在服务中运行 AsyncTask - Android

Posted 2023-05-07

【中文标题】在服务中运行 AsyncTask - Android

【英文标题】：Run AsyncTask in Service - Android

【发布时间】：2017-07-01 20:24:31

【问题描述】：

我正在尝试在 android Service 中使用 AsyncTask，但它不起作用。有人可以帮助我吗？我正在使用片段，我是新手。提前致谢。错误：无法解析方法。这是我的实现。

public class MyService extends Service implements Runnable 

final String numeroPorta = "80";
final String nomeParametro = "num";
String respostaServidor;
private boolean ativo;

@Override
public IBinder onBind(Intent intent) 
    return null;


@Override
public void onCreate() 
    super.onCreate();


@Override
public int onStartCommand(Intent intent, int flags, int startID) 

    ativo = true;
    new Thread(this, "MyService" + startID).start();
    return super.onStartCommand(intent, flags, startID);


@Override
public void run() 
    myService();


@Override
public void onDestroy() 
    ativo = false;


public void myService() 
    new Thread() 
        public void run() 
            runOnUiThread(new Runnable() 
                public void run() 
                    if (enderecoIP.length() > 0 && numeroPorta.length() > 0 && !Objects.equals(valorParametro, "0")) 
                        new HttpRequestAsyncTask(getApplicationContext(), valorParametro, enderecoIP, numeroPorta, nomeParametro).execute();
                    
                
            );
        
    .start();


public class HttpRequestAsyncTask extends AsyncTask<Void, Void, Void> 

    private String requisicaoResposta, enderecoIP, numeroPorta;
    private Context contexto;
    private AlertDialog alerta;
    private String parametro, valorParametro;

    HttpRequestAsyncTask(Context contexto, String valorParametro, String enderecoIP, String numeroPorta, String parametro) 

        this.contexto = contexto;

        alerta = new AlertDialog.Builder(this.contexto)
                .setTitle("Resposta HTTP:")
                .setCancelable(true)
                .create();

        this.enderecoIP = enderecoIP;
        this.numeroPorta = numeroPorta;
        this.valorParametro = valorParametro;
        this.parametro = parametro;
    


    @Override
    protected Void doInBackground(Void... voids) 

        alerta.setMessage("Dados enviados, aguardando resposta do servidor...");
        if (!alerta.isShowing()) 
            alerta.show();
        

        requisicaoResposta = sendRequest(valorParametro, enderecoIP, numeroPorta, parametro);
        return null;
    

    @Override
    protected void onPostExecute(Void avoid) 

        alerta.setMessage(requisicaoResposta);
        if (!alerta.isShowing()) 
            alerta.show();
        
    

    @Override
    protected void onPreExecute() 

        alerta.setMessage("Enviando dados ao servidor, por favor aguarde...");
        if (!alerta.isShowing()) 
            alerta.show();
        
    

【问题讨论】：

您正在尝试在服务中调用runOnUiThread；此方法仅在 Activity 中可用。就此而言，在服务中您甚至不需要使用 AsyncTask，只需使用您创建的线程来发出请求。

【参考方案1】：

看看这段代码是否可行..

public​ class ​MyService ​extends​ Service​ 

    ​​​​@Override
​​​​    public​ IBinder ​onBind(Intent​ arg0)​ 
    ​​​​​​​​    return ​null;
    ​​​​

    @Override ​
    ​​​public​ int ​onStartCommand(Intent ​intent,​int​ flags,​int ​startId)​ 

        //​We​ want ​this ​service ​to ​continue ​running ​until​ it ​is ​explicitly    
    ​​​​​​​​    //​stopped,​so​ return ​sticky. ​​​​​​​​

        Toast.makeText(this, "Service​Started",​Toast.LENGTH_LONG).show();

        ​​​​​​​​try 
            ​​​​​​​​​​​​new DoBackgroundTask().execute(​​​​​​​​​​​​​​​new URL(""), ​​​​​​​​​​​​​​​​​​​​new URL("")); ​​​​​​​​
         catch (MalformedURLException e) 
            ​​​​​​​​​​​​e.printStackTrace();
    ​​​​​​​​    

    ​​​​​​​​    return ​START_STICKY;
​​​    

    @Override
​​​​    public ​void ​onDestroy() ​    
    ​​​​​​​​    super.onDestroy();

    ​​​​​​​​    Toast.makeText(this,​"Service​Destroyed",​Toast.LENGTH_LONG).show(); ​​
​     ​​​​

    ​​​​private ​int ​DownloadFile(URL​ url) 
        ​try ​    
    ​​​​​​​​​​​​        //---simulate​ taking ​some​time ​to ​download ​a​ file--- ​​​​​​​​​​​​

            Thread.sleep(5000);
    ​​​​​​​​     catch​(InterruptedException ​e)​ 
        ​​​​​​​​​​​​    e.printStackTrace(); ​
    ​​​​​​​    

    ​​​​​​​​    //---return ​an ​arbitrary ​number​ representing ​
        ​​​​​​//​the ​size​ of ​the ​file ​downloaded--- ​    

    ​​​​​​​    return​ 100;    
    ​​​

    private class DoBackgroundTask extends AsyncTask<URL, Integer, Long> 

​​​​​​​​        protected Long doInBackground(URL... urls)     
        ​​​​​​​​​​​​    int count = urls.length;
    ​​​​​​​​​​​        ​long totalBytesDownloaded = 0;

            ​​​​​​​​​​​​for (int i = 0; i < count; i++) 
                ​​​​​​​​​​​​​​​​totalBytesDownloaded += DownloadFile(urls[i]);

                ​​​​​​​​​​​​​​​​//---calculate percentage downloaded and
            ​​​​​​​​​​​​​​​​    // report its progress--- ​

                ​​​​​​​​​​​​​​​publishProgress((int) (((i+1) / (float) count) * 100));
​​​​​​​​​​​            

            ​​​​​​​​​​​​return totalBytesDownloaded; ​​    
        ​​​​​​

        protected void onProgressUpdate(Integer... progress) 
            ​​​​​​​​​​​​Log.d("Downloading files", ​​​​​​​​​​​​​​​​​​​​String.valueOf(progress[0]) + "% downloaded");

            Toast.makeText(getBaseContext(), ​​​​​​​​​​​​​​​​String.valueOf(progress[0]) + "% downloaded", ​​​​​​​​​​​​​​​​Toast.LENGTH_LONG).show();
        

        protected void onPostExecute(Long result) 
            ​​​​​​​​​​​​Toast.makeText(getBaseContext(), ​​​​​​​​​​​​​​​​​​​​"Downloaded " + result + " bytes", ​​​​​​​​​​​​​​​​​​​​Toast.LENGTH_LONG).show();

​​​​​​​​​​            stopSelf();
    ​​​​​​​​     
​​​    

【讨论】：

我想发出一个 http 请求。