My code for before android Q is here
but for android Q this function return "unknown ssid".
I know that for android Q must use this ConnectivityManager.NetworkCallback and ConnectivityManager#getNetworkCapabilities and ConnectivityManager#getLinkProperties.but i cant find sample code or guid.
private String get_connected_ssid() {
String s1 = null ,s2 = null;
try {
WifiManager wifi = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
assert wifi != null;
WifiInfo wifiinfo = wifi.getConnectionInfo();
List<WifiConfiguration> listOfConfigurations = wifi.getConfiguredNetworks();
for (int index = 0; index < listOfConfigurations.size(); index++) {
WifiConfiguration configuration = listOfConfigurations.get(index);
if (configuration.networkId == wifiinfo.getNetworkId()) {
s1 = configuration.SSID;
}
}
}catch (Exception e){
e.printStackTrace();
}
/* NetworkInfo Deprecated in API level 29
Callers should instead use the ConnectivityManager.NetworkCallback API to learn about connectivity changes,
or switch to use ConnectivityManager#getNetworkCapabilities or ConnectivityManager#getLinkProperties to
get information synchronously. Keep in mind that while callbacks are guaranteed to be called for every
event in order, synchronous calls have no such constraints, and as such it is unadvisable to use the
synchronous methods inside the callbacks as they will often not offer a view of networking that is
consistent (that is: they may return a past or a future state with respect to the event being processed
by the callback). Instead, callers are advised to only use the arguments of the callbacks, possibly
memorizing the specific bits of information they need to keep from one callback to another.
*/
//getActiveNetworkInfo Deprecated in API level 29 -->useUse NetworkCallbacks instead for apps that target Android 10 (API level 29) and higher-->refrence : developer.android
//getExtraInfo() Deprecated in API level 29
try {
ConnectivityManager cm = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
assert cm != null;
NetworkInfo info = cm.getActiveNetworkInfo();
if (info != null && info.isConnected()) {
}
}catch (Exception e){
e.printStackTrace();
}
return s1 + s2;
}
Related
I am trying to implement a feature where I want the user to see if all requests to the server have been handled, i.e. that the client is in sync with the server so that the user can be confident that all his changes are saved.
My idea was to override Meteor.call and keep a counter for each call and then when a reply/error is returned I decrease the counter. I will then on the client show a message saying "Synced" if the counter is zero otherwise I will show "Unsynced".
Basically my question is if there is any "built-in" feature in Meteor which already handles this, keeping track of outgoing Meteor calls, or if I should proceed as I have started?
This is what my code looks at this moment:
var originalMeteorCall = Meteor.call;
var counter = 0;
Meteor.call = function() {
if (this.isClient) {
if (arguments && arguments.length > 1) {
counter++;
var returnFunc = arguments[arguments.length - 1];
var newReturnFunc = function (err, result) {
counter--;
return returnFunc(err, result);
}
arguments[arguments.length - 1] = newReturnFunc;
}
}
var result = originalMeteorCall.apply(this, arguments);
return result;
}
I have been implementing the module to send the bytes in chunks, 20 bytes each onto the MCU device via BLE. When it comes to writing the bytes more than 60 bytes and so on, the last chunk of the bytes ( usually less than 20 bytes) is often missed. Hence, the MCU device cannot get the checksum and write the value. I have modified the call back to Thread.sleep(200) to change it but it sometimes works on writing 61 bytes or sometimes not. Would you please tell me are there any synchronous method to write the bytes in chunks ? The below is my working :
#Override
public void onCharacteristicWrite(BluetoothGatt gatt,
BluetoothGattCharacteristic characteristic, int status) {
try {
Thread.sleep(300);
if (status != BluetoothGatt.GATT_SUCCESS) {
disconnect();
return;
}
if(status == BluetoothGatt.GATT_SUCCESS) {
System.out.println("ok");
broadcastUpdate(ACTION_DATA_READ, mReadCharacteristic, status);
}
else {
System.out.println("fail");
broadcastUpdate(ACTION_DATA_WRITE, characteristic, status);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public synchronized boolean writeCharacteristicData(BluetoothGattCharacteristic characteristic ,
byte [] byteResult ) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
return false;
}
boolean status = false;
characteristic.setValue(byteResult);
characteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);
status = mBluetoothGatt.writeCharacteristic(characteristic);
return status;
}
private void sendCommandData(final byte [] commandByte) {
// TODO Auto-generated method stub
if(commandByte.length > 20 ){
final List<byte[]> bytestobeSent = splitInChunks(commandByte);
for(int i = 0 ; i < bytestobeSent.size() ; i ++){
for(int k = 0 ; k < bytestobeSent.get(i).length ; k++){
System.out.println("LumChar bytes : "+ bytestobeSent.get(i)[k] );
}
BluetoothGattService LumService = mBluetoothGatt.getService(A_SERVICE);
if (LumService == null) { return; }
BluetoothGattCharacteristic LumChar = LumService.getCharacteristic(AW_CHARACTERISTIC);
if (LumChar == null) { System.out.println("LumChar"); return; }
//Thread.sleep(500);
writeCharacteristicData(LumChar , bytestobeSent.get(i));
}
}else{
....
You need to wait for the onCharacteristicWrite() callback to be invoked before sending the next write. The typical solution is to make a job queue and pop a job off the queue for each callback you get to onCharacteristicWrite(), onCharacteristicRead(), etc.
In other words, you can't do it in a for loop unfortunately, unless you want to set up some kind of lock that waits for the callback before going on to the next iteration. In my experience a job queue is a cleaner general-purpose solution though.
I am trying to retrieve a value from a Zebra printer by interrogating it with this code:
public static string GetSettingFromPrinter(string cmd)
{
string setting = string.Empty;
try
{
BasicPortSettings bps = new BasicPortSettings();
bps.BaudRate = BaudRates.CBR_19200;
bps.Parity = OpenNETCF.IO.Serial.Parity.none;
bps.StopBits = OpenNETCF.IO.Serial.StopBits.one;
Port serialPort = new Port("COM1:", bps);
serialPort.Open();
byte[] sendBytes = Encoding.ASCII.GetBytes(cmd);
MessageBox.Show(Encoding.ASCII.GetString(sendBytes, 0, sendBytes.Length));
serialPort.Output = sendBytes;
serialPort.Query(); // <= this is new
byte[] responseBytes = serialPort.Input;
setting = GetString(responseBytes);
serialPort.Close();
return setting;
}
catch (Exception x)
{
MessageBox.Show(x.ToString());
return setting;
}
}
However, I don't see where the Output is actually sent, or how to do that. My best guess was calling the Port.Query() method, but that doesn't work, either - at least there is nothing in setting / the Port.Input value after doing so.
I have successfully passed commands to the printer using the older SerialPort class:
public static bool SendCommandToPrinter(string cmd)
{
bool success; // init'd to false by default
try
{
SerialPort serialPort = new SerialPort();
serialPort.BaudRate = 19200;
serialPort.Handshake = Handshake.XOnXOff;
serialPort.Open();
serialPort.Write(cmd);
serialPort.Close();
success = true;
}
catch // may not need a try/catch block, as success defaults to false
{
success = false;
}
return success;
}
...but was advised not to use that due to its longness of tooth.
I would revert back to this snaggletooth if I knew how to read from the old SerialPort class. Does anybody know what I need to do to send sendBytes (and receive responseBytes)?
UPDATE
I tested "COM1" instead of "COM1:" (I used the latter because there is a post that says the colon is necessary (<= not medical advice, although that is doubtless true in that sense, too), but sans the ":" made no noticeable difference.
I then tried "string.Empty" in place of giving it a name, and got, "OpenNETCF.IO.Serial.CommPortException: CreateFileFailed 2 ..."
Onward...or is it Sideward...
FWIW, setting the Output property immediately sends the data on the wire. No additional call is necessary.
I want to create an application wide feed on my ASP.net 3.5 web site using the application cache. The data that I am using to populate the cache is slow to obtain, maybe up to 10 seconds (from a remote server's data feed). My question/confusion is, what is the best way to structure the cache management.
private const string CacheKey = "MyCachedString";
private static string lockString = "";
public string GetCachedString()
{
string data = (string)Cache[CacheKey];
string newData = "";
if (data == null)
{
// A - Should this method call go here?
newData = SlowResourceMethod();
lock (lockString)
{
data = (string)Cache[CacheKey];
if (data != null)
{
return data;
}
// B - Or here, within the lock?
newData = SlowResourceMethod();
Cache[CacheKey] = data = newData;
}
}
return data;
}
The actual method would be presented by and HttpHandler (.ashx).
If I collect the data at point 'A', I keep the lock time short, but might end up calling the external resource many times (from web pages all trying to reference the feed). If I put it at point 'B', the lock time will be long, which I am assuming is a bad thing.
What is the best approach, or is there a better pattern that I could use?
Any advice would be appreciated.
I add the comments on the code.
private const string CacheKey = "MyCachedString";
private static readonly object syncLock = new object();
public string GetCachedString()
{
string data = (string)Cache[CacheKey];
string newData = "";
// start to check if you have it on cache
if (data == null)
{
// A - Should this method call go here?
// absolut not here
// newData = SlowResourceMethod();
// we are now here and wait for someone else to make it or not
lock (syncLock)
{
// now lets see if some one else make it...
data = (string)Cache[CacheKey];
// we have it, send it
if (data != null)
{
return data;
}
// not have it, now is the time to look for it.
// B - Or here, within the lock?
newData = SlowResourceMethod();
// set it on cache
Cache[CacheKey] = data = newData;
}
}
return data;
}
Better for me is to use mutex and lock depended on the name CacheKey and not lock all resource and the non relative one. With mutex one basic simple example will be:
private const string CacheKey = "MyCachedString";
public string GetCachedString()
{
string data = (string)Cache[CacheKey];
string newData = "";
// start to check if you have it on cache
if (data == null)
{
// lock it base on resource key
// (note that not all chars are valid for name)
var mut = new Mutex(true, CacheKey);
try
{
// Wait until it is safe to enter.
// but also add 30 seconds max
mut.WaitOne(30000);
// now lets see if some one else make it...
data = (string)Cache[CacheKey];
// we have it, send it
if (data != null)
{
return data;
}
// not have it, now is the time to look for it.
// B - Or here, within the lock?
newData = SlowResourceMethod();
// set it on cache
Cache[CacheKey] = data = newData;
}
finally
{
// Release the Mutex.
mut.ReleaseMutex();
}
}
return data;
}
You can also read
Image caching issue by using files in ASP.NET
Using GraphEdit, I can add the filter to the editor and use it to render a video. When I create the instance via COM (using DirectShow.NET), the method EnumPins (followed by Next checks) returns no pins.
Is there a reason why GraphEdit would show the pins and I cannot get a reference to the pins via the COM interfaces?
EDIT: Here is the method I am using to get the first available pin (of any type). Nothing is ever returned for this filter, but I can see 4 pins (two in, two out) in graph edit.
public static IPin GetPins(IBaseFilter vSource, int iIndex)
{
IEnumPins pins;
var ppPins = new IPin[1];
if (vSource == null)
return null;
DsError.ThrowExceptionForHR(vSource.EnumPins(out pins));
try
{
while (pins.Next(1, ppPins, IntPtr.Zero) == 0)
{
return ppPins[0];
}
}
finally
{
Marshal.ReleaseComObject(pins);
}
return null;
}