MyBatisUtil.java.工具类，连接数据库库

可以在每一个项目里直接使用

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连接数据库的工具类
 * @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错误，请�?��配置文件或数据库");
            
        }
    }
    public static SqlSessionFactory getSqlSessionFactory(){
        return sqlSessionFactory;
    }
    public static SqlSession getSession(){
        //sessionTL的get()方法根据当前线程返回其对应的线程内部变量�?
        //也就是我们需要的Session，多线程情况下共享数据库链接是不安全的�?
        //ThreadLocal保证了每个线程都有自己的Session�?
        SqlSession session = threadLocal.get();
        // 如果session为null，则打开�?��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();
        }
    }
}