mybatis 02 别名与工具类

基本数据类型别名

mybatis别名	映射数据类型
string	String
byte	Byte
long	Long
short	Short
int	Integer
integer	Integer
double	Double
float	Float
boolean	Boolean
date	Date
decimal	BigDecimal

自定义别名：

在 “myBatis-config.xml” 中添加<typeAliases>标签

Paste_Image.png

那么在userMapper.xml中就可以使用这些别名了

Paste_Image.png

工具类

public class MybatisSessionFactory {


    private static final ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
    private static SqlSessionFactory sessionFactory;
    

    private static String CONFIG_FILE_LOCATION = "myBatis-config.xml";

    static {
        buildSessionFactory();
    }
    
    private MybatisSessionFactory() {
    }
    
    /**获取session*/
    public static SqlSession getSession() throws Exception {
        SqlSession session = (SqlSession) threadLocal.get();

        if (session == null ) {
            if (sessionFactory == null) {
                buildSessionFactory();
            }
            session = (sessionFactory != null) ? sessionFactory.openSession()
                    : null;
            threadLocal.set(session);
        }

        return session;
    }


    /**构建session工厂*/
    private static void buildSessionFactory() {
        Reader reader =null;
        try {
          //到src目录下获取主配置文件
            reader = Resources.getResourceAsReader(CONFIG_FILE_LOCATION);
            sessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (Exception e) {
            System.err.println("%%%% Error Creating SessionFactory %%%%");
            e.printStackTrace();
        }finally{
            if(reader!=null){
                try {
                    reader.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    }

    /**关闭session*/
    public static void closeSession() throws Exception {
        SqlSession session = (SqlSession) threadLocal.get();
        threadLocal.set(null);

        if (session != null) {
            session.close();
        }
    }

}

/*
 * 该工具类是线程安全的：
 * threadLocal.set(session)相当于是
 * threadLocal.put(threadLocal.currentThead,session)
 * 
 * threadLocal.get()相当于是
 * threadLocal.get(threadLocal.currentThead)
 * */