JavaWeb开发-09-MyBatis

 官网：https://mybatis.org/mybatis-3/zh/index.html

一.Mybatis入门

1.快速入门

 

2.JDBC介绍

3.数据库连接池

 官方地址：https://github.com/alibaba/druid/tree/master/druid-spring-boot-starter

4.lombok

二.Mybatis基础增删改查

1.准备

2.删除

 

3.新增

 

4.更新

5.查询

# 配置数据库的连接信息 - 四要素

#驱动类名称
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#数据库连接的url
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis
#连接数据库的用户名
spring.datasource.username=root
#连接数据库的密码
spring.datasource.password=1234

# 配置mybatis的日志信息,指定到输出控制台
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

#开启mybatis的驼峰命名自动映射开关
mybatis.configuration.map-underscore-to-camel-case=true

package com.wjh.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.time.LocalDate;
import java.time.LocalDateTime;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Emp {

    private Integer id;
    private String username;
    private String password;
    private String name;
    private Short gender;
    private String image;
    private Short job;
    private LocalDate entrydate;
    private Integer deptId;
    private LocalDateTime createTime;
    private LocalDateTime updateTime;

}

package com.wjh.mapper;

import com.wjh.pojo.Emp;
import org.apache.ibatis.annotations.*;

import java.time.LocalDate;
import java.util.List;

@Mapper
public interface EmpMapper {

    //查询所有员工信息
    @Select("select * from emp")
    public List select();

    //根据ID删除员工信息操作
    @Delete("delete from emp where id = #{id}")
    //public void delete(Integer id);
    public int delete(Integer id);

    //新增员工
    @Options(useGeneratedKeys = true, keyProperty = "id")
    @Insert("insert into emp(username, name, gender, image, job, entrydate, dept_id, create_time, update_time)" +
            "values (#{username}, #{name}, #{gender}, #{image}, #{job}, #{entrydate}, #{deptId}, #{createTime}, #{updateTime}) ")
    public void insert(Emp emp);

    //更新员工信息(修改)
    @Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}, job = #{job}, entrydate = #{entrydate}, dept_id = #{deptId}, update_time = #{updateTime} where id = #{id};")
    public void update(Emp emp);

    //根据id查询用户信息
    @Select("select * from emp where id = #{id}")
    public Emp selectId(Integer id);

//    //方案一给字段起别名,让别名与实体名一致
//    @Select("select id, username, password, name, gender, image, job, entrydate, " +
//            "dept_id deptId, create_time createTime, update_time updateTime from emp where id = #{id}")
//    public Emp selectId2(Integer id);
//
//    //方案二: 通过#@Result注解手动映射
//    @Results({
//            @Result(column = "dept_id",property =  "deptId"),
//            @Result(column = "create_time",property =  "createTome"),
//            @Result(column = "update_time",property =  "updateTime")
//    })
//    @Select("select * from emp where id = #{id}")
//    public Emp selectId3(Integer id);

    //方案三: 开启mybatis的驼峰命名自动映射开关 -- a_column --------> aColumn

    //条件查询员工信息
    @Select("select * from emp where name like concat('%', #{name},'%') and gender = #{gender} " +
            "and entrydate between #{begin} and #{end} order by update_time desc")
    public List list(String name, Short gender, LocalDate begin, LocalDate end );

//    select concat('hello', 'mysql', 'word');
//     select * from emp where name like concat('%', '张', '%') and gender = '1' and
//     entrydate between '2010-01-01' and '2020-01-01' order by update_time desc;

}

package com.wjh;

import com.wjh.mapper.EmpMapper;
import com.wjh.pojo.Emp;
import org.apache.ibatis.annotations.Mapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;

@SpringBootTest
class SpringbootMybatisCrudApplicationTests {

    @Autowired
    private EmpMapper EmpMapper;

    //查询所有员工测试类
    @Test
    public void testListEmp(){
        List empList = EmpMapper.select();
        empList.stream().forEach(selectEmp -> {
            System.out.println(selectEmp);
        });
    }

    //根据id删除员工信息测试类
    @Test
    public void testDelete(){
        EmpMapper.delete(4);
        //int delete = EmpMapper.delete(4);
        //System.out.println("删除了" + delete + "条数据");
        testListEmp();
    }

    //新增员工测试类

    @Test
    public void testInsert(){
        Emp empInsert = new Emp();
        empInsert.setUsername("ikun6");
        empInsert.setName("坤坤6");
        empInsert.setGender((short)2);
        empInsert.setImage("#");
        empInsert.setJob((short)1);
        empInsert.setEntrydate(LocalDate.of(2000,01,01));
        empInsert.setDeptId(1);
        empInsert.setCreateTime(LocalDateTime.now());
        empInsert.setUpdateTime(LocalDateTime.now());
        //执行员工信息操作
        EmpMapper.insert(empInsert);
        System.out.println("主键:" + empInsert.getId());
    }

    //修改员工信息测试类
    @Test
    public void testUpdate(){
        Emp empUpdate = new Emp();
        empUpdate.setId(10);
        empUpdate.setUsername("zhaomingming");
        empUpdate.setName("赵敏");
        empUpdate.setGender((short)1);
        empUpdate.setImage("#");
        empUpdate.setJob((short)1);
        empUpdate.setEntrydate(LocalDate.of(2000,01,01));
        empUpdate.setDeptId(1);
        empUpdate.setUpdateTime(LocalDateTime.now());

        //执行员工信息操作
        EmpMapper.update(empUpdate);
    }

    //根据id查询用户信息测试类
    @Test
    public void testSelectId(){
        Emp emp = EmpMapper.selectId(10);
        System.out.println(emp);
    }

    //根据条件查询员工
    @Test
    public void testSelect(){
        EmpMapper.list("张", (short) 1, LocalDate.of(2010, 01, 01), LocalDate.of(2020, 01 , 01));
    }

}

 三.Mybatis动态SQL

1.XML映射文件

 

 

 

 //条件查询员工信息
    public List list(String name, Short gender, LocalDate begin, LocalDate end);

    
        select *
        from emp
        where name like concat('%', #{name}, '%')
          and gender = #{gender}
          and entrydate between #{begin} and #{end}
        order by update_time desc
    

//根据条件查询员工
    @Test
    public void testSelect(){
        List empList = EmpMapper.list("张", (short) 1,
                LocalDate.of(2010, 01, 01),
                LocalDate.of(2020, 01 , 01));
        System.out.println(empList);
    }

 

 

 

官方说明https://mybatis.net.cn/getting-started.html

 

2.动态SQL

(1).

 

 

        
        select *
        from emp
        
        
            name like concat('%', #{name}, '%')
        
        
            and gender = #{gender}
        
        
            and entrydate between #{begin} and #{end}
        
        
            order by update_time desc
    

 

//动态更新员工信息(修改)
    //@Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}, job = #{job}, " +
    //        "entrydate = #{entrydate}, dept_id = #{deptId}, update_time = #{updateTime} where id = #{id};")
    public void update2(Emp emp);

 

    
        update emp
        
            
                username = #{username},
            
            
                name = #{name},
            
            
                gender = #{gender},
            
            
                image = #{image},
            
            
                job = #{job},
            
            
                entrydate = #{entrydate},
            
            
                dept_id = #{deptId},

            
            
                update_time = #{updateTime}
            
        
          where id = #{id}
    

 

 //动态更新员工信息-- 跟新id = 18 的员工 username 为 Tom11,name = 汤姆111, gander更新为2

    @Test
    public void testUpdate2(){
        //构造员工对象
        Emp emp = new Emp();
        emp.setId(19);
        emp.setUsername("tanmgu11");
        emp.setName("汤姆111");
        emp.setGender((short) 2);
        emp.setUpdateTime(LocalDateTime.now());
        //执行员工操作
        EmpMapper.update2(emp);

    }

(2).

 

//批量删除员工
    public void deleteByIds(List ids);

    
        delete from emp where id in
        
            #{id}
        
    

//批量删除员工
    @Test
    public void testdeleteByIds(){
        List list = Arrays.asList(16,17,18);
        EmpMapper.deleteByIds(list);
    }

(3).

 

 

    
    
        select id, username, password, name, gender, image, job, entrydate, dept_id, create_time, update_time
        from emp
    

    













        -- if
        
        
        
            name like concat('%', #{name}, '%')
        
        
            and gender = #{gender}
        
        
            and entrydate between #{begin} and #{end},
        
        
            order by update_time desc
    



    
        update emp
        
            
                username = #{username},
            
            
                name = #{name},
            
            
                gender = #{gender},
            
            
                image = #{image},
            
            
                job = #{job},
            
            
                entrydate = #{entrydate},
            
            
                dept_id = #{deptId},

            
            
                update_time = #{updateTime}
            
        
          where id = #{id}
    



    
        delete from emp where id in
        
            #{id}