[JDBC 라이브러리 구현하기 - 1단계] 마코(이규성) 미션 제출합니다.

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

@@ -1,121 +1,58 @@
 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;
 
 public class UserDao {
 
     private static final Logger log = LoggerFactory.getLogger(UserDao.class);
 
-    private final DataSource dataSource;
+    private final JdbcTemplate jdbcTemplate;
+
+    private RowMapper<User> rowMapper = rs -> {
+        Long id = rs.getLong("id");
+        String account = rs.getString("account");
+        String password = rs.getString("password");
+        String email = rs.getString("email");
+        return new User(id, account, password, email);
+    };
 
     public UserDao(final DataSource dataSource) {
-        this.dataSource = dataSource;
+        this(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) {}
-        }
+        jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail());
     }
 
     public void update(final User user) {
-        // todo
+        final var sql = "update users set account = ?, password = ?, email = ? where id = ?";
+        jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail(), user.getId());
     }
 
     public List<User> findAll() {
-        // todo
-        return null;
+        final var 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) {}
-        }
+        return jdbcTemplate.queryForObject(sql, rowMapper, 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, rowMapper, account);
     }
 }

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

@@ -5,6 +5,7 @@
 import com.techcourse.support.jdbc.init.DatabasePopulatorUtils;
 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;
 

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

@@ -0,0 +1,4 @@
+package org.springframework.dao;
+
+public class EmptyResultAccessException extends RuntimeException {
+}

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

@@ -0,0 +1,20 @@
+package org.springframework.jdbc.core;
+
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+
+public class ArgumentPreparedStatementSetter implements PreparedStatementSetter{
+
+    private final Object[] args;
+
+    public ArgumentPreparedStatementSetter(Object[] args) {
+        this.args = args;
+    }
+
+    @Override
+    public void setValues(PreparedStatement pstmt) throws SQLException {
+        for (int i = 0; i < args.length; i++) {
+            pstmt.setObject(i + 1, args[i]);
+        }
+    }
+}

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

@@ -2,8 +2,16 @@
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.dao.DataAccessException;
+import org.springframework.dao.EmptyResultAccessException;
 
 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;
 
 public class JdbcTemplate {
 
@@ -14,4 +22,44 @@ public class JdbcTemplate {
     public JdbcTemplate(final DataSource dataSource) {
         this.dataSource = dataSource;
     }
+
+    public <T> T queryForObject(final String sql, final RowMapper<T> rowMapper, final Object... args) {
+        List<T> results = query(sql, rowMapper, args);
+        if (results.isEmpty()) {
+            throw new EmptyResultAccessException();
+        }
+        return results.get(0);
+    }
+
+    public <T> List<T> query(final String sql, final RowMapper<T> rowMapper, final Object... args) {
+        try (Connection conn = dataSource.getConnection();
+             PreparedStatement pstmt = conn.prepareStatement(sql)) {
+            log.debug("query : {}", sql);
+
+            PreparedStatementSetter pstSetter = new ArgumentPreparedStatementSetter(args);
+            pstSetter.setValues(pstmt);
+            ResultSet resultSet = pstmt.executeQuery();
+
+            List<T> results = new ArrayList<>();
+            while (resultSet.next()) {
+                results.add(rowMapper.mapRow(resultSet));
+            }
+            return results;
+        } catch (SQLException e) {
+            throw new DataAccessException(e);
+        }
+    }
+
+    public void update(final String sql, final Object... args) {
+        try (Connection conn = dataSource.getConnection();
+             PreparedStatement pstmt = conn.prepareStatement(sql)) {
+            log.debug("query : {}", sql);
+
+            PreparedStatementSetter pstSetter = new ArgumentPreparedStatementSetter(args);
+            pstSetter.setValues(pstmt);
+            pstmt.executeUpdate();
+        } catch (SQLException e) {
+            throw new DataAccessException(e);
+        }
+    }
 }

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

@@ -0,0 +1,10 @@
+package org.springframework.jdbc.core;
+
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+
+@FunctionalInterface
+public interface PreparedStatementSetter {
+
+    void setValues(PreparedStatement preparedStatement) throws SQLException;
+}

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

@@ -0,0 +1,10 @@
+package org.springframework.jdbc.core;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+@FunctionalInterface
+public interface RowMapper<T> {
+
+    T mapRow(ResultSet rs) throws SQLException;
+}