《从零打造项目》系列文章
东西
- 比MyBatis Generator更强壮的代码生成器
ORM框架选型
- SpringBoot项目根底设施建立
- SpringBoot集成Mybatis项目实操
- SpringBoot集成Mybatis Plus项目实操
- SpringBoot集成Spring Data JPA项目实操
数据库改变办理
- 数据库改变办理：Liquibase or Flyway
- SpringBoot结合Liquibase完成数据库改变办理
守时使命框架
- Java守时使命技能分析
- SpringBoot结合Quartz完成守时使命
- SpringBoot结合XXL-JOB完成守时使命
缓存
- Spring Security结合Redis完成缓存功用
安全框架
- Java应用程序安全框架
- Spring Security系列文章
- Spring Security结合JWT完成认证与授权
开发标准
- 后端必知：遵循Google Java标准并引入checkstyle检查
前语
该说的在《SpringBoot集成Mybatis项目实操》一文中都讲了，本文仅仅将 Mybatis 换成了 Mybatis Plus，带咱们将整个项目跑起来。
本文将完成 SpringBoot+Mybatis Plus 的项目建立，Mybatis Plus 作为 Mybatis 的增强东西，功用更佳强壮，所以需求咱们自界说的代码就少了，完成起来也更加简略。
不说废话了，咱们直接进入主题。
数据库
本项目选用的是 MySQL 数据库，版本为 8.x，建表句子如下：
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'
建立SpringBoot项目
运用 IDEA 新建一个 Maven 项目，叫做 mybatisplus-springboot。
一些共用的根底代码能够参阅上篇文章，这儿不做重复介绍，会介绍一些 MybatisPlus 相关的代码。
引入依靠
<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>
有些依靠纷歧定是最新版本，并且你看到这篇文章时，可能已经发布了新版本，到时候能够先仿照着将项目跑起来后，再依据自己的需求来晋级各项依靠，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，此处选用的是 IPage 方式。具体操作步骤如下：
1、界说 Mapper
@Repository
public interface TeacherMapper extends BaseMapper<Teacher> {
}
2、自界说 IPage 的完成类
@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、恳求体承继 MbpPage
@Getter
@Setter
public class TeacherQueryPageDTO extends MbpPage<Teacher> {
private String name;
}
4、服务层的接口界说分页查询方法，其回来值类型是 IPage<实体类> 。
// 获取教师分页列表
IPage<TeacherVO> queryPage(TeacherQueryPageDTO dto);
5、服务的完成类要承继 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 的运用，除了上述这种用法，还有其他用法，能够参阅这篇文章。
咱们得到的分页查询成果是 IPage 目标，能够直接运用，也能够依据需求进行修正，比方下面这个文件：
@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;
/**
* 当时页码
*/
private Integer pageNum;
/**
* 分页数据
*/
private List<T> data;
/**
* 处理Mybatis Plus分页成果
*/
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根底实体类
作为其他实体类的父类，封装了所有的公共字段，包括逻辑删去标志，版本号，创立人和修正人信息。相较于 Mybatis 供给的根底实体类，咱们不需求自界说注解，MybatisPlus 供给的注解比较全面。
@Data
@Schema(title = "核心根底实体类")
@NoArgsConstructor
@AllArgsConstructor
@SuperBuilder(toBuilder = true)
public class CoreBase implements Serializable {
@TableId(value = "id", type = IdType.ASSIGN_ID)
@Schema(name = "")
private String id;
@Schema(description = "是否删去 0未删去（默认），1已删去")
@TableField(value = "del_flag")
@TableLogic(delval = "1", value = "0")
private Integer delFlag;
@Schema(description = "创立人")
@TableField(value = "create_user_code", fill = FieldFill.INSERT)
private String createUserCode;
@Schema(description = "创立人名称")
@TableField(value = "create_user_name", fill = FieldFill.INSERT)
private String createUserName;
@Schema(description = "创立时刻")
@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 = "修正人代码")
@TableField(value = "last_modified_code", fill = FieldFill.INSERT_UPDATE)
private String lastModifiedCode;
@Schema(description = "修正人名称")
@TableField(value = "last_modified_name", fill = FieldFill.INSERT_UPDATE)
private String lastModifiedName;
@Schema(description = "修正时刻")
@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;
}
关于主键生成战略，本项目选用的是 IdType.ASSIGN_ID，即雪花算法，关于其他生成战略，能够参阅MybatisPlus 主键战略（type=IdType.ASSIGN_ID等详解） 一文。
至于实体类中的一些注解，详细介绍推荐阅览MyBatisPlus–注解 和@TableLogic注解
MybatisPlus装备类
MetaObjectHandler是元目标字段填充控制器抽象类，完成公共字段主动写入。
比方通常，咱们在建表时，会设置几个公共字段：创立人（creator）、更新人（uptater）、创立时刻（create_time）、更新时刻（update_time）。
每次将实体目标新增入库时，都要设置创立人和创立时刻；每次更新实体目标时，都要设置更新人和更新时刻；
MetaObjectHandler 中主要供给了两个方法:
public interface MetaObjectHandler {
/**
* 刺进元目标字段填充（用于刺进时对公共字段的填充）
*
* @param metaObject 元目标
*/
void insertFill(MetaObject metaObject);
/**
* 更新元目标字段填充（用于更新时对公共字段的填充）
*
* @param metaObject 元目标
*/
void updateFill(MetaObject metaObject);
}
这些公共字段咱们都会封装在一个 Super Entity 类中,所以在这个类中,咱们把所有更新和刺进时需求做改动的字段都加上 @TableField 注解,并且设置 fill 特点。比方上面咱们界说的 CoreBase 类。
检查咱们自界说的完成类：
@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;
}
}
关于上述代码依据项目实践需求进行调整，来填充非关键数据。
最终在 resources 目录下创立META-INF目录下，在 META-INF 目录下创立 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，略微修正一下引证就好了。
功用完成
恳求日志输出
比方说咱们访问 /teachers/queryPage 接口，看看控制台输出状况：
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}
能够看到，日志输出中包含前端传来的恳求体，恳求 API，回来成果，API 描述，API 耗时。
统一回来格式
比方说分页查询，回来成果如下：
{
"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
}
假如是新增恳求，回来成果为：
{
"data": null,
"code": "200",
"message": "操作成功",
"success": true
}
此处 data 没有新增的数据，假如项目需求新增的实体信息，能够稍作修正。
异常处理
下面简略演示一下参数异常的状况，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));
}
假如传递的 name 值为空，则回来成果为：
{
"data": null,
"code": "400",
"message": "name 不能为空",
"success": false
}
@Validated分组校验
修正 TeacherDTO，当新增数据时，校验 name 不为空，修正数据时，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;
}
最终修正 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，成心将 name 置为空，回来成果为：
{
"data": null,
"code": "400",
"message": "name不能为空",
"success": false
}
填充公共字段
此处依靠于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正者信息，暂时是写死的状况，实践项目中，能够依据 token 信息进行解析，然后来填充新增者和修正者信息。
批量操作
这儿简略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);
}
履行作用如下：
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;
}
查询成果为：
{
"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 的晋级版，的确有不少优势，比方批量操作、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);
}
履行成果如下：
{
"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
比方说咱们界说的 User 和 Job 类，存在着一对多的联系，所以查询 User 信息时，还需求回来相关的 Job 数据。
关于 Mybatis 一对多、多对一处理手段，能够参阅我之前的文章。
本项目选用的是成果嵌套处理方式。
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="teacherResultMap2">
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 装备，假如服务层获取到回来成果后，不需求其他事务操作，能够直接获取 TeacherVO，但是这就要求咱们界说的 resultMap 是符合 VO 类而非 Model 类，不然那些主键 id、创立时刻等字段就无法处理了。反之，咱们需求查询得到 Teacher，处理完其他操作后，再转换为 TeacherVO。teacherVoResultMap 对应 TeacherVO 回来成果，teacherVoResultMap2 对应 Teacher 成果。咱们最终获取的是 UserVO，能够直接回来给前端。
对应的 UserMapper 文件
@Repository
public interface TeacherMapper extends BaseMapper<Teacher> {
List<Teacher> queryList(TeacherDTO dto);
}
咱们修正 UserService 中的查询方法如下：
public List<TeacherVO> queryList(TeacherDTO dto) {
List<Teacher> teachers = teacherMapper.queryList(dto);
return teacherStruct.modelToVO(teachers);
}
此刻 Teacher 实体类界说如下：
public class Teacher extends CoreBase {
private static final long serialVersionUID = 1L;
@TableField("name")
@Schema(name = "")
private String name;
@TableField("age")
@Schema(name = "")
private Integer age;
@TableField("address")
@Schema(name = "")
private String address;
// 数据库表中不存在的字段，需求疏忽掉
@TableField(exist = false)
private List<Student> students;
}
同时在 application.yml 文件中打开 SQL 输出装备：
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，能够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
回来成果为：
{
"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：
总结
不重复总结了，该说的在上篇文章结束已经说完了，本文便是把 Mybatis 换成 MybatisPlus，这两种框架本来就比较相似，部分代码是能够复用的，所以假如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。
那么咱们就期待下一篇，看看如何玩转 Spring Data JPA 。
感兴趣的朋友能够去我的 Github 下载相关代码，假如对你有所协助，不妨 Star 一下，谢谢咱们支撑！
