Mybatis-plus

特性

  • 无侵入式：只做增强不做改变，不会对现有的工程产生影响

  • 强大的CRUD操作，内置通用Mapper，少量配置即可实现表单CRUD操作

  • 支持Lambda：编写查询字段无需担心写错

  • 支持主键自动生成

  • 内置分页插件

查询条件：https://mybatis.plus/guide/wrapper.html#abstractwrapper

CUID

  • pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>mybatisplus-quickStart</artifactId>
    <version>0.0.1-SNAPSHOT</version>
​
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.12</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
​
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>
        <!--代码生成器-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.4.1</version>
        </dependency>
        <!--velocity模板引擎-->
        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity-engine-core</artifactId>
            <version>2.3</version>
        </dependency>
    </dependencies>
​
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
​
</project>
​

  • application.yml & 

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatisplus_db?serverTimezone=UTC
    username: root
    password: root
  #关闭springBoot logo
  main:
    banner-mode: off
​
mybatis-plus:
  configuration:
    #打印log信息
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  #关闭mybatis logo
  global-config:
    banner: false
    db-config:
      #主键生成策略
      id-type: assign_id
      #table表映射
      table-prefix: td_
      #设置逻辑删除
      logic-delete-field: deleted
      logic-not-delete-value: 0
      logic-delete-value: 1

  • logback.xml 可以将很多日志信息不输出

<?xml version="1.0" encoding="UTF-8"?>
<configuration >
​
</configuration>

  • MPConfig 配置分页和锁

package com.yang.config;
​
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.OptimisticLockerInnerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
​
@Configuration
public class MPConfig {
    @Bean
    public MybatisPlusInterceptor plusInterceptor(){
        MybatisPlusInterceptor plusInterceptor = new MybatisPlusInterceptor();
        //分页
        plusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        //乐观锁
        plusInterceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
        return plusInterceptor;
    }
}
​

  • dao . UserDao 要继承 BaseMapper<User>，，@Mapper

package com.yang.dao;
​
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.yang.domain.User;
import org.apache.ibatis.annotations.Mapper;
​
@Mapper
public interface UserDao extends BaseMapper<User> {
}
​

  • domain . User

package com.yang.domain;
​
import com.baomidou.mybatisplus.annotation.*;
import lombok.Data;
​
@Data
//@TableName("td_user")//和表名不一致时，映射,配置中设置了前缀
public class User {
    //配置中设置了id生成策略
//    @TableId(type=IdType.AUTO)
//    @TableId(type = IdType.ASSIGN_ID)//雪花算法生成id，可兼容字符串和数值型，64位的二进制
//    @TableId(type = IdType.INPUT)//用户自己输入
//@TableId(type = IdType.ASSIGN_UUID)//使用UUID算法生成id策略
    private Long id;
    private String name;
//    @TableField(select = false)//不参与查询
    private String password;
//    @TableField(value = "ages")和表中的字段映射
    private Integer age;
    private String tel;
    @TableField(exist = false)//不存在的字段
    private String online;
    //逻辑删除
//    @TableLogic(value = "0",delval = "1")//在配置中已经做了
    private Integer deleted;
​
    @Version//乐观锁，要加这个
    private Integer versions;
​
}
​

  • Test

package com.yang;
​
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.yang.dao.UserDao;
import com.yang.domain.User;
import com.yang.query.UserQuery;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
​
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
​
@SpringBootTest
class MybatisplusQuickStartApplicationTests {
    @Autowired
    private UserDao userDao;
​
​
    @Test
    public void pageTest(){
        //分页查询，需要添加分页配置MPConfig
        IPage page = new Page(2,2);
        System.out.println(page.getCurrent());
        System.out.println(page.getSize());
        System.out.println(page.getPages());
        System.out.println(page.getTotal());
        System.out.println(page.getRecords());
        userDao.selectPage(page,null);
    }
​
    @Test
    void contextLoads() {
        //特殊情况下
        QueryWrapper qw = new QueryWrapper<>();
        qw.lt("age",20);
        List<User> userList = userDao.selectList(qw);
        System.out.println(userList);
        //常用这个
        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper();
        //小于20岁的
        lqw.lt(User::getAge,25);
        List<User> userList1 = userDao.selectList(lqw);
        System.out.println(userList1);
    }
​
    @Test
    public void doNull(){
        //封装条件,上限和下限
        UserQuery userQuery = new UserQuery();
        userQuery.setAge2(19);
        userQuery.setAge(25);
​
        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper();
        //条件查询，判断条件是否为空
        lqw.gt(null != userQuery.getAge2(),User::getAge, userQuery.getAge2() )
           .lt(null != userQuery.getAge(),User::getAge, userQuery.getAge() );
        List<User> userList = userDao.selectList(lqw);
        System.out.println(userList);
​
​
    }
    @Test
    public void doAlso(){//并且
        //多条件10<?<25
//        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper();
        //小于25岁的
//        lqw.lt(User::getAge,25);
        //大于20岁的
//        lqw.gt(User::getAge,20);
        //链式：大于19小于20
        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
        lqw.gt(User::getAge,20).lt(User::getAge,25);
        List<User> userList = userDao.selectList(lqw);
        System.out.println(userList);
​
    }
​
    @Test
    public void doPerhaps(){//或者
        //或者关系<19 or  >20
        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
        lqw.lt(User::getAge,19).or().gt(User::getAge,20);
        List<User> userList = userDao.selectList(lqw);
    }
    @Test
    public void doProjection(){
        //查询投影
        //第一种
        LambdaQueryWrapper<User> lq = new LambdaQueryWrapper();
        lq.select(User::getAge,User::getName,User::getTel);
        List<User> userList = userDao.selectList(lq);
        System.out.println(userList);
        //第二种
        QueryWrapper<User> lqw = new QueryWrapper();
        lqw.select("age","name","tel");
        //聚合
        lqw.select("count(*) as count");
​
        List<User> userList1 = userDao.selectList(lqw);
        System.out.println(userList1);
​
    }
    @Test
    public void doGroupBy(){
        //分组查询,聚合
        QueryWrapper<User> lqw = new QueryWrapper();
        lqw.select("count(*) as count,password");
        lqw.groupBy("password");
        //map集合
        List<Map<String, Object>> maps = userDao.selectMaps(lqw);
        System.out.println(maps);
    }
    @Test
    public void doCondition(){
        //条件查询
        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper();
        lqw.eq(User::getName,"张无忌").eq(User::getPassword,"123");
        //查询一个对象
        User userLogin = userDao.selectOne(lqw);
        System.out.println(userLogin);
    }
    @Test
    public void doBetween(){
        //范围查询
        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper();
        lqw.between(User::getAge,20,25);
        List<User> userList = userDao.selectList(lqw);
        System.out.println(userList);
    }
    @Test
    public void doLike(){
        //模糊查询
        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper();
//        lqw.like(User::getName,"冰");
        lqw.likeRight(User::getName,"冰");//冰%
//        lqw.likeLeft(User::getName,"冰");//%冰
        List<User> userList = userDao.selectList(lqw);
        System.out.println(userList);
    }
​
    /**
     * 开始 UID操作
     */
    @Test
    public void insert(){
        //插入数据
        User user = new User();
        user.setName("Brown");
        user.setAge(26);
        user.setPassword("222");
        user.setTel("333");
        userDao.insert(user);
    }
    @Test
    public void delete(){
        //删除多条
        List<Long> ids = new ArrayList<>();
        ids.add(1543416990979026946L);
        ids.add(1543417335125848066L);
        userDao.deleteBatchIds(ids);
        //查询多条
        List<Long> ids1 = new ArrayList<>();
        ids1.add(1L);
        ids1.add(2L);
        ids1.add(3L);
        userDao.selectBatchIds(ids1);
​
    }
    @Test
    public void doDelete(){
        userDao.deleteById(1543433893889941506L);
    }
    @Test
    public void update(){
        User user = new User();
        user.setName("jack");
        user.setAge(18);
        user.setPassword("123");
        user.setTel("111");
        userDao.updateById(user);
    }
​
    @Test
    public void updateLock(){
       //乐观锁 versions+1
        User user = userDao.selectById(3L); //versions=1
        User user1 = userDao.selectById(3L);//versions=1
​
        user1.setName("范冰冰888");
        userDao.updateById(user1); //versions=2
​
        user.setName("范冰冰688");//versions=1
        userDao.updateById(user);
    }
​
}

 

  • td_user 数据库

屏幕截图 2022-07-03 143352

代码生成器

  • pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>mybatis-plus-generate</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mybatis-plus-generate</name>
    <description>mybatis-plus-generate</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.12</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>
        <!--代码生成器-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.4.1</version>
        </dependency>
        <!--velocity模板引擎-->
        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity-engine-core</artifactId>
            <version>2.3</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
​
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
​
</project>
​

  • Generator.java

package com.yang;
​
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.config.DataSourceConfig;
import com.baomidou.mybatisplus.generator.config.GlobalConfig;
import com.baomidou.mybatisplus.generator.config.PackageConfig;
import com.baomidou.mybatisplus.generator.config.StrategyConfig;
​
public class Generator {
    public static void main(String[] args) {
        //创建代码生成器对象
        AutoGenerator autoGenerator = new AutoGenerator();
        
        //设置连接数据库信息
        DataSourceConfig datasource = new DataSourceConfig();
        datasource.setDriverName("com.mysql.cj.jdbc.Driver");
        datasource.setUrl("jdbc:mysql://localhost:3306/mybatisplus_db?serverTimezone=UTC");
        datasource.setUsername("root");
        datasource.setPassword("root");
        autoGenerator.setDataSource(datasource);
​
        //设置全局配置
        GlobalConfig globalConfig = new GlobalConfig();
        globalConfig.setOutputDir(System.getProperty("user.dir")+"/src/main/java");
        globalConfig.setAuthor("yangzl");
        globalConfig.setOpen(false);//设置生成代码后是否打开
        globalConfig.setFileOverride(true);//是否覆盖生成原始的代码
        globalConfig.setMapperName("%sDao");//设置数据层接口名，%s是占位符，指代模块名称
        globalConfig.setIdType(IdType.ASSIGN_ID);
        autoGenerator.setGlobalConfig(globalConfig);
        
        //包相关config
        PackageConfig packageInfo = new PackageConfig();
        packageInfo.setParent("com.yang");
        packageInfo.setEntity("domain");
        packageInfo.setMapper("dao");
        autoGenerator.setPackageInfo(packageInfo);
        
        //策略相关的配置
        StrategyConfig strategy = new StrategyConfig();
        strategy.setInclude("td_user");
        strategy.setTablePrefix("td_");
        strategy.setRestControllerStyle(true);
        strategy.setEntityLombokModel(true);
        strategy.setLogicDeleteFieldName("deleted");
        strategy.setVersionFieldName("versions");
        autoGenerator.setStrategy(strategy);
        //执行
        autoGenerator.execute();
    }
}
​