[英]Null check in DB singleton
我已經編寫了一個數據庫單例類來提供單個數據庫連接,並且我在另一個類中接受該連接,如果它為null,則必須具有null檢查條件,請解釋一下告訴我最佳實踐
public class DBSingleton {
private static final DBSingleton ONLY_ONE = new DBSingleton();
private Connection connection = null;
private DBSingleton() {
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection("url", "username","pwd");// SQLException
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
}
public static DBSingleton getInstance() {
return ONLY_ONE;
}
public Connection getcon() {
return connection;
}
}
另一堂課
private Connection con = DBSingleton.getInstance().getcon();
你可以試試
public class BDConnection {
private static final Logger LOGGER = LoggerFactory.getLogger(BDConnection.class);
private static Connection connection = null;
public static Connection getConnection() {
if(connection == null){
createConnection();
}
return connection;
}
private static void createConnection() {
try {
Class.forName(ImportExportFilesUtils.getResourceMessage("driver.name")).newInstance();
connection = DriverManager.getConnection(ImportExportFilesUtils.getResourceMessage("database.test.url"), ImportExportFilesUtils.getResourceMessage("database.test.username"),
ImportExportFilesUtils.getResourceMessage("database.test.password"));
} catch (Exception ex) {
LOGGER.error("Cannot load the driver for ojdbc", ex);
}
}
public static void closeConnection() {
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
LOGGER.error("Cannot close the connection with the database", e);
}
}
}
}
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