在外部java方法中调用datasource

Question

我想将托管bean拆分成几个文件，因为源代码重复了几次。

这是我想要放入外部文件的外部Java方法：

public class CalcWeight implements Serializable
{

    // Call the Oracle JDBC Connection driver as service
    @Resource(name = "jdbc/Oracle")
    // Data source
    private DataSource ds;

    public float TotalDCWeightCalc(int dcId) throws SQLException
    {

        float DCWeight = 0;

        if (ds == null)
        {
            throw new SQLException("Can't get data source");
        }

        ........... SQL query

        return DCWeight;
    }
}

我使用此代码调用外部Java方法：

@ViewScoped
public class DCProfileTabGeneral implements Serializable
{

    // Call the Oracle JDBC Connection driver as service
    @Resource(name = "jdbc/Oracle")
    // Data source
    private DataSource ds;

    // Weight initialization
    private CalcWeight weight;
    // Power initialization
    private CalcPower power;
    // Cooling initialization
    private CalcCooling cooling;

    // Constructor
    public DCProfileTabGeneral()
    {

        // Weight initialization
        weight = new CalcWeight();

    }
    ..........................
    weight.TotalDCWeightCalc(id)
    .....................
}

运行此代码时收到此错误消息：

java.sql.SQLException: Can't get data source

我如何解决这个问题？