Activity中使用kotlin协程的几种写法-白红宇

Activity中使用kotlin协程的几种写法

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发布时间：2019-05-24

本文共 3478 字，大约阅读时间需要 11 分钟。

一、AppCompatActivity实现CoroutineScope接口：

class Test1Activity : AppCompatActivity(), CoroutineScope {    private lateinit var job: Job    override val coroutineContext: CoroutineContext        get() = Dispatchers.Main + job    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        job = Job()        test()    }    private fun test() {        launch {            val result = withContext(Dispatchers.IO) {                delay(1000)                "0"            }            Log.d("result", result)        }    }    override fun onDestroy() {        super.onDestroy()        job.cancel()    }}

二、直接实例化MainScope：

class Test2Activity : AppCompatActivity() {    private val mailScope = MainScope()    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        test()    }    private fun test() {        mailScope.launch {            val result = withContext(Dispatchers.IO) {                delay(1000)                "0"            }            Log.d("result", result)        }    }    override fun onDestroy() {        super.onDestroy()        mailScope.cancel()    }}

三、导入implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.3.0-alpha02'，就可以直接在AppCompatActivity调用lifecycleScope：

class Test3Activity : AppCompatActivity() {    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        test()    }    private fun test() {        lifecycleScope.launch {            val result = withContext(Dispatchers.IO) {                delay(1000)                "0"            }            Log.d("result", result)        }    }    override fun onDestroy() {        super.onDestroy()        lifecycleScope.cancel()    }}

最后发一下使用协程和RxJava的代码量和可读性对比：

协程：

dialog.show()        lifecycleScope.launch {            val result = withContext(Dispatchers.IO) {                sendHtmlMail()            }            dialog.dismiss()            if (result == OK) {                makeText(this@EmailReplyActivity, getString(R.string.mail_send_success_hint))                finish()            } else if (result == ERR) {                makeText(this@EmailReplyActivity, getString(R.string.mail_send_fail_hint))            }        }

RxJava：

dialog.show()        Observable.create { emitter: ObservableEmitter
   
     ->            val result = sendHtmlMail()            emitter.onNext(result)            emitter.onComplete()        }.subscribeOn(Schedulers.io())                .observeOn(AndroidSchedulers.mainThread())                .subscribe(object : Observer
    
      {                    override fun onSubscribe(d: Disposable) {                        compositeDisposable.add(d)                    }                    override fun onNext(value: String?) {                        if (value.equals(OK)) {                            makeText(this@EmailReplyActivity, getString(R.string.mail_send_success_hint))                            finish()                        } else if (value.equals(ERR)) {                            makeText(this@EmailReplyActivity, getString(R.string.mail_send_fail_hint))                        }                    }                    override fun onError(e: Throwable) {                        dialog.dismiss()                        e.printStackTrace()                    }                    override fun onComplete() {                        dialog.dismiss()                    }                })

突然觉得RxJava很恶心有没有

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