Integrate the basic use of Mybatis-plus and mybatis-puls in SpringBoot

Create a SpringBoot project

        1. Select Create Project

         2. Create a SpringBoot project

         3. Select the version and dependencies of SpringBoot

        4. Import the dependencies of mysql, druid, mybatis-plus and lombok, remember to update the dependencies after importing

         <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.17</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.22</version>
            <scope>compile</scope>
        </dependency>

        5. Write configuration files

# MySQL数据库连接配置,SpringBoot默认使用的连接池是Hikari     连接速度最快的  被SpringBoot默认整合的
# 手动改成alibaba的连接池
spring.datasource.url=jdbc:mysql://localhost:3306/leq_pro?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=0216

#添加并配置第三方数据源Druid
#数据源类型
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
#初始化连接数
spring.datasource.initialSize=20
#最小空闲数
spring.datasource.minIdle=10
#最大连接数
spring.datasource.maxActive=100



#配置MyBatis-Plus的xml配置文件的位置
mybatis-plus.mapper-locations=classpath:mapper/*.xml
mybatis-plus.type-aliases-package=com.example.mybatisplus.pojo
# 显示sql语句
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

         6. Prepare the data in advance and run the following code in navcat

create database leq_pro;
create table my(
mid int primary key auto_increment,
mname varchar(255),
mage varchar(255),
msex varchar(255),
mbirthday varchar(255)
);
insert into my values(0,'小满','18','女','2023-5-10');

       

        7. To create the entity class of the table, mybatis-plus needs to specify the table name and primary key id field

 

import com.baomidou.mybatisplus.annotation.IdType;
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
@AllArgsConstructor
@NoArgsConstructor
@TableName("my")
public class My {
    @TableId(type = IdType.AUTO)
    private Integer mid;
    private String mname;
    private String mage;
    @TableField("msex")
    private String sex;
    private String mbirthday;
}

         

        8. If you want to use druid connection pool, you can use this configuration class to connect

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class DataSourceConfig {
    //获取druid的连接数据源信息
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource getDruid(){
        return new DruidDataSource();
    }
}

 

        9. Create a mapper layer, inherit from BaseMapper, which encapsulates the basic operations on sql

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.springmybatisplus.pojo.My;

public interface MyMaper extends BaseMapper<My> {
}

        10. Add annotations to the startup class or add @Mapper annotations to MyMapper, one is enough

@MapperScan("com.example.springmybatisplus.mapper")

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan("com.example.springmybatisplus.mapper")
@SpringBootApplication
public class SpringMybatisPlusApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringMybatisPlusApplication.class, args);
    }

}

       

        11. Create MyTests in the test directory to perform crud operations on the table

import com.example.springmybatisplus.pojo.My;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
public class MyTests {
    @Autowired
    private MyMaper myMaper;
}

 

 

        This is our initial table        

     

        1. Add new data, because id is set to self-increment, so we don't need to set a value for id

   @Test
    public void test01(){
        My my = new My();
        my.setMname("小元");
        my.setMage("20");
        my.setSex("男");
        my.setMbirthday("2018-5-1");
        int insert = myMaper.insert(my);
        System.out.println(insert>0);
    }

         After running this method, query the table and you can see the new data

         2. Delete data

    @Test
    public void test02(){
        int insert = myMaper.deleteById(2);
    }

        3. Batch delete

        random data added 

 

    @Test
    public void test03(){
        int insert = myMaper.deleteBatchIds(Arrays.asList(4,5,6));
    }

        4. Conditional deletion

    @Test
    public void test04(){
        UpdateWrapper<My> w = new UpdateWrapper<>();
        //        gt() 大于      eq() 等于     or() 或者
        //        and() 并且    like()模糊   ge()大于等于
        w.gt("mid",1);//删除id大于1的
        myMaper.delete(w);
    }

 

        5. Delete by condition of collection

        adding data

 

    @Test
    public void test05(){
        HashMap<String, Object> col = new HashMap<String, Object>(){
            {put("mname","小元");put("mid","7");}//and的关系
        };
        myMaper.deleteByMap(col);
    }

        6. Update

     @Test//更新
    public void test06(){
        My my = new My();
        my.setMid(8);
        my.setMname("小元");
        my.setMage("18");
        myMaper.updateById(my);
    }

        7. Condition update

    @Test//更新
     public void test07(){
        My gtypes = new My();
        gtypes.setMid(8);//执行要更新的id

        UpdateWrapper<My> wrapper = new UpdateWrapper<>();//更新的条件
        wrapper.eq("mid",8).set("mname","小李").set(false,"msex",null);


        myMaper.update(gtypes,wrapper);
}

         8. Query

    @Test//查询
    public void test08(){
        System.err.println(myMaper.selectById(1));
    }

         9. Batch query

    @Test//批量查询
    public void test09(){
        ArrayList<Integer> col =new ArrayList<Integer>(){
            {add(1);add(8);}
        };
        List<My> gtypes = myMaper.selectBatchIds( col);
        gtypes.forEach(System.err::println);
    }

        10 conditions query

 

    @Test//条件查询
    public void test10(){
        QueryWrapper<My> wrapper = new QueryWrapper<>();
        wrapper.select("mname","mage");//要查询的字段
        wrapper.eq("mid","1");//查询的条件
        List<My> mies = myMaper.selectList(wrapper);
        mies.forEach(System.err::println);
    }

        12. Paging query

    @Test//分页查询
    public void test11(){
        Page<My> page = new Page<>(1, 5);
        QueryWrapper<My> wrapper = new QueryWrapper<>();//不加条件就是查询所有
        wrapper.like("mname","小");

        IPage<My> iPage = myMaper.selectPage(page, wrapper);
        List<My> records = iPage.getRecords();//获取查询到的所有记录
        records.forEach(System.out::println);//soutc
    }

    13. Advanced operations (insert)

        Define the fields that need to be changed in the entity class

        Define configuration class

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;

//自动填充数据
//    @TableField(fill = FieldFill.INSERT)  插入
//    @TableField(fill = FieldFill.UPDATE)  更新
//    @TableField(fill = FieldFill.DEFAULT) 删除
//    @TableField(fill = FieldFill.INSERT_UPDATE)   插入更新
@Component
public class MyDataObjectHandler implements MetaObjectHandler {
    @Override//插入数据时调用
    public void insertFill(MetaObject metaObject) {
                                    //   源对象         字段属性       取值类型   具体值
        this.strictInsertFill(metaObject,"mbirthday",String.class,"2000-0-0");
    }

    @Override//更新数据时调用
    public void updateFill(MetaObject metaObject) {
        this.strictInsertFill(metaObject,"mbirthday",String.class,"2000-1-1");
    }
}

        carry out testing

    @Test
    public void test12(){
        My my = new My();
        my.setMname("小元");
        my.setMage("18");
        myMaper.insert(my);//插入数据,没有设置日期
    }

What members can be defined in an interface?
    Before dk1.7:
        1. Static constant public static final int a=10;
        2. Abstract method public abstract String a();
   jdk1.8 and later versions
        3. Static method public static
        4. The default method is public default modified by default

public interface Myinterfae {
    public static final int a=10;
    public abstract String  a();
    public  static  void aa(){
        System.out.println("静态方法");
    }
    public  default   void aaa(){
        System.out.println("静态方法");
    }
}