从两个不同的 AsyncTask 更新一个 ListView

Posted 2023-04-19

【中文标题】从两个不同的 AsyncTask 更新一个 ListView

【英文标题】：Updating One ListView From Two Different AsyncTask

【发布时间】：2020-02-18 15:08:46

【问题描述】：

我有一个具有内部 AsyncTask 类的活动 (MainActivity)。此类获取本地无线配置，例如：ip 地址、子网、网关等。我有一个外部 Asynctask 获取外部 ip 配置。像 ip 地址、主机名、位置等。第二类为此使用 json rest api。但是当我从二等舱发布到列表视图时，我无法做到。我不知道这是否可能。我将当前上下文传递给第二类并使用 Wea​​kReferences 以防主要活动终止。另外，我正在为列表视图使用自定义数组适配器。据我了解，doinbackground() 方法在不同的线程中运行，所以这两个类之间是如何同步的。我正在考虑的替代解决方案不是直接从第二类发布到列表视图中，而是存储在主类上的一个变量中，然后从第一类异步任务输出到列表视图。但这会产生意想不到的结果。这是怎么做的。有没有人做过类似的事情？谢谢 注意：我从 mainactivity 中删除了一些导入，否则课程将在这里占用太多空间。 主要活动

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()
                        
        
    

【问题讨论】：

我不知道编码风格会消失...我不是模特所以我不知道...我虽然这个地方也改变了管理，但这种事情已经消失了。 ..我想我也错了

【参考方案1】：

在 WanAsynTask 中你没有更新适配器

@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();