使用动态代理实现dao接口

•  使用动态代理实现dao接口的实现类

MyBatis允许只声明一个dao接口，而无需写dao实现类的方式实现数据库操作。前提是必须保证Mapper文件中的<mapper>标签的namespace属性值必须要和dao接口的类路径一致，MyBatis容器会自动通过动态代理生成接口的实现类。

Mapper.java

package cn.mybatis.dao;

import cn.mybatis.domain.Student;

public interface StudentMapper {
    public void insertStudent(Student s);
    public void updateStudent(Student s);
    public void deleteStudent(String stuid);
    public Student selectStudentById(String stuid);
}

Mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.mybatis.dao.StudentMapper">
    <resultMap type="student" id="BaseResultMap">
        <id column="stu_id" property="stuId" jdbcType="VARCHAR" javaType="java.lang.String" />
        <result column="stu_name" property="stuName" jdbcType="VARCHAR" javaType="java.lang.String" />
        <result column="stu_birthdate" property="stuBirthdate" jdbcType="DATE" javaType="java.util.Date" />
        <result column="stu_phone" property="stuPhone" jdbcType="VARCHAR" javaType="java.lang.String" />
    </resultMap>

    <!-- 插入数据 -->
    <insert id="insertStudent" parameterType="student">
        insert into student (stu_id,stu_name,stu_birthdate,stu_phone)
        values(#{stuId},#{stuName},#{stuBirthdate},#{stuPhone})
    </insert>
    
    <!-- 更新数据 -->
    <update id="updateStudent" parameterType="student">
        update student set stu_name=#{stuName}, stu_birthdate=#{stuBirthdate},
        stu_phone=#{stuPhone} where stu_id=#{stuId}
    </update>
    <!-- 删除数据 -->
    <delete id="deleteStudent" parameterType="string">
        delete from student where stu_id=#{stuId}
    </delete>
    
    <!-- 查询数据，返回的数据会根据resultMap设置封装到实体类对象中 -->
    <select id="selectStudentById" resultType="cn.mybatis.domain.Student" parameterType="string" >
        select stu_name as stuName from student where stu_id=#{stuId}
    </select>
</mapper>

测试

package cn.mybatis.demo;

import java.io.InputStream;
import java.text.SimpleDateFormat;

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.apache.log4j.Logger;

import cn.mybatis.dao.StudentMapper;
import cn.mybatis.domain.Student;

public class Demo_01 {
    private static SqlSessionFactory fac;
    static{
        InputStream is = null;
        try{
            //处理并根据config配置文件实例化SqlSessionFactory
            is = Resources.getResourceAsStream("SqlMapperConfig.xml");
            //获取session工厂类
            fac = new SqlSessionFactoryBuilder().build(is);
        }catch(Exception e){
            e.printStackTrace();
            Logger.getLogger(Demo_01.class).debug(e.getMessage());
        }
    }
    public static void main(String[] args) throws Exception {
        //创建要保存的学生信息
        Student s = new Student();
        s.setStuId("5");
        s.setStuName("zhou");
        s.setStuBirthdate(new SimpleDateFormat("yyyy-MM-dd").parse("1991-1-12"));
        s.setStuPhone("341324123");
        
        SqlSession session = fac.openSession();
        StudentMapper mapper = session.getMapper(StudentMapper.class);
//        mapper.insertStudent(s);
//        mapper.updateStudent(s);
//        mapper.deleteStudent("5");
        Student s1 = mapper.selectStudentById("1");
        System.out.println(s1.getStuName());
        session.commit();
        session.close();
    }
}