Question

我正在实施网络扫描程序。 ping IP地址。如果返回ping，则使用Node类创建Node。但是，当尝试在doinbackground（）中使用publishupdate方法时，我会收到错误。另外，onprogressupdate（）方法表示不覆盖超类。实施有什么问题。我正在阅读文档，但无法弄清楚。任何帮助赞赏。感谢

package com.example.android.droidscanner;

import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by jlvaz on 3/1/2017.
 */

public class IpScanActivity extends AppCompatActivity {

    String ip;
    String mac;
    ArrayList<Node> hostList;
    ListView networkScan;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.scan_list);

        hostList = new ArrayList<>();

        //inflating adapter
        networkScan  = (ListView) findViewById(R.id.scan_list);
        NodeAdapter networkAdapter = new NodeAdapter(this, R.layout.list_item, hostList);
        networkScan.setAdapter(networkAdapter);

        //scanning network
        TaskScanNetwork scanNetwork = new TaskScanNetwork();
        scanNetwork.execute();



    }

    /*
       * AscynTask to scan the network
       * you should try different timeout for your network/devices
       * it will try to detect localhost ip addres and subnet. then
       * it will use subnet to scan network
       *
       */
    private class TaskScanNetwork extends AsyncTask<Void, String, Void> {

        String localIp;
        String mac;
        String subnet;
        static final int lower = 1;
        static final int upper = 254;
        static final int timeout = 1000;

        @Override
        protected void onPreExecute() {
            WifiManager wifiMan = (WifiManager) getSystemService(WIFI_SERVICE);
            WifiInfo wifiInfo = wifiMan.getConnectionInfo();
            int ipAddress = wifiInfo.getIpAddress();
            localIp  = String.format("%d.%d.%d.%d", (ipAddress & 0xff),(ipAddress >> 8 & 0xff),(ipAddress >> 16 & 0xff),(ipAddress >> 24 & 0xff));
            subnet = ip.substring(0, ip.lastIndexOf("."));
            hostList.clear();
            //textResult.setText("Scanning Network...");
        }

        @Override
        protected Void doInBackground(Void... params) {
            for (int i = lower; i <= upper; i++) {
                String host = subnet + "." + i;
                Log.v("Host: ", host);

                try {
                    InetAddress inetAddress = InetAddress.getByName(host);
                    if (inetAddress.isReachable(timeout)) {
                        Node newNode = new Node(host);
                        publishProgress(newNode);
                    }

                } catch (UnknownHostException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            return null;
        }

        @Override
        protected void onProgressUpdate(Node... values) {
            hostList.add(values[0]);
            networkScan.deferNotifyDataSetChanged();
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            //result.setText("Live Hosts: ");
        }
    }

}

节点类

package com.example.android.droidscanner;

import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * Created by george on 2/14/17.
 */

public class Node {
    String ip;
    String mac;
    String CanonicalHostName;
    String HostName;
    String remark;
    boolean isReachable;

    Node(String ip){
        this.ip = ip;
        //this.mac = mac;
        this.isReachable = true;
    }

    public String getIp() {
        return ip;
    }

    public String getHostName() {
        return HostName;
    }

    public String getMac() {
        return mac;
    }

    public String getRemark() {
        return remark;
    }

    public boolean isReachable() {
        return isReachable;
    }

    @Override
    public String toString() {
        return "IP: " + ip + "\n" +
                "MAC: " + mac + "\n" +
                "CanonicalHostName:\t" + CanonicalHostName + "\n" +
                "HostName:\t" + HostName + "\n" +
                "isReachable: " + isReachable +
                "\n" + remark;
    }

    private void queryHost(){
        try {
            InetAddress inetAddress = InetAddress.getByName(ip);
            CanonicalHostName = inetAddress.getCanonicalHostName();
            HostName = inetAddress.getHostName();

        } catch (UnknownHostException e) {
            e.printStackTrace();
            remark = e.getMessage();
        } catch (IOException e) {
            e.printStackTrace();
            remark = e.getMessage();
        }
    }
}

NodeAdapter类

public class NodeAdapter extends ArrayAdapter<Node>{

    public NodeAdapter(Context context, int num, ArrayList<Node> allHost) {
        super(context, 0, allHost);
    }

    @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        Node host = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
        }
        // Lookup view for data population
        TextView nodeIpTxtView = (TextView) convertView.findViewById(R.id.node_ip);
        TextView nodeMacTxtView = (TextView) convertView.findViewById(R.id.node_mac);
        // Populate the data into the template view using the data object
        nodeIpTxtView.setText(host.getIp());
        nodeMacTxtView.setText(host.getMac());
        // Return the completed view to render on screen
        return convertView;
    }
}

Answer 1

错误，我认为你的意思是编译错误。 AsyncTask是一种泛型类型，它定义了许多通用参数。可以将定义想象如下：

AsyncTask<BACKGROUND, PROGRESS, POST_EXECUTE>

您目前有：

AsyncTask<Void, String, Void>

所以你说：

通过我的方法Void
进度通过我的方法String
on post execute pass my method Void

但是，您的onProgressUpdate方法需要Node类型。因此，请将TaskScanNetwork的定义更改为：

private class TaskScanNetwork extends AsyncTask<Void, Node, Void> {

这里也有一个很好的例子和解释。如果您已经看过这个，请道歉：

https://developer.android.com/reference/android/os/AsyncTask.html#AsyncTask()

我怎么能修复Asynctask类的publishupdate方法

1 个答案: