51工具盒子如果一个人不知道他要驶向哪个码头，那么任何风都不会是顺风。------小塞涅卡
上回我们写到封装了axios的工具类
今天我把OSS上传文件接了，可以去项目目录自取
前端项目：https://gitee.com/VampireAchao/my-vue-app.git
后端项目：https://gitee.com/VampireAchao/simple-springboot.git
传统代码以点到为止，所以这里就不再多聊OSS，想了解可以看这篇博客
然后我们聊聊mybatis-plus的基本使用
首先引入依赖，这个没什么好说的
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| 1 2 3 4 5 | hljs xml <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.1.0</version> </dependency> |
然后我们按照之前创的表去对应新建一个DO
因为之前我们的表结构为这样【Tips：用的SQLite】【创建库表】【整合进项目】
所以我们的DO长这样
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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 | hljs java package com.ruben.pojo.dataObject;/** * @ClassName: UserDataObject * @Date: 2020/11/21 0021 15:55 * @Description: */ import com.baomidou.mybatisplus.annotation.TableField; import com.baomidou.mybatisplus.annotation.TableName; import com.ruben.pojo.UserInfo; import lombok.AllArgsConstructor; import lombok.Builder; import lombok.Data; import lombok.NoArgsConstructor; import java.io.Serializable; /** * @ClassName: UserDataObject * @Description: 我还没有写描述 * @Date: 2020/11/21 0021 15:55 * * * @author: <achao1441470436@gmail.com> * @version: 1.0 * @since: JDK 1.8 */ @Data @Builder @NoArgsConstructor @AllArgsConstructor @TableName("user") public class UserDataObject implements Serializable { private static final long serialVersionUID = -1891465370283313432L; private Integer id; private String username; private String password; @TableField(exist = false) private UserInfo userInfo; } |
注意，这里的@TableName是指定表名的意思
以及我们如果字段名称不对应的话需要使用@TableField注解，这个注解中，可以指定value为我们的表字段名；如果字段不存在与表中，可以指定exist=false
然后我们再新建一个mapper
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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 | hljs java package com.ruben.dao; import com.baomidou.mybatisplus.core.mapper.BaseMapper; import com.ruben.pojo.dataObject.UserDataObject; import org.apache.ibatis.annotations.Mapper; /** * @ClassName: MpUserMapper * @Date: 2020/11/21 0021 15:54 * @Description: */ @Mapper public interface MpUserMapper extends BaseMapper<UserDataObject> { } |
编写测试类测试
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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | hljs java package com.ruben;/** * @ClassName: MybatisPlusDemo * @Date: 2020/11/9 0009 20:51 * @Description: */ import com.baomidou.mybatisplus.core.conditions.Wrapper; import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper; import com.baomidou.mybatisplus.core.metadata.IPage; import com.baomidou.mybatisplus.core.toolkit.Wrappers; import com.baomidou.mybatisplus.extension.api.R; import com.baomidou.mybatisplus.extension.plugins.pagination.Page; import com.ruben.dao.MpUserMapper; import com.ruben.pojo.User; import com.ruben.pojo.dataObject.UserDataObject; import org.junit.jupiter.api.Test; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.context.annotation.DependsOn; import javax.annotation.Resource; import java.io.Serializable; import java.util.function.Function; /** * @ClassName: MybatisPlusDemo * @Description: 我还没有写描述 * @Date: 2020/11/9 0009 20:51 * * * @author: <achao1441470436@gmail.com> * @version: 1.0 * @since: JDK 1.8 */ @SpringBootTest public class MybatisPlusDemo { @Resource private MpUserMapper mpUserMapper; @Test public void test() { IPage<UserDataObject> page = mpUserMapper.selectPage(new Page<>(1, 2), Wrappers.lambdaQuery(UserDataObject.builder().build())); System.out.println(page); } } |
这里我没大意，顺便把springboot-test-starter的依赖放出来
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| 1 2 3 4 | hljs xml <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> |
我们运行后debug可以看到查询出来了我们想要的数据
我们再来一个
例如我们需要根据多个ID查询，并且 名字里有achao 或者 Achao
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| 1 2 3 4 5 6 7 8 9 10 11 | hljs java IPage<UserDataObject> page = mpUserMapper.selectPage(new Page<>(1, 2), Wrappers.lambdaQuery(UserDataObject.builder().build())); System.out.println(page); LambdaQueryWrapper<UserDataObject> wrapper = Wrappers.lambdaQuery(UserDataObject.builder().build()); // 取得用户ids List<Integer> userIds = page.getRecords().stream().map(UserDataObject::getId).collect(Collectors.toList()); // 根据ids用IN查询 wrapper.in(UserDataObject::getId, userIds) // 并且 .and(w -> w.like(UserDataObject::getUsername, "achao").or(wr -> wr.like(UserDataObject::getUsername, "Achao"))); page = mpUserMapper.selectPage(new Page<>(1, 2), wrapper); System.out.println(page); |
很容易就写好了，查询结果，但我们发现这里分页有问题，返回的total为0
我们需要写个mybatis-plus的配置类
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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | hljs java package com.ruben.config; import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor; import com.baomidou.mybatisplus.extension.plugins.pagination.optimize.JsqlParserCountOptimize; import org.mybatis.spring.annotation.MapperScan; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; /** * @ClassName: MybatisPlusConfig * @Description: 我还没有写描述 * @Date: 2020/11/21 0021 16:34 * * * @author: <achao1441470436@gmail.com> * @version: 1.0 * @since: JDK 1.8 */ @Configuration @MapperScan("com.ruben.dao.mapper*") public class MybatisPlusConfig { @Bean public PaginationInterceptor paginationInterceptor() { PaginationInterceptor paginationInterceptor = new PaginationInterceptor(); return paginationInterceptor; } } |
然后我们的分页问题就解决了
