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myabtis-plus使用

1.导入官网的数据库

2.创建springboot项目，添加依赖

<?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>2.2.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>mybatis-plus</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mybatis-plus</name>
    <description>Demo project for Spring Boot</description>
 
    <properties>
        <java.version>1.8</java.version>
    </properties>
 
    <dependencies>
 
        <!--导入mp的依赖
        mybatis-plus 就不需要导入 mybatis！
        -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.5</version>
        </dependency>
 
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <!--
        spring2.x 都是默认配置mysql8的驱动
        <mysql.version>8.0.19</mysql.version>
        8.0 以上的驱动，需要配置时区！
        -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
 
        <!-- IDEA中需要安装lombok插件！  -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>
 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
 
</project>

3.编写数据库对象的实体user对象，编写userMapper接口，userMapper继承BaseMapper<User> ，其中User为对应的实体

package com.example.dao;
 
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.pojo.User;
import org.springframework.stereotype.Repository;
 
// 使用了 MP 之后，我们就不用在编写万恶的CRUD了，只需要继承一个类别即可！
// BaseMapper<T> 泛型T 就是表示你要操作的类
// 这里内置几乎所有的查询，除了十分特殊的查询之外！
// MP，对于复杂的SQL 依旧需要自己编写！
@Repository
public interface UserMapper extends BaseMapper<User> {
 
    // 链表查询
    // 1、编写接口
    // 2、编写接口对应的Mapper，这个就是和MyBatis一样的操作！
 
 
}