要求:

1.配置文件的namespace名稱空間指定為接口的全類名

2.配置文件中的id唯一標(biāo)識(shí)與接口中的方法對(duì)應(yīng)(返回值類型對(duì)應(yīng),方法名對(duì)應(yīng),參數(shù)個(gè)數(shù)和類型對(duì)應(yīng))

接口代碼:

package com.bird.mybatis.dao;import com.bird.mybatis.bean.Employee;public interface EmployeeMapper { public Employee getEmpById(Integer id); }

對(duì)應(yīng)配置文件代碼:

<?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'> <!-- namespace:名稱空間(若使用接口式編程,與EmployeeMapper接口全類名一致) id:唯一標(biāo)識(shí)(與接口中的方法名對(duì)應(yīng)) resultType:返回值類型(與對(duì)應(yīng)方法的返回值對(duì)應(yīng)) #{id}:從傳遞過來的參數(shù)中取出id值 --><mapper namespace='com.bird.mybatis.dao.EmployeeMapper'> <select resultType='com.bird.mybatis.bean.Employee'> select id,last_name lastName,gender,email from tbl_employee where id = #{id} </select></mapper>

測(cè)試代碼:

/** * MyBatis接口編程 * @throws IOException */ @Test void test2() throws IOException { //獲取sqlSessionFactory對(duì)象 SqlSessionFactory ssf = getSqlSessionFactory(); //獲取sqlSession對(duì)象 SqlSession openSession = ssf.openSession(); try { //獲取接口的實(shí)現(xiàn)類對(duì)象 EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class); Employee empById = mapper.getEmpById(1); System.out.println(empById); }finally { openSession.close(); } } /** * 獲取sqlSessionFactory對(duì)象 * @throws IOException */ public static SqlSessionFactory getSqlSessionFactory() throws IOException { String resource = 'mybatis-config.xml'; InputStream is = Resources.getResourceAsStream(resource); return new SqlSessionFactoryBuilder().build(is); }

總結(jié):

1.接口編程:

原生接口: Dao ===> DaoImpl

MyBatis: Dao ===> Mapper.xml

2. SqlSession代表與數(shù)據(jù)庫(kù)的一次會(huì)話,用完要關(guān)閉

3. SqlSession和Connection都是非線程安全的,所以每次都要獲取新的對(duì)象,而不能寫成成員變量

4.mapper接口沒有實(shí)現(xiàn)類,但是MyBatis生成代理對(duì)象

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