SpringBoot 整合 MybatisPlus (項目的創建及簡單的單表查詢)

添加依賴

    <!--mybatis-plus的springboot支持-->
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.0.5</version>
    </dependency>
    <!--mysql驅動-->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.47</version>
    </dependency>

創建數據庫和表

CREATE TABLE `user` (`id` BIGINT(20) not null AUTO_INCREMENT comment '主鍵ID',
    `name` VARCHAR(30) DEFAULT null comment '姓名',
    `age` int(11) DEFAULT null comment '年齡',
    `email` VARCHAR(50) DEFAULT null comment '郵箱',
    PRIMARY KEY (`id`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;
insert into user (id,name,age,email) VALUES ('1','Jone','18','[e-mail]');
 insert into user (id,name,age,email) VALUES ('2','Jack','20','[e-mail]');
 insert into user (id,name,age,email) VALUES ('3','Tom','28','[e-mail]');
 insert into user (id,name,age,email) VALUES ('4','Sandy','21','[e-mail]');
 insert into user (id,name,age,email) VALUES ('5','Billie','24','[e-mail]');
 

 

配置 application.yml

spring:
  application:
    name: spring-boot-mybatis-plus
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/mysqlName?useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true&useSSL=false
    username: root
    password: root

 

創建pojo類

public class User {
    @TableId(value = "ID",type = IdType.AUTO)  //設置id為自增長
    private Long id;
    private String name;
    private Integer age;
    private String email;
		//( set,get,toString方法自行添加 )
}

創建 UserMapper接口

public interface UserMapper extends BaseMapper<User> {
}

注意：BaseMapper接口引入的包是

com.baomidou.mybatisplus.core.mapper.BaseMapper

編寫 SpringBoot 啟動類

@MapperScan("cn.mybatisplus.mapper")
@SpringBootApplication
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class,args);
    }
}

@MapperScan("cn.mybatisplus.mapper"). 掃描 mapper 包

編寫測試代碼

@SpringBootTest
@RunWith(SpringRunner.class)
public class UserMapperTest {
@Autowired
private UserMapper userMapper;

@Test
public void testList(){
    List<User> users = this.userMapper.selectList(null);
    for (User user: users) {
        System.out.println(user);
    }
}

  @Test
public void testSelectById(){
    User user = this.userMapper.selectById(3L);   //根據id查數據
    System.out.println(user);
}


@Test
public void testSelectByLike(){   
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    wrapper.like("name","o");   //查詢 name字段中包含‘o’的數據
    List<User> users = this.userMapper.selectList(wrapper);//返回值是一個list集合
    for (User u : users) {
        System.out.println(u);
    }
}

@Test
public void testSelectByLe(){
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    /**
     * eq : 等於
     * ne : 不等於
     * gt : 大於
     * ge : 大於等於
     * lt : 小於
     * le : 小於等於
     * 更多查看 https://mp.baomidou.com/guide/wrapper.html#abstractwrapper
     */
    wrapper.le("age","20");       //設置年齡小於等於20
    List<User> users = this.userMapper.selectList(wrapper);
    for (User u : users) {
        System.out.println(u);
    }
}
@Test
public void testSave() {
    User user = new User();
    user.setAge(25);
    user.setEmail("[e-mail]");
    user.setName("zhangsan");
    int count = this.userMapper.insert(user);
    System.out.println("新增數據成功  count ==> "+count);
}
@Test
public void testDelete(){
    this.userMapper.deleteById(6L);
    System.out.println("刪除成功");
}

@Test
public void testUpdate(){
    User user = new User();
    user.setId(5L);
    user.setName("Lisi");
    int i = this.userMapper.updateById(user);
    System.out.println(" 有"+i+"條數據被修改");
}

}
 

 

分頁查詢

需要增加分頁插件配置（這里就簡單在啟動類加 Bean）

@MapperScan("cn.itcast.mybatisplus.mapper")
@SpringBootApplication
public class MyApplication {
/*
 * 分頁插件
 */
@Bean
public PaginationInterceptor paginationInterceptor(){
    return new PaginationInterceptor();
}

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

}

測試

    @Test
    public void testSelectPage() {
        Page<User> page = new Page<>(2, 2);
        IPage<User> userIPage = this.userMapper.selectPage(page, null);
        System.out.println("總頁數 ----> " + userIPage.getTotal());
        System.out.println("當前頁數 ----> " + userIPage.getCurrent());
        System.out.println("當前每頁顯示數 ----> " + userIPage.getSize());
        List<User> records = userIPage.getRecords();
        for (User u: records) {
            System.out.println(u);
        }
    }

運行結果

總頁數 ----> 5
當前頁數 ----> 2
當前每頁顯示數 ----> 2
User(id=3, name=Tom, age=28, email=[e-mail])
User(id=4, name=Sandy, age=21, email=[e-mail])