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 自动的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数据库连接  -->

        <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 需要继承BaseMapper<User> 才能使用MP工具
/@Mapper //将接口交给Spring管理

public interface UserDao extends BaseMapper<User> {

    //查询user表的所有的记录

    @Select("select * from user")

    List<User> findAll();

}

pojo层 设置方法
@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一致(包含驼峰规则),可以省略不写
    private String name;
    private Integer age;
    private String sex;

}

加这个注解可以直接 不用在dao层加mappr单注解了
@SpringBootApplication

@MapperScan("com.com.jt.jt.dao") //主要告诉mapper的包路径,会自动的完成包扫描

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: /   #定义项目的发布路径
spring:
  datasource:
    #driver-class-name: com.mysql.cj.jdbc.Driver   springboot程序采用默认的配置
    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

基本数据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: 查询id=11的用户信息   主键...

 */

    @Test

    public void testSelect02(){

        User user = userDao.selectById(11);

        System.out.println(user);

    }

    /**

 * 业务: 查询name属性为"小乔"的数据

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

 * 对象的方式  >  sql方式

 */

    @Test

    public void testSelect03(){

        //条件构造器

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

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

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

        System.out.println(userList);

    }

    /**

 * 业务: 查询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(){

        //条件构造器

        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: 查询name中包含 "精"的用户,并且sex为女

 * 业务: 查询name中包含 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(){

        //条件构造器

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

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

                    .eq("sex", "女");

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

        System.out.println(userList);

    }

    /**

 * 需求: 查询user表中的数据 要求按照年龄降序排列,如果年龄相同按照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);

    }

    /**

 * 需求: 查询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);

    }

    /**

 * 查询name="小乔" age=17 性别=女的用户

 * 如果传递的是对象.会根据对象中不为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);

    }

    /**

 * 查询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,注意使用对象的类型

        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);

        //参数说明  1.实体对象  封装set条件的值

        //           2.更新条件构造器

        User temp = new User();

        temp.setAge(5500);

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

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

        userDao.update(temp,updateWrapper);

    }