这对我来说确实有用:

验证网络可用性。

private Boolean isNetworkAvailable() {
ConnectivityManager connectivityManager 
      = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
return activeNetworkInfo != null && activeNetworkInfo.isConnectedOrConnecting();}

验证互联网接入:

public Boolean isOnline() {
    try {
        Process p1 = java.lang.Runtime.getRuntime().exec("ping -c 1 www.google.com");
        int returnVal = p1.waitFor();
        boolean reachable = (returnVal==0);
        return reachable;
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return false;
}

在我目前所见过的所有方法中，最短、最干净的方法应该是:

public final static boolean isConnected( Context context )
{   
   final ConnectivityManager connectivityManager = 
         (ConnectivityManager) context.getSystemService( Context.CONNECTIVITY_SERVICE );  
   final NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();    
   return networkInfo != null && networkInfo.isConnected();
}

PS:这不会ping任何主机，它只是检查连接状态，所以如果你的路由器没有互联网连接，而你的设备连接到它，这个方法将返回true，尽管你没有互联网。 对于实际的测试，我建议执行一个HttpHead请求(例如到www.google.com)并检查状态，如果它是200 OK，一切正常，并且您的设备有互联网连接。

非常重要的是检查我们是否与isAvailable()有连接，以及是否可能与isConnected()建立连接

private static ConnectivityManager manager;

public static boolean isOnline(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    return networkInfo != null && networkInfo.isAvailable() && networkInfo.isConnected();
}

你可以取消网络活动WiFi的类型:

public static boolean isConnectedWifi(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    return networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_WIFI;
}

或手机Móvil:

public static boolean isConnectedMobile(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    return networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_MOBILE;
}

不要忘记权限:

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

移动设备上的一个重要用例是确保存在实际连接。当移动用户使用“专属门户”进入Wifi网络时，这是一个常见的问题，他们需要在其中登录。我在后台使用这个阻塞功能来确保连接存在。

/*
 * Not Thread safe. Blocking thread. Returns true if it
 * can connect to URL, false and exception is logged.
 */
public boolean checkConnectionHttps(String url){
    boolean responded = false;
    HttpGet requestTest = new HttpGet(url);
    HttpParams params = new BasicHttpParams();
    HttpConnectionParams.setConnectionTimeout(params, 3000);
    HttpConnectionParams.setSoTimeout(params, 5000);
    DefaultHttpClient client = new DefaultHttpClient(params);
    try {
        client.execute(requestTest);
        responded = true;
    } catch (ClientProtocolException e) {
        Log.w(MainActivity.TAG,"Unable to connect to " + url + " " + e.toString());
    } catch (IOException e) {
        Log.w(MainActivity.TAG,"Unable to connect to " + url + " " + e.toString());
        e.printStackTrace();
    }
    return responded;
}

这对我很有用。试试吧。

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    try {
        URL url = new URL("http://stackoverflow.com/posts/11642475/edit" );
        //URL url = new URL("http://www.nofoundwebsite.com/" );
        executeReq(url);
        Toast.makeText(getApplicationContext(), "Webpage is available!", Toast.LENGTH_SHORT).show();
    }
    catch(Exception e) {
        Toast.makeText(getApplicationContext(), "oops! webpage is not available!", Toast.LENGTH_SHORT).show();
    }
}

private void executeReq(URL urlObject) throws IOException
{
    HttpURLConnection conn = null;
    conn = (HttpURLConnection) urlObject.openConnection();
    conn.setReadTimeout(30000);//milliseconds
    conn.setConnectTimeout(3500);//milliseconds
    conn.setRequestMethod("GET");
    conn.setDoInput(true);

    // Start connect
    conn.connect();
    InputStream response =conn.getInputStream();
    Log.d("Response:", response.toString());
}}

public boolean isOnline() {
    boolean var = false;
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    if ( cm.getActiveNetworkInfo() != null ) {
        var = true;
    }
    return var;
} 

我是这样做的。 我想会更短更有可读性。

干杯!

Saiyan