Mybaits-plus

pom文件

        <!-- 数据库驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!-- lombok 简化set get toString -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <!-- mybatis-plus -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3.1</version>
        </dependency>

连接数据库yaml代码

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatis_plus?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai
    username: root
    password: 123456

创建pojo类

@Data
@AllArgsConstructor #有参构造器
@NoArgsConstructor  #无参构造器
public class User {
    @TableId(type = IdType.ASSIGN_ID,value = "id")//枚举注解,使用ID_WORKER策略,全局唯一ID，数据库设置自增也没用
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

分页查询

1.配置拦截器

public class MybatisPlusConfig {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());//创建乐观锁拦截器 OptimisticLockerInnerInterceptor
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL)); 
        return mybatisPlusInterceptor;
    }
}

/**源码
 * 分页构造函数
 *
 * @param current 当前页
 * @param size    每页显示条数
 */
public Page(long current, long size) {
    this(current, size, 0);
}