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⼀、 DAO 层的实现的规律

实体类与数据表存在对应关系，并且是有规律的 —— 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>{
 public int insert(User t);
}

GoodsDAO

public interface GoodsDAO extends GeneralDAO<Goods> {
 public int insert(Goods t);
}

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,goods_name) values(#{goodsId},#
{goodsName})
</insert>

@Table("product")
public class Goods{
 @Id
 @Column("goods_id")
 private int goodsId;
 
 @Column("goods_name")
 private String goodsName; 
}

⼆、 tkMapper 简介

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 创建数据表

CREATE TABLE `users` (
 `user_id` int(64) NOT NULL AUTO_INCREMENT COMMENT '主键id ⽤户id',
 `username` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT
NULL COMMENT '⽤户名 ⽤户名',
 `password` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci NOT
NULL COMMENT '密码 密码',
 `nickname` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci
NULL DEFAULT NULL COMMENT '昵称 昵称',
 `realname` varchar(128) CHARACTER SET utf8 COLLATE utf8_general_ci
NULL DEFAULT NULL COMMENT '真实姓名 真实姓名',
 `user_img` varchar(1024) CHARACTER SET utf8 COLLATE utf8_general_ci
NOT NULL COMMENT '头像 头像',
 `user_mobile` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci
NULL DEFAULT NULL COMMENT '⼿机号 ⼿机号',
 `user_email` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci
NULL DEFAULT NULL COMMENT '邮箱地址 邮箱地址',
 `user_sex` char(1) CHARACTER SET utf8 COLLATE utf8_general_ci NULL
DEFAULT NULL COMMENT '性别 M(男) or F(⼥)',
 `user_birth` date NULL DEFAULT NULL COMMENT '⽣⽇ ⽣⽇',
 `user_regtime` datetime(0) NOT NULL COMMENT '注册时间 创建时间',
 `user_modtime` datetime(0) NOT NULL COMMENT '更新时间 更新时间',
 PRIMARY KEY (`user_id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 2 CHARACTER SET = utf8 COLLATE =
utf8_general_ci COMMENT = '⽤户 ' ROW_FORMAT = Compact;

4.2 创建实体类

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
 private int userId;
 private String username;
 private String password;
 private String nickname;
 private String realname;
 private String userImg;
 private String userMobile;
 private String userEmail;
 private String userSex;
 private Date userBirth;
 private Date userRegtime;
 private Date userModtime;
}

4.3 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

MySqlMapper 接⼝

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

4.4 测试

@RunWith(SpringRunner.class)
@SpringBootTest(classes = TkmapperDemoApplication.class)
public class UserDAOTest {
 @Autowired
 private UserDAO userDAO;
 @Test
 public void test(){
 User user = new User();
 user.setUsername("aaaa");
 user.setPassword("1111");
 user.setUserImg("img/default.png");
 user.setUserRegtime(new Date());
 user.setUserModtime(new Date());
 int i = userDAO.insert(user);
 System.out.println(i);
 }
}

五、 tkMapper 提供的⽅法

@SpringBootTest(classes = TkmapperDemoApplication.class)
public class CategoryDAOTest {
 @Autowired
 private CategoryDAO categoryDAO;
 @Test
 public void testInsert(){
     Category category = new Category(0,"测试类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 testSelect3(){
 //条件查询
 //1.创建⼀个Example封装 类别Category查询条件
 Example example = new Example(Category.class);
 Example.Criteria criteria = example.createCriteria();
 criteria.andEqualTo("categoryLevel",1);
 criteria.orLike("categoryName","%⼲%");
 List<Category> categories =
categoryDAO.selectByExample(example);
 for (Category category: categories) {
 System.out.println(category);
 }
 }
 @Test
 public void testSelect4(){
 //分⻚查询
 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(){
 //带条件分⻚
 //条件
 Example example = new Example(Category.class);
 Example.Criteria criteria = example.createCriteria();
 criteria.andEqualTo("categoryLevel",1);
 //分⻚
 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);
 }
}

六、在使⽤tkMapper是如何进⾏关联查询

6.1 所有的关联查询都可以通过多个单表操作实现

//查询⽤户同时查询订单
Example example = new Example(User.class);
Example.Criteria criteria = example.createCriteria();
criteria.andEqualTo("username","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("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);

6.2 ⾃定义连接查询

在使⽤ tkMapper,DAO 继承 Mapper 和 MySqlMapper 之后，还可以⾃定义查询

6.2.1 在 DAO 接⼝⾃定义⽅法

public interface UserDAO extends GeneralDAO<User> {
 public User selectByUsername(String username);
}

6.2.2 创建 Mapper 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="com.qfedu.fmmall.dao.UserDAO">
 <insert id="insertUser">
 insert into
users(username,password,user_img,user_regtime,user_modtime)
 values(#{username},#{password},#{userImg},#{userRegtime},#
{userModtime})
 </insert>
 <resultMap id="userMap" type="User">
 <id column="user_id" property="userId"/>
 <result column="username" property="username"/>
 <result column="password" property="password"/>
 <result column="nickname" property="nickname"/>
 <result column="realname" property="realname"/>
 <result column="user_img" property="userImg"/>
 <result column="user_mobile" property="userMobile"/>
 <result column="user_email" property="userEmail"/>
 <result column="user_sex" property="userSex"/>
 <result column="user_birth" property="userBirth"/>
 <result column="user_regtime" property="userRegtime"/>
 <result column="user_modtime" property="userModtime"/>
 </resultMap>
 <select id="queryUserByName" resultMap="userMap">
 select
 user_id,
 username,
 password,
 nickname,
 realname,
 user_img,
 user_mobile,
 user_email,
 user_sex,
 user_birth,
 user_regtime,
 user_modtime
 from users
 where username=#{name}
 </select>
</mapper>

七、逆向⼯程

逆向⼯程，根据创建好的数据表，⽣成实体类、 DAO 、映射⽂件

7.1 添加逆向⼯程依赖

是依赖是⼀个 mybatis 的 maven 插件

<plugin>
 <groupId>org.mybatis.generator</groupId>
 <artifactId>mybatis-generator-maven-plugin</artifactId>
 <version>1.3.5</version>
 <dependencies>
 <dependency>
 <groupId>mysql</groupId>
 <artifactId>mysql-connector-java</artifactId>
 <version>5.1.47</version>
 </dependency>
 <dependency>
 <groupId>tk.mybatis</groupId>
 <artifactId>mapper</artifactId>
 <version>3.4.4</version>
 </dependency>
 </dependencies>
</plugin>

7.2 逆向⼯程配置

在resources/generator⽬录下创建generatorConfig.xml

<?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.qfedu.tkmapperdemo.general.GeneralDAO"/>
 </plugin>
 <!-- 配置数据库连接 -->
 <jdbcConnection driverClass="com.mysql.jdbc.Driver"
 connectionURL="jdbc:mysql://localhost:3306/fmmall2"
 userId="root" password="admin123">
 </jdbcConnection>
 <!-- 配置实体类存放路径 -->
 <javaModelGenerator
targetPackage="com.qfedu.tkmapperdemo.beans"
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.qfedu.tkmapperdemo.dao"
targetProject="src/main/java" type="XMLMAPPER"/>
 <!-- 配置需要指定⽣成的数据库和表，% 代表所有表 -->
 <table tableName="%">
 <!-- mysql 配置 -->
<!-- <generatedKey column="id" sqlStatement="Mysql"
identity="true"/>-->
 </table>
<!-- <table tableName="tb_roles">-->
<!-- &lt;!&ndash; mysql 配置 &ndash;&gt;-->
<!-- <generatedKey column="roleid" sqlStatement="Mysql"
identity="true"/>-->
<!-- </table>-->
<!-- <table tableName="tb_permissions">-->
<!-- &lt;!&ndash; mysql 配置 &ndash;&gt;-->
<!-- <generatedKey column="perid" sqlStatement="Mysql"
identity="true"/>-->
<!-- </table>-->
 </context>
</generatorConfiguration>

7.3 将配置⽂件设置到逆向⼯程的maven插件

7.4 执⾏逆向⽣成

tkMapper

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