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GSON Kotlin And TypeToken Retrofit

Gson 解析对象

• Kotlin中:

  • 第一种方式: 

        val turnsType = object : TypeToken<List<Turns>>() {}.type
        val turns = Gson().fromJson<List<Turns>>(pref.turns, turnsType) 
    

  • 第二种方式: 使用泛型

       inline fun <reified T> genericType() = object: TypeToken<T>() {}.type
    //list对象    
       val turnsType = genericType<List<Person>>()
       val turns = Gson().fromJson<List<Person>>(jsonSTR, turnsType) 
    //对象    
       val turnsType = genericType<Person>()
       val turns = Gson().fromJson<Person>(jsonSTR, turnsType) 
    

Springboot 返回图片

• 1.在springboot的application配置类中添加以下代码，使其支持图片返回，不然会报错，获取不到图片

    @Bean
       public BufferedImageHttpMessageConverter bufferedImageHttpMessageConverter() {
           return new BufferedImageHttpMessageConverter();
       }
  

• 2.controller中主要配置GetMapping的produces，使其允许返回图片类型

      @GetMapping("/getBingPic", produces = [MediaType.IMAGE_JPEG_VALUE])
       @ResponseBody
       fun bingPic(): BufferedImage {
           val item = getUrls()[0] as ImageInfo
           LogUtil.info(item.url)
           val url = URL(item.url)
           val input = BufferedInputStream(url.openStream())
           return ImageIO.read(input)
       }
  

• 3.注意如果是网络图片应该使用另一种方式读写，否则会出现 (文件名、目录名或卷标语法不正确。)

    //网络路径读写
    val url = URL(path)
    val input = BufferedInputStream(url.openStream())
    return ImageIO.read(input)
    //本地路径
    return ImageIO.read(FileInputStream(File(path)))
  

Retrofit 请求网络

• 工具类

    import okhttp3.OkHttpClient
    import okhttp3.logging.HttpLoggingInterceptor
    import retrofit2.Retrofit
    import retrofit2.converter.gson.GsonConverterFactory
    import retrofit2.converter.scalars.ScalarsConverterFactory
    import java.util.concurrent.TimeUnit
    object HttpCreator {
      
        private var BASE_URL: String = ""
        private val httpClient = OkHttpClient.Builder()
      
        private var DEFAULT_TIMEOUT: Long = 20L
        private val builder = Retrofit.Builder()
                .addConverterFactory(ScalarsConverterFactory.create())
                .addConverterFactory(GsonConverterFactory.create())
      
        /***
         * 设置连接超时时间默认20s,此函数需在create（）之前调用
         * @param time
         */
        fun setTimeOut(time: Long): HttpCreator {
            DEFAULT_TIMEOUT = time
            httpClient.connectTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS)
            return this
        }
      
        /**
         * 设置base url
         * @param url
         */
        fun setBaseURL(url: String): HttpCreator {
            BASE_URL = url
            builder.baseUrl(BASE_URL)
            return this
        }
      
        fun buildClient(): Retrofit.Builder = builder.client(httpClient.build())
      
        /**
         * 是否设置链接日志过滤,此函数需在create（）之前调用
         * @param isUse
         */
        fun setIsUseLoggingInterceptor(isUse: Boolean): HttpCreator {
            httpClient.addInterceptor(
                    HttpLoggingInterceptor(HttpLoggingInterceptor
                            .Logger { message ->
                                //打印retrofit日志
                                println("RetrofitLog" + "retrofitBack = $message")
                            }
                    )
                            .setLevel(
                                    if (isUse)
                                        HttpLoggingInterceptor.Level.BODY
                                    else
                                        HttpLoggingInterceptor.Level.NONE
                            )
            )
            return this
        }
      
        /***
         * 创建实例
         * @param serviceClass 接口类
         * @exception setBaseURL(url) must be called first.
         */
        fun <T> create(serviceClass: Class<T>): T = if (BASE_URL == "")
            throw RuntimeException("setBaseURL(url) must be called first.") as Throwable
        else {
            buildClient().build().create(serviceClass)
        }
    }
      
  

• 使用

    //api
        class BingInterface {
            interface BingService {
                companion object {
                    val BASE_URL = "https://cn.bing.com/"
                }
          
                @GET("HPImageArchive.aspx?format=js")
                fun getImageInfo(@Query("idx") index:Int, @Query("n") num:Int): Call<BingPicController.Images>
            }
        }
        
    //同步
        HttpCreator
             .setIsUseLoggingInterceptor(true)
             .setTimeOut(20L)
             .setBaseURL(BingInterface.BingService.BASE_URL)
             .create(BingInterface.BingService::class.java)
             .getImageInfo(-1,1)
             .execute()
             .body()
             
    //异步
        HttpCreator
            .setIsUseLoggingInterceptor(true)
            .setTimeOut(20L)
            .setBaseURL(BingInterface.BingService.BASE_URL)
            .create(BingInterface.BingService::class.java)
            .getImageInfo(-1,1).enqueue(object :Callback<Images>(){
                 override fun onFailure(call: Call<Images>,
                 t: Throwable) {
                    TODO("not implemented")  
                }
           
                override fun onResponse(call: Call<Images>, response: Response<Images>) {
                    TODO("not implemented")  
                }
           
            })
  

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