MyBatisUtil的封装

版本一：

public class MyBatisUtil {
    private static SqlSessionFactory factory = null;
    static {
        InputStream is = null;
        try {
            is = Resources.getResourceAsStream("mybatis-config.xml");
            factory = new SqlSessionFactoryBuilder().build(is);
        } catch (IOException e) {
            throw new RuntimeException("mybatis配置文件加载异常",e);
        }finally {
            if(is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 获得SqlSession
     * @throws Exception 
     */
    public static SqlSession getSqlSession() throws Exception {
        SqlSession session = factory.openSession();
        return session;
    }
}

版本二：

public class MyBatisUtil2 {
    private static SqlSessionFactory factory = null;
    private static ThreadLocal<SqlSession> td1 = new ThreadLocal<SqlSession>();
    static {
        InputStream is = null;
        try {
            is = Resources.getResourceAsStream("mybatis-config.xml");
            factory = new SqlSessionFactoryBuilder().build(is);
        } catch (IOException e) {
            throw new RuntimeException("mybatis配置文件加载异常",e);
        }finally {
            if(is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    
    
    /**
     * 获得SqlSession
     * @throws Exception 
     */
    public static SqlSession getSqlSession(){
        //1.获得DAO对象 SqlSession
        SqlSession session = null;
        //2.从当前线程中获得session
        try {
            session = td1.get();
            if(session == null) {
                //当前线程如果没有sqlsession，就赋值
                session = factory.openSession();
                //将session存入当前线程
                td1.set(session);
            }
        } catch (Exception e) {
            throw new RuntimeException("获得sqlsession的异常",e);
        }
        return session;
    }
    
    /**
     * 根据接口的类对象，获得DAO对象
     */
    public static <T> T getMapper(Class<T> clazz) {
        //获得sqlsession
        SqlSession session = getSqlSession();
        //调用session.getMapper(clazz);
        T t = session.getMapper(clazz);
        return t;
    }
    
    /**
     * 提交事务+释放资源
     */
    public static void commit() {
        //sqlsession.commit();
        try {
            SqlSession session = getSqlSession();
            session.commit();
        } catch (RuntimeException e) {
            throw e;
        }finally {
            close();
        }
    }
    
    /**
     * 回滚事务+释放资源
     */
    public static void rollback() {
        try {
            SqlSession session = getSqlSession();
            session.rollback();
        } catch (RuntimeException e) {
            throw e;
        }finally {
            //释放资源
            close();
        }
    }
    
    /**
     * 释放session资源
     */
    public static void close() {
        SqlSession session = getSqlSession();
        if(session != null) {
            session.close();
            //从当前线程中移除该session
            td1.remove();
        }
    }
}