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请帮帮忙。我正在开发一个简单的蓝牙打印机应用程序，在那里我想打印user.My代码输入的数据工作正常蓝牙应用程序，但打印机没有打印数据。目前我使用的是MTP -U- 85蓝牙打印机。当我从我的应用程序发送数据时，打印机颜色从绿色变为蓝色color.Also当我连接和断开蓝牙时，颜色在绿色和蓝色、蓝色和绿色之间变化。所有的工作都正常，但是数据没有打印出来。
我会给你我的密码
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
// will show the statuses like bluetooth open, close or data sent
TextView myLabel;
// will enable user to enter any text to be printed
EditText myTextbox;
// android built in classes for bluetooth operations
BluetoothAdapter mBluetoothAdapter;
BluetoothSocket mmSocket;
BluetoothDevice mmDevice;
// needed for communication to bluetooth device / network
OutputStream mmOutputStream;
InputStream mmInputStream;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
volatile boolean stopWorker;
Button openButton ;
Button sendButton ;
Button closeButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
// we are going to have three buttons for specific functions
openButton = findViewById(R.id.open);
sendButton = findViewById(R.id.send);
closeButton = findViewById(R.id.close);
// text label and input box
myLabel = (TextView) findViewById(R.id.label);
myTextbox = (EditText) findViewById(R.id.entry);
openButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
findBT();
openBT();
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
}
catch(Exception e)
{
e.printStackTrace();
}
// send data typed by the user to be printed
sendButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
sendData();
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
// close bluetooth connection
closeButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
closeBT();
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
}
private void closeBT() throws IOException{
try {
stopWorker = true;
mmOutputStream.close();
mmInputStream.close();
mmSocket.close();
myLabel.setText("Bluetooth Closed");
} catch (Exception e) {
e.printStackTrace();
}
}
// this will send text data to be printed by the bluetooth printer
void sendData() throws IOException {
try {
// if(mmOutputStream==null) {
// the text typed by the user
EditText myTextbox = (EditText) findViewById(R.id.entry);
String msg = myTextbox.getText().toString();
msg += "\n";
mmOutputStream = mmSocket.getOutputStream();
mmOutputStream.write(msg.getBytes());
// tell the user data were sent
myLabel.setText("Data sent.");
// }
} catch (Exception e) {
e.printStackTrace();
}
}
// tries to open a connection to the bluetooth printer device
void openBT() throws IOException {
try {
// Standard SerialPortService ID
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
mmSocket.connect();
mmOutputStream = mmSocket.getOutputStream();
mmInputStream = mmSocket.getInputStream();
beginListenForData();
myLabel.setText("Bluetooth Opened");
} catch (Exception e) {
e.printStackTrace();
}
}
/*
* after opening a connection to bluetooth printer device,
* we have to listen and check if a data were sent to be printed.
*/
void beginListenForData()
{
try {
final Handler handler = new Handler();
// this is the ASCII code for a newline character
final byte delimiter = 10;
stopWorker = false;
readBufferPosition = 0;
readBuffer = new byte[1024];
workerThread = new Thread(new Runnable() {
public void run() {
while (!Thread.currentThread().isInterrupted() && !stopWorker) {
try {
int bytesAvailable = mmInputStream.available();
if (bytesAvailable > 0) {
byte[] packetBytes = new byte[bytesAvailable];
mmInputStream.read(packetBytes);
for (int i = 0; i < bytesAvailable; i++) {
byte b = packetBytes[i];
if (b == delimiter) {
byte[] encodedBytes = new byte[readBufferPosition];
System.arraycopy(
readBuffer, 0,
encodedBytes, 0,
encodedBytes.length
);
// specify US-ASCII encoding
final String data = new String(encodedBytes, "US-ASCII");
readBufferPosition = 0;
// tell the user data were sent to bluetooth printer device
handler.post(new Runnable() {
public void run() {
myLabel.setText(data);
}
});
} else {
readBuffer[readBufferPosition++] = b;
}
}
}
} catch (IOException ex) {
stopWorker = true;
}
}
}
});
workerThread.start();
} catch (Exception e) {
e.printStackTrace();
}
}
private void findBT() {
try {
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(mBluetoothAdapter == null) {
myLabel.setText("No bluetooth adapter available");
}
if(!mBluetoothAdapter.isEnabled()) {
Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBluetooth, 0);
}
Set pairedDevices = mBluetoothAdapter.getBondedDevices();
if(pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
// RPP300 is the name of the bluetooth printer device
// we got this name from the list of paired devices
if (device.getAddress().equals("DC:1D:30:35:3E:64")) {
mmDevice = device;
break;
}
}
}
myLabel.setText("Bluetooth device found.");
}catch(Exception e){
e.printStackTrace();
}
}
}
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