无法连接到服务器通过WiFi在Android

Question

我想连接一个Android设备到另一个使用WiFi。一台设备充当使用热点的服务器。另一个设备连接到它。但是，当我运行以下代码段时，它会给出以下例外。

java.net.ConnectException: failed to connect to /192.168.43.198 (port 5555): connect failed: ENETUNREACH (Network is unreachable) 

我正在使用下面的文件。 HostActivity.java

public class HostActivity extends Activity { 
ListView lvHost; 
HostAdapter adHost; 
final String HostTAG = "Host1"; 
    @Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_host); 
    WifiManager wifiManager = (WifiManager)this.getSystemService (Context.WIFI_SERVICE); 
    new RetrieveFeedTask2(getApplicationContext()).execute(""); 
       int i =0 ; 
    lvHost = (ListView) findViewById(R.id.lvHost); 
    int j = 0; 
    ArrayList<WifiConfiguration> list = (ArrayList<WifiConfiguration>) wifiManager.getConfiguredNetworks(); 
    adHost = new HostAdapter(list,this); 
    lvHost.setAdapter(adHost); 
} 
@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    getMenuInflater().inflate(R.menu.host, menu); 
    return true; 
} 

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    int id = item.getItemId(); 
    if (id == R.id.action_settings) { 
     return true; 
    } 
    return super.onOptionsItemSelected(item); 
} 

}

class RetrieveFeedTask2 extends AsyncTask<String, Context, String> { 
Context ctx = null; 
public RetrieveFeedTask2(Context Dctx) { 
    // TODO Auto-generated constructor stub 
    ctx = Dctx; 
} 
protected String doInBackground(String ...url) { 
    final String HostTAG = "Host1"; 
    final WifiManager wifiManager = (WifiManager)ctx.getSystemService(Context.WIFI_SERVICE); 
     try { 
      Boolean end = false; 
      Log.i("test","HostRun"); 
      ServerSocket ss = new ServerSocket(5555); 
      while(!end){ 
       Log.i("test", "HostRun2"); 
        //Server is waiting for client here, if needed 
        Socket s = ss.accept(); 
        Log.i("test", "HostRun3"); 
        BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream())); 
        PrintWriter output = new PrintWriter(s.getOutputStream(),true); //Autoflush 
        String st = input.readLine(); 
        Log.i("test", "From client: "+st); 
        System.out.println("From client: "+st); 
        //output.println("Good bye and thanks for all the fish :)"); 
        s.close(); 
        // ArrayList<WifiConfiguration> list = (ArrayList<WifiConfiguration>) wifiManager.getConfiguredNetworks(); 

      } 
    ss.close(); 


    } catch (UnknownHostException e) { 
      // TODO Auto-generated catch block 
      Log.i("test","host unknown"); 
      e.printStackTrace(); 
    } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 



    return null; 
} 

protected void onPostExecute(String feed) { 
    // TODO: check this.exception 
    // TODO: do something with the feed 
    } 
} 

ClientActivity.java

public class ClientActivity extends Activity { 
final String ClientTAG = "Client1"; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_client); 
    WifiManager wifiManager = (WifiManager)getSystemService("wifi"); 
    WifiInfo wifiInfo = wifiManager.getConnectionInfo(); 
    int ipAddress = wifiInfo.getIpAddress(); 
     String ip = Formatter.formatIpAddress(ipAddress); 

    new RetrieveFeedTask().execute(ip); 
} 

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

} 

class RetrieveFeedTask extends AsyncTask<String, String, String> { 
//Context context; 

protected String doInBackground(String ...urls) { 

    final String ClientTAG = "Client1"; 
    InetAddress ia=null; 
    Log.i("test", "ClientRun1"); 
     try { 
      try { 
       ia=InetAddress.getLocalHost(); 
       Log.i("test",ia.toString()); 
      } catch (UnknownHostException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 

      Socket s = new Socket("192.168.43.198",5555); 
      Log.i("test", "ClientRun"); 
      //outgoing stream redirect to socket 
      OutputStream out = s.getOutputStream(); 

      PrintWriter output = new PrintWriter(out); 
      output.println("Hello Android!"); 
      BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream())); 

      //read line(s) 
      String st = input.readLine(); 
      //. . . 
      //Close connection 
      s.close(); 


    } catch (UnknownHostException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } 



    return null; 
} 

protected void onPostExecute(String feed) { 
    // TODO: check this.exception 
    // TODO: do something with the feed 
} 

}

我试着用搜索引擎。许多人都提到了同样的问题，我尝试了所有的解决方案，但仍然无法连接。请帮忙。

Answer 1

几点建议：

1. 在android系统Use 10000 < port number <= 65536。 （小于10000, 可能会发生一些错误）。
2. 如果移动网络处于活动状态，则ServerSocket(port number)将使用外出IP（移动网络的IP）。改为尝试ServerSocket(int port, int backlog, InetAddress localAddress)（您需要指定地址，即热点地址。）
3. 在ClientActivity.java中，我看到您通过execute(ip)传递IP，但您没有使用它。你可以做Socket s = new Socket(ip,5555);。
4. AsyncTask不推荐用于长时间工作。改为使用Thread。