我正在嘗試為我的 progressBar 類創(chuàng)建測試，但我無法以標(biāo)準(zhǔn)方式訪問 MySQL 數(shù)據(jù)庫。我應(yīng)該如何在測試中創(chuàng)建與數(shù)據(jù)庫的連接？public class progressBarTest {@Resource(name = "jdbc/movie_user_database")private static DataSource dataSource;@BeforeClasspublic static void setUpClass() throws Exception {    MovieDatabaseUtil.getInstance().setDataSource(dataSource);    System.out.println("DataSource created!");}@AfterClasspublic static void tearDownClass() throws Exception {}@Testpublic void getMovies() {    List<Movie> movies = MovieDatabaseUtil.getInstance().getMovies();    for (Movie m : movies    ) {        System.out.println(m.getTitle());    }}@Testpublic void progressCalculatorMovies() {    ProgressBar progressBar = new ProgressBar();    assertEquals(30, progressBar.progressCalculatorMovies());}}當(dāng)然，運(yùn)行后我得到了 NullPointerException。在運(yùn)行測試之前，我向數(shù)據(jù)庫添加了一些記錄。