mybatis-plus分頁查詢的實現示例
阿新 • • 發佈:2020-08-27
按照官方文件進行的配置:快速開始|mybatis-plus
引入依賴:
<!-- 引入mybatisPlus --> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.2.0</version> </dependency> <!-- 引入mysql驅動包 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.27</version> </dependency> <!-- 引入Druid依賴,阿里巴巴所提供的資料來源 --> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.0.29</version> </dependency>
在application.yml配置
spring: datasource: type: com.alibaba.druid.pool.DruidDataSource driver-class-name: com.mysql.jdbc.Driver url: jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8 username: root password: 123456
在啟動類上面新增@MapperScan註解,掃描mapper包
@SpringBootApplication @MapperScan("com.qiao.demo02.mapper") public class SpringbootDemo02Application { public static void main(String[] args) { SpringApplication.run(SpringbootDemo02Application.class,args); } }
新建User和UserMapper
user類
@Data public class User { @TableId private Integer userId; private String userName; private Integer userAge; private String userEmail; }
UserMapper介面
public interface UserMapper extends BaseMapper<User> { }
最重要的是繼承BaseMapper<E>介面:裡面聲明瞭很強大的CRUD方法
public interface BaseMapper<T> extends Mapper<T> { int insert(T entity); int deleteById(Serializable id); int deleteByMap(@Param("cm") Map<String,Object> columnMap); int delete(@Param("ew") Wrapper<T> wrapper); int deleteBatchIds(@Param("coll") Collection<? extends Serializable> idList); int updateById(@Param("et") T entity); int update(@Param("et") T entity,@Param("ew") Wrapper<T> updateWrapper); T selectById(Serializable id); List<T> selectBatchIds(@Param("coll") Collection<? extends Serializable> idList); List<T> selectByMap(@Param("cm") Map<String,Object> columnMap); T selectOne(@Param("ew") Wrapper<T> queryWrapper); Integer selectCount(@Param("ew") Wrapper<T> queryWrapper); List<T> selectList(@Param("ew") Wrapper<T> queryWrapper); List<Map<String,Object>> selectMaps(@Param("ew") Wrapper<T> queryWrapper); List<Object> selectObjs(@Param("ew") Wrapper<T> queryWrapper); IPage<T> selectPage(IPage<T> page,@Param("ew") Wrapper<T> queryWrapper); IPage<Map<String,Object>> selectMapsPage(IPage<T> page,@Param("ew") Wrapper<T> queryWrapper); }
分頁查詢
這點官方文件講的也很詳細:https://mp.baomidou.com/guide/page.html
新建一個config包,在裡面建一個MybatisPlus配置類 返回一個分頁攔截器
package com.qiao.demo02.config; @Configuration @ConditionalOnClass(value = {PaginationInterceptor.class}) public class MybatisPlusConfig { @Bean public PaginationInterceptor paginationInterceptor() { PaginationInterceptor paginationInterceptor = new PaginationInterceptor(); return paginationInterceptor; } }
這樣就能使用mybatis的分頁功能了
Junit測試
@Resource private UserMapper userMapper; @Test public void queryUserForPage(){ IPage<User> userPage = new Page<>(2,2);//引數一是當前頁,引數二是每頁個數 userPage = userMapper.selectPage(userPage,null); List<User> list = userPage.getRecords(); for(User user : list){ System.out.println(user); } }
Controller返回json串
先定義一個包裝類UserVo,用來儲存分頁所需要的資料
package com.qiao.demo02.vo; @Data public class UserVo { private Integer current; private Integer size; private Long total; private List<User> userList; }
然後在控制器編寫程式碼,這裡省略了service層,實際開發業務程式碼寫在service層,Controller只負責:接受引數、呼叫service層方法處理業務邏輯,返回結果
Controller類貼上了@RestController註解
@GetMapping("queryUser") public UserVo queryList(Integer current,Integer size) { /** * 這些程式碼應該寫在service層 */ UserVo userVo = new UserVo(); IPage<User> page = new Page<>(current,size); userMapper.selectPage(page,null); userVo.setCurrent(current); userVo.setSize(size); userVo.setTotal(page.getTotal()); userVo.setUserList(page.getRecords()); return userVo; }
附上結果,前端直接處理json資料即可
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