Spring Boot Kotlin Web开发 CRUD

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项目地址：https://github.com/aslucky/springBoot-kotlin-crud.git

建立项目

使用IDEA开发Spring Boot + Kotlin搭建后端Restful服务
Java 1.8
File-New project- Spring initializr下一步，语言选择Kotlin，其他根据需要选择，这里使用maven。
下一步，依赖里面选择Web-Web其他的暂时不选，下一步设置项目名称，完毕。
大致如下：

DemoApplication.kt文件里面是main入口函数。

添加控制器代码

新建一个Kotlin类controllerTopic

@RestController
class controllerTopic {

    @RequestMapping(value = "/",method = arrayOf(RequestMethod.GET))
    fun index():String = "hi there"

}

在DemoApplication.kt文件上右键-debug…一般情况下会成功启动服务
使用Postman发送请求Get http://localhost:8080/
会看到回复hi there。

实现CRUD接口

添加一个数据类Topic，设置了默认值。

data class Topic (val id:String="", val name:String="", val description:String="") {
}

添加一个服务类TopicService，实现CRUD服务，这里暂时先使用一个可写列表作为数据源。

@Service
class TopicService {

    private var topics = mutableListOf(
            Topic("spring", "spring framework", "spring description"),
            Topic("java", "java framework", "java description"),
            Topic("java script", "java script framework", "java script description")
    )

    fun getAll(): List<Topic> = topics

    fun getTopic(id: String) = topics.filter({ it -> it.id == id }).firstOrNull()

    // return Boolean. true success otherwise failed
    fun addTopic(topic: Topic) = topics.add(topic)

    fun updateTopic(id: String, topic: Topic):Int {
        var list = topics.filter({ it -> it.id == id }).firstOrNull()
        if (list == null)
            return -1
        else
            topics.set(topics.indexOf(list), topic)
        return 0
    }

    //true : success otherwise false
    fun deleteTopic(id: String): Boolean{
        val ret = topics.removeIf({ it -> it.id.equals(id) })
        return ret
    }
}

创建一个用来返回信息的数据类ProcResp

data class procResp(var code:Int, var message:String,var data:Any? = null)

处理控制器的操作

@RestController
class controllerTopic(val topicService: TopicService) {

    @RequestMapping(value = "/",method = arrayOf(RequestMethod.GET))
    fun index():String = "hi there"

    @RequestMapping(value = "/topics",method = arrayOf(RequestMethod.GET))
    fun getAllTopic(): procResp{
        var resp = procResp(0,"success")
        resp.data = topicService.getAll()
        return resp
    }

    @RequestMapping(value = "topics/{id}",method = arrayOf(RequestMethod.GET))
    fun getTopic(@PathVariable id: String) : procResp
    {
        var resp = procResp(0,"success")
        resp.data = topicService.getTopic(id)
        return resp
    }

    @RequestMapping(value = "topics",method = arrayOf(RequestMethod.POST))
    fun addTopic(@RequestBody topic:Topic):procResp{
        var resp = procResp(if (topicService.addTopic(topic)) 0 else -1,"success")
        return resp
    }

    @RequestMapping(value = "topics/{id}",method = arrayOf(RequestMethod.PUT))
    fun updateTopic(@RequestBody topic:Topic, @PathVariable id:String):procResp{
        val ret = topicService.updateTopic(id, topic)
        var resp = procResp(ret,if (ret != 0) "error" else "success")
        return resp
    }

    @RequestMapping(value = "topics/{id}",method = arrayOf(RequestMethod.DELETE))
    fun deleteTopic(@PathVariable id: String) : procResp{
        val ret = if (topicService.deleteTopic(id)) 0 else -1
        var resp = procResp(ret ,if (ret != 0) "error" else "success")
        return resp
    }
}

现在就可以运行起来了。照比我之前用spring mvc写的CRUD简单的太多了。
和python的flask很像。能自动处理的部分都屏蔽掉了，比较人性化。