MyBatis Plus 2.3 个人笔记-03-Active Record

AR 语法糖  是一种领域模型模式，特点就是一个模型类对应关系型数据库中的一个表，而模型类的一个实例对应表中的一条记录

• 　　实现AR 【在代码生成器中可以添加配置】

import com.baomidou.mybatisplus.activerecord.Model;
import com.baomidou.mybatisplus.annotations.TableField;
import java.io.Serializable;

/**
 * <p>
 *  实现AR 实体类继承  Model 重写 pkVal() 返回主键
 * </p>
 *
 * @author youxiu326@163.com
 * @since 2019-02-17
 */
@TableName("tbl_user")
public class User extends Model<User> {

    @Override
    protected Serializable pkVal() {
        return this.id;
    }
}

• 方法其实是一样的，只不过执行的写法有些区别，看个人喜好 是否使用这种语法糖

package com.huarui.mybatisplus;

import com.baomidou.mybatisplus.mapper.EntityWrapper;
import com.baomidou.mybatisplus.plugins.Page;
import com.huarui.mybatisplus.entity.Employee;
import com.huarui.mybatisplus.mapper.EmployeeMapper;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.List;

/**
 * AR 版CURD操作
 */
@RunWith(SpringRunner.class)
@SpringBootTest
public class TestAr {

    @Autowired
    private EmployeeMapper employeeMapper;

    /**
     * AR  分页复杂操作
     */
    @Test
    public void  testARPage() {

        Employee employee = new Employee();

        Page<Employee> page = employee.selectPage(new Page<>(1, 1),
                new EntityWrapper<Employee>().like("last_name", "老"));
        List<Employee> emps = page.getRecords();
        System.out.println(emps);
    }

    /**
     * AR 删除操作
     *
     * 注意: 删除不存在的数据 逻辑上也是属于成功的.
     */
    @Test
    public void testARDelete() {

        Employee employee = new Employee();
        //boolean result = employee.deleteById(2);
//		employee.setId(2);
//		boolean result = employee.deleteById();
//		System.out.println("result:" +result );

        boolean result = employee.delete(new EntityWrapper<Employee>().like("last_name", "小"));
        System.out.println(result );
    }

    /**
     * AR 查询操作
     */
    @Test
    public void testARSelect() {
        Employee employee = new Employee();

        //Employee result = employee.selectById(14);
//		employee.setId(14);
//		Employee result = employee.selectById();
//		System.out.println(result );

//		List<Employee> emps = employee.selectAll();
//		System.out.println(emps);

//		List<Employee > emps=
//				employee.selectList(new EntityWrapper<Employee>().like("last_name", "老师"));
//		System.out.println(emps);

        Integer result = employee.selectCount(new EntityWrapper<Employee>().eq("gender", 0));
        System.out.println("result: " +result );

    }

    /**
     * AR 修改操作
     */
    @Test
    public void testARUpdate() {
        Employee employee = new Employee();
        employee.setId(20L);
        employee.setLastName("宋老湿");
        employee.setEmail("sls@atguigu.com");
        employee.setGender("1");
        employee.setAge(36);

        boolean result = employee.updateById();
        System.out.println("result:" +result );

    }

    /**
     * AR  插入操作
     */
    @Test
    public void  testARInsert() {
        Employee employee = new Employee();
        employee.setLastName("李老师");
        employee.setEmail("youxiu326@163.com");
        employee.setGender("1");
        employee.setAge(35);
        employee.setId(1L);

        boolean result = employee.insert();
        System.out.println("result:" +result );
    }

}