sqlmapsequencedao.java

java写的blog

/*
 * Created on 2004-9-28
 * Author: Xuefeng, Copyright (C) 2004, Xuefeng.
 */
package org.crystalblog.dao.ibatis;

import java.sql.SQLException;

import org.crystalblog.dao.SequenceDao;

import com.ibatis.sqlmap.client.SqlMapClient;

/**
 * @author Xuefeng
 */
public final class SqlMapSequenceDao implements SequenceDao {

    private SqlMapClient sqlMap;

    private static final int ID_ACCOUNT = 0;
    private static final int ID_CATEGORY = 1;
    private static final int ID_ARTICLE = 2;
    private static final int ID_FEEDBACK = 3;
    private static final int ID_LINK = 4;
    private static final int ID_IMAGE = 5;
    private static final int ID_MESSAGE = 6;

    private int nextAccountId = 0;
    private int nextCategoryId = 0;
    private int nextArticleId = 0;
    private int nextFeedbackId = 0;
    private int nextLinkId = 0;
    private int nextImageId = 0;
    private int nextMessageId = 0;

    private int stepAccount = 0;
    private int stepCategory = 0;
    private int stepArticle = 0;
    private int stepFeedback = 0;
    private int stepLink = 0;
    private int stepImage = 0;
    private int stepMessage = 0;

    public SqlMapSequenceDao() {
        sqlMap = SqlConfig.getSqlMapInstance();
        try {
            // this statement do 2 things:
            // 1. set nextId = 0
            // 2. set nextId = (select max(id) from [TABLE])
            //    where sequenceId=## and (select max(id) from [TABLE]) is not null
            // to make sure the next id will never conflict.
            sqlMap.update("setMaxId", null);
        }
        catch(SQLException sqle) {
            sqle.printStackTrace();
        }
    }

    private int getNextId(int sequenceId) {
        try {
            Integer seq = new Integer(sequenceId);
            sqlMap.update("updateNextId", seq);
            Integer I = (Integer) sqlMap.queryForObject("getNextId", seq);
            System.out.println("[INFO] Next id = " + I.intValue());
            return I.intValue();
        }
        catch(SQLException sqle) {
            sqle.printStackTrace();
            throw new RuntimeException("Runtime Exception caused by: " + sqle);
        }
    }

    public synchronized int getNextAccountId() {
        if(stepAccount == 0) {
            nextAccountId = getNextId(ID_ACCOUNT);
            stepAccount = 9;
            return (nextAccountId - stepAccount);
        }
        stepAccount--;
        return nextAccountId - stepAccount;
    }

    public synchronized int getNextCategoryId() {
        if(stepCategory==0) {
            nextCategoryId = getNextId(ID_CATEGORY);
            stepCategory = 9;
            return (nextCategoryId - stepCategory);
        }
        stepCategory--;
        return nextCategoryId - stepCategory;
    }

    public synchronized int getNextArticleId() {
        if(stepArticle==0) {
            nextArticleId = getNextId(ID_ARTICLE);
            stepArticle = 9;
            return (nextArticleId - stepArticle);
        }
        stepArticle--;
        return nextArticleId - stepArticle;
    }

    public synchronized int getNextFeedbackId() {
        if(stepFeedback==0) {
            nextFeedbackId = getNextId(ID_FEEDBACK);
            stepFeedback = 9;
            return (nextFeedbackId - stepFeedback);
        }
        stepFeedback--;
        return nextFeedbackId - stepFeedback;
    }

    public synchronized int getNextLinkId() {
        if(stepLink==0) {
            nextLinkId = getNextId(ID_LINK);
            stepLink = 9;
            return (nextLinkId - stepLink);
        }
        stepLink--;
        return nextLinkId - stepLink;
    }

    public synchronized int getNextImageId() {
        if(stepImage==0) {
            nextImageId = getNextId(ID_IMAGE);
            stepImage = 9;
            return (nextImageId - stepImage);
        }
        stepImage--;
        return nextImageId - stepImage;
    }

    public synchronized int getNextMessageId() {
        if(stepMessage==0) {
            nextMessageId = getNextId(ID_MESSAGE);
            stepMessage = 9;
            return (nextMessageId - stepMessage);
        }
        stepMessage--;
        return nextMessageId - stepMessage;
    }
}