mybatis_02

基于接口的方式，不需要写实现类

1.在dao中编写方法 2.在Mapper.xml中使用dao中定义好的方法名

dao中的编写

package dao;

import java.util.List;

import entity.Author;
import entity.AuthorVO;

/**
 * 操作author表的dao接口
 * dao 的实现类是由mybatis取代了JDBC
 * 通过映射文件+框架
 * @author Admin
 *
 */
public interface AuthorDao {
	public Author findById(int id);
	public int insert(Author author);
	public int delete(int id);
	public int update(Author author);
	//查询所有的用户
	public List<Author> findAll();
	//联查的实现
	public List<AuthorVO> findBlog();
	
}

Mapper.xml中的编写

<?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"> 
<!--这个xml文件是通过接口的形式实现  -->
<mapper namespace="dao.AuthorDao">
	<!--id名必须与dao中定义的方法名一致  -->
	<select id="findById" parameterType="int" resultType="entity.Author">
		select *from author where id=#{id}
	</select>
	<!-- 属性是一个对象的时候 -->
	<insert id="insert" parameterType="entity.Author">
		insert into author(id,userName,pwd,sex)values
		(#{id},#{userName},#{password},#{sex})
	</insert>
	
	<!-- 当查询的结果为一个List的时候  会把查询的结果集映射为一个author对象，并且变成一个List-->
	<!-- <select id="findAll" resultType="entity.Author">
		select * from author
	</select> -->
	
	<!-- 当查询的列有别名的时候resultType的映射不能够进行匹配 -->
	<!-- <select id="findAll" resultType="entity.Author">
		select id,userName name,pwd pass,sex from author
	</select> -->
	<!--resultMap可以解决列有别名的问题  -->
	<resultMap type="entity.Author" id="authorMap">
		<result column="name" property="userName"/>
		<result column="pass" property="pwd"/>
	</resultMap>
	
	<select id="findAll" resultMap="authorMap">
		select id,userName name,pwd pass,sex from author
	</select>
	
	
	<select id="findBlog" resultType="entity.AuthorVO">
	
		select author.userName,blog.title from author join blog on author.id=blog.author_id 
	</select>
</mapper>

编写测试类Test3

package test;

import java.io.InputStream;
import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import dao.AuthorDao;
import entity.Author;
import entity.AuthorVO;

/**
 * 从此类开始，通过实现接口的方式得到连接
 * 此类与AuthorMapper2.xml对应
 * @author Admin
 *
 */
public class Test3 {
	public static void main(String[] args) {
		// 1.读取配置文件，得到连接工厂
		String resource = "SqlMapConfig.xml";
		InputStream is = Test2.class.getClassLoader().getResourceAsStream(resource);
		SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);

		// 2.从工厂中拿到真正的连接
		SqlSession session = factory.openSession();

		// 3.通过接口去实现数据库
		//Mapper核心类：得到dao接口的代理类
		AuthorDao dao=session.getMapper(AuthorDao.class);
		
		/*Author author=dao.findById(10001);
		System.out.println(author);*/
		
		/*Author author2=new Author(10020, "sssuuuu", "1232sa", "male");
		dao.insert(author2);*/
		
		//查询所有
		/*List<Author> list=dao.findAll();
		System.out.println(list);*/
		List<AuthorVO> blogList=dao.findBlog();
		System.out.println(blogList);
		//在进行增删改的时候一定进行提交
		session.commit();
		session.close();
	}
}

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