Retrofit 使用

基本用法

Retrofit 地址

先添加依赖：

implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

创建接口文件：

interface AppService {

    @GET("get_data.json")
    fun getAppData(): Call<List<App>>
}

通常 Retrofit 的接口文件以具体的功能种类名开头，并以 Service 结尾。

val retrofit = Retrofit.Builder()
    .baseUrl("http://10.0.2.2/")
    .addConverterFactory(GsonConverterFactory.create())
    .build()
val appService = retrofit.create(AppService::class.java)
appService.getAppData().enqueue(object : Callback<List<App>> {
    override fun onResponse(call: Call<List<App>>, response: Response<List<App>>) {
        val list = response.body()
        if (list != null) {
            for (app in list) {
                Log.d(TAG, "id is ${app.id}")
                Log.d(TAG, "name is ${app.name}")
                Log.d(TAG, "version is ${app.version}")
            }
        }
    }

    override fun onFailure(call: Call<List<App>>, t: Throwable) {
        t.printStackTrace()
    }

})

处理复杂的接口地址类型

@GET("get_data.json")
fun getAppData(): Call<List<App>>

// 传入不同的页数
@GET("{page}/get_data.json")
fun getData(@Path("page") page: Int): Call<Data>

// 传入参数 GET http://example.com/get_data.json?u=<user>&t=<token>
@GET("get_data.json")
fun getData(@Query("u") user: String, @Query("t") token: String): Call<Data>

// 删除接口 DELETE http://example.com/data/<id>
// ResponseBody表示能够接收任何类型的响应数据并不会解析
@DELETE("data/{id}")
fun deleteData(@Path("id") id: String): Call<ResponseBody>

// POST http://example.com/data/create
// {"id":1,"content":"The description for this data."}
@POST("data/create")
fun createData(@Body data: Data): Call<ResponseBody>

/** 静态声明header
    * GET http://example.com/get_data.json
    * User-Agent: okhttp
    * Cache-Control: max-age=0
    **/
@Headers("User-Agent: okhttp", "Cache-Control: max-age=0")
@GET("get_data.json")
fun getData(): Call<Data>

// 动态声明header
@GET("get_data.json")
fun getData2(
    @Header("User-Agent") userAgent: String,
    @Header("Cache-Control") cacheControl: String
): Call<Data>

代码封装

ServiceCreator

object ServiceCreator {

    private const val BASE_URL = "https://api.caiyunapp.com/"

    private val client = OkHttpClient.Builder().addInterceptor(HttpLoggingInterceptor().apply {
        level = HttpLoggingInterceptor.Level.BODY
    }).build()

    private val retrofit = Retrofit.Builder()
        .client(client)
        .baseUrl(BASE_URL)
        .addConverterFactory(GsonConverterFactory.create())
        .build()

    fun <T> create(serviceClass: Class<T>): T = retrofit.create(serviceClass)

    inline fun <reified T> create(): T = create(T::class.java)
}

// 使用：
val appService = ServiceCreator.create<AppService>()

XxxNetwork

object XxxNetwork {
    private suspend fun <T> Call<T>.await(): T {
        return suspendCoroutine { continuation ->
            enqueue(object : Callback<T> {
                override fun onResponse(call: Call<T>, response: Response<T>) {
                    val body = response.body()
                    if (body != null) continuation.resume(body)
                    else continuation.resumeWithException(RuntimeException("response body is null"))
                }

                override fun onFailure(call: Call<T>, t: Throwable) {
                    continuation.resumeWithException(t)
                }
            })
        }
    }
}

参考

• 第一行代码 第 3 版