SpringBoot与MyBatisplus双剑合璧

一.项目结构

二.依赖与配置

1.pom.xml文件导入相关依赖：

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>


        <!--MybatisPlus依赖-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.2.0</version>
        </dependency>


        <!--lombok依赖-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>

		 <!--MySQL依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>


        <!--阿里巴巴druid-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.19</version>
        </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>
        

2.准备实体类(User)
3.准备mapper类(UserMapper)

4.配置数据库驱动(在application.properties中配置)

spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test(根据自己的库)?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
spring.datasource.username=root
spring.datasource.password=root

#开启日志
logging.level.root=info
logging.level.com.superliu.springboot.mapper=debug

5.准备测试类(TestMapper)

@SpringBootTest
public class TestMapper {

    @Autowired
     UserMapper userMapper;


    /**
     * 查询所有
     */
    @Test
    public void FindUserAll(){
        List<User> users = userMapper.selectList(null);
        users.forEach(user -> System.out.println("user  ="+user));
    }

    /**
     * 根据ID查询
     */
    @Test
    public void FindUserById(){
        User user = userMapper.selectById(2);
        System.out.println("user  ="+user);
    }

    /**
     * 条件查询
     */
    @Test
    public void FindByUser(){
        QueryWrapper<User> qw = new QueryWrapper<User>();
        qw.eq("age",18);//等值查询
        qw.lt("age",15);//小于查询（less than）
        qw.le("age",15);//小于等于查询(less equals)
        qw.gt("age",15);//大于查询(greater than)
        qw.ge("age",15);//大于等于查询(greater equals)
        List<User> users = userMapper.selectList(qw);
        users.forEach(user -> System.out.println("user ="+user));
    }

    /**
     * 模糊查询
     */
    @Test
    public void FindUserLike(){
        QueryWrapper<User> qw = new QueryWrapper<User>();
        qw.like("u_name","a");//like ---> %?%(包含什么的查询)    likeLeft ---> %?(以什么结尾的查询)    likeRight ---> ?%(以什么开头的查询)
        List<User> users = userMapper.selectList(qw);
        users.forEach(user -> System.out.println("user "+user));
    }

    /**
     * 新增
     */
    @Test
    public void UserSave(){
        User user = new User();
        user.setName("小刘").setAge(23).setBir(new Date()).setId("3");
        userMapper.insert(user);
    }

    /**
     * 根据Id更新
     */
    @Test
    public void UpdateById(){
        User user = userMapper.selectById(3);
        user.setName("刘xx").setAge(21);
        userMapper.updateById(user);
    }

    /**
     *  批量修改(将age=15时的用户名字改为`阿峰`)
     */
    @Test
    public void Update(){
        User user = userMapper.selectById("3");
        user.setName("阿峰");
        user.setBir(null);
        QueryWrapper<User> updateWrapper = new QueryWrapper<User>();
        updateWrapper.eq("age",15);
        userMapper.update(user,updateWrapper);
    }

    /**
     * 根据Id删除
     */
    @Test
    public void DeleteById(){
        userMapper.deleteById("4");
    }


    /**
     * 根据条件批量删除
     */
    @Test
    public void DeleteByUser(){
        QueryWrapper<User> qw = new QueryWrapper<User>();
        qw.gt("age",15);
        userMapper.delete(qw);
    }

    /**
     * 分页查询使用
     */
    @Test
    public void FindPage(){
        Page<User> page = new Page<>(1,2);//参数1：当前页  默认值1        参数2：每页显示记录数  默认值10
        IPage<User> userIPage = userMapper.selectPage(page, null);
        long total = userIPage.getTotal();
        System.out.println("总记录数"+total);
        userIPage.getRecords().forEach(user -> System.out.println("user =" +user));
    }

    /**
     * 分页条件查询
     */
    @Test
    public void FindPageLike(){
        QueryWrapper<User> qw = new QueryWrapper<User>();
        qw.eq("age",23);
        Page<User> page = new Page<>(1,5);//参数1：当前页  默认值1        参数2：每页显示记录数  默认值10
        IPage<User> userIPage = userMapper.selectPage(page, qw);
        long total = userIPage.getTotal();
        System.out.println("总记录数"+total);
        userIPage.getRecords().forEach(user -> System.out.println("user =" +user));
    }
}

注意: 关于有关分页查询的使用，必须要配置分页拦截器对象(MybatisPlusConfig) 配置如下：

@EnableTransactionManagement
@Configuration
@MapperScan("com.superliu.springboot.mapper")//对应的Mapper类的位置
public class MybatisPlusConfig {

    /**
     * 分页拦截器对象
     * @return
     */

    //注意事项:目前分页查询仅仅支持单表查询，不能再表连接时使用分页插件
    @Bean
    public PaginationInterceptor paginationInterceptor(){
        PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
        return paginationInterceptor;
    }
}

三.多数据源配置

对于 多数据源的配置 ，(可对数据库读写分离，起到更高的效率)，对不同的库进行操作。

1.导入依赖:

        <!--多数据源依赖-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>3.0.0</version>
        </dependency>

2.配置数据库驱动（application.properties）:

spring.datasource.primary=master    #指定默认数据源
spring.datasource.dynamic.datasource.master.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.dynamic.datasource.master.url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
spring.datasource.dynamic.datasource.master.username=root
spring.datasource.dynamic.datasource.master.password=root


spring.datasource.dynamic.datasource.slave_1.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.dynamic.datasource.slave_1.url=jdbc:mysql://localhost:3306/test_01?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
spring.datasource.dynamic.datasource.slave_1.username=root
spring.datasource.dynamic.datasource.slave_1.password=root

#开启日志
logging.level.root=info
logging.level.com.superliu.springboot.mapper=debug

注意：master与slave_1为数据源的名字，test与test_01为不同库的表名。

3.准备Service类(UserService):
4.准备ServiceImpl实现类(UserServiceImpl):

注意：@DS注解是指明对哪一个库进行操作，配置文件中spring.datasource.primary=master 指定默认数据源为master 。

5.准备测试类(TestService)：

@SpringBootTest
public class TestService {
    @Autowired
    UserServiceImpl userService;
    @Test
    public void findAll(){
        userService.findAll().forEach(user -> System.out.println("user = "+user));
    }


    @Test
    public void addUser(){
        User user = new User();
        user.setAge(32).setId("5").setBir(new Date()).setName("ZZc");
        userService.addUser(user);
    }
}