这段代码用来在程序中检查当前是否已经联网

java代码

ConnectivityManager con=(ConnectivityManager)getSystemService(Activity.CONNECTIVITY_SERVICE);  boolean wifi=con.getNetworkInfo(ConnectivityManager.TYPE_WIFI).isConnectedOrConnecting();  boolean internet=con.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).isConnectedOrConnecting();

AndroidManifest.xml

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