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发布日期:   2022-03-27
更新日期:   2022-04-01
文章字数:   1.4k
阅读时长:   7 分
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一、tkMapper

实体类与数据表存在对应关系，并且是有规律的一一只要知道了数据表的结构，就能够生成实体类;
所有实体的DAO接口中定义的方法也是有规律的，不同点就是实体类型不同

  • UserDAO
public interface UserDAO extends GeneralDAO<User>{
}
  • GoodsDAO
public interface GoodsDAO extends GeneralDAO<Goods> {
}
  • GeneralDAO
public interface GeneralDAO<T>{
    //通用方法
    public int insert(T t);
    public T queryOneByPrimarykey(int i);
）
  • 对于GeneralDAO接口定义的数据库操作方法因为使用了泛型，无需映射文件；对于UserDAO和GoodsDAO需要
    映射文件，所有DAO的相同操作的映射文件也是有规律可循的
  • UserMapper
<insert id="insert">
    insert into users(user_id,username) values(#{userId},#{username}）
</insert>

@Table("users")
public class User{
   
    @Id
    @Column("user_id")
    private int userId;
    
    @Column("username")
    private String username;
}
  • GoodsMapper
<insert id="insert">
    insert into goods(goods_id,goodsrname) values(#{goodsId},#{goodsname}）
</insert>

@Table("product")
public class User{
   
    @Id
    @Column("goods_id")
    private int userId;
    
    @Column("goodsname")
    private String username;
}

二、tkMapper

基于MyBatis提供了很多第三方插件，这些插件通常可以完成数据操作方法的封装（GeneralDAO）、数据库逆向工程工作(根据数据表生成实体类、生成映射文件)

  • MyBatis-plus
  • tkMapper

tkMapper就是一个MyBatis插件，是在MyBatis的基础上提供了很多工具，让开发变得简单，提高开发效率。

  • 提供了针对单表通用的数据库操作方法
  • 逆向工程（根据数据表生成实体类、dao接口、映射文件）

三、tkMapper整合

3.1 基于SpringBoot完成MyBatis的整合

3.2整合tkMapper

3.2.1添加tkMapper的依赖

<dependency>
    <groupId>tk.mybatis</groupId>
    <artifactId>mapper-spring-boot-starter</artifactId>
    <version>2.1.5</version>
</dependency>

3.2.2修改启动类的@MapperScan 注解的包

  • 为 tk .mybatis .spring.annotation.MapperScan
import tk.mybatis.spring.annotation.MapperScan;

@SpringBootApplication
@MapperScan("com.qfedu.tkmapperdemo.dao")
public class TkmapperDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(TkmapperDemoApplication.class, args);
    }
}

四、tkMapper使用

4.1 创建DAO接口

tkMapper已经完成了对单表的通用操作的封装，封装在Mapper接口和MySqlMapper接口；因此如果我们要完成对单表的操作，只需自定义DAO接口继承Mapper接口和MySqIMapper接口

public interface UserDAO extends Mapper<User>, MySqlMapper<User> {
}

4.2 tkMapper提供的方法

@RunWith(SpringRunner.class)
@SpringBootTest(classes = TkmapperDemoApplication.class)

public class CategoryDAOTest {
    @Autowired
    private CategoryDAO categoryDAO;
    
    @Test
    public vold testInsert(){
        Category category = new Category(日,"测试类别3",1,0,"03.png","xixi","aaa.jpg","black");
        //int i = categoryDAO.insert(category);
        int i = categoryDAO.insertUseGeneratedKeys(category);
        System.out.println(category.getCategoryId());
        assertEquals(1,i);
    }
    
    @Test
    public void testUpdate(){
        Category category = new Category(48,"测试类别4",1,0,"04.png","heihei","aaa.jpg","black");
        int i = categoryDAO.updateByPrimaryKey(category);
        //根据自定义条件修改，Example example就是封装条件的
        // int i1 = categoryDAO.updateByExample( Example example);
        assertEquals(1,i);
    }
    
    @Test
    public void testDelete(){
        int i = categoryDAO.deleteByPrimaryKey(48);
        // 根据条件删除
        //int i1 = categoryDAO.deleteByExample(Example example);
        assertEquals(1,i);
    }
    
    @Test
    public void testSelect1(){
        //查询所有
        List<Category> categories = categoryDAO.selectAll();
        for (Category category: categories) {
            System.out.println(category);
        }
    }
    
    @Test
    public void testSelect2(){
        //根据主键查询
        Category category = categoryDAO.selectByPrimaryKey(47);
        System.out.println(category);
    }
    
    @Test
    public void testSelect4(){
        //分页查询
        int pageNum = 2;
        int pageSize = 10;
        int start = (pageNum-1)*pageSize;
        
        RowBounds rowBounds = new RowBounds(start,pageSize);
        
        List<Category> categories = categoryDAO.selectByRowBounds(new Category(), rowBounds);
        for (Category category: categories) {
            System.out.println(category);
        }
        
        //查询总记录数
        int i = categoryDAO.selectCount(new Category());
        System.out.println(i);
    }
    
    @Test
    public void testSelect5(){
        //带条件分页
        //条件
        Example example = new Example(Category.class);
        Example.Criteria criteria = example.createCriteria();
        criteria.andEqualTo("categoryLevel",1);
        //分页
        int pageNum = 2;
        int pageSize = 3;
        int start = (pageNum-1)*pageSize;
        RowBounds rowBounds = new RowBounds(start,pageSize);
        
        List<Category> categories = categoryDAO.selectByExampleAndRowBounds(example,rowBounds);
        for (Category category: categories) {
            System.out.println(category);
        }
        
        //查询总记录数（满足条件）
        int i = categoryDAO.selectCountByExample(example);
        System.out.println(i);
    }
}

4.3 多表关联查询

public void testSelect(){
    //查询用户同时查询订单
    Example example = new Example(User.class);
    Example.Criteria criteria = example.createCriteria();
    criteria.andEqualTo( property."username", value:"zhangsan");
    
    //根据用户名查询用户
    //1.先根据用户名查询用户信息
    List<User> users = userDAO.selectByExample(example);
    User user = users.get(0);
    
    //2.再根据用户id到订单表查询订单
    Example example1 = new Example(Orders.class);
    Example.Criteria criteria1 = example1.createCriteria();
    criteria1.andEqualTo(lproperty:"userId",user.getUserId());
    List<Orders> ordersList = orderDAO.selectByExample(example1);
    
    //3.将查询到订单集合设置到user
    user.setordersList(ordersList);

    System.out.println(user);
}
  • 也可以自定义sql语句进行关联查询

4.4 逆向工程——类似代码生成器

  • 引入插件和依赖
  • 在resource/gnerator目录下创建generatorConfig.xml
<!-- mysql的驱动版本要和pom文件中的mysql驱动版本一致 -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.5</version>
                <configuration>
                   <configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>8.0.27</version>
                    </dependency>
                    <dependency>
                        <groupId>tk.mybatis</groupId>
                        <artifactId>mapper</artifactId>
                        <version>4.0.0</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>

    <!-- 引入数据库连接配置 -->
    <!-- <properties resource="jdbc.properties "/>-->
    <context id="Mysql" targetRuntime="MyBatis3Simple" defaultModelType="flat">
        <property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>

        <!-- 配置 GeneralDAO -->
        <plugin type="tk.mybatis.mapper.generator.MapperPlugin">
            <property name="mappers" value="com.ly.lymall.general.GeneralDAO"/>
        </plugin>
        <!-- 配置数据库连接-->
        <jdbcConnection
            driverClass="com.mysql.cj.jdbc.Driver"
            connectionURL="jdbc:mysql://localhost:3306/mall"
            userId="root"
            password="123456">
            <!-- connectionURL属性，防止乱码 -->
            <property name="useUnicode" value="true"/>
            <!-- connectionURL属性，防止乱码 -->
            <property name="characterEncoding" value="utf-8"/>
            <!-- connectionURL属性，防止报时间错误 -->
            <property name="serverTimezone" value="UTC"/>
            <!-- connectionURL属性，防止生成不同数据库同名表的代码 -->
            <property name="nullCatalogMeansCurrent" value="true"/>
        </jdbcConnection>

        <!-- 配置实体类存放路径 -->
        <javaModelGenerator targetPackage="com.ly.lymall.entity" targetProject="src/main/java"/>

        <!-- 配置 XML 存放路径 -->
        <sqlMapGenerator targetPackage="/" targetProject="src/main/resources/mappers"/>

        <!-- 配置 DAO 存放路径 -->
        <javaClientGenerator  targetPackage="com.ly.lymall.dao" targetProject="src/main/java" type="XMLMAPPER"/>

        <!-- %代表要生成所有表 -->
        <table tableName="%"></table>
        
    </context>
</generatorConfiguration>
  • 将配置文件设置到逆向工程的maven插件

image-20220327234318471

  • 启动generator

image-20220401090955559

文章作者: 寜笙
文章链接: https://lycode1202.github.io/2022/03/27/tkmapper-zheng-he-shi-yong/
版权声明: 本博客所有文章除特別声明外，均采用 CC BY 4.0 许可协议。转载请注明来源 寜笙 !
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