/main/java/org/springframework/dao/EmptyDataAccessException.java

@@ -0,0 +1,8 @@
+package org.springframework.dao;
+
+public class EmptyDataAccessException extends DataAccessException {
+
+    public EmptyDataAccessException() {
+        super("조회 결과가 없습니다.");
+    }
+}

jdbc/src/main/java/org/springframework/dao/IncorrectResultSizeDataAccessException.java

@@ -0,0 +1,8 @@
+package org.springframework.dao;
+
+public class IncorrectResultSizeDataAccessException extends DataAccessException {
+
+    public IncorrectResultSizeDataAccessException(final int expected, final int actual) {
+        super(String.format("의도한 것과 다른 개수의 데이터가 조회되었습니다. Expected: %d, Actual: %d", expected, actual));
+    }
+}

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

@@ -9,6 +9,9 @@
 import javax.sql.DataSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.dao.DataAccessException;
+import org.springframework.dao.EmptyDataAccessException;
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
 
 public class JdbcTemplate {
 
@@ -20,60 +23,53 @@ public JdbcTemplate(final DataSource dataSource) {
         this.dataSource = dataSource;
     }
 
-    public <T> List<T> query(final String sql, final RowMapper<T> rowMapper, final Object... args) {
-        try (final Connection connection = dataSource.getConnection();
-            final PreparedStatement pstmt = connection.prepareStatement(sql)) {
-            log.debug("query : {}", sql);
+    public <T> T queryForObject(final String sql, final RowMapper<T> rowMapper, final Object... args) {
+        final List<T> results = query(sql, rowMapper, args);
 
-            setParamsToPreparedStatement(pstmt, args);
+        if (results.size() > 1) {
+            throw new IncorrectResultSizeDataAccessException(1, results.size());
+        }
+        if (results.isEmpty()) {
+            throw new EmptyDataAccessException();
+        }
+
+        return results.get(0);
+    }
 
+    public <T> List<T> query(final String sql, final RowMapper<T> rowMapper, final Object... args) {
+        return executeInternal(sql, pstmt -> {
             final ResultSet resultSet = pstmt.executeQuery();
             final List<T> results = new ArrayList<>();
-            if (resultSet.next()) {
-                results.add(rowMapper.mapRow(resultSet, resultSet.getRow()));
+
+            while (resultSet.next()) {
+                results.add(rowMapper.mapRow(resultSet));
             }
 
             return results;
-        } catch (SQLException e) {
-            throw new RuntimeException(e);
-        }
-    }
-
-    private void setParamsToPreparedStatement(final PreparedStatement pstmt, final Object[] args)
-        throws SQLException
-    {
-        for (int i = 0; i < args.length; i++) {
-            pstmt.setObject(i + 1, args[i]);
-        }
+        }, args);
     }
 
-    public <T> T queryForObject(final String sql, final RowMapper<T> rowMapper, final Object... args) {
-        try (final Connection connection = dataSource.getConnection();
-            final PreparedStatement pstmt = connection.prepareStatement(sql)) {
+    private <T> T executeInternal(final String sql, final QueryExecutor<T> executor, final Object... args) {
+        try (
+            final Connection connection = dataSource.getConnection();
+            final PreparedStatement pstmt = connection.prepareStatement(sql)
+        ) {
             log.debug("query : {}", sql);
-
             setParamsToPreparedStatement(pstmt, args);
 
-            final ResultSet resultSet = pstmt.executeQuery();
-            if (resultSet.next()) {
-                return rowMapper.mapRow(resultSet, resultSet.getRow());
-            }
-            return null;
+            return executor.run(pstmt);
         } catch (SQLException e) {
-            throw new RuntimeException(e);
+            throw new DataAccessException(e);
         }
     }
 
-    public int update(final String sql, final Object... args) {
-        try (final Connection connection = dataSource.getConnection();
-            final PreparedStatement pstmt = connection.prepareStatement(sql)) {
-            log.debug("query : {}", sql);
-
-            setParamsToPreparedStatement(pstmt, args);
-
-            return pstmt.executeUpdate();
-        } catch (SQLException e) {
-            throw new RuntimeException(e);
+    private void setParamsToPreparedStatement(final PreparedStatement pstmt, final Object[] args) throws SQLException {
+        for (int i = 0; i < args.length; i++) {
+            pstmt.setObject(i + 1, args[i]);
         }
     }
+
+    public int update(final String sql, final Object... args) {
+        return executeInternal(sql, PreparedStatement::executeUpdate, args);
+    }
 }

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

@@ -0,0 +1,10 @@
+package org.springframework.jdbc.core;
+
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+
+@FunctionalInterface
+public interface QueryExecutor<T> {
+
+     T run(final PreparedStatement pstmt) throws SQLException;
+}

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

@@ -6,5 +6,5 @@
 @FunctionalInterface
 public interface RowMapper<T> {
 
-    T mapRow(final ResultSet resultSet, final int count) throws SQLException;
+    T mapRow(final ResultSet resultSet) throws SQLException;
 }