java - 应以静态方式访问 DBConnection 类型的静态方法 getDBConnection()

Question

我有一个如下所示的单例类，用于访问数据库连接

public class DBConnection {
    private static volatile DBConnection instance;
    private static DataSource dataSource;
    private DBConnection(){ 
    }
    public static synchronized DBConnection getInstance() {
        if (instance == null) {
            instance = new DBConnection();
        }
        return instance;
    }
    static {
        try {
            dataSource = (DataSource) new InitialContext()
                    .lookup("java:comp/env/jdbc/MySQLDataSource");
        } catch (NamingException e) {
            e.printStackTrace();
            try {
                throw new Exception("'jndifordbconc' not found in JNDI", e);
            } catch (Exception e1) {
                logger.error("Error description", e);
            }
        }
    }

    public static Connection getDBConnection() {
        try {
            return dataSource.getConnection();
        } catch (SQLException e) {
            e.printStackTrace();
            logger.error("Error description", e);
            return null;
        }

    }
}

当我尝试以这种方式访问​​ DBConnection

独立类

我收到黄色警告

  public String fetchGlobalIndicesData(@QueryParam("region_name") String region_name )
    {
       Connection dbConnection = null;
        String selectsql = "";

        try
        {

            dbConnection = DBConnection.getInstance().getDBConnection();
            selectpstmt = dbConnection.prepareStatement(selectsql);
            selectpstmt.setString(1, region_name);
            selectRset = selectpstmt.executeQuery();
        }
        catch (Exception e)
        {
            logger.error("Error description",e);
        }

    }

Eclipse IDE 向我发出黄色警告

The static method getDBConnection() from the type DBConnection should be accessed in a static way

你能告诉我这样做的正确方法是什么吗？

我将代码修改为

public static Connection getDBConnection() {
    try {
        return getInstance().dataSource.getConnection();
    } catch (SQLException e) {
        e.printStackTrace();
        logger.error("Error description", e);
        return null;
    }

}

Answer 1

由于它是静态的，因此您应该直接在类上调用该方法，而不是在类的实例上调用:

DBConnection.getDBConnection()

尽管有可能，但在实例上调用该方法没有任何意义。