Yjs2952/step2

src/main/java/next/dao/JdbcTemplate.java

@@ -0,0 +1,73 @@
+package next.dao;
+
+import core.jdbc.ConnectionManager;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+
+class JdbcTemplate {
+
+    List<Object> query(String sql, PreparedStatementSetter setter, RowMapper rowMapper) throws SQLException {
+
+        ResultSet rs = null;
+        try (Connection con = ConnectionManager.getConnection();
+             PreparedStatement pstmt = con.prepareStatement(sql);
+        ) {
+            setter.values(pstmt);
+
+            rs = pstmt.executeQuery();
+
+            List<Object> list = new ArrayList<>();
+            while (rs.next()) {
+                list.add(rowMapper.mapRow(rs));
+            }
+
+            return list;
+
+        } catch (SQLException e) {
+            e.printStackTrace();
+        } finally {
+            if (rs != null) {
+                rs.close();
+            }
+        }
+
+        return null;
+    }
+
+    Object queryForObject(String sql, PreparedStatementSetter setter, RowMapper rowMapper) throws SQLException {
+        ResultSet rs = null;
+        try (Connection con = ConnectionManager.getConnection();
+             PreparedStatement pstmt = con.prepareStatement(sql);
+             ){
+
+            setter.values(pstmt);
+
+            rs = pstmt.executeQuery();
+
+            if (rs.next()) {
+                return rowMapper.mapRow(rs);
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        } finally {
+            if (rs != null) {
+                rs.close();
+            }
+        }
+
+        return null;
+    }
+
+    void update(String query, PreparedStatementSetter setter) throws SQLException {
+        try (
+                Connection con = ConnectionManager.getConnection();
+                PreparedStatement pstmt = con.prepareStatement(query);){
+            setter.values(pstmt);
+        }
+    }
+}

src/main/java/next/dao/PreparedStatementSetter.java

@@ -0,0 +1,8 @@
+package next.dao;
+
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+
+public interface PreparedStatementSetter {
+    void values(PreparedStatement preparedStatement) throws SQLException;
+}

src/main/java/next/dao/RowMapper.java

@@ -0,0 +1,8 @@
+package next.dao;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+public interface RowMapper<T> {
+    T mapRow(ResultSet rs) throws SQLException;
+}

src/main/java/next/dao/UserDao.java

@@ -1,78 +1,77 @@
 package next.dao;
 
-import java.sql.Connection;
-import java.sql.PreparedStatement;
+import next.model.User;
+
 import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.util.ArrayList;
 import java.util.List;
-
-import core.jdbc.ConnectionManager;
-import next.model.User;
+import java.util.stream.Collectors;
 
 public class UserDao {
     public void insert(User user) throws SQLException {
-        Connection con = null;
-        PreparedStatement pstmt = null;
-        try {
-            con = ConnectionManager.getConnection();
-            String sql = "INSERT INTO USERS VALUES (?, ?, ?, ?)";
-            pstmt = con.prepareStatement(sql);
+
+        String query = "INSERT INTO USERS VALUES (?, ?, ?, ?)";
+
+        JdbcTemplate insertJdbcTemplate = new JdbcTemplate();
+        PreparedStatementSetter pss = pstmt -> {
             pstmt.setString(1, user.getUserId());
             pstmt.setString(2, user.getPassword());
             pstmt.setString(3, user.getName());
             pstmt.setString(4, user.getEmail());
 
             pstmt.executeUpdate();
-        } finally {
-            if (pstmt != null) {
-                pstmt.close();
-            }
-
-            if (con != null) {
-                con.close();
-            }
-        }
+        };
+
+        insertJdbcTemplate.update(query, pss);
     }
 
     public void update(User user) throws SQLException {
-        // TODO 구현 필요함.
+
+        String query = "UPDATE USERS SET password = ?, name = ?, email = ? where userId = ?";
+
+        JdbcTemplate updateJdbcTemplate = new JdbcTemplate();
+        PreparedStatementSetter pss = pstmt -> {
+            pstmt.setString(1, user.getPassword());
+            pstmt.setString(2, user.getName());
+            pstmt.setString(3, user.getEmail());
+            pstmt.setString(4, user.getUserId());
+
+            pstmt.executeUpdate();
+        };
+
+        updateJdbcTemplate.update(query, pss);
     }
 
     public List<User> findAll() throws SQLException {
-        // TODO 구현 필요함.
-        return new ArrayList<User>();
+
+        String sql = "SELECT userId, password, name, email FROM USERS";
+
+        JdbcTemplate sjt = new JdbcTemplate();
+
+        PreparedStatementSetter setter = preparedStatement -> {};
+
+        RowMapper rowMapper = this::getUser;
+
+        return sjt.query(sql, setter, rowMapper).stream()
+                .map(o -> (User) o)
+                .collect(Collectors.toList());
+    }
+
+    private User getUser(ResultSet rs) throws SQLException {
+        return new User(rs.getString("userId"), rs.getString("password"), rs.getString("name"),
+                rs.getString("email"));
     }
 
     public User findByUserId(String userId) throws SQLException {
-        Connection con = null;
-        PreparedStatement pstmt = null;
-        ResultSet rs = null;
-        try {
-            con = ConnectionManager.getConnection();
-            String sql = "SELECT userId, password, name, email FROM USERS WHERE userid=?";
-            pstmt = con.prepareStatement(sql);
-            pstmt.setString(1, userId);
-
-            rs = pstmt.executeQuery();
-
-            User user = null;
-            if (rs.next()) {
-                user = new User(rs.getString("userId"), rs.getString("password"), rs.getString("name"),
-                        rs.getString("email"));
-            }
-
-            return user;
-        } finally {
-            if (rs != null) {
-                rs.close();
-            }
-            if (pstmt != null) {
-                pstmt.close();
-            }
-            if (con != null) {
-                con.close();
-            }
-        }
+
+        String sql = "SELECT userId, password, name, email FROM USERS WHERE userid=?";
+
+        JdbcTemplate sjt = new JdbcTemplate();
+
+        PreparedStatementSetter setter = pstmt -> pstmt.setString(1, userId);
+
+        RowMapper rowMapper = this::getUser;
+
+        return (User) sjt.queryForObject(sql, setter, rowMapper);
     }
 }