[JDBC 라이브러리 구현하기 - 1단계] 하마드(이건회) 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;
 
 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) {}
-        }
+        jdbcTemplate.update(sql, user.getAccount(), user.getPassword(), user.getEmail());
     }
 
     public void update(final User user) {
-        // todo
+        String 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;
+        String sql = "SELECT id, account, password, email FROM users";
+        return jdbcTemplate.query(sql, getUserRowMapper());
     }
 
+
     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,getUserRowMapper(), id);
     }
 
     public User findByAccount(final String account) {
-        // todo
-        return null;
+        String sql = "SELECT id, account, password, email FROM users WHERE account = ?";
+        return jdbcTemplate.queryForObject(sql, getUserRowMapper(), account);
+    }
+
+    private RowMapper<User> getUserRowMapper() {
+        return (rs, rowNum) ->
+                new User(
+                        rs.getLong("id"),
+                        rs.getString("account"),
+                        rs.getString("password"),
+                        rs.getString("email")
+                );
     }
 }

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

@@ -4,6 +4,13 @@
 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.ArrayList;
+import java.util.List;
+import java.util.NoSuchElementException;
 
 public class JdbcTemplate {
 
@@ -14,4 +21,57 @@ public class JdbcTemplate {
     public JdbcTemplate(final DataSource dataSource) {
         this.dataSource = dataSource;
     }
+
+    public void update(String sql, Object... arguments) {
+        try (Connection conn = dataSource.getConnection();
+             PreparedStatement pstmt = conn.prepareStatement(sql)) {
+            log.debug("query : {}", sql);
+            setArguments(pstmt, arguments);
+            pstmt.executeUpdate();
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw new RuntimeException(e);
+        }
+    }
+
+    public <T> T queryForObject(String sql, RowMapper<T> rowMapper, Object... arguments) {
+        try (Connection conn = dataSource.getConnection();
+             PreparedStatement pstmt = conn.prepareStatement(sql)) {
+            setArguments(pstmt, arguments);
+            log.debug("query : {}", sql);
+            try (ResultSet rs = pstmt.executeQuery()) {
+                if (rs.next()) {
+                    return rowMapper.getRow(rs, rs.getRow());
+                }
+            }
+            throw new NoSuchElementException();
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw new RuntimeException(e);
+        }
+    }
+
+    public <T> List<T> query(String sql, RowMapper<T> rowMapper, Object... arguments) {
+        try (Connection conn = dataSource.getConnection();
+             PreparedStatement pstmt = conn.prepareStatement(sql)) {
+            setArguments(pstmt, arguments);
+            log.debug("query : {}", sql);
+            List<T> results = new ArrayList<>();
+            try (ResultSet rs = pstmt.executeQuery()) {
+                while (rs.next()) {
+                    results.add(rowMapper.getRow(rs, rs.getRow()));
+                }
+                return results;
+            }
+        } catch (SQLException e) {
+            log.error(e.getMessage(), e);
+            throw new RuntimeException(e);
+        }
+    }
+
+    private void setArguments(PreparedStatement pstmt, Object[] arguments) throws SQLException {
+        for (int i = 1; i < arguments.length + 1; i++) {
+            pstmt.setObject(i, arguments[i - 1]);
+        }
+    }
 }

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 getRow(ResultSet rs, int rowNum) throws SQLException;
+}