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();
     }
 }