MyBatis约定及基于动态代理方式的增删改查

mapper动态代理方式的crud(MyBatis接口开发)
原则 :约定优于配置
硬编码方式；
abc.java
Configuration conf=new Configuration();
con.setName("myProject");
配置方式；
abc.xml
<name>myProject</name>
约定:默认值就是myProject

具体实现步骤；
1.基础环境:mybatis.jar、ojdbc.jar、conf.xml、mapper.xml
2.(不同之处)
约定的目标:省略掉statement,即根据约定直接可以定位出SQL语句
a.接口,接口中的方法必须遵循以下约定
1.方法名和mapper.xml文件中的标签的id值相同
2.方法的输入参数和mapper.xml文件中的标签的parameterType类型一致
3.方法的返回值和mapper.xml文件中标签的resultType类型一致(无论查询结果是一个还是多个，mapperxml的便签中只写一个;如果没有resultType,则返回值为void)
除了以上约定,要实现接口中的方法和mapper.xml中的SQL标签一一对应,还需要以下一点；
namespace的值,就是接口的全类名(接口-mapper.xml一一对应)

匹配的过程:(约定的过程)
1.根据接口名找到mapper.xml文件(根据的是namespace=接口全类名)
2.根据接口的方法名找到mapper.xml文件中的SQL标签(方法名=SQL标签的ID值)

以上2点可以保证:当我们调用接口的方法时,
程序能自动定位到某一个mapper.xml文件中的sql标签

习惯:SQL映射文件(mapper.xml)和接口放在同一个包中(注意修改conf.xml)

/MyBatisProject3/src/org/myy/test/Test.java

package org.myy.test;

import java.io.IOException;
import java.io.Reader;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.myy.entity.Student;
import org.myy.mapper.StudentMapper;

import oracle.net.aso.s;

public class Test {
    //查询单个学生
    public static void queryStudentByStuno() throws IOException {
        //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,"development");
                SqlSession session = sessionFactory.openSession();
                
                StudentMapper studentMapper = session.getMapper(StudentMapper.class);
                Student student = studentMapper.queryStudentByStuno(1);
                System.out.println(student);
                session.close();
    }
    //查询全部学生
    public static void queryAllStudent() throws IOException {
        //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,"development");
                SqlSession session = sessionFactory.openSession();
                
                
                StudentMapper studentMapper = session.getMapper(StudentMapper.class);
                List<Student> students = studentMapper.queryAllStudent();
                System.out.println(students);
                session.close();
    }
    //增加学生
    public static void addStudent() throws IOException {
        //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,"development");
                SqlSession session = sessionFactory.openSession();
                
                Student student=new Student(3,"myy",200,"yym");
                StudentMapper studentMapper = session.getMapper(StudentMapper.class);
                int count = studentMapper.addStudent(student);
                session.commit();//提交事务
                System.out.println("增加"+count+"个学生");
                session.close();
    }
    //删除学生
    public static void deleteStudentByStuno() throws IOException {
        //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,"development");
                SqlSession session = sessionFactory.openSession();
                
                StudentMapper studentMapper = session.getMapper(StudentMapper.class);
                int count = studentMapper.deleteStudentByStuno(3);
                session.commit();//提交事务
                System.out.println("删除"+count+"个学生");
                session.close();
    }
    //修改学生
        public static void updateStudentByStuno() throws IOException {
            //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,"development");
                    SqlSession session = sessionFactory.openSession();
                    
                    Student student=new Student();
                    //修改哪个人
                    student.setStuNo(2);
                    student.setStuName("lss");
                    student.setStuAge(9);
                    student.setGraName("222");
                    
                    StudentMapper studentMapper = session.getMapper(StudentMapper.class);
                    int count = studentMapper.updateStudentByStuno(student);
                    session.commit();//提交事务
                    System.out.println("修改"+count+"个学生");
                    session.close();
        }
    public static void main(String[] args) throws IOException {
        queryStudentByStuno();
        addStudent();
        queryAllStudent();
        deleteStudentByStuno();
        queryAllStudent();
        updateStudentByStuno();
        queryAllStudent();
    }
}

/MyBatisProject3/src/org/myy/mapper/StudentMapper.java

package org.myy.mapper;

import java.util.List;

import org.myy.entity.Student;

//操作Mybatis的接口
public interface StudentMapper {
    /* 
     1.方法名和mapper.xml文件中的标签的id值相同 
     2.方法的输入参数和mapper.xml文件中的标签的parameterType类型一致
     3.方法的返回值和mapper.xml文件中标签的resultType类型一致
     */
    //public abstract Student1 queryStudentByStuno(int stuno);
    Student queryStudentByStuno(int stuno);
    //查询qun
    List<Student> queryAllStudent();
    
    int addStudent(Student student);
    
    int deleteStudentByStuno(int stuno);
    
    int updateStudentByStuno(Student student);
}