mybatis逆向生成代码，生成代码的使用

首先，在上一篇博客中通过逆向工程生成了代码；这篇博客主要内容就是怎么使用生成的逆向工程代码；

使用逆向工程的项目如下：

1.使用普通的逆向工程代码:

    @Before
	public void setUp() throws Exception {
		//mybatis配置文件
		String resource = "sqlMapConfig.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		//使用SqlSessionFactoryBuilder创建sessionFactory
		sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
	}
	@Test
	public void testfindUserById()throws Exception{
		//获取session
		SqlSession session = sqlSessionFactory.openSession();
		//获限mapper接口实例
		UserMapper userMapper = session.getMapper(UserMapper.class);
		//查询user信息
		User user = userMapper.selectByPrimaryKey(88);
		System.out.println(user);
		//关闭session
		session.close();
	}

查询结果:

log4j:WARN No appenders could be found for logger (org.apache.ibatis.logging.LogFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
User [id=88, username=张宇, birthday=Fri Jul 30 00:00:00 CST 1993, sex=2, address=苏州市]

2.使用带Example类的逆向工程代码:

对UserExample类进行介绍；

    //升序,降序:字段+空格+asc(desc)
    protected String orderByClause;
    //去除重复:true是选择不重复记录,false,反之
    protected boolean distinct;
    //自定义查询条件
    protected List<Criteria> oredCriteria;

对Example类的代码进行使用：

    @Test
    public void testFindUserByName(){
		//获取session
		SqlSession session = sqlSessionFactory.openSession();
		//获限mapper接口实例
		UserMapper userMapper = session.getMapper(UserMapper.class);
		
        //通过criteria构造查询条件
        UserExample userExample = new UserExample();
        userExample.setOrderByClause("id desc"); //asc升序,desc降序排列
        userExample.setDistinct(false); //去除重复,true是选择不重复记录,false反之
        UserExample.Criteria criteria = userExample.createCriteria(); //构造自定义查询条件
        //criteria.andUsernameEqualTo("张宇");
        //criteria.andUsernameLike("张三");
        //criteria.andUsernameBetween("张三", "张宇");
        criteria.andIdGreaterThan(1);
        //自定义查询条件可能返回多条记录,使用List接收
        List<User> users = userMapper.selectByExample(userExample);
       
        for (User user : users) {
        	System.out.println(user);
		}
        
    }

查询结果：

log4j:WARN No appenders could be found for logger (org.apache.ibatis.logging.LogFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
User [id=96, username=唐拓, birthday=Sat Aug 11 00:00:00 CST 2018, sex=2, address=中国]
User [id=94, username=tangtuo, birthday=Wed Aug 08 00:00:00 CST 2018, sex=null, address=北京]
User [id=93, username=tangtuo, birthday=Wed Aug 08 00:00:00 CST 2018, sex=null, address=北京]
User [id=91, username=张小明, birthday=null, sex=1, address=郑州]
User [id=90, username=zhangfei, birthday=Tue Aug 07 00:00:00 CST 2018, sex=2, address=北京]
User [id=88, username=张宇, birthday=Fri Jul 30 00:00:00 CST 1993, sex=2, address=苏州市]
User [id=25, username=陈小明, birthday=null, sex=1, address=河南郑州]
User [id=24, username=张三丰, birthday=null, sex=1, address=河南郑州]
User [id=22, username=陈小明, birthday=null, sex=1, address=河南郑州]
User [id=16, username=张小明, birthday=null, sex=1, address=郑州]
User [id=10, username=张三, birthday=Thu Jul 10 00:00:00 CST 2014, sex=1, address=北京市]

上面就是对带有example类的使用，可以向数据库中查到数据；

mybatis逆向生成代码，生成代码的使用

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