SpringBoot集成MybatisPlus项目实操
前言
该说的在《SpringBoot集成Mybatis项目实操》一文中都讲了,本文只是将 Mybatis 换成了 Mybatis Plus,带大家将整个项目跑起来。
本文将实现 SpringBoot+Mybatis Plus 的项目搭建,Mybatis Plus 作为 Mybatis 的增强工具,功能更佳强大,所以需要我们自定义的代码就少了,实现起来也更加简单。
不说废话了,我们直接进入主题。
数据库
本项目采用的是 MySQL 数据库,版本为 8.x,建表语句如下:
CREATE TABLE `teacher` ( `id` varchar(36) NOT NULL, `name` varchar(20) DEFAULT NULL, `age` int(11) DEFAULT NULL, `address` varchar(100) DEFAULT NULL, `created_date` timestamp NULL DEFAULT NULL, `last_modified_date` timestamp NULL DEFAULT NULL, `del_flag` int(2) NOT NULL DEFAULT '0', `create_user_code` varchar(36) DEFAULT NULL, `create_user_name` varchar(50) DEFAULT NULL, `last_modified_code` varchar(36) DEFAULT NULL, `last_modified_name` varchar(50) DEFAULT NULL, `version` int(11) NOT NULL DEFAULT '1', PRIMARY KEY (`id`), UNIQUE KEY `uk_name` (`name`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='教师' CREATE TABLE `student` ( `id` varchar(36) NOT NULL, `name` varchar(20) DEFAULT NULL, `teacher_id` varchar(36) NOT NULL, `address` varchar(100) DEFAULT NULL, `created_date` timestamp NULL DEFAULT NULL, `last_modified_date` timestamp NULL DEFAULT NULL, `del_flag` int(2) NOT NULL DEFAULT '0', `create_user_code` varchar(30) DEFAULT NULL, `create_user_name` varchar(50) DEFAULT NULL, `last_modified_code` varchar(30) DEFAULT NULL, `last_modified_name` varchar(50) DEFAULT NULL, `version` int(11) NOT NULL DEFAULT '1', PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='学生' 复制代码
搭建SpringBoot项目
使用 IDEA 新建一个 Maven 项目,叫做 mybatisplus-springboot。
一些共用的基础代码可以参考上篇文章,这里不做重复介绍,会介绍一些 MybatisPlus 相关的代码。
引入依赖
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.6.3</version> </parent> <properties> <java.version>1.8</java.version> <fastjson.version>1.2.73</fastjson.version> <hutool.version>5.5.1</hutool.version> <mysql.version>8.0.19</mysql.version> <mybatis.version>2.1.4</mybatis.version> <mapper.version>4.1.5</mapper.version> <org.mapstruct.version>1.4.2.Final</org.mapstruct.version> <org.projectlombok.version>1.18.20</org.projectlombok.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-validation</artifactId> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>${fastjson.version}</version> </dependency> <dependency> <groupId>cn.hutool</groupId> <artifactId>hutool-all</artifactId> <version>${hutool.version}</version> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>${org.projectlombok.version}</version> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>${mysql.version}</version> <scope>runtime</scope> </dependency> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.5.1</version> </dependency> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus</artifactId> <version>3.5.1</version> </dependency> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-commons</artifactId> <version>2.4.6</version> </dependency> <dependency> <groupId>org.springdoc</groupId> <artifactId>springdoc-openapi-ui</artifactId> <version>1.6.9</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.18</version> </dependency> <dependency> <groupId>org.mapstruct</groupId> <artifactId>mapstruct</artifactId> <version>${org.mapstruct.version}</version> </dependency> <dependency> <groupId>org.mapstruct</groupId> <artifactId>mapstruct-processor</artifactId> <version>${org.mapstruct.version}</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> 复制代码
有些依赖不一定是最新版本,而且你看到这篇文章时,可能已经发布了新版本,到时候可以先模仿着将项目跑起来后,再根据自己的需求来升级各项依赖,有问题咱再解决问题。
分页处理
MybatisPlus关于分页处理有好几种方式,此处采用的是 IPage 方式。具体操作步骤如下:
1、定义 Mapper
@Repository public interface TeacherMapper extends BaseMapper<Teacher> { } 复制代码
2、自定义 IPage 的实现类
@Data public class MbpPage<T> implements IPage<T> { private List<T> records; private long total; private long pageSize; private long pageNum; private List<OrderItem> orders; private boolean optimizeCountSql; private boolean isSearchCount; private boolean hitCount; public MbpPage() { this.records = Collections.emptyList(); this.total = 0L; this.pageSize = 10L; this.pageNum = 1L; this.orders = new ArrayList(); this.optimizeCountSql = true; this.isSearchCount = true; this.hitCount = false; } public MbpPage(long pageNum, long pageSize) { this(pageNum, pageSize, 0L); } public MbpPage(long pageNum, long pageSize, long total) { this(pageNum, pageSize, total, true); } public MbpPage(long pageNum, long pageSize, boolean isSearchCount) { this(pageNum, pageSize, 0L, isSearchCount); } public MbpPage(long pageNum, long pageSize, long total, boolean isSearchCount) { this.records = Collections.emptyList(); this.total = 0L; this.pageSize = 10L; this.pageNum = 1L; this.orders = new ArrayList(); this.optimizeCountSql = true; this.isSearchCount = true; this.hitCount = false; if (pageNum > 1L) { this.pageNum = pageNum; } this.pageSize = pageSize; this.total = total; this.isSearchCount = isSearchCount; } public boolean hasPrevious() { return this.pageNum > 1L; } public boolean hasNext() { return this.pageNum < this.getPages(); } @Override public List<T> getRecords() { return this.records; } @Override public MbpPage<T> setRecords(List<T> records) { this.records = records; return this; } @Override public long getTotal() { return this.total; } @Override public MbpPage<T> setTotal(long total) { this.total = total; return this; } @Override public long getSize() { return this.pageSize; } @Override public MbpPage<T> setSize(long pageSize) { this.pageSize = pageSize; return this; } @Override public long getCurrent() { return this.pageNum; } @Override public MbpPage<T> setCurrent(long current) { this.pageNum = current; return this; } @Override public List<OrderItem> orders() { return this.getOrders(); } public List<OrderItem> getOrders() { return this.orders; } public void setOrders(List<OrderItem> orders) { this.orders = orders; } } 复制代码
3、请求体继承 MbpPage
@Getter @Setter public class TeacherQueryPageDTO extends MbpPage<Teacher> { private String name; } 复制代码
4、服务层的接口定义分页查询方法,其返回值类型是 IPage<实体类> 。
// 获取教师分页列表 IPage<TeacherVO> queryPage(TeacherQueryPageDTO dto); 复制代码
5、服务的实现类要继承 ServiceImpl< Mapper接口类,实体类 > ,重写分页查询方法。
@Service @RequiredArgsConstructor public class TeacherServiceImpl extends ServiceImpl<TeacherMapper, Teacher> implements TeacherService { private final TeacherStruct teacherStruct; @Override public IPage<TeacherVO> queryPage(TeacherQueryPageDTO dto) { IPage<TeacherVO> teacherPage = this.lambdaQuery().page(dto) .convert(teacher -> teacherStruct.modelToVO(teacher)); return teacherPage; } } 复制代码
关于 IPage 的使用,除了上述这种用法,还有别的用法,可以参考这篇文章。
我们得到的分页查询结果是 IPage 对象,可以直接使用,也可以根据需要进行修改,比如下面这个文件:
@Getter @Setter public class PageResult<T> { /** * 总条数 */ private Long total; /** * 总页数 */ private Integer pageCount; /** * 每页数量 */ private Integer pageSize; /** * 当前页码 */ private Integer pageNum; /** * 分页数据 */ private List<T> data; /** * 处理Mybatis Plus分页结果 */ public static <T> PageResult<T> ok(IPage<T> iPage) { PageResult<T> result = new PageResult<T>(); result.setTotal(iPage.getTotal()); int pageCount = (int) Math.ceil((double) result.getTotal() / iPage.getSize()); result.setPageCount(pageCount); result.setPageNum((int) iPage.getCurrent()); result.setPageSize((int) iPage.getSize()); result.setData(iPage.getRecords()); return result; } } 复制代码
MybatisPlus基础实体类
作为其他实体类的父类,封装了所有的公共字段,包括逻辑删除标志,版本号,创建人和修改人信息。相较于 Mybatis 提供的基础实体类,我们不需要自定义注解,MybatisPlus 提供的注解比较全面。
@Data @Schema(title = "核心基础实体类") @NoArgsConstructor @AllArgsConstructor @SuperBuilder(toBuilder = true) public class CoreBase implements Serializable { @TableId(value = "id", type = IdType.ASSIGN_ID) @Schema(name = "") private String id; @Schema(description = "是否删除 0未删除(默认),1已删除") @TableField(value = "del_flag") @TableLogic(delval = "1", value = "0") private Integer delFlag; @Schema(description = "创建人") @TableField(value = "create_user_code", fill = FieldFill.INSERT) private String createUserCode; @Schema(description = "创建人名称") @TableField(value = "create_user_name", fill = FieldFill.INSERT) private String createUserName; @Schema(description = "创建时间") @TableField(value = "created_date", fill = FieldFill.INSERT) @DateTimeFormat( pattern = "yyyy-MM-dd HH:mm:ss" ) @JsonFormat( pattern = "yyyy-MM-dd HH:mm:ss" ) private LocalDateTime createdDate; @Schema(description = "修改人代码") @TableField(value = "last_modified_code", fill = FieldFill.INSERT_UPDATE) private String lastModifiedCode; @Schema(description = "修改人名称") @TableField(value = "last_modified_name", fill = FieldFill.INSERT_UPDATE) private String lastModifiedName; @Schema(description = "修改时间") @TableField(value = "last_modified_date", fill = FieldFill.INSERT_UPDATE) @DateTimeFormat( pattern = "yyyy-MM-dd HH:mm:ss" ) @JsonFormat( pattern = "yyyy-MM-dd HH:mm:ss" ) private LocalDateTime lastModifiedDate; @Schema(description = "版本号") @Version @TableField(value = "version") private String version; } 复制代码
关于主键生成策略,本项目采用的是 IdType.ASSIGN_ID,即雪花算法,关于其他生成策略,可以参考MybatisPlus 主键策略(type=IdType.ASSIGN_ID等详解) 一文。
至于实体类中的一些注解,详细介绍推荐阅读MyBatisPlus--注解 和@TableLogic注解
MybatisPlus配置类
MetaObjectHandler是元对象字段填充控制器抽象类,实现公共字段自动写入。
比如通常,我们在建表时,会设置几个公共字段:创建人(creator)、更新人(uptater)、创建时间(create_time)、更新时间(update_time)。
每次将实体对象新增入库时,都要设置创建人和创建时间;每次更新实体对象时,都要设置更新人和更新时间;
MetaObjectHandler
中主要提供了两个方法:
public interface MetaObjectHandler { /** * 插入元对象字段填充(用于插入时对公共字段的填充) * * @param metaObject 元对象 */ void insertFill(MetaObject metaObject); /** * 更新元对象字段填充(用于更新时对公共字段的填充) * * @param metaObject 元对象 */ void updateFill(MetaObject metaObject); } 复制代码
这些公共字段我们都会封装在一个 Super Entity
类中,所以在这个类中,我们把所有更新和插入时需要做改动的字段都加上 @TableField
注解,并且设置 fill
属性。比如上面我们定义的 CoreBase 类。
查看我们自定义的实现类:
@ConditionalOnBean({com.baomidou.mybatisplus.autoconfigure.MybatisPlusAutoConfiguration.class}) public class MybatisPlusAutoConfiguration { @Bean public MetaObjectHandler metaObjectHandler() { return new FillFieldConfiguration(); } public static class FillFieldConfiguration implements MetaObjectHandler { @Override public void insertFill(MetaObject metaObject) { LocalDateTime now = DateUtil.toLocalDateTime(new Date()); metaObject.setValue("createUserCode", "1"); metaObject.setValue("createUserName", "admin"); metaObject.setValue("createdDate", now); metaObject.setValue("lastModifiedCode", "1"); metaObject.setValue("lastModifiedName", "admin"); metaObject.setValue("lastModifiedDate", now); } @Override public void updateFill(MetaObject metaObject) { DateTime now = DateUtil.date(); metaObject.setValue("lastModifiedCode", "1"); metaObject.setValue("lastModifiedName", "admin"); metaObject.setValue("lastModifiedDate", now); } } /** * 分页插件 * * @return */ @Bean public MybatisPlusInterceptor mybatisPlusInterceptor() { MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor(); mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL)); return mybatisPlusInterceptor; } } 复制代码
关于上述代码根据项目实际需求进行调整,来填充非关键数据。
最后在 resources 目录下创建META-INF目录下,在 META-INF 目录下创建 spring.factories 文件,文件内容如下:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ com.msdn.orm.hresh.common.mybatisPlus.config.MybatisPlusAutoConfiguration 复制代码
一键式生成模版代码
运行 orm-generate 项目,在 swagger 上调用 /build 接口,调用参数如下:
{ "database": "mysql_db", "flat": true, "type": "mybatisplus", "group": "hresh", "host": "127.0.0.1", "module": "orm", "password": "root", "port": 3306, "table": [ "teacher", "student" ], "username": "root", "tableStartIndex":"0" } 复制代码
代码文件直接移到项目中就行了,稍微修改一下引用就好了。
功能实现
请求日志输出
比如说我们访问 /teachers/queryPage 接口,看看控制台输出情况:
Request Info : {"classMethod":"com.msdn.orm.hresh.controller.TeacherController.queryPage","ip":"127.0.0.1","requestParams":{"dto":{"hitCount":false,"optimizeCountSql":true,"records":[{"name":"hresh2","age":46},{"name":"hresh1","age":46},{"name":"hresh0","age":46},{"address":"湖北大学","name":"hresh","age":44},{"address":"武汉大学","name":"acorn2","age":46}],"pageSize":5,"pageNum":1,"total":7,"orders":[{"column":"name","asc":false}],"isSearchCount":true}},"httpMethod":"GET","url":"http://localhost:8802/teachers/queryPage","result":{"code":"200","message":"操作成功","success":true},"methodDesc":"获取教师分页列表","timeCost":93} 复制代码
可以看到,日志输出中包含前端传来的请求体,请求 API,返回结果,API 描述,API 耗时。
统一返回格式
比如说分页查询,返回结果如下:
{ "data": { "total": 7, "pageCount": 2, "pageSize": 5, "pageNum": 1, "data": [ { "name": "hresh2", "age": 46, "address": null }, { "name": "hresh1", "age": 46, "address": null }, { "name": "hresh0", "age": 46, "address": null }, { "name": "hresh", "age": 44, "address": "湖北大学" }, { "name": "acorn2", "age": 46, "address": "武汉大学" } ] }, "code": "200", "message": "操作成功", "success": true } 复制代码
如果是新增请求,返回结果为:
{ "data": null, "code": "200", "message": "操作成功", "success": true } 复制代码
此处 data 没有新增的数据,如果项目需要新增的实体信息,可以稍作修改。
异常处理
下面简单演示一下参数异常的情况,在 add user 时校验参数值是否为空。
public Boolean add(TeacherDTO dto) { if (StringUtils.isBlank(dto.getName())) { BusinessException.validateFailed("name 不能为空"); } return this.save(teacherStruct.dtoToModel(dto)); } 复制代码
如果传递的 name 值为空,则返回结果为:
{ "data": null, "code": "400", "message": "name 不能为空", "success": false } 复制代码
@Validated分组校验
修改 TeacherDTO,当新增数据时,校验 name 不为空,修改数据时,address 不为空。
@Getter @Setter @AllArgsConstructor @NoArgsConstructor public class TeacherDTO { @Schema(name = "") @NotBlank(groups = {Add.class}) private String name; @Schema(name = "") private Integer age; @Schema(name = "") @NotBlank(groups = {Edit.class}) private String address; } 复制代码
最后修改 controller 文件
@PostMapping @Operation(description = "新增教师") public Result add(@Validated(Add.class) @RequestBody TeacherDTO dto) { boolean flag = teacherService.add(dto); if (!flag) { return Result.failed(); } return Result.ok(); } 复制代码
调用新增接口,故意将 name 置为空,返回结果为:
{ "data": null, "code": "400", "message": "name不能为空", "success": false } 复制代码
填充公共字段
此处依赖于MetaObjectHandler,重点在 MybatisPlusAutoConfiguration 文件。
public static class FillFieldConfiguration implements MetaObjectHandler { @Override public void insertFill(MetaObject metaObject) { LocalDateTime now = DateUtil.toLocalDateTime(new Date()); metaObject.setValue("createUserCode", "1"); metaObject.setValue("createUserName", "admin"); metaObject.setValue("createdDate", now); metaObject.setValue("lastModifiedCode", "1"); metaObject.setValue("lastModifiedName", "admin"); metaObject.setValue("lastModifiedDate", now); } @Override public void updateFill(MetaObject metaObject) { DateTime now = DateUtil.date(); metaObject.setValue("lastModifiedCode", "1"); metaObject.setValue("lastModifiedName", "admin"); metaObject.setValue("lastModifiedDate", now); } } 复制代码
上述代码中关于新增者信息和修改者信息,暂时是写死的状态,实际项目中,可以根据 token 信息进行解析,然后来填充新增者和修改者信息。
批量操作
这里简单演示一下关于批量新增的代码
@Override public Boolean batchAdd(TeacherDTO dto) { List<Teacher> teachers = new ArrayList<>(); for (int i = 0; i < 3; i++) { Teacher teacher = Teacher.builder().name(dto.getName() + i).age(46).address(dto.getAddress()) .build(); teachers.add(teacher); } return this.saveBatch(teachers); } 复制代码
执行效果如下:
分页查询
前端参数传递:
{ "pageNum": 1, "pageSize": 5, "orders": [ { "column": "name", "asc": false } ] } 复制代码
后端代码:
public IPage<TeacherVO> queryPage(TeacherQueryPageDTO dto) { IPage<TeacherVO> teacherPage = this.lambdaQuery().page(dto) .convert(teacher -> teacherStruct.modelToVO(teacher)); return teacherPage; } 复制代码
查询结果为:
{ "data": { "total": 7, "pageCount": 2, "pageSize": 5, "pageNum": 1, "data": [ { "name": "hresh2", "age": 46, "address": "华中", "studentVOS": null }, { "name": "hresh1", "age": 46, "address": "华师", "studentVOS": null }, { "name": "hresh0", "age": 46, "address": "华科", "studentVOS": null }, { "name": "hresh", "age": 44, "address": "湖北大学", "studentVOS": null }, { "name": "acorn2", "age": 46, "address": "武汉大学", "studentVOS": null } ] }, "code": "200", "message": "操作成功", "success": true } 复制代码
动态查询
MybatisPlus 作为 Mybatis 的升级版,确实有不少优势,比如批量操作、动态查询等。
查询方法如下:
public List<TeacherVO> queryList(TeacherDTO dto) { List<Teacher> teachers = this.lambdaQuery().like(Teacher::getName, dto.getName()) .orderByDesc(Teacher::getName).list(); return teacherStruct.modelToVO(teachers); } 复制代码
执行结果如下:
{ "data": [ { "name": "hresh2", "age": 46, "address": null }, { "name": "hresh1", "age": 46, "address": null }, { "name": "hresh0", "age": 46, "address": null }, { "name": "hresh", "age": 44, "address": "湖北大学" } ], "code": "200", "message": "操作成功", "success": true } 复制代码
一对多查询
比如说我们定义的 User 和 Job 类,存在着一对多的关系,所以查询 User 信息时,还需要返回关联的 Job 数据。
关于 Mybatis 一对多、多对一处理手段,可以参考我之前的文章。
本项目采用的是结果嵌套处理方式。
StudentMapper.xml 内容如下:
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.msdn.orm.hresh.mapper.StudentMapper"> <resultMap id="studentResultMap" type="com.msdn.orm.hresh.model.Student"> <id column="id" property="id"/> <result column="name" property="name"/> <result column="teacher_id" property="teacherId"/> <result column="address" property="address"/> <result column="created_date" property="createdDate"/> <result column="last_modified_date" property="lastModifiedDate"/> <result column="del_flag" property="delFlag"/> <result column="create_user_code" property="createUserCode"/> <result column="create_user_name" property="createUserName"/> <result column="last_modified_code" property="lastModifiedCode"/> <result column="last_modified_name" property="lastModifiedName"/> <result column="version" property="version"/> </resultMap> </mapper> 复制代码
TeacherMapper.xml 文件
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.msdn.orm.hresh.mapper.TeacherMapper"> <resultMap id="teacherResultMap" type="com.msdn.orm.hresh.model.Teacher"> <id column="id" property="id"/> <result column="name" property="name"/> <result column="age" property="age"/> <result column="address" property="address"/> <result column="created_date" property="createdDate"/> <result column="last_modified_date" property="lastModifiedDate"/> <result column="del_flag" property="delFlag"/> <result column="create_user_code" property="createUserCode"/> <result column="create_user_name" property="createUserName"/> <result column="last_modified_code" property="lastModifiedCode"/> <result column="last_modified_name" property="lastModifiedName"/> <result column="version" property="version"/> </resultMap> <resultMap id="teacherResultMap2" type="com.msdn.orm.hresh.model.Teacher" extends="com.msdn.orm.hresh.mapper.TeacherMapper.teacherResultMap"> <collection property="students" resultMap="com.msdn.orm.hresh.mapper.StudentMapper.studentResultMap" columnPrefix="st_"/> </resultMap> <resultMap id="teacherVoResultMap" type="com.msdn.orm.hresh.vo.TeacherVO" extends="com.msdn.orm.hresh.mapper.TeacherMapper.teacherResultMap"> <collection property="studentVOS" resultMap="com.msdn.orm.hresh.mapper.StudentMapper.studentResultMap" columnPrefix="st_"/> </resultMap> <select id="queryList" resultMap="teacherVoResultMap"> SELECT t.*, st.name st_name, st.address st_address FROM teacher t LEFT JOIN student st ON t.id = st.teacher_id <where> <if test="name!=null and name!=''"> and t.name like concat('%',#{name},'%') </if> <if test="address != null and address !=''"> and t.address like concat('%',#{address},'%') </if> </where> </select> </mapper> 复制代码
关于上述 xml 配置,如果服务层获取到返回结果后,不需要其他业务操作,可以直接获取 UserVO,反之,我们需要查询得到 User,处理完其他操作后,再转换为 UserVO。userVoResultMap 对应 UserVO 返回结果,userResultMap2 对应 User 结果。我们最终获取的是 UserVO,可以直接返回给前端。
对应的 UserMapper 文件
@Repository public interface TeacherMapper extends BaseMapper<Teacher> { List<TeacherVO> queryList(TeacherDTO dto); } 复制代码
我们修改 UserService 中的查询方法如下:
public List<TeacherVO> queryList(TeacherDTO dto) { return teacherMapper.queryList(dto); // List<Teacher> teachers = teacherMapper.queryList(dto); // return teacherStruct.modelToVO(teachers); } 复制代码
同时在 application.yml 文件中打开 SQL 输出配置:
mybatis-plus: mapper-locations: classpath:mapper/*Mapper.xml configuration: log-impl: org.apache.ibatis.logging.stdout.StdOutImpl type-aliases-package: com.msdn.orm.hresh.model 复制代码
调用接口,可以发现控制台输出如下:
==> Preparing: SELECT t.*, st.name st_name, st.address st_address FROM teacher t LEFT JOIN student st ON t.id = st.teacher_id WHERE t.name like concat('%',?,'%') ==> Parameters: hresh(String) <== Columns: id, name, age, address, created_date, last_modified_date, del_flag, create_user_code, create_user_name, last_modified_code, last_modified_name, version, st_name, st_address <== Row: 1572579347365912577, hresh0, 46, 华科, 2022-09-21 21:31:48, 2022-09-21 21:31:48, 0, 1, admin, 1, admin, 1, 小明, 襄阳四中 <== Row: 1572579347365912577, hresh0, 46, 华科, 2022-09-21 21:31:48, 2022-09-21 21:31:48, 0, 1, admin, 1, admin, 1, 小军, 襄阳四中 <== Row: 1572579347877617665, hresh1, 46, 华师, 2022-09-21 21:31:48, 2022-09-21 21:31:48, 0, 1, admin, 1, admin, 1, 小红, 襄阳五中 <== Row: 1572579347877617665, hresh1, 46, 华师, 2022-09-21 21:31:48, 2022-09-21 21:31:48, 0, 1, admin, 1, admin, 1, 小杰, 襄阳五中 <== Row: 1572578485562318850, hresh, 44, 湖北大学, 2022-09-21 21:28:23, 2022-09-21 21:28:23, 0, 1, admin, 1, admin, 1, null, null <== Row: 1572579347881811969, hresh2, 46, 华中, 2022-09-21 21:31:48, 2022-09-21 21:31:48, 0, 1, admin, 1, admin, 1, null, null <== Total: 6 复制代码
返回结果为:
{ "data": [ { "name": "hresh0", "age": 46, "address": "华科", "studentVOS": [ { "name": "小明", "teacherId": null, "address": "襄阳四中" }, { "name": "小军", "teacherId": null, "address": "襄阳四中" } ] }, { "name": "hresh1", "age": 46, "address": "华师", "studentVOS": [ { "name": "小红", "teacherId": null, "address": "襄阳五中" }, { "name": "小杰", "teacherId": null, "address": "襄阳五中" } ] }, { "name": "hresh", "age": 44, "address": "湖北大学", "studentVOS": [] }, { "name": "hresh2", "age": 46, "address": "华中", "studentVOS": [] } ], "code": "200", "message": "操作成功", "success": true } 复制代码
Swagger
启动项目后,访问 swagger,页面展示如下:
总结
不重复总结了,该说的在上篇文章结尾已经说完了,本文就是把 Mybatis 换成 MybatisPlus,这两种框架本来就比较类似,部分代码是可以复用的,所以如果你完全掌握了上篇文章中提及的知识点,学习本篇内容就比较轻松了。
那么我们就期待下一篇,看看如何玩转 Spring Data JPA 。
感兴趣的朋友可以去我的 Github 下载相关代码,如果对你有所帮助,不妨 Star 一下,谢谢大家支持!
作者:hresh
链接:https://juejin.cn/post/7168731998549671967