ResultMap&&鉴别器&&别名

ResultMap:字段和属性名的对应关系

修改数据库列名称

alter table student1 rename column stuno to sno;
alter table student1 rename column stuname to sname;
alter table student1 rename column stuage to sage;
alter table student1 rename column graname to gname;

 字段名->属性名

src\org\myy\mapper\studentMapper.xml

    
    
            resultMap="studentResultMap">
        select sno,sname,sage,gname from student1 where sno=#{sno}
    
    id="studentResultMap" type="student">
        
        
        
        
        
        
    

 

src\org\myy\mapper\StudentMapper.java

    //stuNo stuName stuAge
    Student queryStudentByStunoWithResultMap(int sno);

 

src\org\myy\test\Test.java

        //Connection - SqlSession操作Mybatis
        //conf.xml->reader
        Reader reader = Resources.getResourceAsReader("conf.xml");
        //reader->sqlSession

        //可以通过build的第二参数 指定数据库环境
        SqlSessionFactory sessionFactory=new SqlSessionFactoryBuilder().build(reader,"devOracle");
        SqlSession session = sessionFactory.openSession();

        StudentMapper studentMapper=session.getMapper(StudentMapper.class);

        Student student=studentMapper.queryStudentByStunoWithResultMap(1);
        System.out.println(student);

        session.close();

 

 

在resultMap中还可以使用鉴别器：对相同sql中不同字段值进行判断，从而进行不同得处理。

src\org\myy\mapper\studentMapper.xml

    
            resultMap="studentResultMap">
        select sno,sname,nikename,sage,gname from student1
    
    
        
        
        
        
        
        
        
        
            
                
            
            
                
            
        
    

 

src\org\myy\mapper\StudentMapper.java

    List queryStudentsWithResultMap();

 

src\org\myy\test\Test.java

        //Connection - SqlSession操作Mybatis
        //conf.xml->reader
        Reader reader = Resources.getResourceAsReader("conf.xml");
        //reader->sqlSession

        //可以通过build的第二参数 指定数据库环境
        SqlSessionFactory sessionFactory=new SqlSessionFactoryBuilder().build(reader,"devOracle");
        SqlSession session = sessionFactory.openSession();

        StudentMapper studentMapper=session.getMapper(StudentMapper.class);

        List students=studentMapper.queryStudentsWithResultMap();
        System.out.println(students);

        session.close();

 

 

别名

src\conf.xml

    
        
        
        
        <package name="org.myy.entity"/>
    

 

如果在批量设置别名时，出现了冲突。可以使用@Alias("student")区分

src\org\myy\entity\Student.java

@Alias("student1")
public class Student {