mybatis-plus提供支持ActiveRecord模式

矫情吗；* 2021-07-16 11:29 302阅读 0赞

在Mybatis-Plus中提供了ActiveRecord的模式，支持 ActiveRecord 形式调用，实体类只需继承 Model 类即可实现基本 CRUD 操作，简单来说就是一个实体类继承Model类，并通过注解与数据库的表名进行关联，这样就可以通过实体类直接进行表的简单增删改查操作，这样也确实极大的方便了开发人员。

原理理解：

简单来说Mybatis-plus是基于Mybatis的基础之上进行开发的，其基本操作还是一个Mapper操作中对应一条sql语句，通过参数和返回值来处理sql语句的执行结果。那样我们可以理解Mybatis-Plus的ActiveRecord其实就是Mybatis-Plus给我们提供一些简单的增删改查操作SQl语句的自动生成操作，在Mybatis提供的BaseMapper中默认提供了一些简单增删改查操作，其通过自动生成sql来初始化Mybatis的一些操作，其最终实现和我们直接基于Mybatis开发是一致的。

具体实现：

实体继承Model类，以及加上@EqualsAndHashCode(callSuper = false)注解，不调用父类euqals和hashCode方法；

@Data
    @EqualsAndHashCode(callSuper = false)
    public class Department extends Model<Department>

CRUD demo案例：

package com.java1234;
     
     
    import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
    import com.java1234.entity.Department;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.test.context.junit4.SpringRunner;
     
    import java.util.List;
     
     
    /** * @author java1234_小锋 * @site www.java1234.com * @company Java知识分享网 * @create 2020-08-22 17:07 */
    @RunWith(SpringRunner.class)
    @SpringBootTest
    public class ActiveRecordTest { 
     
     
        @Test
        public void insert(){ 
            Department department=new Department();
            department.setName("xx部门");
            department.setRemark("xxx");
            boolean insert = department.insert();
            System.out.println(insert);
        }
     
        @Test
        public void updateById(){ 
            Department department=new Department();
            department.setId(7);
            department.setName("xx部门2");
            department.setRemark("xxx2");
            boolean b = department.updateById();
            System.out.println(b);
        }
     
        @Test
        public void insertOrUpdate(){ 
            Department department=new Department();
            department.setId(8);
            department.setName("xx部门2");
            department.setRemark("xxx2");
            boolean b = department.insertOrUpdate();
            System.out.println(b);
        }
     
        @Test
        public void deleteById(){ 
            Department department=new Department();
            department.setId(7);
            boolean b = department.deleteById();
            System.out.println(b);
        }
     
        @Test
        public void selectById(){ 
            Department department=new Department();
            //Department d = department.selectById(1); // 方式一
            department.setId(1);  // 方式二
            Department d = department.selectById();
            System.out.println(d);
        }
     
        @Test
        public void selectAll(){ 
            Department department=new Department();
            List<Department> departmentList = department.selectAll();
            System.out.println(departmentList);
        }
     
        @Test
        public void selectListByQueryMapper(){ 
            QueryWrapper<Department> queryWrapper=new QueryWrapper();
            // QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
            queryWrapper.like("name","测试");
            Department department=new Department();
            List<Department> departmentList = department.selectList(queryWrapper);
            System.out.println(departmentList);
        }
     
     
     
    }