從兩個不同的 AsyncTask 更新一個 ListView

Question

我有一個具有內部 AsyncTask class 的活動 (MainActivity)。 這個 class 獲取本地無線配置，例如：ip 地址、子網、網關等。我有一個外部 Asynctask 獲取外部 ip 配置。 like ip address, hostname, location etc. the second class uses a json rest api for this. 但是當我從第二個 class 發布到列表視圖時，我無法做到。 我不知道這是否可能。 我將當前上下文傳遞給第二個 class 並使用 WeakReferences 以防主要活動終止。 另外，我正在為列表視圖使用自定義數組適配器。 據我了解，doinbackground() 方法在不同的線程中運行，所以這兩個類之間是如何同步的。 我正在考慮的替代解決方案不是直接從第二個 class 發布到列表視圖中，而是存儲在 mainclass 上的變量中，然后將 output 存儲到第一個異步任務的列表視圖中。 但這會產生意想不到的結果。 這是怎么做的。 有沒有人做過類似的事情？ 謝謝 注意：我從 mainactivity 中刪除了一些導入，否則 class 會在這里占用太多空間。 主要活動

package org.techgeorge.netxcan;
import org.apache.commons.net.util.SubnetUtils;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import utils.IpUtils;

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private ArrayList<String> wifiIface;
    private WifiAdapter wifiAdapter;
    private String TAG = this.getClass().getName();
    private String extIpv6;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        wifiIface = new ArrayList<>();

        listView = (ListView) findViewById(R.id.output_list);
        wifiAdapter = new WifiAdapter(this, R.layout.list_item, wifiIface);
        listView.setAdapter(wifiAdapter);

        WifiAsyncTask wifiTask = new WifiAsyncTask(this);
        wifiTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);

        getWanIpInfo();

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public void setExtIpv6(String ipv6) {
        this.extIpv6 = ipv6;
    }

    public ArrayList<String> getWifiIface() {
        return wifiIface;
    }

    public ArrayAdapter<String> getArrayAdapter() {
        return wifiAdapter;
    }

    public void getWanIpInfo() {
        WanIpTask wanIpTask = new WanIpTask(this);
        wanIpTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
    }

    public class WifiAsyncTask extends AsyncTask<Void, Void, Void> {
        WeakReference<MainActivity> weakReference;
        private static final String WEB_IP_SERVICE = "https://ipinfo.io/json";
        String error = "Couldn't get external IP";
        int subnet;
        Wireless wifi;

        public WifiAsyncTask(MainActivity activity) {
            weakReference = new WeakReference<>(activity);
        }

        @Override
        protected void onPreExecute() {
            wifi = new Wireless(getApplicationContext());
            wifi.getInternalMobileIpAddress();
        }

        @Override
        protected Void doInBackground(Void... params) {
            try {
                if ( wifi.getNetworkInfo() != null && wifi.getNetworkInfo().isConnected()) {
                    adding Lan stuff
                    subnet = wifi.getInternalWifiSubnet();
                    wifiIface.add("LAN Information");
                    wifiIface.add("Ipv6 "+wifi.getIpv6());
                    wifiIface.add("Mac "+wifi.getMacAddress());
                    wifiIface.add("Ipv4 "+wifi.getWifiInetAddress().getHostAddress()+"/"+subnet);
                    wifiIface.add("Host "+wifi.getWifiInetAddress().getHostName());
                    wifiIface.add("Dns1 "+IpUtils.getIpToString(wifi.getDhcpInfo().dns1));
                    wifiIface.add("Dns2 "+IpUtils.getIpToString(wifi.getDhcpInfo().dns2));
                    wifiIface.add("Gateway "+IpUtils.getIpToString(wifi.getDhcpInfo().gateway));

                    //adding wireless stuff
                    wifiIface.add("WIFI Information");
                    wifiIface.add("SSID "+wifi.getSSID());
                    wifiIface.add("Speed "+wifi.getLinkSpeed()+ "Mbs");
                    wifiIface.add("Signal "+wifi.getWifiInfo().getRssi() + "db");
                    wifiIface.add("Channel "+wifi.getWifiInfo().getNetworkId() + "");

                    }
                }
            } catch (Wireless.NoConnectivityManagerException e) {
                e.printStackTrace();
            } catch (Wireless.NoWifiManagerException e) {
                e.printStackTrace();
            } catch (SocketException e) {
                e.printStackTrace();
            } catch (Wireless.NoWifiInterface noWifiInterface) {
                noWifiInterface.printStackTrace();
            } catch (UnknownHostException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            wifiAdapter.notifyDataSetChanged();
        }

        @Override
        protected void onPostExecute(Void... values) {
            MainActivity activity = weakReference.get();
            if(activity != null || !activity.isFinishing()) {
                wifiAdapter.notifyDataSetChanged();
            }
        }

    }
}

WanAsynTask

package org.techgeorge.netxcan;

import android.annotation.SuppressLint;
import android.os.AsyncTask;
import android.util.Log;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.WeakReference;

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class WanIpTask extends AsyncTask<Void, Void, String> {

    // IP service is 100% open source https://github.com/aaronjwood/public-ip-api
//    private static final String EXTERNAL_IP_SERVICE = "https://public-ip-api.appspot.com/";
    private static final String EXTERNAL_IP_SERVICE = "https://ipinfo.io/json";
    private final WeakReference<MainActivity> delegate;

    /**
     * Constructor to set the delegate
     *
     * @param delegate Called when the external IP has been fetched
     */
    public WanIpTask(MainActivity delegate) {
        this.delegate = new WeakReference<>(delegate);
    }

    /**
     * Fetch the external IP address
     *
     * @param params
     * @return External IP address
     */
    @Override
    @SuppressLint("NewApi")
    protected String doInBackground(Void... params) {
        String error = "Couldn't get external IP";
        OkHttpClient httpClient = new OkHttpClient();
        Request request = new Request.Builder().url(EXTERNAL_IP_SERVICE).build();

        try (Response response = httpClient.newCall(request).execute()) {
            if (!response.isSuccessful()) {
                return error;
            }
            return response.body().string().trim();
        } catch (IOException e) {
            return error;
        }
    }

    /**
     * Calls the delegate when the external IP has been fetched
     *
     * @param result External IP address
     */
    @Override
    protected void onPostExecute(String result) {
        MainActivity activity = delegate.get();
        if (activity != null) {
            activity.getWifiIface().add(result);
            String[] wanResult = result.split("\n");
            for(int i = 0; i < wanResult.length; i++) {
                activity.getWifiIface.add()
            }            
        }
    }
}

Answer 1

在 WanAsynTask 你沒有更新適配器

@Override
protected void onPostExecute(String result) {
    MainActivity activity = delegate.get();
    if (activity != null) {
        activity.getWifiIface().add(result);
        String[] wanResult = result.split("\n");
        for(int i = 0; i < wanResult.length; i++) {
            activity.getWifiIface.add()
        }  
        // notify adapter    
        activity.wifiAdapter.notifyDataSetChanged();

    }
}