hlidgenerator.java

这是一本描述JDBC数据库的书籍

/*
 * HLIDGenerator.java
 *
 * Created on 2005年6月9日, 下午11:03
 *
 * To change this template, choose Tools | Options and locate the template under
 * the Source Creation and Management node. Right-click the template and choose
 * Open. You can then make changes to the template in the Source Editor.
 */

package oid;

import java.sql.*;
import javax.sql.*;
import java.util.*;
import common.*;
/**
 *
 * @author kevin
 */
public class HLIDGenerator {
    
    private static Map	idMap		= new HashMap();
    
    private static long	personId	= 1;
    
    private static long	studentId	= 1;
    
    private static long	bachelorId	= 1;
    
    private static long	masterId	= 1;
    
    private static long	workerId	= 1;
    
    private static long	driverId	= 1;
    
    private static long	engineerId	= 1;
    
    public synchronized static String nextPerson() {
        String id = (String) idMap.get("PERSON");
        if (id == null) {
            id = String.valueOf(nextId());
            idMap.put("PERSON", id);
        }
        return id + (personId++);
    }
    
    public synchronized static String nextStudent() {
        String id = (String) idMap.get("STUDENT");
        if (id == null) {
            id = String.valueOf(nextId());
            idMap.put("STUDENT", id);
        }
        return id + (studentId++);
    }
    
    public synchronized static String nextBachelor() {
        String id = (String) idMap.get("BACHELOR");
        if (id == null) {
            id = String.valueOf(nextId());
            idMap.put("BACHELOR", id);
        }
        return id + (bachelorId++);
    }
    
    public synchronized static String nextMaster() {
        String id = (String) idMap.get("MASTER");
        if (id == null) {
            id = String.valueOf(nextId());
            idMap.put("MASTER", id);
        }
        return id + (masterId++);
    }
    
    public synchronized static String nextWorker() {
        String id = (String) idMap.get("WORKER");
        if (id == null) {
            id = String.valueOf(nextId());
            idMap.put("WORKER", id);
        }
        return id + (workerId++);
    }
    
    public synchronized static String nextDriver() {
        String id = (String) idMap.get("DRIVER");
        if (id == null) {
            id = String.valueOf(nextId());
            idMap.put("DRIVER", id);
        }
        return id + (driverId++);
    }
    
    public synchronized static String nextEngineer() {
        String id = (String) idMap.get("ENGINEER");
        if (id == null) {
            id = String.valueOf(nextId());
            idMap.put("ENGINEER", id);
        }
        return id + (engineerId++);
    }
    
    public static long nextId() {
        long id = -1;
        Connection con = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            ConnectionFactory factory = ConnectionFactory.getConnectionFactory();
            con = factory.getConnection();
            st = con.createStatement();
            rs = st.executeQuery("SELECT nextval FROM oid_hl_tbl");
            
            rs.next();
            id = rs.getLong(1);
            st.execute("UPDATE oid_hl_tbl SET nextval = nextval + 1");
            
        } catch (Exception e) {
            id = -1;
            e.printStackTrace();
        } finally {
            DBUtils.close(rs, st, con);
        }
        return id;
    }
    
    public static void main(String[] aregs){
        for(int i = 1; i< 12; i++)
            System.out.println(HLIDGenerator.nextDriver());
        System.out.println("****************************");
        for(int i = 1; i< 12; i++)
            System.out.println(HLIDGenerator.nextEngineer());
    }
    
    
}