From my Android phone, I'm trying to read (using Bluetooth) incomming strings from an external GPS device. I've followed mainly the BluetoothChat example and everything seems to work as expected so far. My reading thread is executing and I can see variable bytes packets incoming when looping with the following code:
Log.d(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true)
{
try
{
bytes = mmInStream.read(buffer);
// Test...
String strReadBuf = new String(buffer, 0, bytes);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(BluetoothHandler.MessageType.READ,
bytes, buffer).sendToTarget();
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
sendErrorMessage(R.string.bt_connection_lost);
break;
}
}
The strings I'm supposed to read are text strings (NMEA format) but I'm reading only 0 and -32 bytes in my buffer array. Any idea why I'm getting this?
Log.d(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true)
{
try
{
bytes = mmInStream.read(buffer);
// Test...
//String strReadBuf = new String(buffer, 0, bytes);
//I've changed for
String strReadBuf = new String(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(BluetoothHandler.MessageType.READ,
bytes, buffer).sendToTarget();
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
sendErrorMessage(R.string.bt_connection_lost);
break;
}
}
I used the String constructor String(byte[]), where byte[] is the buffer deprecating the byte[] size. I've used many times and that works for me even if the buffer size changes over time.
Related
I have the following code and i'm trying to save the received bytes to a String until i receive \n.
byte[] buffer = new byte[1024];
int bytes;
String ReceivedMessage = null;
while (true) {
try
{
// Read from the InputStream
bytes = mmInStream.read(buffer);
ReceivedMessage = ReceivedMessage + getString(bytes);
// Send the obtained bytes to the UI Activity
if(ReceivedMessage.endsWith("\\n")) {
String StringToReturn = ReceivedMessage.replace("\\n","");
Message msg = mHandler.obtainMessage(AbstractActivity.MESSAGE_READ);
Bundle bundle = new Bundle();
bundle.putString("Message", StringToReturn);
msg.setData(bundle);
mHandler.sendMessage(msg);
//mHandler.obtainMessage(AbstractActivity.MESSAGE_READ, bytes, -1, buffer)
// .sendToTarget();
}
} catch (IOException e) {
e.printStackTrace();
connectionLost();
BluetoothService.this.stop();
break;
}
The problem is that it is crashing on ReceivedMessage = ReceivedMessage + getString(bytes);, more exactly on getString(bytes)
Can you help me to fix it?
Thanks!
String TempString = new String(buffer,0,bytes);
ReceivedMessage = ReceivedMessage + TempString;
Editing this as I can't post comments:
You can only read a buffer once and
bytes = mmInStream.read(buffer);
reads the contents if indeed it's the same buffer. Hard to tell.
while(true) also means this will eventually trigger an exception.
[EDIT]
What's the stacktrace? What does getString call? Why are you using "while (true)" without any way out? Are you trying to read from the StreamBuffer twice?
(this would be a comment but haven't got enough rep)
I use some of the Bluetooth chat samplecode for sending a SMALL (177 byte to 3617 byte) "settings-file" "securly" between apps.
when it is under 1024 bit everything works fine: (so the 177 works PERFECT)
sendingdevice press "send button" and the reciver gets it (with a dialog if they want it..) (and I save the "string" to a "settings"file on that device)
but if the file is over 1024 it gets chunkt/cut off.. (example: 2000byte)
so the file gets corrupted (data-loss but some info remains..)
Probably I need to "split" my file in 1024 bits and send the bits and in the receiver-end, I need to "add them all up"..
but I don't know the "standard best practices" for this, do you have any suggestions?
I have tryed to "only higher" the 1024 byte to 65536byte, but that don't work..
(or maby I do this wrong..)
public void run() {
Log.i(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(BluetoothChat.MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
connectionLost();
// Start the service over to restart listening mode
BluetoothChatService.this.start();
break;
}
}
}
sedan write:
/**
* Write to the connected OutStream.
* #param buffer The bytes to write
*/
public void write(byte[] buffer) {
try {
mmOutStream.write(buffer);
mmOutStream.flush();
// Share the sent message back to the UI Activity
mHandler.obtainMessage(BluetoothChat.MESSAGE_WRITE, -1, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e(TAG, "Exception during write", e);
}
}
and when i "click on send settings":
String message = view.getText().toString();
String settingInAString = getSettingInALargeString();
sendMessage(settingInAString);
and in "sendMessage":
if (message.length() > 0) {
// Get the message bytes and tell the BluetoothChatService to write
byte[] send = message.getBytes();
mChatService.write(send); //SO convert to byte and then send the byte..
// Reset out string buffer to zero and clear the edit text field
mOutStringBuffer.setLength(0);
mOutEditText.setText(mOutStringBuffer);
}
and:
/**
* Write to the ConnectedThread in an unsynchronized manner
* #param out The bytes to write
* #see ConnectedThread#write(byte[])
*/
public void write(byte[] out) {
// Create temporary object
ConnectedThread r;
// Synchronize a copy of the ConnectedThread
synchronized (this) {
if (mState != STATE_CONNECTED) return;
r = mConnectedThread;
}
// Perform the write unsynchronized
r.write(out);
}
but I think you know what Im lookning for ...
(or can I some how change the "BluetoothChat" so it can sent and recive a large Sring, and not "byte:s"? :-) )
Best REGARDS to you all :-)
EDIT:
on the reader side I have this:
on the "reader end" I have:
....
case MESSAGE_READ:
byte[] readBuf = (byte[]) msg.obj;
//only a byte redebuffer, hmm can I change this? or do i use a whileloop?
// construct a string from the valid bytes in the buffer
String readMessage = new String(readBuf, 0, msg.arg1);
recivedStringCheckFirst(readMessage);
//simple-check if the data is a "data-setting-file"
String [] allSettingsInALargeArray1 = doSplitOnLargeString(readMessage);
int titleArrayLength1 = getLengthOffTheUpCommingTitleArrayFromNew(allSettingsInALargeArray1); //this do a split and looks if it is 1,2,3..20 settings..)
mConversationArrayAdapter.add(titleArrayLength1 + " datasettings recived from " + mConnectedDeviceName + " SAVE THIS?");
//this type this text to the "chatwindow"
break;
Here is the splitting-chunk-problem now..
if i send under ~ 1024 I receive the correct amount of settings ant i can save this fine :-)
If i sent larger then 1024 I get first for exampel "6 settings from.." and then a new message that I recived "1 settings from.." message :-(
just for your info:
protected void recivedStringCheckFirst(String readMessage) {
String eventuellSettings = readMessage;
if (isThisASettingFile(eventuellSettings)){
//of ok..
System.out.println("incommingISAsetting :-) ");
inkommenSettings = eventuellSettings;
showDialog(); //dialog for save settings?
}
if (!isThisASettingFile(eventuellSettings)){
//not a settingsfile!
Toast.makeText(this, "try again..", Toast.LENGTH_LONG).show();
}
}
so i think it is:
case MESSAGE_READ:
is not only called if a complete file is received,
it is also called if a small chunks is received.
So I probably should place the "readFile-chunk" in a separate buffer
(i.e. mNewBufForFile += readFileChunk)
And then check the mNewBufForFile has a complete packet in it (how?). If it is done: I "save" the file message and then clear all buffer.
but how can i "split this from "Message_read", and do I "add a stopping bit" so i can check when i recive all the data? or can i do this better?
You can send as many bytes as you want. They come in in chunks smaller than the size of buffer (1024). Indeed the original code will mix all up caused by using one buffer. Change
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(BluetoothChat.MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
to
while (true) {
try {
byte[] buffer = new byte[1024];
// Read from the InputStream
int nbytes = mmInStream.read(buffer);
Log.i(TAG, "read nbytes: " + nbytes);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(BluetoothChat.MESSAGE_READ, nbytes, -1, buffer)
.sendToTarget();
The data still comes in in chuncks but now you get all displayed in the rigth sequence.
As the chunck sizes -during some tests- are smaller than 1024 it makes no sense to have a bigger buffer. If you want to transfer a real file you should concatenate all together. This is a normal action using sockets.
I need to monitor an InputStream for '\n'. Once the '\n' is found at the end of the InputStream, the code will return all the InputStream buffer back to UI. I have tried several methods without luck.
Here is my pseudo code.
public void run() {
byte[] buffer = new byte[256];
int bytes;
// Keep listening and till InputStream has '\n'
try {
while (true) {
// Read from the InputStream some code here to check the occurrence of '\n';
break;
}
SystemClock.sleep(1);
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer).sendToTarget();
} catch (IOException e) {
// Some code here to handle exception
}
}
I have implemented a bluetooth connection using the now-classic Google Bluetooth Chat code. However, I have a question which I just cannot seem to wrap my brain around.
The reading of the input stream goes something like this:
public void run() {
byte[] buffer = new byte[1024]; // buffer store for the stream
int bytes; // bytes returned from read()
// Keep listening to the InputStream until an exception occurs
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
break;
}
}
}
Now, that's fine if I was just printing out the characters I was receiving as in the original example. However, suppose I wanted to transfer an image file. I don't know the size of the file, so I cannot count the bytes received or anything like that. In my tests, I don't seem to be ever receiving a "-1" from the input stream, which appears to be the "norm" for reading from input streams. So how can I know that I have reached the end of the file that was being sent?
Thank you for your help and your time.
It seems Android bluetooth input streams never return -1.
I guess setup a simple protocol by sending file size in the first place and EOF signals at last will help.
No it does not. Android sends -1 only when the Socket is closed as far as I know. So a workaround could be to do a reconnect, but I was trying that for hours and did not get it working, since I do not understand this "special" Code here (copied from a Stackoverflow Thread) for setting up the socket:
BluetoothSocket tmp = null;
Log.d(TAG, "New Connection initialized");
Method m;
try {
m = device.getClass().getMethod("createRfcommSocket",
new Class[] { int.class });
tmp = (BluetoothSocket) m.invoke(device, 1);
} catch (Exception e) {
e.printStackTrace();
}
mmSocket = tmp;
This Socket only works, when my App is started for the first filetransfer. If I want to "Reconnect" with a completely new instantiated Object (and a new Socket created with that Code), the program freezes on the blocking method mmSocket.connect(). It seems like the Method never comes to an ending. This is driving me nuts...
Try
while ((bytes = mmInStream.read(buffer) != -1)
and see if that helps.
Try this:
public void run() {
byte[] buffer;
ArrayList<Integer> arr_byte = new ArrayList<Integer>();
while (true) {
try {
int data = mmInStream.read();
if(mmInStream.available()>0) {
arr_byte.add(data);
} else {
arr_byte.add(data);
buffer = new byte[arr_byte.size()];
for(int i = 0 ; i < arr_byte.size() ; i++) {
buffer[i] = arr_byte.get(i).byteValue();
}
Log.e("INPUT",new String(buffer));
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
arr_byte = new ArrayList<Integer>();
}
} catch (IOException e) {
break;
}
}
}
Anybody can tell me how to display the bluetooth device (MyGlucoHealth meter) data in LogCat. the following code :
InputStream is = btSocket.getInputStream();
How to read data from "is" and print it. ?
Thanaks,
Chenna
have a look http://code.google.com/p/android-bluetooth/source/browse/tags/AndroidBluetoothLibrary_0_1/AndroidBluetoothLibrarySamples/src/it/gerdavax/android/bluetooth/sample/BluetoothServiceSample.java
Take a look at the BluetoothChat example. ConnectedThread.run() reads data from an InputStream.
public void run() {
Log.i(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(BluetoothChat.MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
connectionLost();
break;
}
}
}