Android 开发 - 子线程到主线程的通信方式（使用 Handler、使用 View 的 post 方法、使用 Activity 的 runOnUiThread 方法等）

一、使用 Handler

TextViewtvContent=findViewById(R.id.tv_content);Handlerhandler=newHandler(Looper.getMainLooper()){@OverridepublicvoidhandleMessage(@NonNullMessagemsg){tvContent.setText("收到消息："+msg.what);}};newThread(()->{try{Thread.sleep(3*1000);}catch(InterruptedExceptione){e.printStackTrace();}Messagemsg=Message.obtain();msg.what=100;handler.sendMessage(msg);try{Thread.sleep(3*1000);}catch(InterruptedExceptione){e.printStackTrace();}handler.post(()->{tvContent.setText("更新 UI");});}).start();

二、使用 View 的 post 方法

TextViewtvContent=findViewById(R.id.tv_content);newThread(()->{try{Thread.sleep(3*1000);}catch(InterruptedExceptione){e.printStackTrace();}tvContent.post(()->{tvContent.setText("更新 UI");});}).start();

三、使用 Activity 的 runOnUiThread 方法

TextViewtvContent=findViewById(R.id.tv_content);newThread(()->{try{Thread.sleep(3*1000);}catch(InterruptedExceptione){e.printStackTrace();}runOnUiThread(()->{tvContent.setText("更新 UI");});}).start();

四、使用 AsyncTask

TextViewtvContent=findViewById(R.id.tv_content);classMyTaskextendsAsyncTask<String,Integer,String>{@OverrideprotectedStringdoInBackground(String...strings){Stringinput=strings[0];try{Thread.sleep(3*1000);}catch(InterruptedExceptione){e.printStackTrace();}return"处理 【"+input+"】 完成";}@OverrideprotectedvoidonPostExecute(Stringstring){tvContent.setText(string);}}newMyTask().execute("task");

五、使用 LiveData

TextViewtvContent=findViewById(R.id.tv_content);MutableLiveData<String>content=newMutableLiveData<>();content.observe(this,s->{tvContent.setText(s);});newThread(()->{try{Thread.sleep(3*1000);}catch(InterruptedExceptione){e.printStackTrace();}content.postValue("更新 UI");}).start();

六、使用 EventBus

implementation'org.greenrobot:eventbus:3.3.1'

publicclassEventBusTestActivityextendsAppCompatActivity{privateTextViewtvContent;@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);EdgeToEdge.enable(this);setContentView(R.layout.activity_event_bus_test);ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main),(v,insets)->{InsetssystemBars=insets.getInsets(WindowInsetsCompat.Type.systemBars());v.setPadding(systemBars.left,systemBars.top,systemBars.right,systemBars.bottom);returninsets;});tvContent=findViewById(R.id.tv_content);newThread(()->{try{Thread.sleep(3*1000);}catch(InterruptedExceptione){e.printStackTrace();}EventBus.getDefault().post("hello event bus");}).start();}@OverrideprotectedvoidonStart(){super.onStart();EventBus.getDefault().register(this);}@OverrideprotectedvoidonStop(){super.onStop();EventBus.getDefault().unregister(this);}@Subscribe(threadMode=ThreadMode.MAIN)publicvoidonMessage(Stringmessage){tvContent.setText(message);}}

七、使用 RxJava

implementation'io.reactivex.rxjava3:rxjava:3.1.8'implementation'io.reactivex.rxjava3:rxandroid:3.0.2'

publicclassRxJavaTestActivityextendsAppCompatActivity{@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);EdgeToEdge.enable(this);setContentView(R.layout.activity_rx_java_test);ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main),(v,insets)->{InsetssystemBars=insets.getInsets(WindowInsetsCompat.Type.systemBars());v.setPadding(systemBars.left,systemBars.top,systemBars.right,systemBars.bottom);returninsets;});TextViewtvContent=findViewById(R.id.tv_content);Observable.create((ObservableEmitter<String>emitter)->{TimeUnit.SECONDS.sleep(3);emitter.onNext("test content");}).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(data->{tvContent.setText(data);});}}

八、使用 BroadcastReceiver

publicclassBroadcastReceiverTestActivityextendsAppCompatActivity{privateTextViewtvContent;classMyBroadcastReceiverextendsBroadcastReceiver{@OverridepublicvoidonReceive(Contextcontext,Intentintent){Stringmessage=intent.getStringExtra("message");tvContent.setText(message);}}@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);EdgeToEdge.enable(this);setContentView(R.layout.activity_broadcast_receiver_test);ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main),(v,insets)->{InsetssystemBars=insets.getInsets(WindowInsetsCompat.Type.systemBars());v.setPadding(systemBars.left,systemBars.top,systemBars.right,systemBars.bottom);returninsets;});tvContent=findViewById(R.id.tv_content);MyBroadcastReceivermyBroadcastReceiver=newMyBroadcastReceiver();IntentFilterintentFilter=newIntentFilter();intentFilter.addAction(MyBroadcastReceiver.class.getSimpleName());registerReceiver(myBroadcastReceiver,intentFilter);newThread(()->{try{Thread.sleep(3*1000);}catch(InterruptedExceptione){e.printStackTrace();}Intentintent=newIntent(MyBroadcastReceiver.class.getSimpleName());intent.putExtra("message","test content");sendBroadcast(intent);}).start();}}

九、使用协程

classCoroutinesTestActivity:AppCompatActivity(){override funonCreate(savedInstanceState:Bundle?){super.onCreate(savedInstanceState)enableEdgeToEdge()setContentView(R.layout.activity_coroutines_test)ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main)){v,insets->val systemBars=insets.getInsets(WindowInsetsCompat.Type.systemBars())v.setPadding(systemBars.left,systemBars.top,systemBars.right,systemBars.bottom)insets}val tvContent=findViewById<TextView>(R.id.tv_content)CoroutineScope(Dispatchers.IO).launch{delay(3000)val message="test content"withContext(Dispatchers.Main){tvContent.text=message}}}}