MyBatisUtil.java.工具類，連接數據庫庫

可以在每一個項目里直接使用

package com.yh.mb.dao;

import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
/**
 * mybatis連接數據庫的工具類
 * @author Administrator
 *
 */
public class MyBatisUtil {
    private MyBatisUtil(){
    }
    private static final String RESOURCE = "mybatis-config.xml";
    private static SqlSessionFactory sqlSessionFactory = null;
    private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
    static {
        Reader reader = null;
        try {
            reader = Resources.getResourceAsReader(RESOURCE);
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
            sqlSessionFactory = builder.build(reader);
        } catch (Exception e1) {
            e1.printStackTrace();
            throw new ExceptionInInitializerError("初始化MyBatis錯誤，請�?��配置文件或數據庫");
            
        }
    }
    public static SqlSessionFactory getSqlSessionFactory(){
        return sqlSessionFactory;
    }
    public static SqlSession getSession(){
        //sessionTL的get()方法根據當前線程返回其對應的線程內部變量�?
        //也就是我們需要的Session，多線程情況下共享數據庫鏈接是不安全的�?
        //ThreadLocal保證了每個線程都有自己的Session�?
        SqlSession session = threadLocal.get();
        // 如果session為null，則打開�?��新的session
        if (session == null){
            session = (sqlSessionFactory !=null) ?sqlSessionFactory.openSession():null;
            threadLocal.set(session); // 5
        }
        return session;
    }
    public static void closeSession(){
        SqlSession session = (SqlSession) threadLocal.get(); // 2
        threadLocal.set(null);
        if (session !=null){
            session.close();
        }
    }
}