检测android设备是否连接到互联网

Question

这是我的课程，用于检查设备是否已连接到互联网。

import android.app.Activity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.util.Log;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;


public class ConnectionDetector {
    private Context _context;

    public ConnectionDetector(Context context) {
        this._context = context;
    }

    public boolean isConnectingToInternet() {
        if (networkConnectivity()) {
            try {
                HttpURLConnection urlc = (HttpURLConnection) (new URL(
                        "http://www.google.com").openConnection());
                urlc.setRequestProperty("User-Agent", "Test");
                urlc.setRequestProperty("Connection", "close");
                urlc.setConnectTimeout(3000);
                urlc.setReadTimeout(4000);
                urlc.connect();
                // networkcode2 = urlc.getResponseCode();
                return (urlc.getResponseCode() == 200);
            } catch (IOException e) {
                return (false);
            }
        } else
            return false;

    }

    private boolean networkConnectivity() {
    ConnectivityManager cm = (ConnectivityManager) _context
            .getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = cm.getActiveNetworkInfo();
    if (networkInfo != null && networkInfo.isConnected()) {
        return true;
    }
    return false;
}

}

然后我在这里调用它，但它似乎没有返回真或假。没有错误，我的应用程序不会崩溃，只是不会打印任何内容。有人知道为什么吗？

public void CheckInternet(){

   // Boolean isInternetPresent;

    ConnectionDetector cd = new ConnectionDetector(getApplicationContext());

 //   isInternetPresent = cd.isConnectingToInternet();

    if (cd.isConnectingToInternet()) {
        // Internet Connection is Present

        Log.i(TAG, "INTERNET IS GUUD");

    } else {
        // Internet connection is not present
        // Ask user to connect to Internet
        Log.i(TAG, "INTERNET IS NOOOO GUUD");

    }
}

Answer 1

创建一个类：

public class Utility {
    public static boolean isNetworkAvailable(Context context) {
        ConnectivityManager connectivityManager
                = (ConnectivityManager)  context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
        return activeNetworkInfo != null && activeNetworkInfo.isConnected();
    }
}

然后你从activity调用methode，它会返回true或false：

Utility.isNetworkAvailable(AnyActivity.this);

别忘了给 android manifest 添加权限

    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>

Answer 2

这不是检查互联网连接的正确方法。为此，您应该使用 Android 内置的 ConnectivityManager 类。

它使用起来非常简单，您只需执行以下操作即可检查网络连接：

ConnectivityManager cm =
        (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null &&
                      activeNetwork.isConnectedOrConnecting();

这还可以让您确定连接类型、是否受监控等，以便您可以就正在执行的网络任务做出明智的决定。

在 Android 开发者网站上的this lesson 中有更多信息。

Answer 3

您必须在异步任务中执行此操作。我用http://clients3.google.com/generate_204 检测连接。

    import java.net.HttpURLConnection;
    import java.net.URL;


    ...

    private int inter = 0;   


    ...


     new checkconne().execute();

    ...



    class checkconne extends AsyncTask<String, String, String> {

                            @Override
                            protected void onPreExecute() {
                                super.onPreExecute();



                            }
                            @Override
                            protected String doInBackground(String... args) {

                                int kk=0;
                                try {
                                    HttpURLConnection urlc = (HttpURLConnection)
                                            (new URL("http://clients3.google.com/generate_204")
                                                    .openConnection());
                                    urlc.setRequestProperty("User-Agent", "Android");
                                    urlc.setRequestProperty("Connection", "close");
                                    urlc.setConnectTimeout(1500);
                                    urlc.connect();
                                    kk= urlc.getResponseCode();
                                } catch (IOException e) {


        Log.e("qweqwe", "Error checking internet connection", e);
                            }

                            inter=kk;



                            return null;
                        }
                        @Override
                        protected void onPostExecute(String file_url) {


                            if (inter == 204){       
             Toast.makeText(MainActivity3.this, "is connected", Toast.LENGTH_LONG).show();             

                            }else{    


                                Toast.makeText(MainActivity3.this, "No connection", Toast.LENGTH_LONG).show();

                            }


                        }
                    }

Answer 4

调用这个函数：

     public static boolean isNetworkAvailable()
     {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);

        HttpGet httpGet = new HttpGet("http://www.google.com");
        HttpParams httpParameters = new BasicHttpParams();
        int timeoutConnection = 1000;
        HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
        int timeoutSocket = 1500;
        HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
        DefaultHttpClient httpClient = new DefaultHttpClient(httpParameters);
        try
        {
           httpClient.execute(httpGet);
           return true;
        }
        catch(ClientProtocolException e)
        {
           e.printStackTrace();
        }
        catch(IOException e)
        {
           e.printStackTrace();
        }
    return false;
  }