关于springboot:02第四阶段内容

 整合 mtbatis plus 这个是 pom 依赖

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <parent>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-parent</artifactId>

        <version>2.3.4.RELEASE</version>

        <relativePath/> <!-- lookup parent from repository -->

    </parent>

    <groupId>com.com.jt.jt</groupId>

    <artifactId>springboot_demo2_mybatis</artifactId>

    <version>0.0.1-SNAPSHOT</version>

    <name>springboot_demo2_mybatis</name>

    <description>Demo project for Spring Boot</description>

    <properties>

        <java.version>1.8</java.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-web</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-test</artifactId>

            <scope>test</scope>

            <exclusions>

                <exclusion>

                    <groupId>org.junit.vintage</groupId>

                    <artifactId>junit-vintage-engine</artifactId>

                </exclusion>

            </exclusions>

        </dependency>

        <!-- 引入插件 lombok 主动的 set/get/ 构造方法插件  -->

        <dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

        </dependency>

        <!-- 引入数据库驱动 -->

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

            <scope>runtime</scope>

        </dependency>

        <!--springBoot 数据库连贯  -->

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-jdbc</artifactId>

        </dependency>

        <!--spring 整合 mybatis-plus -->

        <dependency>

            <groupId>com.baomidou</groupId>

            <artifactId>mybatis-plus-boot-starter</artifactId>

            <version>3.2.0</version>

        </dependency>

    </dependencies>

    <build>

        <plugins>

            <plugin>

                <groupId>org.springframework.boot</groupId>

                <artifactId>spring-boot-maven-plugin</artifactId>

            </plugin>

        </plugins>

    </build>

</project>

dao 层接口 须要继承 BaseMapper<User> 能力应用 MP 工具
/@Mapper // 将接口交给 Spring 治理

public interface UserDao extends BaseMapper<User> {

    // 查问 user 表的所有的记录

    @Select("select * from user")

    List<User> findAll();}

pojo 层 设置办法
@Data
@Accessors(chain = true)
@TableName  //("user")      //1. 将对象与表 进行一对一关联
public class User implements Serializable {@TableId(type = IdType.AUTO)    // 主键的信息  设定自增
    private Integer Id;
    //@TableField("name")     // 如果字段名称与属性的名称统一 (蕴含驼峰规定), 能够省略不写
    private String name;
    private Integer age;
    private String sex;

}

 加这个注解能够间接 不必在 dao 层加 mappr 单注解了
@SpringBootApplication

@MapperScan("com.com.jt.jt.dao") // 次要通知 mapper 的包门路, 会主动的实现包扫描

public class SpringbootDemo2MybatisApplication {public static void main(String[] args) {SpringApplication.run(SpringbootDemo2MybatisApplication.class, args);

    }

}

xml 总配置

server:
  port: 8090    #定义端口
  servlet:
    context-path: /   #定义我的项目的公布门路
spring:
  datasource:
    #driver-class-name: com.mysql.cj.jdbc.Driver   springboot 程序采纳默认的配置
    url: jdbc:mysql://127.0.0.1:3306/jtdb?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true
    username: root
    password: root
mybatis-plus:
  #定义别名包
  type-aliases-package: com.com.jt.jt.pojo
  #加载 user 标签的 mapper 文件
  mapper-locations: classpath:/mybatis/mappers/*.xml
  #开启驼峰映射
  configuration:
    map-underscore-to-camel-case: true
#引入日志信息.
logging:
  level:
    com.jt.dao: debug

 根本数据 MP 工具
@SpringBootTest

class SpringbootDemo2MybatisApplicationTests {

    @Autowired

    private UserDao userDao;

    @Test

    public void testFind(){List<User> userList = userDao.findAll();

        System.out.println(userList);

    }

    @Test

    public void testSelect01(){List<User> userList = userDao.selectList(null);

        System.out.println(userList);

    }

    /**

 * 业务: 查问 id=11 的用户信息   主键...

 */

    @Test

    public void testSelect02(){User user = userDao.selectById(11);

        System.out.println(user);

    }

    /**

 * 业务: 查问 name 属性为 "小乔" 的数据

 * sql:  select * from user where name="小乔";

 * 对象的形式  >  sql 形式

 */

    @Test

    public void testSelect03(){

        // 条件结构器

        QueryWrapper<User> queryWrapper = new QueryWrapper<>();

        queryWrapper.eq("name", "小乔");

        List<User> userList = userDao.selectList(queryWrapper);

        System.out.println(userList);

    }

    /**

 * 业务: 查问 name 属性为 "小乔" 的数据 并且 age >=18 岁

 * sql:  select * from user where name="小乔" and age>=18;

 *

 * 大于   >  gt| 小于 <  lt   |

 * 大于等于  >= ge  |  小于等于 le

 */

    @Test

    public void testSelect04(){

        // 条件结构器

        QueryWrapper<User> queryWrapper = new QueryWrapper<>();

        queryWrapper.eq("name", "小乔")

                    .ge("age", 18);

        List<User> userList = userDao.selectList(queryWrapper);

        System.out.println(userList);

    }

    /**

 * 业务: 查问 name 中蕴含 "精" 的用户, 并且 sex 为女

 * 业务: 查问 name 中蕴含 以精结尾的数据, 并且 sex 为女

 * sql:  select * from user where name like "% 精 %" and sex="女";

 */

    @Test

    public void testSelect05(){

        // 条件结构器

        QueryWrapper<User> queryWrapper = new QueryWrapper<>();

        queryWrapper.likeLeft("name", "精")

                    .eq("sex", "女");

        List<User> userList = userDao.selectList(queryWrapper);

        System.out.println(userList);

    }

    /**

 * 需要: 查问 user 表中的数据 要求依照年龄降序排列, 如果年龄雷同依照 id 降序排列

 */

    @Test

    public void testSelect06(){QueryWrapper<User> queryWrapper = new QueryWrapper<>();

        queryWrapper.orderByDesc("age","id");

        List<User> userList = userDao.selectList(queryWrapper);

        System.out.println(userList);

    }

    /**

 * 需要: 查问 name 属性为 null 的数据.

 * where name is null

 */

    @Test

    public void testSelect07(){QueryWrapper<User> queryWrapper = new QueryWrapper<>();

        queryWrapper.isNull("name");

        List<User> userList = userDao.selectList(queryWrapper);

        System.out.println(userList);

    }

    /**

 * 查问 name="小乔" age=17 性别 = 女的用户

 * 如果传递的是对象. 会依据对象中不为 null 的属性充当 where 条件.

 */

    @Test

    public void testSelect08(){User user = new User();

        user.setName("小乔").setAge(17).setSex("女");

        QueryWrapper<User> queryWrapper = new QueryWrapper<>(user);

        List<User> userList = userDao.selectList(queryWrapper);

        System.out.println(userList);

    }

    /**

 * 查问 id=1,3,5,10 数据.

 * sql: select * from user where id in (1,3,5,10)

 */

    @Test

    public void testSelect09(){

        // 转化时, 留神应用对象的类型

        Integer[] ids = {1,3,5,10};

        List<Integer> idList = Arrays.asList(ids);

        List<User> userList = userDao.selectBatchIds(idList);

        System.out.println(userList);

    }

    @Test

    public void testInsert(){User user = new User();

        user.setName("特朗普").setAge(70).setSex("男");

        userDao.insert(user);

    }

    /**

 * 删除 name=null 的数据, 或者 name="特朗普"

 */

    @Test

    public void testDelete(){QueryWrapper<User> queryWrapper = new QueryWrapper<>();

        queryWrapper.isNull("name")

                    .or()

                    .eq("name", "特朗普");

        userDao.delete(queryWrapper);

    }

    /**

 * 案例 1: 将 id= 1 的数据的年龄改为 8000 岁.

 * sql1:  update user set age=8000 where id=1;

 * 案例 2: 要求将 name="黑熊精" age=5500.

 * sql2:  update user set age=5500 where name="黑熊精";

 */

    @Test

    public void testUpdate(){User user = new User();

        user.setId(1);    // 主键充当 where 条件

        user.setAge(8000);

        userDao.updateById(user);

        // 参数阐明  1. 实体对象  封装 set 条件的值

        //           2. 更新条件结构器

        User temp = new User();

        temp.setAge(5500);

        UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();

        updateWrapper.eq("name", "黑熊精");

        userDao.update(temp,updateWrapper);

    }