MyBatis

1.基础

  1.1 pom

        
        
            org.mybatis
            mybatis
            3.5.7
        

        
        
            mysql
            mysql-connector-java
            5.1.49
        

  1.2 jdbc.properties

jdbc.driver= com.mysql.jdbc.Driver
jdbc.url= jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8
jdbc.username= root
jdbc.password= root

  1.3 核心配置

        mybatis-config文件中的标签必须按照固定的顺序(有的标签可以不写，但顺序一定不能乱)： properties、settings、typeAliases、typeHandlers、objectFactory、objectWrapperFactory、reflectorFactory、plugins、environments、databaseIdProvider、mappers

  1.4 mapper接口

public interface PaymentMapper {

    List selectAll();

}

  1.5 映射文件

    
        select * from payment
    

  1.6 文件结构

  1.7 测试功能

//读取MyBatis的核心配置文件
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");

//获取SqlSessionFactoryBuilder对象
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();

//通过核心配置文件所对应的字节输入流创建工厂类SqlSessionFactory，生产SqlSession对象
SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);

//获取sqlSession，此时通过SqlSession对象所操作的sql都必须手动提交或回滚事务
SqlSession sqlSession = sqlSessionFactory.openSession(true);

//通过代理模式创建UserMapper接口的代理实现类对象
PaymentMapper mapper = sqlSession.getMapper(PaymentMapper.class);

List payments = mapper.selectAll(); 

  1.8 MyBatisX

       安装之后会出现小鸟图标,直接导航和快速生成映射文件

  1.9 log4j日志功能

        1) pom

            log4j
            log4j
            1.2.17

        2) log4j.xml文件,存放的位置是src/main/resources目录下

  1.10 mappers 包

    1) 映射文件

    2) package结构必须和mapper文件结构一样，名字也必须一样

2.查询

  2.1 无参数

    
        
    
    
        select * from payment
    

  2.2 带参数

    1) 接口

public interface PaymentMapper {

    List selectAll(@Param("id") int id);

}

    2) 映射文件

    
        
    
    
        select * from payment where id = #{id}
    

  2.3 实体参数

    1) 接口

public interface PaymentMapper {
    List selectAll(Payment id);
}

    2) 映射文件

    
        
    
    
        select *
        from payment
        where id = #{id}
          and serial_name like concat('%',#{serialName,jdbcType=VARCHAR},'%')
          and serial_name like "%"#{serialName,jdbcType=VARCHAR}"%"
    

  2.4 map参数

    1) 接口

public interface PaymentMapper {
    List selectAll(Map map);
}

    2) 映射文件

        用2.3即可

  2.5 动态条件 if

    1) 接口

        按2.3即可

    2) 映射文件

    
        
    
    
        select *
        from payment
        
          
              and serial_name like "%"#{serialName,jdbcType=VARCHAR}"%"
          
        
    

  2.6 动态条件 choose

    
        
    
    
        select *
        from payment
        where
            
                
                    serial_name like "%"#{serialName,jdbcType=VARCHAR}"%"
                
                
                    1=1
                
            
    

  2.7 参数

    
        
    
    
        select *
        from payment
        where id = ${arg0} and id = ${arg1}
    

    
        select *
        from payment
        where id = ${param1} and id = ${param2}
    

  2.8 多对一

    
    
        
        
        
        
        
            
            
        
    
    
        select *, t_dept.id as did
            from t_emp left join t_dept  on t_emp.dept_id = t_dept.id
    

  2.9 一对多

    
        
        
        
            
            
            
            
        
    
    
        select *,t_emp.id as empid from t_dept left join t_emp on t_dept.id = t_emp.dept_id
    

3.分页

  3.1 添加依赖

            com.github.pagehelper
            pagehelper
            5.2.0

  3.2 配置分页插件

    在MyBatis的核心配置文件（mybatis-config.xml）中配置插件，注意顺序

  3.3 代码

InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
EmpMapper mapper = sqlSession.getMapper(EmpMapper.class);

//访问第一页，每页四条数据
PageHelper.startPage(2,2);
List selects = mapper.selectAll();

  3.4 PageInfo

InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
	SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
	SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
	SqlSession sqlSession = sqlSessionFactory.openSession(true);
	EmpMapper mapper = sqlSession.getMapper(EmpMapper.class);
	PageHelper.startPage(1, 4);
	List emps = mapper.selectByExample(null);
	PageInfo page = new PageInfo<>(emps,5);
	System.out.println(page);

4.添加，修改，删除

  4.1 添加

        insert into payment(serial_name)
        values (#{serialName})

  4.2 修改

!--int updateUser();-->

    update t_user set username = '张三' where id = 5

  4.3 删除

    delete from t_user where id = 6

  4.4 批量删除

	delete from t_user where id in (${ids})

//测试类
@Test
public void deleteMore() {
	SqlSession sqlSession = SqlSessionUtils.getSqlSession();
	SQLMapper mapper = sqlSession.getMapper(SQLMapper.class);
	int result = mapper.deleteMore("1,2,3,8");
	System.out.println(result);
}