01 MyBatis
lix_uan 30 0

环境准备

  • 导入POM依赖

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    
    <dependencies>
        <!--mybatis 依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>
    
        <!--mysql 驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.46</version>
        </dependency>
    
        <!--junit 单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>
    
        <!-- 添加slf4j日志api -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.20</version>
        </dependency>
        <!-- 添加logback-classic依赖 -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>
        <!-- 添加logback-core依赖 -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.2.3</version>
        </dependency>
    
    </dependencies>
  • logback.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <configuration>
        <appender name="Console" class="ch.qos.logback.core.ConsoleAppender">
            <encoder>
                <pattern>[%level]  %cyan([%thread]) %boldGreen(%logger{15}) - %msg %n</pattern>
            </encoder>
        </appender>
    
        <logger name="com.itheima" level="DEBUG" additivity="false">
            <appender-ref ref="Console"/>
        </logger>
    
        <root level="DEBUG">
            <appender-ref ref="Console"/>
        </root>
    </configuration>
  • mybatis-config.xml

    <?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>
    
        <typeAliases>
            <package name="cn.lixuan.pojo"/>
        </typeAliases>
    
        <!--
        environments:配置数据库连接环境信息。可以配置多个environment,通过default属性切换不同的environment
        -->
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <!--数据库连接信息-->
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql:///mybatis?useSSL=false&amp;serverTimezone=Asia/Shanghai"/>
                    <property name="username" value="root"/>
                    <property name="password" value="root"/>
                </dataSource>
            </environment>
    
            <environment id="test">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <!--数据库连接信息-->
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
                    <property name="username" value="root"/>
                    <property name="password" value="root"/>
                </dataSource>
            </environment>
        </environments>
        <mappers>
            <!--加载sql映射文件-->
           <!-- <mapper resource="cn/lixuan/mapper/UserMapper.xml"/>-->
    
            <!--Mapper代理方式-->
            <package name="cn.lixuan.mapper"/>
        </mappers>
    
    </configuration>
  • 建表(tb_brand)

    -- 删除tb_brand表
    drop table if exists tb_brand;
    -- 创建tb_brand表
    create table tb_brand
    (
        -- id 主键
        id           int primary key auto_increment,
        -- 品牌名称
        brand_name   varchar(20),
        -- 企业名称
        company_name varchar(20),
        -- 排序字段
        ordered      int,
        -- 描述信息
        description  varchar(100),
        -- 状态:0:禁用  1:启用
        status       int
    );
    -- 添加数据
    insert into tb_brand (brand_name, company_name, ordered, description, status)
    values ('三只松鼠', '三只松鼠股份有限公司', 5, '好吃不上火', 0),
           ('华为', '华为技术有限公司', 100, '华为致力于把数字世界带入每个人、每个家庭、每个组织,构建万物互联的智能世界', 1),
           ('小米', '小米科技有限公司', 50, 'are you ok', 1);
  • 编写实体类(cn.lixuan.brand.pojo.Brand)

    // 这里用Lombok自动生成Getter、Setter方法
    @Getter
    @Setter
    @ToString
    public class Brand {
        // id 主键
        private Integer id;
        // 品牌名称
        private String brandName;
        // 企业名称
        private String companyName;
        // 排序字段
        private Integer ordered;
        // 描述信息
        private String description;
        // 状态:0:禁用  1:启用
        private Integer status;
    }
  • 编写测试用例(cn.lixuan.test.MybatisTest)

查询所有数据

  • 编写接口方法(cn.lixuan.mapper.BrandMapper)

    public interface BrandMapper {
    
        /**
         * 查询所有
         */
        List<Brand> selectAll();
    }
  • 编写SQL语句(BrandMapper.xml)

    <!-- 在 reources 下创建 cn/lixuan/mapper 目录结构,并在该目录下创建名为 BrandMapper.xml 的映射配置文件 -->
    
    <?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">
    
    <mapper namespace="cn.lixuan.mapper.BrandMapper">
        <select id="selectAll" resultType="brand">
            select *
            from tb_brand;
        </select>
    </mapper>
  • 使用resultMap解决SQL表字段和实体类名称不一致问题

    <resultMap id="brandResultMap" type="brand">
        <result column="brand_name" property="brandName"/>
        <result column="company_name" property="companyName"/>
    </resultMap>
    
    <select id="selectAll" resultMap="brandResultMap">
        select *
        from tb_brand;
    </select>
  • 编写测试方法(MybatisTest)

    @Test
    public void testSelectAll() throws IOException {
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    
        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
    
        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
    
        //4. 执行方法
        List<Brand> brands = brandMapper.selectAll();
        System.out.println(brands);
    
        //5. 释放资源
        sqlSession.close();
    }

查询详情

  • 编写接口方法

    /**
      * 查看详情:根据Id查询
      */
    Brand selectById(int id);
  • 编写SQL语句

    <select id="selectById"  resultMap="brandResultMap">
        select *
        from tb_brand where id = #{id};
    </select>
  • SQL语句中特殊字段处理

    • 使用转义字符
    • 使用CDATA区包裹
  • 编写测试方法

     @Test
    public void testSelectById() throws IOException {
        //接收参数,该id以后需要传递过来
        int id = 1;
    
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    
        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
    
        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
    
        //4. 执行方法
        Brand brand = brandMapper.selectById(id);
        System.out.println(brand);
    
        //5. 释放资源
        sqlSession.close();
    }

多条件查询

  • 编写接口方法

    // 1
    List<Brand> selectByCondition(@Param("status") int status, @Param("companyName") String companyName,@Param("brandName") String brandName);
    
    // 2
    List<Brand> selectByCondition(Brand brand);
    
    // 3
    List<Brand> selectByCondition(Map map);
  • 编写SQL语句

    <select id="selectByCondition" resultMap="brandResultMap">
        select *
        from tb_brand
        where status = #{status}
        and company_name like #{companyName}
        and brand_name like #{brandName}
    </select>
  • 编写测试方法

    @Test
    public void testSelectByCondition() throws IOException {
        //接收参数
        int status = 1;
        String companyName = "华为";
        String brandName = "华为";
    
        // 处理参数
        companyName = "%" + companyName + "%";
        brandName = "%" + brandName + "%";
    
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
    
        //4. 执行方法
        //方式一 :接口方法参数使用 @Param 方式调用的方法
        //List<Brand> brands = brandMapper.selectByCondition(status, companyName, brandName);
    
        //方式二 :接口方法参数是 实体类对象 方式调用的方法
         //封装对象
        /* Brand brand = new Brand();
            brand.setStatus(status);
            brand.setCompanyName(companyName);
            brand.setBrandName(brandName);*/
    
        //List<Brand> brands = brandMapper.selectByCondition(brand);
    
        //方式三 :接口方法参数是 map集合对象 方式调用的方法
        Map map = new HashMap();
        map.put("status" , status);
        map.put("companyName", companyName);
        map.put("brandName" , brandName);
        List<Brand> brands = brandMapper.selectByCondition(map);
        System.out.println(brands);
    
        //5. 释放资源
        sqlSession.close();
    }

动态SQL

  • 多条件 if, where

    <select id="selectByCondition" resultMap="brandResultMap">
        select *
        from tb_brand
        <where>
            <if test="status != null">
                and status = #{status}
            </if>
            <if test="companyName != null and companyName != '' ">
                and company_name like #{companyName}
            </if>
            <if test="brandName != null and brandName != '' ">
                and brand_name like #{brandName}
            </if>
        </where>
    </select>
  • 单条件 choose,when

    <select id="selectByConditionSingle" resultMap="brandResultMap">
        select *
        from tb_brand
        <where>
            <choose><!--相当于switch-->
                <when test="status != null"><!--相当于case-->
                    status = #{status}
                </when>
                <when test="companyName != null and companyName != '' "><!--相当于case-->
                    company_name like #{companyName}
                </when>
                <when test="brandName != null and brandName != ''"><!--相当于case-->
                    brand_name like #{brandName}
                </when>
            </choose>
        </where>
    </select>
  • 编写测试方法

    @Test
    public void testSelectByConditionSingle() throws IOException {
        //接收参数
        int status = 1;
        String companyName = "华为";
        String brandName = "华为";
    
        // 处理参数
        companyName = "%" + companyName + "%";
        brandName = "%" + brandName + "%";
    
        //封装对象
        Brand brand = new Brand();
        //brand.setStatus(status);
        brand.setCompanyName(companyName);
        //brand.setBrandName(brandName);
    
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        //4. 执行方法
        List<Brand> brands = brandMapper.selectByConditionSingle(brand);
        System.out.println(brands);
    
        //5. 释放资源
        sqlSession.close();
    }

添加数据

  • 编写接口方法

     /**
       * 添加
       */
    void add(Brand brand);
  • 编写SQL语句

    <!-- useGeneratedKeys="true" keyProperty="id" 添加成功后返回主键 -->
    <insert id="add" useGeneratedKeys="true" keyProperty="id">
        insert into tb_brand (brand_name, company_name, ordered, description, status)
        values (#{brandName}, #{companyName}, #{ordered}, #{description}, #{status});
    </insert>
  • 编写测试方法

    @Test
    public void testAdd() throws IOException {
        //接收参数
        int status = 1;
        String companyName = "波导手机";
        String brandName = "波导";
        String description = "手机中的战斗机";
        int ordered = 100;
    
        //封装对象
        Brand brand = new Brand();
        brand.setStatus(status);
        brand.setCompanyName(companyName);
        brand.setBrandName(brandName);
        brand.setDescription(description);
        brand.setOrdered(ordered);
    
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true); //设置自动提交事务,这种情况不需要手动提交事务了
        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        //4. 执行方法
        brandMapper.add(brand);
        //提交事务
        sqlSession.commit();
        //5. 释放资源
        sqlSession.close();
    }

修改

  • 编写接口类

     /**
       * 修改
       */
    void update(Brand brand);
  • 编写SQL语句

    <update id="update">
        update tb_brand
        <set>
            <if test="brandName != null and brandName != ''">
                brand_name = #{brandName},
            </if>
            <if test="companyName != null and companyName != ''">
                company_name = #{companyName},
            </if>
            <if test="ordered != null">
                ordered = #{ordered},
            </if>
            <if test="description != null and description != ''">
                description = #{description},
            </if>
            <if test="status != null">
                status = #{status}
            </if>
        </set>
        where id = #{id};
    </update>
  • 编写测试方法

    @Test
    public void testUpdate() throws IOException {
        //接收参数
        int status = 0;
        String companyName = "波导手机";
        String brandName = "波导";
        String description = "波导手机,手机中的战斗机";
        int ordered = 200;
        int id = 6;
    
        //封装对象
        Brand brand = new Brand();
        brand.setStatus(status);
        //        brand.setCompanyName(companyName);
        //        brand.setBrandName(brandName);
        //        brand.setDescription(description);
        //        brand.setOrdered(ordered);
        brand.setId(id);
    
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        //4. 执行方法
        int count = brandMapper.update(brand);
        System.out.println(count);
        //提交事务
        sqlSession.commit();
        //5. 释放资源
        sqlSession.close();
    }

删除一行数据

  • 编写接口方法

    /**
      * 根据id删除
      */
    void deleteById(int id);
  • 编写SQL语句

    <delete id="deleteById">
        delete from tb_brand where id = #{id};
    </delete>
  • 编写测试方法

     @Test
    public void testDeleteById() throws IOException {
        //接收参数
        int id = 6;
    
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        //4. 执行方法
        brandMapper.deleteById(id);
        //提交事务
        sqlSession.commit();
        //5. 释放资源
        sqlSession.close();
    }

批量删除

  • 编写接口方法

    /**
      * 批量删除
      */
    void deleteByIds(int[] ids);
  • 编写SQL语句

    <delete id="deleteByIds">
        delete from tb_brand where id
        in
        <foreach collection="array" item="id" separator="," open="(" close=")">
            #{id}
        </foreach>
        ;
    </delete>
  • 编写测试方法

    @Test
    public void testDeleteByIds() throws IOException {
        //接收参数
        int[] ids = {5,7,8};
    
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        //4. 执行方法
        brandMapper.deleteByIds(ids);
        //提交事务
        sqlSession.commit();
        //5. 释放资源
        sqlSession.close();
    }

注解实现CRUD

  • 查询 :@Select
  • 添加 :@Insert
  • 修改 :@Update
  • 删除 :@Delete
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