2022最新MyBatis-Plus的入门，使用MybatisX逆向生成文件阶段一_java

MyBatis 简称（MP）是一个 MyBatis (opens new window)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。

Mybatis官网:https://baomidou.com/pages/226c21/

快速开始

1. 在navicat,下建一个数据库，在数据库下执行.

		DROP TABLE IF EXISTS user;
	CREATE TABLE user
	(
	    id BIGINT(20) NOT NULL COMMENT '主键ID',
	    name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
	    age INT(11) NULL DEFAULT NULL COMMENT '年龄',
	    email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
	    PRIMARY KEY (id)
	);

2. 执行相应的sql代码

			DELETE FROM user;
			INSERT INTO user (id, name, age, email) VALUES
			(1, 'Jone', 18, '[email protected]'),
			(2, 'Jack', 20, '[email protected]'),
			(3, 'Tom', 28, '[email protected]'),
			(4, 'Sandy', 21, '[email protected]'),
			(5, 'Billie', 24, '[email protected]');

3.创建一个空的 Spring Boot 工程.

添加依赖pom.xml
使用的版本jdk1.8+springboot2.6.7+mybatis-plus3.5.1+mysql-connector5.1.38****

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </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>
            <version>5.1.38</version>
        </dependency>

    </dependencies>

application.properties配置

spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true
spring.datasource.username=root
spring.datasource.password=sasa

ideal下载MybatisX插件再重启

idea连接DataBase

1。点击user表下MybatisX-Generator

2.basePackge:会在java包下生成你自定义的com.lyj.demo包
basePath:生成路径在java下
relative Package:生成实体类pojo包名

3.生成的效果图如下

4.配置user类

	@TableId
    private Long id;


@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.ANNOTATION_TYPE})
public @interface TableId {

    /**
     * 字段名（该值可无）
     */
    String value() default "";

    /**
     * 主键类型
     * {@link IdType}
     */
    IdType type() default IdType.NONE;
}

现在 default IdType.NONE;主键默认为none

配置id 字段type =IdType.ASSIGN_ID使用是雪花算法

  /**
     * 主键ID
     * IdType.ASSIGN_ID:**主键类型为number或string**
     */
    @TableId(type =IdType.ASSIGN_ID )
    private Long id;

**
把mapper下UserMapper.xml和UserMapper接口放在一起
@MapperScan(“com.lyj.demo.mapper”)
springboot扫描mapper包

@MapperScan("com.lyj.demo.mapper")
@SpringBootApplication
public class MybatisPlusApplication {

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

}