学习plus真的觉得写代码真的越来越舒服了。昨天开始接触吧,只要学会了多表关联查询。plus就能随意搭配使用了。
关于怎么搭建的就自行了去研究了哦。这里直接进入主题。
我用的是springboot+mybatis-plus。新项目我打算以后都是这样了。
配置一个分页插件!
import org.mybatis.spring.annotation.MapperScan; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.Profile; import org.springframework.transaction.annotation.EnableTransactionManagement; import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor; import com.baomidou.mybatisplus.extension.plugins.PerformanceInterceptor; @EnableTransactionManagement @Configuration @MapperScan("com.szpdc.Dao")//输入你的dao层的包 public class MybatisPlusConfig { /** * 分页插件 */ @Bean public PaginationInterceptor paginationInterceptor() { return new PaginationInterceptor(); } /** * SQL执行效率插件 */ @Bean // @Profile({ "dev", "test" }) // 设置 dev test 环境开启 public PerformanceInterceptor performanceInterceptor() { return new PerformanceInterceptor(); } }
Controller
@RequestMapping("syscal") public Object syscal() { Page<Map<String, Object>> page=userService.selectListPage(1, 2); return page.getRecords(); }
Service
import java.util.Map; import com.baomidou.mybatisplus.extension.plugins.pagination.Page; public interface UserService { Page<Map<String,Object>> selectListPage(int current, int number); }
ServiceImpl
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import java.util.List; import java.util.Map; import org.springframework.stereotype.Service; import com.baomidou.mybatisplus.extension.plugins.pagination.Page; import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl; /** * * @Author By Yirs * @Date 2018-12-01 21:18:06 * @Description mybatis-plus 在服务层继承了ServiceImpl 就有了 UserMapper的 就少了以前的@Autowired 注入dao层 */ @Service public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService { @Override public Page<Map<String,Object>> selectListPage(int current, int number) { // 新建分页 Page<Map<String,Object>> page = new Page<Map<String,Object>>(current, number); // 返回分页结果 1为id return page.setRecords(this.baseMapper.dyGetUserList(page,1)); } }
Dao
import java.util.List; import java.util.Map; import org.apache.ibatis.annotations.Select; import com.baomidou.mybatisplus.core.mapper.BaseMapper; import com.baomidou.mybatisplus.extension.plugins.pagination.Page; /** * *@Author By Yirs *@Date 2018-12-01 22:27:13 */ public interface UserMapper extends BaseMapper<User> { /** * 为了区别plus原来的查询select*的字段 ,自定义为dy * @param 分页查询 * @return 多表关联查询 */ @Select("SELECT a.id,a.`name`,a.age,b.`describe` FROM USER a LEFT JOIN userinfo b ON a.id = b.user_id where a.id=#{id}") List<Map<String, Object>> dyGetUserList(Page<Map<String,Object>> page,Integer id); }
结果
Sql语句
需要就拿去当测试。
DROP TABLE IF EXISTS `user`; CREATE TABLE `user` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(255) CHARACTER SET utf8 DEFAULT NULL, `age` int(11) DEFAULT NULL, `email` varchar(255) CHARACTER SET utf8 DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of user -- ---------------------------- INSERT INTO `user` VALUES ('1', '谢谢', '18', '[email protected]'); INSERT INTO `user` VALUES ('2', '行政村v', '22', '[email protected]'); INSERT INTO `user` VALUES ('3', '查询啊', '60', '[email protected]'); INSERT INTO `user` VALUES ('4', '才表报错', '30', '32弟媳妇[email protected]'); INSERT INTO `user` VALUES ('5', 'asdasd', '22', 'sdfsad'); INSERT INTO `user` VALUES ('6', 'dsfds', '32', 'sdafsdf'); INSERT INTO `user` VALUES ('7', 'sdfxczv', '33', 'xcvbvchrwt'); INSERT INTO `user` VALUES ('8', 'dfsalkcxjv', '99', 'jklsdhcfvlkjsda'); INSERT INTO `user` VALUES ('9', 'jskdchvc,m', '34', 'dvclkjh'); -- ------------------------------ ------------------------------ ---------------------------- DROP TABLE IF EXISTS `userinfo`; CREATE TABLE `userinfo` ( `id` int(11) NOT NULL, `user_id` int(11) DEFAULT NULL, `describe` varchar(255) CHARACTER SET utf8 DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of userinfo -- ---------------------------- INSERT INTO `userinfo` VALUES ('1', '1', '用户1');
只要mybatis基础够好这个很好理解的