SpringBoot如何使用Scala进行开发的实现

Scala是一门多范式的编程语言，一种类似Java的编程语言，设计初衷是实现可伸缩的语言并集成面向对象编程。Scala把Erlang风格的基于actor的并发带进了JVM，开发者可以利用Scala的actor模型在JVM上设计具伸缩性的并发应用程序，它会自动获得多核心处理器带来的优势，而不必依照复杂的Java线程模型来编写程序，接下来就介绍一下如何在SpringBoot框架中使用Scala来进行简单的Web开发，对scala不了解的建议先去学习基础哦

一、导入依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>2.2.1.RELEASE</version>
  <relativePath/> <!-- lookup parent from repository -->
 </parent>
 <groupId>com.gjing.project</groupId>
 <artifactId>scala-demo</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <name>scala-demo</name>
 <description>Demo project for Spring Boot</description>

 <properties>
  <java.version>1.8</java.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-data-jpa</artifactId>
  </dependency>
  <dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
  </dependency>
  <!--加入Scala依赖库-->
  <dependency>
   <groupId>org.scala-lang</groupId>
   <artifactId>scala-library</artifactId>
   <version>2.13.1</version>
  </dependency>

  <dependency>
   <groupId>cn.gjing</groupId>
   <artifactId>tools-starter-swagger</artifactId>
   <version>1.3.0</version>
  </dependency>
  <dependency>
   <groupId>cn.gjing</groupId>
   <artifactId>tools-common</artifactId>
   <version>1.2.7</version>
  </dependency>
 </dependencies>

 <build>
  <plugins>
   <!--加入Scala的编译插件，否则无法进行编译-->
   <plugin>
    <groupId>org.scala-tools</groupId>
    <artifactId>maven-scala-plugin</artifactId>
    <version>2.15.2</version>
    <executions>
     <execution>
      <goals>
       <goal>compile</goal>
       <goal>testCompile</goal>
      </goals>
     </execution>
    </executions>
   </plugin>
   <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
   </plugin>
  </plugins>
 </build>

</project>

通过上面我们可以发现，和创建Java版本的SpringBoot项目没啥不同，只是引入了scala-library这个我们之前没引入的包，同时增加了对scala编译的插件

二、配置YML文件

server:
 port: 8080
spring:
 application:
 name: scala-demo
 datasource:
 driver-class-name: com.mysql.cj.jdbc.Driver
 url: jdbc:mysql://127.0.0.1:3306/demo?characterEncoding=utf8&useSSL=false
 username: root
 password: root
 type: com.zaxxer.hikari.HikariDataSource
 hikari:
  maximum-pool-size: 5
  minimum-idle: 1
  idle-timeout: 30000
  connection-timeout: 30000
 jpa:
 database: mysql
 hibernate:
  ddl-auto: update
 # 设置创表引擎为Innodb，不然默认为MyiSam
 database-platform: org.hibernate.dialect.MySQL5InnoDBDialect

swagger:
 base-package: com.gjing.project.scala.controller
 title: scala学习的demo

三、创建实体类

import javax.persistence._

import scala.beans.BeanProperty

/**
 * @author Gjing
 **/
@Entity
@Table(name = "scala_customer")
class Customer {

 @Id
 @GeneratedValue(strategy = GenerationType.IDENTITY)
 @BeanProperty
 var id:Integer = _

 @BeanProperty
 var customerName:String = _

 def this(customerName:String){
 this()
 this.customerName = customerName
 }

 override def toString: String = s"Customer($id,$customerName)"
}

这块和我们用java开发没啥不同，只是@BeanProperty注解会帮我们生成get和set

四、Repository层

import com.gjing.project.scala.entity.Customer
import org.springframework.data.jpa.repository.JpaRepository
import org.springframework.stereotype.Repository

/**
 * @author Gjing
 **/
@Repository
trait CustomerRepository extends JpaRepository[Customer, Integer] {
 /**
 * 通过用户名查询
 * @param name 用户名
 * @return Customer
 */
 def findByCustomerName(name:String) : Customer
}

这里和JAVA不同的是泛型采用的是[]中括号，这点要注意

五、Service层

import cn.gjing.tools.common.result.PageResult
import com.gjing.project.scala.entity.Customer
import com.gjing.project.scala.exceptions.MyServiceException
import com.gjing.project.scala.repository.CustomerRepository
import javax.annotation.Resource
import org.springframework.data.domain.Pageable
import org.springframework.stereotype.Service

/**
 * @author Gjing
 **/
@Service
class CustomerService @Resource()(customerRepository: CustomerRepository) {
 /**
 * 保存用户
 *
 * @param name 用户名
 */
 def saveCustomer(name: String): Unit = {
 var customer = customerRepository.findByCustomerName(name)
 if (customer != null) {
  throw MyServiceException("添加失败，用户已存在")
 }
 customer = new Customer(name)
 customerRepository.save(customer)
 }

 /**
 * 分页查询
 *
 * @param pageable 分页对象
 * @return
 */
 def pageCustomer(pageable: Pageable): PageResult[java.util.List[Customer]] = {
 val page = customerRepository.findAll(pageable)
 return PageResult.of(page.getContent, page.getTotalPages, page.getSize, page.getTotalElements, page.getNumber)
 }

 /**
 * 更新用户名
 * @param id 用户id
 * @param name 用户名
 */
 def updateCustomer(id: Integer, name: String): Unit = {
 val customer = customerRepository.findById(id).orElseThrow(() => MyServiceException("更新失败，用户不存在"))
 customer.setCustomerName(name)
 customerRepository.saveAndFlush(customer)
 }

 /**
 * 删除指定用户
 * @param id 用户id
 */
 def deleteCustomer(id:Integer): Unit = {
 val customer = customerRepository.findById(id).orElseThrow(() => MyServiceException("删除失败，用户不存在"))
 customerRepository.delete(customer)
 }
}

有意思的是，在scala中依赖注入是写在类名上的

六、Controller层

import cn.gjing.tools.common.annotation.NotEmpty
import cn.gjing.tools.common.result.PageResult
import com.gjing.project.scala.entity.Customer
import com.gjing.project.scala.service.CustomerService
import io.swagger.annotations.{Api, ApiImplicitParam, ApiImplicitParams, ApiOperation}
import javax.annotation.Resource
import org.springframework.data.domain.PageRequest
import org.springframework.http.ResponseEntity
import org.springframework.web.bind.annotation._

/**
 * @author Gjing
 **/
@RestController
@Api(tags = Array("用户的相关功能"))
class CustomerController @Resource()(customerService:CustomerService){
 @PostMapping(Array("/customer"))
 @ApiOperation("添加用户")
 @ApiImplicitParam(name = "customerName",value = "用户名",dataType = "String",required = true,paramType = "query")
 @NotEmpty
 def saveCustomer(customerName:String): ResponseEntity[String] ={
 customerService.saveCustomer(customerName)
 ResponseEntity.ok("添加成功")
 }

 @GetMapping(Array("/customer_page"))
 @ApiOperation("分页查询")
 @ApiImplicitParams(Array(
 new ApiImplicitParam(name = "page",value = "页数",required = true,dataType = "int",paramType = "query"),
 new ApiImplicitParam(name = "size",value = "条数",required = true,dataType = "int",paramType = "query"),
 ))
 def pageCustomer(page:Integer,size:Integer): ResponseEntity[PageResult[java.util.List[Customer]]]={
 ResponseEntity.ok(customerService.pageCustomer(PageRequest.of(page, size)))
 }

 @NotEmpty
 @PutMapping(Array("/customer"))
 @ApiOperation("更新用户")
 @ApiImplicitParams(Array(
 new ApiImplicitParam(name = "id",value = "用户ID",required = true,dataType = "int",paramType = "query"),
 new ApiImplicitParam(name = "name",value = "用户名",required = true,dataType = "String",paramType = "query")
 ))
 def updateCustomer(id:Integer,name:String): ResponseEntity[String] = {
 customerService.updateCustomer(id, name)
 ResponseEntity.ok("修改成功")
 }

 @DeleteMapping(Array("/customer/{id}"))
 @ApiOperation("删除用户")
 def deleteCustomer(id:Integer): ResponseEntity[String] = {
 customerService.deleteCustomer(id)
 ResponseEntity.ok("删除成功")
 }
}

这样我们一个简单的Scala版本的Web项目就写好啦，只需要启动就可以试着运行啦，本文的源代码地址：scala-demo，有任何不清楚的可以在评论区回复哈

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