转载请标明出处：http://blog.csdn.net/zhaoyanjun6/article/details/118085035
本文出自【赵彦军的博客】

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先定义实体类

class Repo(val id: String, val name: String)

Retrofit 正常使用

定义接口 GitHubService

interface GitHubService {

    @GET("users/{user}/repos")
    fun listRepos(@Path("user") user: String?): Call<List<Repo>>
}

使用

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val retrofit = Retrofit.Builder()
            .baseUrl("https://api.github.com/")
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        val service: GitHubService = retrofit.create(GitHubService::class.java)

        val call = service.listRepos("zyj1609wz")
        call.enqueue(object : Callback<List<Repo>> {

            override fun onResponse(call: Call<List<Repo>>, response: Response<List<Repo>>) {
                val list = response.body()
                tv.text = "ok ${list?.get(0)?.name}"
            }

            override fun onFailure(call: Call<List<Repo>>, t: Throwable) {
                tv.text = "fail ${t.message}"
            }

        })
    }
}

Retrofit结合协程方式一

下面我们来使用协程请求网络接口

定义接口 GitHubService

interface GitHubService {

    @GET("users/{user}/repos")
    fun listRepos(@Path("user") user: String?): Call<List<Repo>>
}

在协程里面请求网络

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val retrofit = Retrofit.Builder()
            .baseUrl("https://api.github.com/")
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        val service: GitHubService = retrofit.create(GitHubService::class.java)

        GlobalScope.launch {
            try {
                val call = service.listRepos("zyj1609wz")
                val response = call.execute()
                val list = response.body()
                tv.text = "ok ${list?.get(0)?.name}"
            } catch (e: Exception) {
                tv.text = "fail ${e.message}"
            }
        }
    }
}

这样我们就完成了, 协程和retrofit 结合，这只是一个简单的运用，仅仅把协程当做线程来使用。

Retrofit结合协程方式二

把 GitHubService 函数改为挂起函数，并且把返回值从 Call 改为List

interface GitHubService {

    @GET("users/{user}/repos")
    suspend fun listRepos(@Path("user") user: String?): List<Repo>
}

使用

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val retrofit = Retrofit.Builder()
            .baseUrl("https://api.github.com/")
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        val service: GitHubService = retrofit.create(GitHubService::class.java)

        GlobalScope.launch(Dispatchers.Main) {
            try {
                //这是一个挂起函数
                val list = service.listRepos("zyj1609wz")
                tv.text = "ok ${list?.get(0)?.name}"
            } catch (e: Exception) {
                tv.text = "fail ${e.message}"
            }
        }
    }

}

Retrofit结合协程方式三

async 模拟两个并行任务

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val retrofit = Retrofit.Builder()
            .baseUrl("https://api.github.com/")
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        val service: GitHubService = retrofit.create(GitHubService::class.java)

        GlobalScope.launch(Dispatchers.Main) {
            try {
                val list = async { service.listRepos("zyj1609wz") }
                val list2 = async { service.listRepos("zyj1609wz") }

                //两个请求是并行的
                val result1 = list.await()
                val result2 = list2.await()

                tv.text = "ok ${result1[0].name} ${result2[0].name}"
            } catch (e: Exception) {

            }
        }
    }
}