Question

我添加了AsyncTask以将网络操作卸载到后台线程。我需要确保UI操作在UI线程上。所以我想在我的Activity中使用runOnUiThread（）。

感谢您的帮助

WifiApManager

public class WifiApManager {
private final WifiManager mWifiManager;

public WifiApManager(Context context) {
    mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
}

public boolean setWifiApEnabled(WifiConfiguration wifiConfig, boolean enabled) {
    try {
        if (enabled) { // disable WiFi in any case
            mWifiManager.setWifiEnabled(false);
        }

        Method method = mWifiManager.getClass().getMethod("setWifiApEnabled", WifiConfiguration.class, boolean.class);
        return (Boolean) method.invoke(mWifiManager, wifiConfig, enabled);
    } catch (Exception e) {
        Log.e(this.getClass().toString(), "wifi", e);
        return false;
    }
}

public WIFI_AP_STATE getWifiApState() {
    try {
        Method method = mWifiManager.getClass().getMethod("getWifiApState");

        int tmp = ((Integer)method.invoke(mWifiManager));

        // Fix for Android 4
        if (tmp > 10) {
            tmp = tmp - 10;
        }

        return WIFI_AP_STATE.class.getEnumConstants()[tmp];
    } catch (Exception e) {
        Log.e(this.getClass().toString(), "wifi", e);
        return WIFI_AP_STATE.WIFI_AP_STATE_FAILED;
    }
}


public boolean isWifiApEnabled() {
    return getWifiApState() == WIFI_AP_STATE.WIFI_AP_STATE_ENABLED;
}


public WifiConfiguration getWifiApConfiguration() {
    try {
        Method method = mWifiManager.getClass().getMethod("getWifiApConfiguration");
        return (WifiConfiguration) method.invoke(mWifiManager);
    } catch (Exception e) {
        Log.e(this.getClass().toString(), "wifi", e);
        return null;
    }
}


public boolean setWifiApConfiguration(WifiConfiguration wifiConfig) {
    try {
        Method method = mWifiManager.getClass().getMethod("setWifiApConfiguration", WifiConfiguration.class);
        return (Boolean) method.invoke(mWifiManager, wifiConfig);
    } catch (Exception e) {
        Log.e(this.getClass().toString(), "wifi", e);
        return false;
    }
}


public ArrayList<ClientScanResult> getClientList(boolean onlyReachables) {
    return getClientList(onlyReachables, 10);
}


public ArrayList<ClientScanResult> getClientList(boolean onlyReachables, int reachableTimeout) {
    BufferedReader br = null;
    ArrayList<ClientScanResult> result = null;

    try {
        result = new ArrayList<ClientScanResult>();
        br = new BufferedReader(new FileReader("/proc/net/arp"));
        String line;
        while ((line = br.readLine()) != null) {
            String[] splitted = line.split(" +");

            if ((splitted != null) && (splitted.length >= 4)) {
                // Basic sanity check
                String mac = splitted[3];

                if (mac.matches("..:..:..:..:..:..")) {
                    boolean isReachable = InetAddress.getByName(splitted[0]).isReachable(reachableTimeout);

                    if (!onlyReachables || isReachable) {
                        result.add(new ClientScanResult(splitted[0], splitted[3], splitted[5], isReachable));
                    }
                }
            }
        }
    } catch (Exception e) {
        Log.e(LOGTAG, e.toString());
    } finally {
        try {
            br.close();
        } catch (IOException e) {
            Log.e(LOGTAG, e.toString());
        }
    }
return result;
}
}

connect.java

public class connect extends Activity{
WifiApManager wifiApManager;
TextView tv;
Button scan;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.connect);
    tv =(TextView) findViewById(R.id.iptv);
    new scan().execute();
}
public class scan extends AsyncTask<String, Integer, String> {

public Object WIFI_SERVICE;
@Override
protected void onProgressUpdate(Integer...integers)  {
     ArrayList<ClientScanResult> clients = wifiApManager.getClientList(false);
        tv.setText("WifiApState: " + wifiApManager.getWifiApState() + "\n\n");
        tv.append("Clients: \n");
        for (ClientScanResult clientScanResult : clients) {
            tv.append("####################\n");
            tv.append("IpAddr: " + clientScanResult.getIpAddr() + "\n");
            tv.append("Device: " + clientScanResult.getDevice() + "\n");
            tv.append("HWAddr: " + clientScanResult.getHWAddr() + "\n");
            tv.append("isReachable: " + clientScanResult.isReachable()+ "\n");
            }
}
@Override
        protected void onPostExecute(String result){
            tv.setText(result);             
        }
@Override
protected String doInBackground(String... params) {
    wifiApManager = new WifiApManager(this);
    // the above line shows a Error
    return null;
}
}
}

修改

我想在TextView中显示已处理的文本

class scan extends AsyncTask<String, Void, Void> { 
public Context context;
ArrayList<ClientScanResult> clients;
public scan(Context c)  // constructor to take Context
{
    context = c;   // Initialize your Context variable
}

protected Void doInBackground(String... params) {
        wifiApManager = new WifiApManager(context);  // use the variable here
         clients = wifiApManager.getClientList(false);
        return null;
}
}           
protected void onPostExecute(Void result){
    ArrayList<ClientScanResult> clients;
    tv.setText("WifiApState: " + wifiApManager.getWifiApState() + "\n\n");
    tv.append("Clients: \n");
    for (ClientScanResult clientScanResult : clients)//showin error in clients
 {
            tv.append("####################\n");
            tv.append("IpAddr: " + clientScanResult.getIpAddr() + "\n");
            tv.append("Device: " + clientScanResult.getDevice() + "\n");
            tv.append("HWAddr: " + clientScanResult.getHWAddr() + "\n");
            tv.append("isReachable: " + clientScanResult.isReachable()+ "\n");
                       }
}
}

Answer 1

您不应该访问doInBackground中的任何UI元素，此方法在后台线程中运行。你应该做的是覆盖onPostExecute()方法并访问那里的TextView。 onPostExecute在UI线程中运行，因此您无需致电runOnUiThread()

Answer 2

我添加了AsyncTask以将网络操作卸载到后台线程。我需要确保UI操作在UI线程上。所以我想在我的Activity中使用runOnUiThread（）。

唉！没有！！！ AsyncTask的每个方法都在UI Thread上运行，但doInBackground()除外。在doInBackground()中进行网络操作，并通过UI调用onPostExecute()来更新onProgressUpdate()或publishProgress()中的doInBackground()。

请勿将runOnUiThread()与AsyncTask一起使用。我至少知道没有理由将其与AsyncTask一起使用，因为它具有已经在UI Thread上运行的方法。我从来没有看到它做任何事情，但会造成麻烦。

您可以从publishProgress()致电loop并更新TextView中的onProgressUpdate()或将值添加到ArrayList并更新onProgressUpdate() }}

Please read the docs several times。 AsyncTask一开始有点棘手，但是一旦你了解它做了什么，它就会变得很美好。

修改

创建AsyncTask的实例并将Activity Context传递给它

Scan myScan = new scan(this); // pass the context to the constructor myScan.execute();

然后在AsyncTask中创建一个构造函数，让它接受Context。

public class scan extends AsyncTask<String, Integer, String> { public Object WIFI_SERVICE; public Context context; // Context variable public scan(Context c) // constructor to take Context { context = c; // intialize your Context variable }

现在使用该变量

@Override protected String doInBackground(String... params) { wifiApManager = new WifiApManager(context); // use the variable here return null; }

另一个编辑

class scan extends AsyncTask<String, Void, Void> { ArrayList<ClientScanResult> clients; Context context; ... then initialize your `clients` in `doInBackground()` clients = wifiApManager.getClientList(false);

将onPostExecute()更改为不接受任何内容

protected void onPostExecute(Void result){

并将您的代码更新为TextView。

如何在我的Activity中添加runOnUiThread（）

2 个答案: