dbhelper.java

j2ee API 开发重要工具 免费下载 欢迎使用

/*
 * Copyright (c) 2003 Sun Microsystems, Inc.  All rights reserved.  U.S. 
 * Government Rights - Commercial software.  Government users are subject 
 * to the Sun Microsystems, Inc. standard license agreement and 
 * applicable provisions of the FAR and its supplements.  Use is subject 
 * to license terms.  
 * 
 * This distribution may include materials developed by third parties. 
 * Sun, Sun Microsystems, the Sun logo, Java and J2EE are trademarks 
 * or registered trademarks of Sun Microsystems, Inc. in the U.S. and 
 * other countries.  
 * 
 * Copyright (c) 2003 Sun Microsystems, Inc. Tous droits reserves.
 * 
 * Droits du gouvernement americain, utilisateurs gouvernementaux - logiciel
 * commercial. Les utilisateurs gouvernementaux sont soumis au contrat de 
 * licence standard de Sun Microsystems, Inc., ainsi qu'aux dispositions 
 * en vigueur de la FAR (Federal Acquisition Regulations) et des 
 * supplements a celles-ci.  Distribue par des licences qui en 
 * restreignent l'utilisation.
 * 
 * Cette distribution peut comprendre des composants developpes par des 
 * tierces parties. Sun, Sun Microsystems, le logo Sun, Java et J2EE 
 * sont des marques de fabrique ou des marques deposees de Sun 
 * Microsystems, Inc. aux Etats-Unis et dans d'autres pays.
 */

package com.sun.ebank.util;

import java.sql.*;
import javax.sql.*;
import com.sun.ebank.util.*;
import com.sun.ebank.ejb.exception.*;

/**
 * This class contains helper methods for components
 * that access Cloudscape databases.
 */

public final class DBHelper {

    // The getNext<name>Id methods retrieve the next unique
    // primary key.

    public static final String getNextAccountId(Connection con) 
        throws SQLException, MissingPrimaryKeyException {

        Debug.print("DBHelper getNextAccountId");
        return getNextId(con, "next_account_id");
    } // getNextAccountId

    public static final String getNextCustomerId(Connection con) 
        throws SQLException, MissingPrimaryKeyException {

        Debug.print("DBHelper getNextCustomerId");
        return getNextId(con, "next_customer_id");
    } // getNextCustomerId

    public static final String getNextTxId(Connection con)
        throws SQLException, MissingPrimaryKeyException {

        Debug.print("DBHelper getNextTxId");
        return getNextId(con, "next_tx_id");
    } // getNextTxId

    private static final String getNextId(Connection con, String table)
        throws SQLException, MissingPrimaryKeyException {

        Debug.print("DBHelper getNextId");

        String selectStatement =
                "select max(id) from " + table;
        String updateStatement =
                "update " + table + " " +
                "set id = id + 1 ";

        PreparedStatement prepSelect =
                con.prepareStatement(selectStatement);
        PreparedStatement prepUpdate =
                con.prepareStatement(updateStatement);
 
        prepUpdate.executeUpdate();
        ResultSet rs = prepSelect.executeQuery();
        rs.next();
        int i = rs.getInt(1);
        rs.close();
        prepSelect.close();
        prepUpdate.close();

        if (i <= 0) {
            throw new MissingPrimaryKeyException
            ("Table " + table + " is empty.");
        }

        return Integer.toString(i);

    } // getNextId


    public static final java.sql.Date toSQLDate(java.util.Date inDate) {

        // This method returns a sql.Date version of the util.Date arg.

        return new java.sql.Date(inDate.getTime());
    }


} // class