Mybatis（三）动态代理方式实现增删改查

  在上一篇文章中，我们使用静态代理的方式，通过一个类来实现DAO接口从而实现增删改查；在这篇文章中，将使用动态代理的方式进行功能的实现，其原理是Java的反射机制。话不多说，先上代码为敬。

1. 更改TestMybatis文件如下：

package cn.krain;

import cn.krain.dao.StudentDao;
import cn.krain.domain.Student;
import cn.krain.utils.MybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class TestMybatis {
   
    //查询功能，sqlSession执行完毕后都需要关闭
    @Test
    public void testSelectStudents(){
   
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        StudentDao dao = sqlSession.getMapper(StudentDao.class);
        List<Student> students = dao.selectStudents();
        sqlSession.close();
        for (Student stu:students) {
   
            System.out.println(stu);
        }
    }

    //插入功能
    @Test
    public void testInsertStudent(){
   
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        StudentDao dao = sqlSession.getMapper(StudentDao.class);
        Student student = new Student();
        student.setId(7);
        student.setName("花花2");
        student.setEmail("8654@qq.com");
        student.setAge(21);
        int n = dao.insertStudent(student);
        sqlSession.commit();
        sqlSession.close();
        System.out.println(n);
    }

    //更新功能
    @Test
    public void testUpdateStudent(){
   
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        StudentDao dao = sqlSession.getMapper(StudentDao.class);
        Student student = new Student();
        student.setId(7);
        student.setAge(10);
        int n = dao.updateStudent(student);
        sqlSession.commit();
        sqlSession.close();
        System.out.println(n);
    }

    //删除功能
    @Test
    public void testDeleteStudent(){
   
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        StudentDao dao = sqlSession.getMapper(StudentDao.class);
        Student student = new Student();
        student.setId(7);
        int n = dao.deleteStudent(student);
        sqlSession.commit();
        sqlSession.close();
        System.out.println(n);
    }
}

  在上篇文章 使用静态代理实现 的基础上，我只需要去掉实现接口的类，同时修改TestMybatis类；在TestMybatis类中，当每个方法获取DAO对象时，使用SqlSession对象中的getMapper(dao.class)方法即可。