SpringBoot 1项目创建及Mybatis-plus实现数据增删改查

一. 项目创建及配置

1.项目创建

点击finish完成创建

2. pom.xml

  <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>
		 <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.16</version>
        </dependency>
		   <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
            <scope>runtime</scope>
        </dependency>

3. applicatio.yml

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3307/shiro
    username: root
    password: 123
logging:
  level:
    com.mapper: trace
	

二、增删改查实现

1. 实体类 entity

@Data
@AllArgsConstructor
@NoArgsConstructor
@TableName("tb_user")
public class User {
    @TableId(value="id",type = IdType.AUTO)
    private Integer id;
    @TableField("username")
    private String username;
    @TableField(value = "password",select = false) //查询密码不显示
    private String password;
    private String gender;
    private String addr;
}

2. UserMapper

@Mapper
public interface UserMapper extends BaseMapper<User> {
}

3. test

//insert
    @Test
    void insert(){
        User user =new User(null,"武松","123","男","梁山");
        int insert = userMapper.insert(user);
        System.out.println(insert);
    }
    //update
    @Test
    void updata(){
        User user = userMapper.selectById(1);
        user.setPassword("111");
        int update = userMapper.updateById(user);
        System.out.println(update);
    }
    //delete
    @Test
    void delete(){
        int delete = userMapper.deleteById(7);
        System.out.println(delete);
    }
    //selectOne
    @Test
    void selectOne1(){
        User user = userMapper.selectById(1);
        System.out.println(user);
    }
    //selectAll
    @Test
    void selectAll(){
        Wrapper<User> wrapper = new QueryWrapper<>();
        List<User> users = userMapper.selectList(wrapper);
        System.out.println(users);
    }
   //分页
    @Test
    void page(){
        int pageNo=1;
        int pageSize=3;
        IPage<User> page = new Page<>(pageNo,pageSize);
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        IPage<User> iPage = userMapper.selectPage(page,queryWrapper);
        System.out.println("总页数："+page.getPages());
        System.out.println("当前页码："+page.getCurrent());
        System.out.println("每页记录数："+page.getSize());
        System.out.println("总条数："+page.getTotal());
        System.out.println("当前页的记录："+page.getRecords());
    }
	 // 条件查询
    @Test
    void select(){
        QueryWrapper<User> userQueryWrapper = new QueryWrapper<>();
/*        userQueryWrapper.lambda().gt(User::getId,3)
                                 .like("username","%宋%");*/
       /* LambdaQueryWrapper<User> userLambdaQueryWrapper = new LambdaQueryWrapper<>();
        userLambdaQueryWrapper.gt(User::getId,3)
                .like(User::getUsername,"%宋%");*/
        userQueryWrapper.gt("id",2)
                        .like("username","%宋%");
        List<User> user = userMapper.selectList(userQueryWrapper);
        System.out.println(user);
    }

    // 分组查询
    @Test
    void group(){
    QueryWrapper<User> userQueryWrapper = new QueryWrapper<>();
     userQueryWrapper.select("gender","count(*) as gc")
                    .groupBy("gender");
     List<Map<String,Object>> maps = userMapper.selectMaps(userQueryWrapper);         System.out.println(maps);
    }
    //投影查询
    @Test
    void touying(){
        QueryWrapper<User> userQueryWrapper = new QueryWrapper<>();
        userQueryWrapper.select("id,username,gender");
        List<User> user = userMapper.selectList(userQueryWrapper);
        System.out.println(user);
    }