mybatis入门程序

导入依赖包和驱动包

实体类User 放在pojo包下

package xyz.db361.mybatis.pojo;import java.io.Serializable;import java.util.Date;public class User implements Serializable {    /**     *      */    private static final long serialVersionUID = 1L;    private Integer id;    private String username;// 用户姓名    private String sex;// 性别    private Date birthday;// 生日    private String address;// 地址    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public String getSex() {        return sex;    }    public void setSex(String sex) {        this.sex = sex;    }    public Date getBirthday() {        return birthday;    }    public void setBirthday(Date birthday) {        this.birthday = birthday;    }    public String getAddress() {        return address;    }    public void setAddress(String address) {        this.address = address;    }    @Override    public String toString() {        return "User [id=" + id + ", username=" + username + ", sex=" + sex                + ", birthday=" + birthday + ", address=" + address + "]";    }}

创建User.xml映射文件，放在sqlmap包下

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><!-- namespace：命名空间，用于隔离sql，还有一个很重要的作用，后面会讲 --><!-- 写Sql语句 --><mapper namespace="xyz.db361.mybatis.mapper.UserMapper">    <!-- 通过id查询一个用户 -->    <select id="findUserById" parameterType="Integer"        resultType="xyz.db361.mybatis.pojo.User">        select * from user where id = #{v}    </select>    <!-- #{}占位符 ？ = ‘ ’ = ‘五’ ${} 字符串拼接 不带单引号 = ‘%五%’ -->    <select id="findUserByUserName" parameterType="String"        resultType="User">        select * from user where username like '%${value}%'        <!-- select * from user where username like "%"#{value}"%" -->    </select>    <!-- 添加用户 -->    <!-- User运用了别名 -->    <insert id="insertUser" parameterType="User">        <selectKey keyProperty="id" resultType="Integer" order="AFTER">            select LAST_INSERT_ID()        </selectKey>        insert into        user(username, birthday, address, sex) values(#{username},        #{birthday}, #{address}, #{sex})    </insert>    <!-- 更新 -->    <update id="updateUserById" parameterType="User">        update user set        username = #{username}, sex = #{sex},        birthday = #{birthday},        address =        #{address} where id = #{id}    </update>    <!-- 删除 -->    <delete id="deleteUserById" parameterType="Integer">        delete from user where        id = #{id}    </delete></mapper>

创建mybatis配置文件SqlMapConfig.xml文件放在src下

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration>    <properties resource="jdbc.properties"/>    <!-- 别名 -->    <typeAliases>        <!-- <typeAlias type="xyz.db361.mybatis.pojo.User" alias="User"/> -->        <!-- User  user 都对 -->        <package name="xyz.db361.mybatis.pojo"/>    </typeAliases>    <!-- 和spring整合后 environments配置将废除 -->    <environments default="development">        <environment id="development">            <!-- 使用jdbc事务管理 -->            <transactionManager type="JDBC" />            <!-- 数据库连接池 -->            <dataSource type="POOLED">                <property name="driver" value="${jdbc.driver}" />                <property name="url"                    value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />                <property name="username" value="root" />                <property name="password" value="root" />            </dataSource>        </environment>    </environments>    <!-- 告诉Mapper文件的位置 -->    <mappers>        <!-- resource class url其中一个 -->        <mapper resource="sqlmap/User.xml"/>        <!-- 要求mapper名称和映射文件相同且在同意目录下 -->        <!-- <mapper class="xyz.db361.mybatis.mapper.UserMapper"/> -->    </mappers></configuration>

使用Mapper动态代理开发，创建mapper接口放在mapper包下

package xyz.db361.mybatis.mapper;import xyz.db361.mybatis.pojo.User;public interface UserMapper {    /**     * 遵循四个原则     * 接口方法名 = User.xml文件中的id名     * 返回值类型与xml文件中返回类型一致     * 方法的入参类型与xml文件中入参的类型要一致     * 接口和xml文件绑定(在xml文件中进行)     * */    public User findUserById(Integer id);    public Integer deleteUserById(Integer id);}

进行测试，一段测试代码如下

@Test    public void testMapper() throws IOException {        // 加载核心配置文件        String resource = "SqlMapConfig.xml";        // Resources.get        InputStream in = Resources.getResourceAsStream(resource);        // 创建SqlSessionFactory        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);        // 创建SqlSession        SqlSession sqlSession = sqlSessionFactory.openSession();        //SqlSession帮我生成一个实现类(给接口)        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);        User u = userMapper.findUserById(34);        System.out.println(u);    }