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：
<?xml version=”1.0″ encoding=”UTF-8″?>
<project xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance” xmlns=”http://maven.apache.org/POM/4.0.0″
xsi:schemaLocation=”http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd”>
<modelVersion>4.0.0</modelVersion>
<groupId>com.edurt.ski</groupId>
<artifactId>springboot-kotlin-integration</artifactId>
<version>1.0.0</version>
<packaging>jar</packaging>
<name>springboot kotlin integration</name>
<description>SpringBoot Kotlin Integration is a open source springboot, kotlin integration example.</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.3.RELEASE</version>
<relativePath/> <!– lookup parent from repository –>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<!– plugin config –>
<plugin.maven.kotlin.version>1.2.71</plugin.maven.kotlin.version>
</properties>
<dependencies>
<!– spring boot –>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!– kotlin –>
<dependency>
<groupId>com.fasterxml.jackson.module</groupId>
<artifactId>jackson-module-kotlin</artifactId>
</dependency>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-stdlib-jdk8</artifactId>
</dependency>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-reflect</artifactId>
</dependency>
</dependencies>
<build>
<sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
<testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<artifactId>kotlin-maven-plugin</artifactId>
<groupId>org.jetbrains.kotlin</groupId>
<configuration>
<args>
<arg>-Xjsr305=strict</arg>
</args>
<compilerPlugins>
<plugin>spring</plugin>
<plugin>jpa</plugin>
<plugin>all-open</plugin>
</compilerPlugins>
<pluginOptions>
<option>all-open:annotation=javax.persistence.Entity</option>
</pluginOptions>
</configuration>
<dependencies>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-maven-allopen</artifactId>
<version>${plugin.maven.kotlin.version}</version>
</dependency>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-maven-noarg</artifactId>
<version>${plugin.maven.kotlin.version}</version>
</dependency>
</dependencies>
<executions>
<execution>
<id>kapt</id>
<goals>
<goal>kapt</goal>
</goals>
<configuration>
<sourceDirs>
<sourceDir>src/main/kotlin</sourceDir>
</sourceDirs>
<annotationProcessorPaths>
<annotationProcessorPath>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<version>${project.parent.version}</version>
</annotationProcessorPath>
</annotationProcessorPaths>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
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<String>) {
runApplication<SpringBootKotlinIntegration>(*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
<!– mustache –>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-mustache</artifactId>
</dependency>
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
<h1>Hello, Kotlin</h1>
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)
<!– data jpa and db –>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
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<UserModel, Long> {
}
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<UserModel>
修改 UserServiceImpl 增加以下代码
override fun getAll(page: Pageable): Page<UserModel> {
return this.userSupport.findAll(page)
}
修改 UserController 增加以下代码
@GetMapping(value = “list”)
fun get(): Page<UserModel> = 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
<!– test –>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</exclusion>
<exclusion>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
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