SpringBoot整合Kotlin构建Web服务

今天我们尝试Spring Boot整合Kotlin，并决定建立一个非常简单的Spring Boot微服务，使用Kotlin作为编程语言进行编码构建。

创建一个简单的Spring Boot应用程序。我会在这里使用maven构建项目：

    4.0.0

    com.edurt.ski
    springboot-kotlin-integration
    1.0.0
    jar

    springboot kotlin integration
    SpringBoot Kotlin Integration is a open source springboot, kotlin integration example.

    
        org.springframework.boot
        spring-boot-starter-parent
        2.1.3.RELEASE
         
    

    
        UTF-8
        UTF-8
        1.8
        
        1.2.71
    

    
        
        
            org.springframework.boot
            spring-boot-starter-web
        
        
        
            com.fasterxml.jackson.module
            jackson-module-kotlin
        
        
            org.jetbrains.kotlin
            kotlin-stdlib-jdk8
        
        
            org.jetbrains.kotlin
            kotlin-reflect
        
    

    
        ${project.basedir}/src/main/kotlin
        ${project.basedir}/src/test/kotlin
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
            
                kotlin-maven-plugin
                org.jetbrains.kotlin
                
                    
                        -Xjsr305=strict
                    
                    
                        spring
                        jpa
                        all-open
                    
                    
                        all-open:annotation=javax.persistence.Entity
                    
                
                
                    
                        org.jetbrains.kotlin
                        kotlin-maven-allopen
                        ${plugin.maven.kotlin.version}
                    
                    
                        org.jetbrains.kotlin
                        kotlin-maven-noarg
                        ${plugin.maven.kotlin.version}
                    
                
                
                    
                        kapt
                        
                            kapt
                        
                        
                            
                                src/main/kotlin
                            
                            
                                
                                    org.springframework.boot
                                    spring-boot-configuration-processor
                                    ${project.parent.version}
                                
                            
                        
                    
                
            
        
    

添加所有必需的依赖项：

• kotlin-stdlib-jdk8 kotlin jdk8的lib包
• kotlin-reflect kotlin反射包

一个简单的应用类：

package com.edurt.ski

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication

@SpringBootApplication
class SpringBootKotlinIntegration

fun main(args: Array) {
    runApplication(*args)
}

添加Rest API接口功能

---

创建一个HelloController Rest API接口,我们只提供一个简单的get请求获取hello,kotlin输出信息:

package com.edurt.ski.controller

import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RestController

@RestController
class HelloController {

    @GetMapping(value = "hello")
    fun hello(): String {
        return "hello,kotlin"
    }

}

修改SpringBootKotlinIntegration文件增加以下设置扫描路径

@ComponentScan(value = [
    "com.edurt.ski",
    "com.edurt.ski.controller"
])

添加页面功能

---

• 修改pom.xml文件增加以下页面依赖

    org.springframework.boot
    spring-boot-starter-mustache

• 在src/main/resources路径下创建templates文件夹
• 在templates文件夹下创建一个名为hello.mustache的页面文件

Hello, Kotlin

• 创建页面转换器HelloView

package com.edurt.ski.view

import org.springframework.stereotype.Controller
import org.springframework.ui.Model
import org.springframework.web.bind.annotation.GetMapping

@Controller
class HelloView {

    @GetMapping(value = "hello_view")
    fun helloView(model: Model): String {
        return "hello"
    }

}

• 浏览器访问http://localhost:8080/hello_view即可看到页面内容

添加数据持久化功能

---

• 修改pom.xml文件增加以下依赖(由于测试功能我们使用h2内存数据库)

    org.springframework.boot
    spring-boot-starter-data-jpa


    com.h2database
    h2
    runtime

• 创建User实体

package com.edurt.ski.model

import javax.persistence.Entity
import javax.persistence.GeneratedValue
import javax.persistence.Id

@Entity
//class UserModel(
//        @Id
//        @GeneratedValue
//        private var id: Long? = 0,
//        private var name: String
//)
class UserModel {

        @Id
        @GeneratedValue
        var id: Long? = 0
                get() = field
                set

        var name: String? = null
                get() = field
                set

}

• 创建UserSupport dao数据库操作工具类

package com.edurt.ski.support

import com.edurt.ski.model.UserModel
import org.springframework.data.repository.PagingAndSortingRepository

interface UserSupport : PagingAndSortingRepository {

}

• 创建UserService服务类

package com.edurt.ski.service

import com.edurt.ski.model.UserModel

interface UserService {

    /**
     * save model to db
     */
    fun save(model: UserModel): UserModel

}

• 创建UserServiceImpl实现类

package com.edurt.ski.service

import com.edurt.ski.model.UserModel
import com.edurt.ski.support.UserSupport
import org.springframework.stereotype.Service

@Service(value = "userService")
class UserServiceImpl(private val userSupport: UserSupport) : UserService {

    override fun save(model: UserModel): UserModel {
        return this.userSupport.save(model)
    }

}

• 创建用户UserController进行持久化数据

package com.edurt.ski.controller

import com.edurt.ski.model.UserModel
import com.edurt.ski.service.UserService
import org.springframework.web.bind.annotation.PathVariable
import org.springframework.web.bind.annotation.PostMapping
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RestController

@RestController
@RequestMapping(value = "user")
class UserController(private val userService: UserService) {

    @PostMapping(value = "save/{name}")
    fun save(@PathVariable name: String): UserModel {
        val userModel = UserModel()
//        userModel.id = 1
        userModel.name = name
        return this.userService.save(userModel)
    }

}

• 使用控制台窗口执行以下命令保存数据

curl -X POST http://localhost:8080/user/save/qianmoQ

收到返回结果

{"id":1,"name":"qianmoQ"}

表示数据保存成功

增加数据读取渲染功能

---

• 修改UserService增加以下代码

/**
 * get all model
 */
fun getAll(page: Pageable): Page

• 修改UserServiceImpl增加以下代码

override fun getAll(page: Pageable): Page {
    return this.userSupport.findAll(page)
}

• 修改UserController增加以下代码

@GetMapping(value = "list")
fun get(): Page = this.userService.getAll(PageRequest(0, 10))

• 创建UserView文件渲染User数据

package com.edurt.ski.view

import com.edurt.ski.service.UserService
import org.springframework.data.domain.PageRequest
import org.springframework.stereotype.Controller
import org.springframework.ui.Model
import org.springframework.ui.set
import org.springframework.web.bind.annotation.GetMapping

@Controller
class UserView(private val userService: UserService) {

    @GetMapping(value = "user_view")
    fun helloView(model: Model): String {
        model["users"] = this.userService.getAll(PageRequest(0, 10))
        return "user"
    }

}

• 创建user.mustache文件渲染数据(自行解析返回数据即可)

{{users}}

• 浏览器访问http://localhost:8080/user_view即可看到页面内容

增加单元功能

---

• 修改pom.xml文件增加以下依赖

    org.springframework.boot
    spring-boot-starter-test
    test
    
        
            junit
            junit
        
        
            org.mockito
            mockito-core
        
    


    org.junit.jupiter
    junit-jupiter-engine
    test

• 创建UserServiceTest文件进行测试UserService功能

package com.edurt.ski

import com.edurt.ski.service.UserService
import org.junit.jupiter.api.AfterAll
import org.junit.jupiter.api.Test
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.boot.test.context.SpringBootTest
import org.springframework.data.domain.PageRequest

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
class UserServiceTest(@Autowired private val userService: UserService) {

    @Test
    fun `get all`() {
        println(">> Assert blog page title, content and status code")
        val entity = this.userService.getAll(PageRequest(0, 1))
        print(entity.totalPages)
    }

}

源码地址：GitHub