[2단계 - 리팩터링] 링크(손준형) 미션 제출합니다. (#959)

* test: update test

* refactor: isolation of methods and interfaces

* refactor: delete unused annotation

* refactor: handle resource leak

Author: sonjh919

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

@@ -37,7 +37,11 @@ void findById() {
 
     @Test
     void findByAccount() {
-        final var account = "gugu";
+        final var account = "link";
+        final var password = "password";
+        final var email = " [email protected]";
+        userDao.insert(new User(account, password, email));
+
         final var user = userDao.findByAccount(account);
 
         assertThat(user.getAccount()).isEqualTo(account);

jdbc/src/main/java/com/interface21/jdbc/core/ArgumentPreparedStatementSetter.java

@@ -0,0 +1,19 @@
+package com.interface21.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 idx = 1; idx <= args.length; idx++) {
+            pstmt.setObject(idx, args[idx - 1]);
+        }
+    }
+}

jdbc/src/main/java/com/interface21/jdbc/core/JdbcTemplate.java

@@ -42,9 +42,10 @@ public JdbcTemplate(final DataSource dataSource) {
      * @return 제네릭 타입 결과값 (쿼리 결과나 update 결과 등)
      */
     public <R> R execute(String sql, Object[] args, StatementExecutor<R> executor) {
-        try (Connection conn = dataSource.getConnection();
-             PreparedStatement pstmt = conn.prepareStatement(sql)) {
-
+        try (
+                Connection conn = getConnection();
+                PreparedStatement pstmt = conn.prepareStatement(sql)
+        ) {
             setPreparedStatementParameter(args, pstmt);
             log.info("query = {}", sql);
 
@@ -54,6 +55,18 @@ public <R> R execute(String sql, Object[] args, StatementExecutor<R> executor) {
         }
     }
 
+    /**
+     * PreparedStatement에 파라미터를 순서대로 바인딩하는 내부 메서드.
+     *
+     * @param args SQL ? 에 바인딩할 파라미터
+     * @param pstmt PreparedStatement 객체
+     * @throws SQLException SQL 실행 중 발생한 예외
+     */
+    private void setPreparedStatementParameter(Object[] args, PreparedStatement pstmt) throws SQLException {
+        final PreparedStatementSetter pss = new ArgumentPreparedStatementSetter(args);
+        pss.setValues(pstmt);
+    }
+
     /**
      * INSERT, UPDATE, DELETE 문과 같이 데이터 변경 쿼리를 실행하는 메서드.
      * 내부적으로 execute()를 호출하여 PreparedStatement.executeUpdate()를 수행한다.
@@ -120,15 +133,16 @@ private <T> List<T> getQueryResult(RowMapper<T> rowMapper, PreparedStatement pst
     }
 
     /**
-     * PreparedStatement에 파라미터를 순서대로 바인딩하는 내부 메서드.
+     * DataSource에서 새로운 데이터베이스 Connection 객체 획득
      *
-     * @param args SQL ? 에 바인딩할 파라미터
-     * @param pstmt PreparedStatement 객체
-     * @throws SQLException SQL 실행 중 발생한 예외
+     * @return 데이터베이스에 연결된 Connection 객체
+     * @throws DataAccessException 커넥션 획득 과정에서 SQL 오류가 발생한 경우
      */
-    private void setPreparedStatementParameter(Object[] args, PreparedStatement pstmt) throws SQLException {
-        for (int idx = 1; idx <= args.length; idx++) {
-            pstmt.setObject(idx, args[idx - 1]);
+    private Connection getConnection() {
+        try {
+            return dataSource.getConnection();
+        } catch (SQLException e) {
+            throw new DataAccessException(e);
         }
     }
 }

jdbc/src/main/java/com/interface21/jdbc/core/PreparedStatementSetter.java

@@ -0,0 +1,9 @@
+package com.interface21.jdbc.core;
+
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+
+@FunctionalInterface
+public interface PreparedStatementSetter {
+    void setValues(PreparedStatement pstmt) throws SQLException;
+}