mybatis入门——mybatis使用实例

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mybatis区别于其他ORM工具的地方是，他不需要dao成实现类，只提供接口，数据库操作的方法写到配置文件中。
贴个例子来理解下：
测试项目结构：
这里写图片描述

mybatis-config.xml:

<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"    "http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration>    <environments default="yitu">        <environment id="yitu">            <transactionManager type="JDBC"></transactionManager>            <dataSource type="POOLED">                <property name="driver" value="com.mysql.jdbc.Driver"/>                <property name="url" value="jdbc:mysql://localhost:3306/yitu"/>                <property name="username" value="root"/>                <property name="password" value="root"/>            </dataSource>        </environment>    </environments>    <!--         配置映射文件     -->    <mappers>        <mapper resource="com/etoak/dao/CityDaoIf-mapper.xml"/>    </mappers></configuration>

CityDaoIf-mapper.xml

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"     "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.etoak.dao.CityDaoIf" >    <insert id="addCity" parameterType="com.etoak.bean.City">        insert into city values(null,#{pid},#{name});    </insert>    <delete id="delCityById" parameterType="java.lang.Integer">        delete from city where id=#{id};    </delete>    <update id="updateCity" parameterType="com.etoak.bean.City">        update city set pid=#{pid},name=#{name} where id=#{id};    </update>    <!--         resultMap： 返回数据类型              需要在下文中解释     -->    <select id="selectCityById" parameterType="java.lang.Integer" resultMap="city">        select * from city where id=#{id};    </select>    <!--         这里返回的是list，但list里面存放的还是city对象，所以还是city     -->    <select id="selectAllCitys" resultMap="city">        select * from city;    </select>    <select id="selectCityCount" resultType="java.lang.Integer">        select count(*) from city;    </select>    <select id="selectCityByPage" parameterType="java.util.Map" resultMap="city">        select * from city limit #{start},#{max};    </select>       <!--         返回类型解释     -->    <resultMap type="com.etoak.bean.City" id="city">        <result property="id" column="id"/>        <result property="pid" column="pid"/>        <result property="name" column="name"/>    </resultMap></mapper>

CityDaoIf.java

package com.etoak.dao;import java.util.List;import java.util.Map;import com.etoak.bean.City;public interface CityDaoIf {    /**     * 使用mybatis时需注意：     * 1 添加、删除、修改 返回值为 int类型      *          影响的行数 ==1 判断是否成功     * 2 如果方法涉及到传入的参数量多余一条；需要封装成map     */    public int addCity(City city);    public int delCityById(Integer id);    public int updateCity(City city);    public City selectCityById(Integer id);    public List<City> selectAllCitys();    public int selectCityCount();    // map: start end    public List<City> selectCityByPage(Map map);}

MybatisFactory.java

package com.etoak.factory;import java.io.IOException;import java.io.Reader;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class MybatisFactory {       private static SqlSessionFactory factory;    static{        try {            Reader reader = Resources.getResourceAsReader("mybatis-config.xml");            factory = new SqlSessionFactoryBuilder().build(reader);        } catch (IOException e) {            e.printStackTrace();        }    }    public static SqlSessionFactory getSqlSessionFactory(){        return factory;    }}

实体类City.java

package com.etoak.bean;public class City implements java.io.Serializable {    private Integer id;    private Integer pid;    private String name;    public City() {    }    public City(Integer pid, String name) {        this.pid = pid;        this.name = name;    }    public Integer getId() {        return this.id;    }    public void setId(Integer id) {        this.id = id;    }    public Integer getPid() {        return this.pid;    }    public void setPid(Integer pid) {        this.pid = pid;    }    public String getName() {        return this.name;    }    public void setName(String name) {        this.name = name;    }}

测试类：

package com.etoak.test;import java.util.HashMap;import java.util.Map;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import com.etoak.bean.City;import com.etoak.dao.CityDaoIf;import com.etoak.factory.MybatisFactory;public class Test {    public static void main(String[] args){        SqlSessionFactory factory = MybatisFactory.getSqlSessionFactory();        SqlSession session = factory.openSession();        CityDaoIf dao = session.getMapper(CityDaoIf.class);        int add = dao.addCity(new City(55,"e"));        int del = dao.delCityById(4);        City c = new City();        c.setId(3);        c.setPid(1);        c.setName("aaaa");        int update = dao.updateCity(c);        City city = dao.selectCityById(3);        Map map = new HashMap();        map.put("start", 1);        map.put("max", 5);        //List list = dao.selectCityByPage(new Map());        //System.out.println("add="+add+"del="+del+"update="+update);        System.out.println(dao.selectCityByPage(map));        session.commit();        session.close();    }}

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