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 mapper
PUBLIC "-//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 configuration
PUBLIC "-//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);
    }