嗨，我尝试使用以下方法检查网络连接和Internet存在
check = new ConnectionDetector（getApplicationContext（））;
conn = check.isConnectingToInternet（）;
public class ConnectionDetector {
private Context _context;
public ConnectionDetector(Context context){
this._context = context;
}
/**
* Checking for all possible internet providers
* **/
/*public boolean isConnectingToInternet(){
ConnectivityManager connectivity = (ConnectivityManager) _context.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivity != null)
{
NetworkInfo[] info = connectivity.getAllNetworkInfo();
if (info != null)
for (int i = 0; i < info.length; i++)
if (info[i].getState() == NetworkInfo.State.CONNECTED)
{
return true;
}
}
return false;
}*/
public boolean isConnectingToInternet(){
try{
ConnectivityManager cm = (ConnectivityManager)_context.getSystemService
(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
Log.d("NetInfo", String.valueOf(netInfo));
if (netInfo != null && netInfo.isConnected())
{
//Network is available but check if we can get access from the network.
URL url = new URL("http://www.Google.com/");
HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
urlc.setRequestProperty("Connection", "close");
urlc.setConnectTimeout(2000); // Timeout 2 seconds.
urlc.connect();
Log.d("NetInfo Response Code", String.valueOf(urlc.getResponseCode()));
// Toast.makeText(getApplicationContext(), String.valueOf(urlc.getResponseCode()), Toast.LENGTH_LONG).show();
if (urlc.getResponseCode() == 200) //Successful response.
{
return true;
}
else
{
Log.d("NO INTERNET", "NO INTERNET");
return false;
}
}
}
catch(Exception e)
{
e.printStackTrace();
}
return false;
}
}
注意：
但这将返回NetworkOnMainThread异常，如下所示。任何人都建议我犯了什么错误.......
03-27 12:53:35.617: W/System.err(1095): android.os.NetworkOnMainThreadException
03-27 12:53:35.627: W/System.err(1095): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1084)
03-27 12:53:35.637: W/System.err(1095): at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
03-27 12:53:35.637: W/System.err(1095): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
03-27 12:53:35.647: W/System.err(1095): at java.net.InetAddress.getAllByName(InetAddress.java:220)
03-27 12:53:35.647: W/System.err(1095): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:71)
03-27 12:53:35.657: W/System.err(1095): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
03-27 12:53:35.668: W/System.err(1095): at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351)
03-27 12:53:35.668: W/System.err(1095): at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86)
03-27 12:53:35.677: W/System.err(1095): at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
03-27 12:53:35.687: W/System.err(1095): at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308)
03-27 12:53:35.699: W/System.err(1095): at libcore.net.http.HttpEngine.connect(HttpEngine.java:303)
03-27 12:53:35.699: W/System.err(1095): at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
03-27 12:53:35.707: W/System.err(1095): at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
03-27 12:53:35.718: W/System.err(1095): at libcore.net.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:80)
03-27 12:53:35.727: W/System.err(1095): at com.slet.routemytrips.beta.ConnectionDetector.isConnectingToInternet(ConnectionDetector.java:50)
03-27 12:53:35.727: W/System.err(1095): at com.slet.routemytrips.beta.Disclaimer$1.onClick(Disclaimer.java:178)
03-27 12:53:35.738: W/System.err(1095): at android.view.View.performClick(View.java:3480)
03-27 12:53:35.738: W/System.err(1095): at android.view.View$PerformClick.run(View.java:13983)
03-27 12:53:35.748: W/System.err(1095): at android.os.Handler.handleCallback(Handler.java:605)
03-27 12:53:35.757: W/System.err(1095): at android.os.Handler.dispatchMessage(Handler.java:92)
03-27 12:53:35.757: W/System.err(1095): at android.os.Looper.loop(Looper.java:137)
03-27 12:53:35.767: W/System.err(1095): at android.app.ActivityThread.main(ActivityThread.java:4340)
03-27 12:53:35.777: W/System.err(1095): at java.lang.reflect.Method.invokeNative(Native Method)
03-27 12:53:35.777: W/System.err(1095): at java.lang.reflect.Method.invoke(Method.java:511)
03-27 12:53:35.787: W/System.err(1095): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
03-27 12:53:35.797: W/System.err(1095): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
03-27 12:53:35.807: W/System.err(1095): at dalvik.system.NativeStart.main(Native Method)
03-27 12:57:05.237: D/dalvikvm(90): GC_CONCURRENT freed 666K, 10% free 12624K/14023K, paused 6ms+10ms
答案 0 :(得分：8)
您无法在主线程上发出HTTP请求，这会导致UI冻结。所以它引发了异常。您需要在AsyncTask或其他线程中执行此操作。
答案 1 :(得分：1)
http://developer.android.com/reference/android/os/NetworkOnMainThreadException.html
如果您尝试在主UI线程中发出网络请求，则抛出 NetworkOnMainThreadException。因此，所有与网络相关的操作都应该在后台线程上完成。
AsyncTask旨在成为Thread和Handler的辅助类，并不构成通用的线程框架。 AsyncTasks理想情况下应该用于短操作（最多几秒钟。）如果需要保持线程长时间运行，强烈建议您使用java提供的各种API .util.concurrent pacakge，如Executor，ThreadPoolExecutor和FutureTask。
http://developer.android.com/reference/android/os/AsyncTask.html
class TheTask extends AsyncTask<Void,Void,Void>
{
protected void onPreExecute()
{ super.onPreExecute();
//display progressdialog.
}
protected void doInBackground(Void ...params)
{
//http request. do not update ui here
return null;
}
protected void onPostExecute(Void result)
{
super.onPostExecute(result);
//dismiss progressdialog.
//update ui
}
}
asynctask的替代品是Robospice。可以制作多个香料请求。通知ui线程。 https://github.com/octo-online/robospice
检查Netowrk连接。
在您的活动中
public class MainActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
if(CheckNetwork.isInternetAvailable(MainActivity.this))
{
//call asyntask and make http request.
}
}
CheckNetwork类
public class CheckNetwork {
private static final String TAG = CheckNetwork.class.getSimpleName();
public static boolean isInternetAvailable(Context context)
{
NetworkInfo info = (NetworkInfo) ((ConnectivityManager)
context.getSystemService(Context.CONNECTIVITY_SERVICE)).getActiveNetworkInfo();
if (info == null)
{
Log.d(TAG,"no internet connection");
return false;
}
else
{
if(info.isConnected())
{
Log.d(TAG," internet connection available...");
return true;
}
else
{
Log.d(TAG," internet connection");
return true;
}
}
}
}