一、MyBatisPlus入门案例与简介

1、入门案例

a、开发方式

  1. 基于MyBatis使用MP
  2. 基于Spring使用MP

  3. 基于SpringBoot使用MP

    b、SpringBoot整合MyBatis开发过程

  4. 创建SpringBoot工程

  5. 勾选配置使用的技术
  6. 设置dataSource相关属性
  7. 定义数据层接口映射配置

c、案例

  1. 创建项目工程
  2. 创建数据库及数据表 ```sql create database if not exists db_mybatisplus character set utf8; use db_mybatisplus;

CREATE TABLE tb_user ( user_id BIGINT(20) PRIMARY KEY auto_increment, user_name VARCHAR(32) DEFAULT(“default_name”), user_pwd VARCHAR(32) DEFAULT(“default_pwd”), user_age INT(3) DEFAULT(21), user_tel VARCHAR(32) DEFAULT(“default_tel”) );

drop table tb_user;

insert into tb_user values(1,’Tom’,’tom’,3,’18866668888’); insert into tb_user values(2,’Jerry’,’jerry’,4,’16688886666’); insert into tb_user values(3,’Jock’,’123456’,41,’18812345678’); insert into tb_user values(4,’zhouge’,’aa’,15,’4006184000’);

SELECT * from tb_user;

  2. 3. 修改application.yml
  3. ```yaml
  4. spring:
  5.   datasource:
  6.     type: com.alibaba.druid.pool.DruidDataSource
  7.     driver-class-name: com.mysql.cj.jdbc.Driver
  8.     url: jdbc:mysql://localhost:3306/db_mybatisplus
  9.     username: root
  10.     password: root
  1. 创建pojo实体类 ```java package xyz.zhouge.pojo;

import com.baomidou.mybatisplus.annotation.TableField; import com.baomidou.mybatisplus.annotation.TableId; import com.baomidou.mybatisplus.annotation.TableName; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor;

@Data @NoArgsConstructor @AllArgsConstructor @TableName(“tb_user”) public class User {

@TableId(“user_id”) private long userId ;

  1. @TableField("user_name")
  2. private String userName ;
  4. @TableField("user_pwd")
  5. private String password ;
  7. @TableField("user_age")
  8. private Integer userAge ;
  10. @TableField("user_tel")
  11. private String userTel ;

}

  2. 5. 创建dao接口
  3. ```java
  4. package xyz.zhouge.dao;
  6. import com.baomidou.mybatisplus.core.mapper.BaseMapper;
  7. import org.apache.ibatis.annotations.Mapper;
  8. import xyz.zhouge.pojo.User;
  10. @Mapper
  11. public interface UserDao extends BaseMapper<User>{
  13. }
  1. 创建service业务层
  2. 测试

2、MyBatisPlus简介

二、标准数据层开发

1、项目搭建

1,创建项目

image.png

2，引入maven依赖

  1. <dependencies>
  3.   <dependency>
  4.     <groupId>org.springframework.boot</groupId>
  5.     <artifactId>spring-boot-starter</artifactId>
  6.   </dependency>
  8.   <dependency>
  9.     <groupId>mysql</groupId>
  10.     <artifactId>mysql-connector-java</artifactId>
  11.     <scope>runtime</scope>
  12.   </dependency>
  14.   <dependency>
  15.     <groupId>org.springframework.boot</groupId>
  16.     <artifactId>spring-boot-starter-test</artifactId>
  17.     <scope>test</scope>
  18.   </dependency>
  20.   <!-- 引入数据库连接池 -->
  21.   <dependency>
  22.     <groupId>com.alibaba</groupId>
  23.     <artifactId>druid</artifactId>
  24.     <version>1.1.10</version>
  25.   </dependency>
  27.   <!-- 引入lombok -->
  28.   <dependency>
  29.     <groupId>org.projectlombok</groupId>
  30.     <artifactId>lombok</artifactId>
  31.     <version>1.18.12</version>
  32.   </dependency>
  34.   <!-- 引入mybatis-plus -->
  35.    <dependency>
  36.     <groupId>com.baomidou</groupId>
  37.     <artifactId>mybatis-plus-boot-starter</artifactId>
  38.     <version>3.4.1</version>
  39.   </dependency>
  42. </dependencies>

3，配置yml文件

  1. spring:
  2.   datasource:
  3.     type: com.alibaba.druid.pool.DruidDataSource
  4.     driver-class-name: com.mysql.cj.jdbc.Driver
  5.     url: jdbc:mysql://zhouge.xyz:3306/db_mybatisplus
  6.     username: admin
  7.     password: 991227zg@.
  8.   profiles:
  9.     active: dev
  11. server:
  12.   port: 80

4，创建数据模型

  1. import com.baomidou.mybatisplus.annotation.TableField;
  2. import com.baomidou.mybatisplus.annotation.TableId;
  3. import com.baomidou.mybatisplus.annotation.TableName;
  4. import lombok.AllArgsConstructor;
  5. import lombok.Data;
  6. import lombok.NoArgsConstructor;
  8. @Data
  9. @NoArgsConstructor
  10. @AllArgsConstructor
  11. @TableName("tb_user")
  12. public class User {
  14.     @TableId("user_id")
  15.     private long userId ;
  17.     @TableField("user_name")
  18.     private String userName ;
  20.     @TableField("user_pwd")
  21.     private String password ;
  23.     @TableField("user_age")
  24.     private Integer userAge ;
  26.     @TableField("user_tel")
  27.     private String userTel ;
  29.     public User(String userName, String password) {
  30.         this.userName = userName;
  31.         this.password = password;
  32.     }
  34.     public User(long userId, String userName, String password) {
  35.         this.userId = userId;
  36.         this.userName = userName;
  37.         this.password = password;
  38.     }
  39. }

5，创建数据持久层

  1. import com.baomidou.mybatisplus.core.mapper.BaseMapper;
  2. import org.apache.ibatis.annotations.Mapper;
  3. import xyz.zhouge.pojo.User;
  5. @Mapper
  6. public interface UserDao extends BaseMapper<User>{
  8. }

6，创建测试

  1. import org.junit.jupiter.api.Test;
  2. import org.springframework.beans.factory.annotation.Autowired;
  3. import org.springframework.boot.test.context.SpringBootTest;
  4. import xyz.zhouge.dao.UserDao;
  5. import xyz.zhouge.pojo.User;
  6. import java.util.List;
  8. @SpringBootTest
  9. public class TestUserService {
  11.     @Autowired
  12.     private UserService userService;
  14.     @Autowired
  15.     private UserDao userDao ;
  18.     @Test
  19.     public void testInsertUser(){
  20.         int res = userDao.insert(new User("zhouge1","123456"));
  21.         System.out.println(res > 0 ? "添加成功" : "添加失败");
  22.     }
  24.     @Test
  25.     public void testDeleteUser(){
  26.         int res = userDao.deleteById(6L);
  27.         System.out.println(res > 0 ? "删除成功" : "删除失败");
  28.     }
  30.     @Test
  31.     public void testUpdateUser(){
  32.         int res = userDao.updateById(new User(4L,"admin","123456"));
  33.         System.out.println(res > 0 ? "修改成功" : "修改失败");
  34.     }
  36.     @Test
  37.     public void testGetAllUsers(){
  38.         List<User> users = userService.getAllUsers();
  39.         for (User user : users) {
  40.             System.out.println(user);
  41.         }
  42.     }
  44.     @Test
  45.     public void testGetUserById(){
  46.         User user = userDao.selectById(1L);
  47.         System.out.println(user);
  48.     }
  50. }

2、新增

  1. import org.junit.jupiter.api.Test;
  2. import org.springframework.beans.factory.annotation.Autowired;
  3. import org.springframework.boot.test.context.SpringBootTest;
  4. import xyz.zhouge.dao.UserDao;
  5. import xyz.zhouge.pojo.User;
  6. import java.util.List;
  8. @SpringBootTest
  9. public class TestUserService {
  11.     @Autowired
  12.     private UserService userService;
  14.     @Autowired
  15.     private UserDao userDao ;
  18.     @Test
  19.     public void testInsertUser(){
  20.         int res = userDao.insert(new User("zhouge1","123456"));
  21.         System.out.println(res > 0 ? "添加成功" : "添加失败");
  22.     }
  26. }

3、删除

  1. import org.junit.jupiter.api.Test;
  2. import org.springframework.beans.factory.annotation.Autowired;
  3. import org.springframework.boot.test.context.SpringBootTest;
  4. import xyz.zhouge.dao.UserDao;
  5. import xyz.zhouge.pojo.User;
  6. import java.util.List;
  8. @SpringBootTest
  9. public class TestUserService {
  11.     @Autowired
  12.     private UserService userService;
  14.     @Autowired
  15.     private UserDao userDao ;
  17.     @Test
  18.     public void testDeleteUser(){
  19.         int res = userDao.deleteById(6L);
  20.         System.out.println(res > 0 ? "删除成功" : "删除失败");
  21.     }
  24. }

4、修改

  1. import org.junit.jupiter.api.Test;
  2. import org.springframework.beans.factory.annotation.Autowired;
  3. import org.springframework.boot.test.context.SpringBootTest;
  4. import xyz.zhouge.dao.UserDao;
  5. import xyz.zhouge.pojo.User;
  6. import java.util.List;
  8. @SpringBootTest
  9. public class TestUserService {
  11.     @Autowired
  12.     private UserService userService;
  14.     @Autowired
  15.     private UserDao userDao ;
  18.     @Test
  19.     public void testUpdateUser(){
  20.         int res = userDao.updateById(new User(4L,"admin","123456"));
  21.         System.out.println(res > 0 ? "修改成功" : "修改失败");
  22.     }
  25. }

5、根据Id查询

  1. import org.junit.jupiter.api.Test;
  2. import org.springframework.beans.factory.annotation.Autowired;
  3. import org.springframework.boot.test.context.SpringBootTest;
  4. import xyz.zhouge.dao.UserDao;
  5. import xyz.zhouge.pojo.User;
  6. import java.util.List;
  8. @SpringBootTest
  9. public class TestUserService {
  11.     @Autowired
  12.     private UserService userService;
  14.     @Autowired
  15.     private UserDao userDao ;
  18.     @Test
  19.     public void testGetUserById(){
  20.         User user = userDao.selectById(1L);
  21.         System.out.println(user);
  22.     }
  24. }

6、查询所有

  1. import org.junit.jupiter.api.Test;
  2. import org.springframework.beans.factory.annotation.Autowired;
  3. import org.springframework.boot.test.context.SpringBootTest;
  4. import xyz.zhouge.dao.UserDao;
  5. import xyz.zhouge.pojo.User;
  6. import java.util.List;
  8. @SpringBootTest
  9. public class TestUserService {
  11.     @Autowired
  12.     private UserService userService;
  14.     @Autowired
  15.     private UserDao userDao ;
  17.     @Test
  18.     public void testGetAllUsers(){
  19.         List<User> users = userService.getAllUsers();
  20.         for (User user : users) {
  21.             System.out.println(user);
  22.         }
  23.     }
  26. }

7,分页查询

7.1，搭建项目

image.png

7.2，修改maven依赖

  1. <dependencies>
  2.   <dependency>
  3.     <groupId>org.mybatis.spring.boot</groupId>
  4.     <artifactId>mybatis-spring-boot-starter</artifactId>
  5.     <version>2.2.2</version>
  6.   </dependency>
  8.   <dependency>
  9.     <groupId>mysql</groupId>
  10.     <artifactId>mysql-connector-java</artifactId>
  11.     <scope>runtime</scope>
  12.   </dependency>
  14.   <dependency>
  15.     <groupId>org.springframework.boot</groupId>
  16.     <artifactId>spring-boot-starter-test</artifactId>
  17.     <scope>test</scope>
  18.   </dependency>
  20.   <!--引入druid数据库连接池-->
  21.   <dependency>
  22.     <groupId>com.alibaba</groupId>
  23.     <artifactId>druid</artifactId>
  24.     <version>1.1.10</version>
  25.   </dependency>
  27.   <!--引入mybatis-plus-->
  28.   <dependency>
  29.     <groupId>com.baomidou</groupId>
  30.     <artifactId>mybatis-plus-boot-starter</artifactId>
  31.     <version>3.4.1</version>
  32.   </dependency>
  34.   <!--引入lombok-->
  35.   <dependency>
  36.     <groupId>org.projectlombok</groupId>
  37.     <artifactId>lombok</artifactId>
  38.     <version>1.18.12</version>
  39.   </dependency>
  41.     </dependencies>

7.3，配置application.yml

  1. spring:
  2.   datasource:
  3.     type: com.alibaba.druid.pool.DruidDataSource
  4.     driver-class-name: com.mysql.cj.jdbc.Driver
  5.     url: jdbc:mysql://zhouge.xyz:3306/db_mybatisplus
  6.     username: admin
  7.     password: 991227zg@.
  8.   profiles:
  9.     active: dev
  10.   main:
  11.     #springBoot 日志
  12.     log-startup-info: off
  16. server:
  17.   port: 80
  19. mybatis-plus:
  20.   configuration:
  21.     #mp 日志设置为标准日志
  22.     log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

7.4，创建数据模型

  1. import com.baomidou.mybatisplus.annotation.TableField;
  2. import com.baomidou.mybatisplus.annotation.TableId;
  3. import com.baomidou.mybatisplus.annotation.TableName;
  4. import lombok.AllArgsConstructor;
  5. import lombok.Data;
  6. import lombok.NoArgsConstructor;
  8. @Data
  9. @NoArgsConstructor
  10. @AllArgsConstructor
  11. @TableName("tb_user")
  12. public class User {
  14.     @TableId("user_id")
  15.     private long userId ;
  17.     @TableField("user_name")
  18.     private String userName ;
  20.     @TableField("user_pwd")
  21.     private String password ;
  23.     @TableField("user_age")
  24.     private Integer userAge ;
  26.     @TableField("user_tel")
  27.     private String userTel ;
  29.     public User(String userName, String password) {
  30.         this.userName = userName;
  31.         this.password = password;
  32.     }
  34.     public User(long userId, String userName, String password) {
  35.         this.userId = userId;
  36.         this.userName = userName;
  37.         this.password = password;
  38.     }
  39. }

7.5，创建数据访问层

  1. import com.baomidou.mybatisplus.core.mapper.BaseMapper;
  2. import org.apache.ibatis.annotations.Mapper;
  3. import xyz.zhouge.pojo.User;
  5. @Mapper
  6. public interface UserDao extends BaseMapper<User>{
  8. }

7.6，创建拦截器

  1. import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
  2. import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
  3. import org.springframework.context.annotation.Bean;
  4. import org.springframework.context.annotation.Configuration;
  6. @Configuration
  7. public class PageInterceptor{
  9.     @Bean
  10.     public MybatisPlusInterceptor mybatisPlusInterceptor(){
  11.         //1, 创建一个通用的拦截器
  12.         MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
  14.         //2，指定（添加） 特定的拦截器  分页拦截器
  15.         interceptor.addInnerInterceptor(new PaginationInnerInterceptor());
  17.         //3，返回拦截器
  18.         return interceptor;
  19.     }
  21. }

7.7,添加logback配置文件

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <configuration>
  4. </configuration>

7.8，测试

  1. import com.baomidou.mybatisplus.core.metadata.IPage;
  2. import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
  3. import org.junit.jupiter.api.Test;
  4. import org.springframework.beans.factory.annotation.Autowired;
  5. import org.springframework.boot.test.context.SpringBootTest;
  6. import xyz.zhouge.pojo.User;
  8. @SpringBootTest
  9. public class UserDaoTest {
  11.     @Autowired
  12.     private UserDao userDao;
  14.     /**
  15.     * 未添加分页拦截器
  16.     */
  17.     @Test
  18.     public void testPage1() {
  19.         //1,创建分页对象
  20.         Page<User> page = new Page<User>(1, 2);
  22.         //2，执行分页查询
  23.         Page<User> userPage = userDao.selectPage(page, null);
  25.         //3，获取分页结果
  26.         System.out.println("当前页码值：" + userPage.getCurrent());
  27.         System.out.println("每页显示数：" + userPage.getSize());
  28.         System.out.println("一共多少页：" + userPage.getPages());
  29.         System.out.println("一共多少条数据：" + userPage.getTotal());
  30.         System.out.println("数据：" + userPage.getRecords());
  31.     }
  33.     @Test
  34.     public void testPage2() {
  35.         IPage page = new Page(1, 2);
  37.         //2，执行分页查询
  38.         IPage userPage = userDao.selectPage(page, null);
  40.         //3，获取分页结果
  41.         System.out.println("当前页码值：" + userPage.getCurrent());
  42.         System.out.println("每页显示数：" + userPage.getSize());
  43.         System.out.println("一共多少页：" + userPage.getPages());
  44.         System.out.println("一共多少条数据：" + userPage.getTotal());
  45.         System.out.println("数据：" + userPage.getRecords());
  46.     }
  47. }

三、DQL编程控制

image.png

1、条件查询

方法名 作用
lt(column ， val） 查询column 该字段的值小于val的集合
gt(column ， val） 查询column 该字段的值大于val的集合
eq(column ， val） 查询column 该字段的值等于val的集合
or(） 或 关系
…. …

1.1,搭建项目

1.2，引入maven依赖

  1. <dependencies>
  2.   <dependency>
  3.     <groupId>org.mybatis.spring.boot</groupId>
  4.     <artifactId>mybatis-spring-boot-starter</artifactId>
  5.     <version>2.2.2</version>
  6.   </dependency>
  8.   <dependency>
  9.     <groupId>mysql</groupId>
  10.     <artifactId>mysql-connector-java</artifactId>
  11.     <scope>runtime</scope>
  12.   </dependency>
  13.   <dependency>
  14.     <groupId>org.springframework.boot</groupId>
  15.     <artifactId>spring-boot-starter-test</artifactId>
  16.     <scope>test</scope>
  17.   </dependency>
  19.   <!--引入mybatis-plus-->
  20.   <dependency>
  21.     <groupId>com.baomidou</groupId>
  22.     <artifactId>mybatis-plus-boot-starter</artifactId>
  23.     <version>3.4.1</version>
  24.   </dependency>
  26.   <!--引入数据库连接池-->
  27.   <dependency>
  28.     <groupId>com.alibaba</groupId>
  29.     <artifactId>druid</artifactId>
  30.     <version>1.1.10</version>
  31.   </dependency>
  33.   <!--引入lombok-->
  34.   <dependency>
  35.     <groupId>org.projectlombok</groupId>
  36.     <artifactId>lombok</artifactId>
  37.     <version>1.18.12</version>
  38.   </dependency>
  40.     </dependencies>

1.3，配置application.yml

  1. spring:
  2.   datasource:
  3.     type: com.alibaba.druid.pool.DruidDataSource
  4.     driver-class-name: com.mysql.cj.jdbc.Driver
  5.     url: jdbc:mysql://zhouge.xyz:3306/db_mybatisplus
  6.     username: admin
  7.     password: 991227zg@.
  8.   profiles:
  9.     active: dev
  10.   main:
  11.     #springBoot 日志
  12.     log-startup-info: off
  13.     banner-mode: off
  17. server:
  18.   port: 80
  20. mybatis-plus:
  21.   configuration:
  22.     #mp 日志设置为标准日志
  23.     log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  24.   global-config:
  25.     banner: off

1.4，配置logback.xml

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <configuration>
  4. </configuration>

1.5，创建数据模型

  1. import com.baomidou.mybatisplus.annotation.TableField;
  2. import com.baomidou.mybatisplus.annotation.TableId;
  3. import com.baomidou.mybatisplus.annotation.TableName;
  4. import lombok.AllArgsConstructor;
  5. import lombok.Data;
  6. import lombok.NoArgsConstructor;
  8. @Data
  9. @NoArgsConstructor
  10. @AllArgsConstructor
  11. @TableName("tb_user")
  12. public class User {
  14.     @TableId("user_id")
  15.     private long userId ;
  17.     @TableField("user_name")
  18.     private String userName ;
  20.     @TableField("user_pwd")
  21.     private String password ;
  23.     @TableField("user_age")
  24.     private Integer userAge ;
  26.     @TableField("user_tel")
  27.     private String userTel ;
  29.     public User(String userName, String password) {
  30.         this.userName = userName;
  31.         this.password = password;
  32.     }
  34.     public User(long userId, String userName, String password) {
  35.         this.userId = userId;
  36.         this.userName = userName;
  37.         this.password = password;
  38.     }
  39. }

1.6，创建数据持久层

  1. import com.baomidou.mybatisplus.core.mapper.BaseMapper;
  2. import org.apache.ibatis.annotations.Mapper;
  3. import xyz.zhouge.pojo.User;
  5. @Mapper
  6. public interface UserDao extends BaseMapper<User>{
  8. }

1.7，测试

  1. import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
  2. import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
  3. import org.junit.jupiter.api.Test;
  4. import org.springframework.beans.factory.annotation.Autowired;
  5. import org.springframework.boot.test.context.SpringBootTest;
  6. import xyz.zhouge.pojo.User;
  7. import xyz.zhouge.pojo.quert.QueryUser;
  9. import java.util.List;
  11. @SpringBootTest
  12. public class UserDaoTest {
  14.     @Autowired
  15.     private UserDao userDao ;
  17.     @Test
  18.     public void testSelectList(){
  19.         List<User> users = userDao.selectList(null);
  20.         users.forEach(user -> System.out.println(user));
  21.     }
  23.     // todo 测试QueryWrapper
  24.     @Test
  25.     public void testSelectList1(){
  26.         //创建查询条件包装器  未添加条件，则为空条件
  27.         QueryWrapper<User> queryWrapper = new QueryWrapper<>();
  29.         //执行查询
  30.         List<User> users = userDao.selectList(queryWrapper);
  32.         //输出
  33.         users.forEach(user -> System.out.println(user));
  34.     }
  36.     // todo 多条件查询
  37.     @Test
  38.     public void testSelectList2(){
  39.         //创建查询条件包装器
  40.         QueryWrapper<User> queryWrapper = new QueryWrapper<>();
  41.         queryWrapper.gt("user_age",10);//添加查询条件，user_age 字段大于10
  42.         queryWrapper.lt("user_age",40);//添加查询条件，user_age 字段小于40
  44.         //执行查询
  45.         List<User> users = userDao.selectList(queryWrapper);
  47.         //输出
  48.         users.forEach(user -> System.out.println(user));
  49.     }
  51.     // todo 测试 LambdaQueryWrapper
  52.     @Test
  53.     public void testSelectList3(){
  54.         //创建查询条件包装器
  55.         LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
  56.         lambdaQueryWrapper.gt(User::getUserAge,10);
  57.         lambdaQueryWrapper.lt(User::getUserAge,40);
  59.         //执行查询
  60.         List<User> users = userDao.selectList(lambdaQueryWrapper);
  62.         //输出
  63.         users.forEach(user -> System.out.println(user));
  64.     }
  67.     // todo 测试 or()
  68.     @Test
  69.     public void testSelectList4(){
  70.         //创建查询条件包装器
  71.         LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
  72.         lambdaQueryWrapper.gt(User::getUserAge,20)
  73.             .or()
  74.             .lt(User::getUserAge,10);
  76.         //执行查询
  77.         List<User> users = userDao.selectList(lambdaQueryWrapper);
  79.         //输出
  80.         users.forEach(user -> System.out.println(user));
  81.     }
  84.     // todo 测试eq()
  85.     @Test
  86.     public void testSelectList5(){
  87.         //创建查询条件包装器
  88.         LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
  89.         lambdaQueryWrapper.eq(User::getUserName,"Tom");
  91.         //执行查询
  92.         List<User> users = userDao.selectList(lambdaQueryWrapper);
  94.         //输出
  95.         users.forEach(user -> System.out.println(user));
  96.     }
  98.     // todo 测试null 1
  99.     @Test
  100.     public void testSelectNull(){
  102.         //模拟从网页传递过来的数据
  103.         QueryUser queryUser = new QueryUser();
  104.         //queryUser.setUserAge(20);
  105.         queryUser.setAge2(40);
  107.         //创建查询条件包装器
  108.         LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
  109.         lambdaQueryWrapper.gt(User::getUserAge,queryUser.getUserAge());
  110.         lambdaQueryWrapper.lt(User::getUserAge,queryUser.getAge2());
  112.         //执行查询
  113.         List<User> users = userDao.selectList(lambdaQueryWrapper);
  115.         //输出
  116.         users.forEach(user -> System.out.println(user));
  117.     }
  119.     // todo 测试null 2
  120.     @Test
  121.     public void testSelectNull2(){
  123.         //模拟从网页传递过来的数据
  124.         QueryUser queryUser = new QueryUser();
  125.         queryUser.setUserAge(20);
  126.         //queryUser.setAge2(40);
  128.         //创建查询条件包装器
  129.         LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
  130.         if (null != queryUser.getUserAge()){
  131.             lambdaQueryWrapper.gt(User::getUserAge,queryUser.getUserAge());
  132.         }
  134.         if (null != queryUser.getAge2()){
  135.             lambdaQueryWrapper.lt(User::getUserAge,queryUser.getAge2());
  136.         }
  138.         //执行查询
  139.         List<User> users = userDao.selectList(lambdaQueryWrapper);
  141.         //输出
  142.         users.forEach(user -> System.out.println(user));
  143.     }
  145.     // todo 测试null 3
  146.     @Test
  147.     public void testSelectNull3(){
  149.         //模拟从网页传递过来的数据
  150.         QueryUser queryUser = new QueryUser();
  151.         //queryUser.setUserAge(10);
  152.         queryUser.setAge2(40);
  154.         //创建查询条件包装器
  155.         LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
  157.         // 如果condition 为 true ，则添加条件 ； 如果为false 则不添加
  158.         lambdaQueryWrapper.gt(null != queryUser.getUserAge() , User::getUserAge ,queryUser.getUserAge());
  159.         lambdaQueryWrapper.lt(null != queryUser.getAge2() , User::getUserAge ,queryUser.getAge2());
  161.         //执行查询
  162.         List<User> users = userDao.selectList(lambdaQueryWrapper);
  164.         //输出
  165.         users.forEach(user -> System.out.println(user));
  166.     }
  168. }

2、查询投影

  1. package xyz.zhouge.dao;
  3. import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
  4. import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
  5. import org.junit.jupiter.api.Test;
  6. import org.springframework.beans.factory.annotation.Autowired;
  7. import org.springframework.boot.test.context.SpringBootTest;
  8. import xyz.zhouge.pojo.User;
  10. import java.util.List;
  11. import java.util.Map;
  13. @SpringBootTest
  14. public class UserDaoTest {
  16.     @Autowired
  17.     private UserDao userDao ;
  19.     @Test
  20.     public void testField(){
  21.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  22.         List<User> users = userDao.selectList(lqw);
  23.         users.forEach(user -> System.out.println(user));
  24.     }
  26.     @Test
  27.     public void testField1(){
  28.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  30.         //指定需要查询的字段 LambdaQueryWrapper 可以用 Lambda 来表示
  31.         lqw.select(User::getUserId,User::getUserName,User::getUserTel);
  33.         List<User> users = userDao.selectList(lqw);
  34.         users.forEach(user -> System.out.println(user));
  35.     }
  38.     @Test
  39.     public void testField2(){
  40.         QueryWrapper<User> qw = new QueryWrapper<>();
  42.         //指定需要查询的字段  QueryWrapper 只能使用字符串来表示
  43.         qw.select("user_id","user_name","user_tel");
  45.         List<User> users = userDao.selectList(qw);
  46.         users.forEach(user -> System.out.println(user));
  47.     }
  49.     @Test
  50.     public void testField3(){
  51.         QueryWrapper<User> qw = new QueryWrapper<>();
  53.         //指定需要查询的字段  不能使用 LambdaQueryWrapper
  54.         //qw.select("avg(user_age)");
  55.         //qw.select("max(user_age)");
  56.         qw.select("count(*) as count");
  58.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  59.         List<Map<String, Object>> maps = userDao.selectMaps(qw);
  61.         maps.forEach(map -> System.out.println(map));
  62.     }
  65.     //todo 分组查询
  66.     @Test
  67.     public void testField4(){
  68.         QueryWrapper<User> qw = new QueryWrapper<>();
  70.         //指定需要查询的字段  不能使用 LambdaQueryWrapper
  71.         qw.select("count(*) as count,user_tel");
  72.         //qw.groupBy("user_tel");
  74.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  75.         List<Map<String, Object>> maps = userDao.selectMaps(qw);
  77.         maps.forEach(map -> System.out.println(map));
  78.     }
  80.     //todo 模糊查询
  81.     @Test
  82.     public void testField5(){
  83.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  84.         lqw.select(User::getUserId,User::getUserName,User::getPassword);
  85.         //lqw.like(User::getUserName,"tom");
  86.         //lqw.likeLeft(User::getUserName,"om");
  87.         //lqw.likeRight(User::getUserName,"T");
  89.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  90.         List<Map<String, Object>> maps = userDao.selectMaps(lqw);
  92.         maps.forEach(map -> System.out.println(map));
  93.     }
  95.     //todo 等值判定
  96.     @Test
  97.     public void testField6(){
  98.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  99.         lqw.select(User::getUserId,User::getUserName,User::getPassword);
  100.         lqw.eq(User::getUserName ,"Tom").eq(User::getPassword,"tom");
  102.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  103.         User user = userDao.selectOne(lqw);
  105.         System.out.println(user);
  106.     }
  108.     //todo 范围查询
  109.     @Test
  110.     public void testField7(){
  111.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  112.         lqw.select(User::getUserId,User::getUserName,User::getPassword,User::getUserAge);
  113.         lqw.between(User::getUserAge,20,45);
  115.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  116.         List<User> users = userDao.selectList(lqw);
  118.         users.forEach(user -> System.out.println(user));
  119.     }
  121.     // todo 排序查询
  122.     @Test
  123.     public void testField8(){
  124.         QueryWrapper<User> qw = new QueryWrapper<>();
  125.         qw.select("user_name","user_pwd","user_tel","user_age");
  126.         qw.groupBy("user_age");
  127.         List<Map<String, Object>> maps = userDao.selectMaps(qw);
  128.         System.out.println(maps);
  129.     }
  131. }

3、查询条件

  1. package xyz.zhouge.dao;
  3. import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
  4. import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
  5. import org.junit.jupiter.api.Test;
  6. import org.springframework.beans.factory.annotation.Autowired;
  7. import org.springframework.boot.test.context.SpringBootTest;
  8. import xyz.zhouge.pojo.User;
  10. import java.util.List;
  11. import java.util.Map;
  13. @SpringBootTest
  14. public class UserDaoTest {
  16.     @Autowired
  17.     private UserDao userDao ;
  19.     @Test
  20.     public void testField(){
  21.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  22.         List<User> users = userDao.selectList(lqw);
  23.         users.forEach(user -> System.out.println(user));
  24.     }
  26.     @Test
  27.     public void testField1(){
  28.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  30.         //指定需要查询的字段 LambdaQueryWrapper 可以用 Lambda 来表示
  31.         lqw.select(User::getUserId,User::getUserName,User::getUserTel);
  33.         List<User> users = userDao.selectList(lqw);
  34.         users.forEach(user -> System.out.println(user));
  35.     }
  38.     @Test
  39.     public void testField2(){
  40.         QueryWrapper<User> qw = new QueryWrapper<>();
  42.         //指定需要查询的字段  QueryWrapper 只能使用字符串来表示
  43.         qw.select("user_id","user_name","user_tel");
  45.         List<User> users = userDao.selectList(qw);
  46.         users.forEach(user -> System.out.println(user));
  47.     }
  49.     @Test
  50.     public void testField3(){
  51.         QueryWrapper<User> qw = new QueryWrapper<>();
  53.         //指定需要查询的字段  不能使用 LambdaQueryWrapper
  54.         //qw.select("avg(user_age)");
  55.         //qw.select("max(user_age)");
  56.         qw.select("count(*) as count");
  58.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  59.         List<Map<String, Object>> maps = userDao.selectMaps(qw);
  61.         maps.forEach(map -> System.out.println(map));
  62.     }
  65.     //todo 分组查询
  66.     @Test
  67.     public void testField4(){
  68.         QueryWrapper<User> qw = new QueryWrapper<>();
  70.         //指定需要查询的字段  不能使用 LambdaQueryWrapper
  71.         qw.select("count(*) as count,user_tel");
  72.         //qw.groupBy("user_tel");
  74.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  75.         List<Map<String, Object>> maps = userDao.selectMaps(qw);
  77.         maps.forEach(map -> System.out.println(map));
  78.     }
  80.     //todo 模糊查询
  81.     @Test
  82.     public void testField5(){
  83.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  84.         lqw.select(User::getUserId,User::getUserName,User::getPassword);
  85.         //lqw.like(User::getUserName,"tom");
  86.         //lqw.likeLeft(User::getUserName,"om");
  87.         //lqw.likeRight(User::getUserName,"T");
  89.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  90.         List<Map<String, Object>> maps = userDao.selectMaps(lqw);
  92.         maps.forEach(map -> System.out.println(map));
  93.     }
  95.     //todo 等值判定
  96.     @Test
  97.     public void testField6(){
  98.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  99.         lqw.select(User::getUserId,User::getUserName,User::getPassword);
  100.         lqw.eq(User::getUserName ,"Tom").eq(User::getPassword,"tom");
  102.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  103.         User user = userDao.selectOne(lqw);
  105.         System.out.println(user);
  106.     }
  108.     //todo 范围查询
  109.     @Test
  110.     public void testField7(){
  111.         LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
  112.         lqw.select(User::getUserId,User::getUserName,User::getPassword,User::getUserAge);
  113.         lqw.between(User::getUserAge,20,45);
  115.         //使用 selectMaps 将查询的字段作为键名 ， 查询的结果作为值
  116.         List<User> users = userDao.selectList(lqw);
  118.         users.forEach(user -> System.out.println(user));
  119.     }
  121.     // todo 排序查询
  122.     @Test
  123.     public void testField8(){
  124.         QueryWrapper<User> qw = new QueryWrapper<>();
  125.         qw.select("user_name","user_pwd","user_tel","user_age");
  126.         qw.groupBy("user_age");
  127.         List<Map<String, Object>> maps = userDao.selectMaps(qw);
  128.         System.out.println(maps);
  129.     }
  131. }

4、映射匹配兼容性

四、DML编程控制

1、id生成策略控制

名称 @TableId
类型 属性注解
位置 模型类中用于表示主键的属性定义上方
作用 模型类中用于表示主键的属性定义上方
相关属性 value(默认)：设置数据库表主键名称
type:设置主键属性的生成策略，值查照IdType的枚举值
type AUTO , INPUT ,ASSIGN_ID,ASSIGN_UUID

2、多记录操作

3、逻辑删除

3.1在数据库表中添加逻辑删除字段

image.png

  1. ALTER TABLE tb_user ADD `user_deleted` int(1) DEFAULT 0 ;

3.2在实体类中添加逻辑删除字段属性

  1. package xyz.zhouge.pojo;
  3. import com.baomidou.mybatisplus.annotation.IdType;
  4. import com.baomidou.mybatisplus.annotation.TableField;
  5. import com.baomidou.mybatisplus.annotation.TableId;
  6. import com.baomidou.mybatisplus.annotation.TableLogic;
  7. import com.baomidou.mybatisplus.annotation.TableName;
  8. import com.baomidou.mybatisplus.annotation.Version;
  9. import lombok.AllArgsConstructor;
  10. import lombok.Data;
  11. import lombok.NoArgsConstructor;
  13. @AllArgsConstructor
  14. @NoArgsConstructor
  15. @Data
  16. @TableName("tb_user")
  17. public class User {
  19.     @TableId(value = "user_id" ,type = IdType.ASSIGN_ID)
  20.     private long userId ;
  22.     @TableField("user_name")
  23.     private String userName ;
  25.     @TableField("user_pwd")
  26.     private String password ;
  28.     @TableField("user_age")
  29.     private Integer userAge ;
  31.     @TableField("user_tel")
  32.     private String userTel ;
  34.     // value 为默认值，即可被查询出来的值。deval为被删除的值
  35.     @TableField("user_deleted")
  36.     @TableLogic(value = "0" ,delval = "1")
  37.     private Integer userDeleted ;
  39.     @TableField("user_version")
  40.     @Version
  41.     private Integer userVersion ;
  44.     public User(String userName, String password, Integer userAge, String userTel) {
  45.         this.userName = userName;
  46.         this.password = password;
  47.         this.userAge = userAge;
  48.         this.userTel = userTel;
  49.     }
  52.     public User(long userId, String userName, String password, Integer userAge, String userTel) {
  53.         this.userId = userId;
  54.         this.userName = userName;
  55.         this.password = password;
  56.         this.userAge = userAge;
  57.         this.userTel = userTel;
  58.     }
  60.     public User(long userId, String userName, String password, Integer userAge, String userTel, Integer userVersion) {
  61.         this.userId = userId;
  62.         this.userName = userName;
  63.         this.password = password;
  64.         this.userAge = userAge;
  65.         this.userTel = userTel;
  66.         this.userVersion = userVersion;
  67.     }
  68. }

3.3在属性上添加 @TableLogic()注解

// value 为默认值，即可被查询出来的值。deval为被删除的值
@TableLogic(value = “0” ,delval = “1”)

3.4测试

4、乐观锁

4.1在数据库表中添加乐观锁字段

MyBatis-Plus快速版(SpringBoot版) - 图5

  1. ALTER TABLE tb_user ADD `user_version` int(10) DEFAULT 1；

4.2在实体类中添加乐观锁属性

  1. package xyz.zhouge.pojo;
  3. import com.baomidou.mybatisplus.annotation.IdType;
  4. import com.baomidou.mybatisplus.annotation.TableField;
  5. import com.baomidou.mybatisplus.annotation.TableId;
  6. import com.baomidou.mybatisplus.annotation.TableLogic;
  7. import com.baomidou.mybatisplus.annotation.TableName;
  8. import com.baomidou.mybatisplus.annotation.Version;
  9. import lombok.AllArgsConstructor;
  10. import lombok.Data;
  11. import lombok.NoArgsConstructor;
  13. @AllArgsConstructor
  14. @NoArgsConstructor
  15. @Data
  16. @TableName("tb_user")
  17. public class User {
  19.     @TableId(value = "user_id" ,type = IdType.ASSIGN_ID)
  20.     private long userId ;
  22.     @TableField("user_name")
  23.     private String userName ;
  25.     @TableField("user_pwd")
  26.     private String password ;
  28.     @TableField("user_age")
  29.     private Integer userAge ;
  31.     @TableField("user_tel")
  32.     private String userTel ;
  34.     // value 为默认值，即可被查询出来的值。deval为被删除的值
  35.     @TableField("user_deleted")
  36.     @TableLogic(value = "0" ,delval = "1")
  37.     private Integer userDeleted ;
  39.     @TableField("user_version")
  40.     @Version
  41.     private Integer userVersion ;
  44.     public User(String userName, String password, Integer userAge, String userTel) {
  45.         this.userName = userName;
  46.         this.password = password;
  47.         this.userAge = userAge;
  48.         this.userTel = userTel;
  49.     }
  52.     public User(long userId, String userName, String password, Integer userAge, String userTel) {
  53.         this.userId = userId;
  54.         this.userName = userName;
  55.         this.password = password;
  56.         this.userAge = userAge;
  57.         this.userTel = userTel;
  58.     }
  60.     public User(long userId, String userName, String password, Integer userAge, String userTel, Integer userVersion) {
  61.         this.userId = userId;
  62.         this.userName = userName;
  63.         this.password = password;
  64.         this.userAge = userAge;
  65.         this.userTel = userTel;
  66.         this.userVersion = userVersion;
  67.     }
  68. }

4.3在字段上添加@Version

@TableField(“user_version”)
@Version
private Integer userVersion ;

4.4添加乐观锁拦截器

  1. package xyz.zhouge.config;
  3. import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
  4. import com.baomidou.mybatisplus.extension.plugins.inner.OptimisticLockerInnerInterceptor;
  5. import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
  6. import org.springframework.context.annotation.Bean;
  7. import org.springframework.context.annotation.Configuration;
  9. @Configuration
  10. public class VersionInterceptor {
  12.     @Bean
  13.     public MybatisPlusInterceptor interceptor(){
  14.         //1, 创建一个通用的拦截器
  15.         MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
  17.         //2，指定（添加） 特定的拦截器  分页拦截器
  18.         interceptor.addInnerInterceptor(new PaginationInnerInterceptor());//添加分页拦截器
  19.         interceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());//添加乐观锁拦截器
  21.         //3，返回拦截器
  22.         return interceptor;
  23.     }
  24. }

4.5测试

五、快速开发

1、代码生成器原理分析

2、代码生成器实现

2.1导入maven依赖

  1. <dependencies>
  3.   <!--mybatis-plus-->
  4.   <dependency>
  5.     <groupId>com.baomidou</groupId>
  6.     <artifactId>mybatis-plus-boot-starter</artifactId>
  7.     <version>3.4.1</version>
  8.   </dependency>
  10.   <!--lombok-->
  11.   <dependency>
  12.     <groupId>org.projectlombok</groupId>
  13.     <artifactId>lombok</artifactId>
  14.     <version>1.18.12</version>
  15.   </dependency>
  17.   <!--druid-->
  18.   <dependency>
  19.     <groupId>com.alibaba</groupId>
  20.     <artifactId>druid</artifactId>
  21.     <version>1.1.10</version>
  22.   </dependency>
  24.   <!--mybatis-plus-generator-->
  25.   <dependency>
  26.     <groupId>com.baomidou</groupId>
  27.     <artifactId>mybatis-plus-generator</artifactId>
  28.     <version>3.4.1</version>
  29.   </dependency>
  31.   <!--模板引擎-->
  32.   <dependency>
  33.     <groupId>org.apache.velocity</groupId>
  34.     <artifactId>velocity</artifactId>
  35.     <version>1.5</version>
  36.   </dependency>
  38. </dependencies>

2.2编写引导类

2.3创建代码生成器类

  1. package xyz.zhouge.generator;
  3. import com.baomidou.mybatisplus.annotation.IdType;
  4. import com.baomidou.mybatisplus.generator.AutoGenerator;
  5. import com.baomidou.mybatisplus.generator.config.DataSourceConfig;
  6. import com.baomidou.mybatisplus.generator.config.GlobalConfig;
  7. import com.baomidou.mybatisplus.generator.config.PackageConfig;
  8. import com.baomidou.mybatisplus.generator.config.StrategyConfig;
  10. /**
  11. * MybatisPlus 代码生成器
  12. */
  13. public class CodeGenerator {
  15.     public static void main(String[] args) {
  17.         try {
  18.             //创建代码生成器对象
  19.             AutoGenerator generator = new AutoGenerator();
  21.             //设置数据库相关配置
  22.             DataSourceConfig dataSourceConfig = new DataSourceConfig();
  23.             dataSourceConfig.setDriverName("com.mysql.cj.jdbc.Driver");
  24.             dataSourceConfig.setUrl("jdbc:mysql://zhouge.xyz/db_mybatisplus");
  25.             dataSourceConfig.setUsername("admin");
  26.             dataSourceConfig.setPassword("991227zg@.");
  27.             generator.setDataSource(dataSourceConfig);//将数据库配置添加到代码生成器中
  29.             //设置全局配置
  30.             GlobalConfig globalConfig = new GlobalConfig();
  31.             globalConfig.setOutputDir(System.getProperty("user.dir")+"/demo6-generator/src/main/java");//设置代码 位置
  32.             globalConfig.setOpen(true);//设置生成完代码之后，是否打开文件管理器
  33.             globalConfig.setAuthor("周葛");//设置作者
  34.             globalConfig.setFileOverride(true);//设置是否覆盖原文件
  35.             globalConfig.setMapperName("%sDao");//设置数据访问层接口名字 %s 为占位符
  36.             globalConfig.setIdType(IdType.ASSIGN_ID);//设置id生成方案
  37.             generator.setGlobalConfig(globalConfig);
  39.             //设置包名相关配置
  40.             PackageConfig packageConfig = new PackageConfig();
  41.             packageConfig.setParent("xyz.zhouge.demo");//设置生成的包名
  42.             packageConfig.setEntity("pojo");//设置实体类的包名
  43.             packageConfig.setMapper("dao");//设置数据访问层包名
  44.             packageConfig.setController("controller");//设置控制层包名
  45.             packageConfig.setService("service");
  46.             generator.setPackageInfo(packageConfig);
  48.             //策略配置
  49.             StrategyConfig strategyConfig = new StrategyConfig();
  50.             strategyConfig.setInclude("tb_user");//设置需要生成的表明，是一个可变参数，可以写多个表名
  51.             strategyConfig.setTablePrefix("tb_");//设置数据表表前缀
  52.             strategyConfig.setRestControllerStyle(true);//设置是否启用REST风格
  53.             strategyConfig.setVersionFieldName("user_version");//设置乐观锁字段名
  54.             strategyConfig.setLogicDeleteFieldName("user_deleted");//设置逻辑删除字段名
  55.             strategyConfig.setEntityLombokModel(true);//设置是否启用lombok
  56.             generator.setStrategy(strategyConfig);
  59.             //执行代码生成器
  60.             generator.execute();
  62.         } catch (Exception e) {
  63.             e.printStackTrace();
  64.         }
  66.     }
  67. }

2.4运行程序

3、MP中Service的CRUD