MyBatis

命令所需的所有方法如selectList、selectOne通过

SqlSession

dependenciesdependencygroupIdorg.mybatis/groupIdartifactIdmybatis/artifactIdversion3.5.10/version/dependencydependencygroupIdjunit/groupIdartifactIdjunit/artifactIdversion4.12/versionscopetest/scope/dependencydependencygroupIdorg.postgresql/groupIdartifactIdpostgresql/artifactIdversion42.6.0/version/dependency

/dependencies

目录下创建/mybatis-config.xml首先需要配置数据库信息其次需要链接

mapper

3.0//ENhttp://mybatis.org/dtd/mybatis-3-config.dtdconfiguration!--设置连接数据库的环境--environments

iddevelopmenttransactionManager

typeJDBC/dataSource

valueorg.postgresql.Driver/property

nameurl

valuejdbc:postgresql://localhost:5432/MyDatabase/property

nameusername

value123456//dataSource/environment/environments!--引入sql映射文件--mappers!--

单独引入一个

resourcemapper/UserMapper.xml//mappers

resource

目录下创建/mapper/mybatis-config.xmlnamespace命名空间一般可以随便写示例一和示例二有所不同id作为当前编写语句的标识符通常与

namespace

3.0//ENhttps://mybatis.org/dtd/mybatis-3-mapper.dtdmapper

idselectAll

resultTypecom.demo.pojo.Userselect

from

Resources.getResourceAsStream(resource);SqlSessionFactory

sqlSessionFactory

SqlSessionFactoryBuilder().build(inputStream);//

2.获取

sqlSessionFactory.openSession();//

3.执行

sqlSession.selectList(MyUser.selectAll);System.out.println(userList);//

三、Mapper

这种硬编码的问题显然不利于后期的维护并且在编写的时候也需要来回查找对应的

SQL

Resources.getResourceAsStream(resource);SqlSessionFactory

sqlSessionFactory

SqlSessionFactoryBuilder().build(inputStream);SqlSession

sqlSession

sqlSessionFactory.openSession();//

mapper

sqlSession.getMapper(UserMapper.class);ListUser

userList

userMapper.selectAll();System.out.println(userList);sqlSession.close();

2Mapper

3.0//ENhttp://mybatis.org/dtd/mybatis-3-config.dtdconfiguration!--设置连接数据库的环境--environments

iddevelopmenttransactionManager

typeJDBC/dataSource

valueorg.postgresql.Driver/property

nameurl

valuejdbc:postgresql://localhost:5432/MyDatabase/property

nameusername

value123456//dataSource/environment/environments!--引入sql映射文件--mappersmapper

resourcecom/demo/mapper/UserMapper.xml//mappers

?xml

3.0//ENhttps://mybatis.org/dtd/mybatis-3-mapper.dtdmapper

namespacecom.demo.mapper.UserMapperselect

idselectAll

resultTypecom.demo.pojo.Userselect

from

详情可以参考https://mybatis.org/mybatis-3/zh/configuration.html

1、environment

类配置一个别名设置好包的路径后它们的别名默认就是不区分大小写的类名。

五、基于

Brand();brand.setStatus(status);brand.setCompanyName(companyName);//

map

Resources.getResourceAsStream(resource);SqlSessionFactory

sqlSessionFactory

SqlSessionFactoryBuilder().build(inputStream);SqlSession

sqlSession

sqlSessionFactory.openSession();BrandMapper

brandMapper

sqlSession.getMapper(BrandMapper.class);ListBrand

brandList1

brandMapper.selectByConditions1(status,

brandList2

brandMapper.selectByConditions2(brand);ListBrand

brandList3

brandMapper.selectByConditions3(map);System.out.println(第一种

brandList1);System.out.println(第二种

brandList2);System.out.println(第三种

brandList3);sqlSession.close();

5Mapper

resultTypecom.demo.pojo.Brandselect

from

resultTypecom.demo.pojo.Brandselect

from

resultTypecom.demo.pojo.Brandselect

from

语句有多痛苦例如拼接时要确保不能忘记添加必要的空格还要注意去掉列表最后一个列名的逗号。

利用动态

ifchoose

resultTypecom.demo.pojo.Brandselect

*from

resultTypecom.demo.pojo.Brandselect

*from

resultTypecom.demo.pojo.Brandselect

*from

Resources.getResourceAsStream(resource);SqlSessionFactory

sqlSessionFactory

SqlSessionFactoryBuilder().build(inputStream);SqlSession

sqlSession

sqlSessionFactory.openSession();BrandMapper

brandMapper

sqlSession.getMapper(BrandMapper.class);Brand

brand

1);brandMapper.addBrand(brand);ListBrand

brandList

brandMapper.selectAll();System.out.println(brandList);//

提交事务sqlSession.commit();sqlSession.close();

2、事务提交

语句的操作提交。

如果不写就会发现我们插入的数据没有添加到数据库。

sqlSession.commit()手动提交事务sqlSessionFactory.openSession(true)在获取

sqlSession

Resources.getResourceAsStream(resource);SqlSessionFactory

sqlSessionFactory

SqlSessionFactoryBuilder().build(inputStream);SqlSession

sqlSession

sqlSessionFactory.openSession();BrandMapper

brandMapper

sqlSession.getMapper(BrandMapper.class);Brand

brand

1);brandMapper.addBrandBackId(brand);Integer

brand.getId();System.out.println(id);Brand

tmp

brandMapper.selectById(id);System.out.println(tmp);//

提交事务sqlSession.commit();sqlSession.close();

3输出结果

Resources.getResourceAsStream(resource);SqlSessionFactory

sqlSessionFactory

SqlSessionFactoryBuilder().build(inputStream);SqlSession

sqlSession

sqlSessionFactory.openSession();BrandMapper

brandMapper

sqlSession.getMapper(BrandMapper.class);int

count

1));System.out.println(count);sqlSession.commit();sqlSession.close();}

2、修改动态字段

对象密码的修改和其他的内容的修改一般是不会放在一起的修改密码时只需要修改

set

Resources.getResourceAsStream(resource);SqlSessionFactory

sqlSessionFactory

SqlSessionFactoryBuilder().build(inputStream);SqlSession

sqlSession

sqlSessionFactory.openSession();BrandMapper

brandMapper

sqlSession.getMapper(BrandMapper.class);int

count

brandMapper.deleteById(9);sqlSession.commit();sqlSession.close();}

2、批量删除

collection表示传入的集合item遍历的每一个元素seperator元素之间的分隔符open/close指定开闭匹配的字符串

collection

Resources.getResourceAsStream(resource);SqlSessionFactory

sqlSessionFactory

SqlSessionFactoryBuilder().build(inputStream);SqlSession

sqlSession

sqlSessionFactory.openSession();BrandMapper

brandMapper

sqlSession.getMapper(BrandMapper.class);//

Brand(null,

brandMapper.selectAll();System.out.println(brandList);sqlSession.commit();sqlSession.close();

3输出结果