SpringBoot集成MybatisPlus项目实操

hresh 547 0

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'

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>

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> {

}

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;
    }
}

3、请求体继承 MbpPage

@Getter
@Setter
public class TeacherQueryPageDTO extends MbpPage<Teacher> {

  private String name;
}

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);

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;
  }
}

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;
  }
}

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;
}

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@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);
}

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;
  }

}

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

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"
}

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}

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
}

如果是新增请求,返回结果为:

{
    "data": null,
    "code": "200",
    "message": "操作成功",
    "success": true
}

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));
  }

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
}

@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;
}

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();
  }

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
}

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);
    }
  }

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);
  }

执行效果如下:

SpringBoot集成MybatisPlus项目实操

分页查询

前端参数传递:

{
    "pageNum": 1,
    "pageSize": 5,
    "orders": [
        {
            "column": "name",
            "asc": false
        }
    ]
}

后端代码:

  public IPage<TeacherVO> queryPage(TeacherQueryPageDTO dto) {
    IPage<TeacherVO> teacherPage = this.lambdaQuery().page(dto)
        .convert(teacher -> teacherStruct.modelToVO(teacher));
    return teacherPage;
  }

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
}

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);
  }

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
}

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>

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>

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);
}

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);
}

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

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

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
}

Swagger

启动项目后,访问 swagger,页面展示如下:

SpringBoot集成MybatisPlus项目实操

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!

发表评论 取消回复
表情 图片 链接 代码

分享