java——mybatis-plus随笔

我不是女神ヾ 2024-02-25 01:37 10阅读 0赞

网上参考总教程：https://www.quanxiaoha.com/mybatis-plus/mybatis-plus-tutorial.html

本地参考教程：https://www.cnblogs.com/xiaobaibailongma/p/17091309.html

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gitee参考教程：

springbootmybatisplus/pom.xml

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/springbootmybatisplus/pom.xml

springbootmybatisplus/src/main/resources/application.properties

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/springbootmybatisplus/src/main/resources/application.properties

springbootmybatisplus/src/main/java/org/example/mapper/UserMapper.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/springbootmybatisplus/src/main/java/org/example/mapper/UserMapper.java

springbootmybatisplus/src/main/java/org/example/Entity/MyUser.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/springbootmybatisplus/src/main/java/org/example/Entity/MyUser.java

springbootmybatisplus/src/main/java/org/example/service/MyUserService.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/springbootmybatisplus/src/main/java/org/example/service/MyUserService.java

springbootmybatisplus/src/main/java/org/example/service/Impl/MyUserServiceImpl.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/springbootmybatisplus/src/main/java/org/example/service/Impl/MyUserServiceImpl.java

springbootmybatisplus/src/main/java/org/example/controller/MyUserController.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/springbootmybatisplus/src/main/java/org/example/controller/MyUserController.java

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## **spring boot集成mybatis-plus——新建工程与查询所有数据** ##

第一步引入依赖：

![复制代码][copycode.gif]

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>org.example</groupId>
        <artifactId>springbootmybatisplus</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <properties>
            <maven.compiler.source>8</maven.compiler.source>
            <maven.compiler.target>8</maven.compiler.target>
        </properties>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.4.5</version>
            <relativePath/>
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>com.baomidou</groupId>
                <artifactId>mybatis-plus-boot-starter</artifactId>
                <version>3.5.1</version>
            </dependency>
    
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
            </dependency>
    
        </dependencies>
    
    </project>

![复制代码][copycode.gif]

![1895087-20230204130218303-905558711.png][]

![1895087-20230204130231439-881648323.png][]

第二步：设置数据库信息：

![复制代码][copycode.gif]

spring.datasource.username=root
    
    spring.datasource.password=123456
    
    spring.datasource.url=jdbc:mysql://localhost:3306/mysql8?characterEncoding=utf8
    
    spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

![复制代码][copycode.gif]

![1895087-20230204130322739-455741225.png][]

数据库信息

![1895087-20230204130416860-1715589949.png][]

第三步：创建实体类：

![复制代码][copycode.gif]

package org.example.Entity;
    
    import com.baomidou.mybatisplus.annotation.TableName;
    
    @TableName("users")        //不一致时，需要映射
    public class MyUser
    {
        private int id;
    
        private String name;
    
        private int age;
    
        public int getId()
        {
    
            return id;
        }
    
        public void setId(int id)
        {
    
            this.id = id;
        }
    
        public String getName()
        {
    
            return name;
        }
    
        public void setName(String name)
        {
    
            this.name = name;
        }
    
        public int getAge()
        {
    
            return age;
        }
    
        public void setAge(int age)
        {
    
            this.age = age;
        }
    
        @Override
        public String toString()
        {
    
            return "MyUser{" +
                    "id=" + id +
                    ", name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

![复制代码][copycode.gif]

![1895087-20230204130458024-1289821592.png][]

![1895087-20230204130512300-895694950.png][]

第四步：常见mapper文件：

![复制代码][copycode.gif]

package org.example.mapper;
    
    import com.baomidou.mybatisplus.core.mapper.BaseMapper;
    import org.apache.ibatis.annotations.Mapper;
    import org.example.Entity.MyUser;
    
    @Mapper
    public interface UserMapper extends BaseMapper<MyUser>
    {
    
        //所有的CRUD都已经完成
        //不需要像以前一样配置一大堆文件：pojo-dao(连接mybatis，配置mapper.xml文件)==>service-controller
    
        
        
    }

![复制代码][copycode.gif]

![1895087-20230204130602506-207863015.png][]

第五步：创建业务层以及实现接口：

![复制代码][copycode.gif]

package org.example.service;
    
    import org.example.Entity.MyUser;
    
    import java.util.List;
    
    public interface MyUserService
    {
    
        // 查询所有用户
        List<MyUser> findAll();
    
        
    
    }

![复制代码][copycode.gif]

![1895087-20230204130738853-1027296429.png][]

![复制代码][copycode.gif]

package org.example.service.Impl;
    
    import org.example.Entity.MyUser;
    import org.example.mapper.UserMapper;
    import org.example.service.MyUserService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import java.util.List;
    
    @Service
    public class MyUserServiceImpl implements MyUserService
    {
    
        //继承了BaseMapper所有的方法，可以编写自己的扩展方法
        @Autowired
        private UserMapper userMapper;
    
    
        @Override
        public List<MyUser> findAll()
        {
    
            return userMapper.selectList(null);
    
    
        }
    
    
    }

![复制代码][copycode.gif]

![1895087-20230204130808120-1932494913.png][]

第六步：控制器接口：

![复制代码][copycode.gif]

package org.example.controller;
    
    import org.example.Entity.MyUser;
    import org.example.service.MyUserService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.*;
    import java.util.List;
    
    @RestController
    public class MyUserController
    {
    
        @Autowired
        private MyUserService myUserService;
    
    
        @GetMapping(value = "/1")
        public List<MyUser> home1()
        {
            // 查询所有用户信息
            List<MyUser> users = myUserService.findAll();
    
            for (MyUser user : users)
            {
                System.out.println(user.getId()+"  "+user.getName()+"  "+user.getAge());
            }
    
            return users;
        }
    
    
    }

![复制代码][copycode.gif]

![1895087-20230204130842037-747587088.png][]

第七步：运行主程序：

![复制代码][copycode.gif]

package org.example;
    
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    @SpringBootApplication
    @MapperScan("org.example.mapper")
    public class HelloWorldApplication
    {
    
        public static void main(String[] args)
        {
    
            SpringApplication.run(HelloWorldApplication.class, args);
    
        }
    }

![复制代码][copycode.gif]

![1895087-20230204130926786-339542542.png][]

实现如下：

![1895087-20230204130948259-550297964.png][]

![1895087-20230204131008989-2030049012.png][]

[copycode.gif]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/5bf6a2e2015241469a37a07e2b16ab4a.png
[1895087-20230204130218303-905558711.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/4433982156a641d3884ad69cb9cde434.png
[1895087-20230204130231439-881648323.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/bb5e6afcff064682bf6bdfd553772bc7.png
[1895087-20230204130322739-455741225.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/51ab20391eda453c9b7b28558ab20a79.png
[1895087-20230204130416860-1715589949.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/33782bbc5aef4d459ac4950ae4a4fbe2.png
[1895087-20230204130458024-1289821592.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/fb519d86ebcf42d5a63cf2920ea0a425.png
[1895087-20230204130512300-895694950.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/13cf39b95bc741148627c707145bbf83.png
[1895087-20230204130602506-207863015.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/e5a7323b00834c42af3c70d070a925f1.png
[1895087-20230204130738853-1027296429.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/1a0cc337114245279521234c1a875e94.png
[1895087-20230204130808120-1932494913.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/439d00c8c7c744a5b53f8986a39e1d09.png
[1895087-20230204130842037-747587088.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/c76c6c01f29e4d10b630355c409f1df4.png
[1895087-20230204130926786-339542542.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/0c486ff3e8a24c0bb27d7fd8a0d77c1b.png
[1895087-20230204130948259-550297964.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/3c7aef1f144f43a981b84fc975a4363e.png
[1895087-20230204131008989-2030049012.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/25/3bbd46227daa4346915203f1e7b268fb.png