安卓检查网络连接，没有连接的话打开网络设置界面

ConnectivityManager manger = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); 

  NetworkInfo info = manger.getActiveNetworkInfo(); 
  if(info!=null&&info.isConnected())//判断是否有网络连接
  {
   Toast.makeText(MainActivity.this, "联网", Toast.LENGTH_SHORT).show();
  }
  else
  {
   Toast.makeText(MainActivity.this, "联网失败", Toast.LENGTH_SHORT).show();
     if(android.os.Build.VERSION.SDK_INT > 10 ){
       //3.0以上打开设置界面，也可以直接用ACTION_WIRELESS_SETTINGS打开到wifi界面
       startActivity(new Intent(android.provider.Settings.ACTION_SETTINGS));
   } else {
       startActivity(new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS));
   }
   
  }

注意要添加权限： <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>

源码下载地址http://download.csdn.net/download/abc5382334/6592275