Mybatis-Plus之CRUD操作

MyBatis-Plus是一个MyBatis的增强工具，在MyBatis的基础上只做增强不做改变，为简化开发，提高效率而生。
官网：baomidou官网（MyBatisPlus官网）

1、主要的依赖库

1.1 mybatis-plus依赖

注意：mybatis-plus的依赖和mybatis的依赖不能混用，不然版本不同的话，就会出现冲突。

 <dependency>
     <groupId>com.baomidou</groupId>
     <artifactId>mybatis-plus-boot-starter</artifactId>
     <version>3.4.1</version>
 </dependency>

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1.2 druid依赖

  <dependency>
       <groupId>com.alibaba</groupId>
       <artifactId>druid</artifactId>
       <version>1.2.11</version>
  </dependency>
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1.3 Lombook插件

  <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
            <scope>provided</scope>
  </dependency>
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2、CRUD样例

2.1 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>2.6.10</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>maybatisplus_01_quickstart</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>maybatisplus_01_quickstart</name>
    <description>maybatisplus_01_quickstart</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>1.2.11</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <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>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

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2.2 实体类User

package com.example.maybatisplus_01_quickstart.domain;

import lombok.Data;

@Data
public class User {
    private Long id;
    private String name;
    private String password;
    private Integer age;
    private String tel;
}
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2.3 UserDao实现增删改查操作

package com.example.maybatisplus_01_quickstart.dao;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.maybatisplus_01_quickstart.domain.User;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface UserDao extends BaseMapper<User> {

}

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2.4 Test类

package com.example.maybatisplus_01_quickstart;

import com.example.maybatisplus_01_quickstart.dao.UserDao;
import com.example.maybatisplus_01_quickstart.domain.User;
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 test1 {
    @Autowired
    private UserDao userDao;

    //新增操作
    @Test
    public void testSave() {
        User user = new User();
        user.setName("蛋糕");
        user.setPassword("1888888");
        user.setAge(22);
        user.setTel("439923993");
        userDao.insert(user);
    }

    //删除操作
    @Test
    public void testDelete() {
        userDao.deleteById(1552215061978689537L);
    }

    //修改操作
    @Test
    public void testUpdate() {
        User user = new User();
        user.setId(1L);
        user.setName("西红柿");
        user.setPassword("wdefef");
        userDao.updateById(user);
    }

    //通过ID查询
    @Test
    public void testGetById() {
        User user = userDao.selectById(1L);
        System.out.println(user);
    }

    //查询所有操作
    @Test
    public void contextLoads() {
        List<User> userList = userDao.selectList(null);
        System.out.println(userList);
    }
}


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