问如何使用ionic 3连接蓝牙打印机？

EN

devices = [];
btnFindDevices() {
   this.bluetoothSerial.isEnabled().then(() => {
   this.bluetoothSerial.discoverUnpaired().then((allDevices) => {
   this.devices = allDevices;
   console.log(allDevices);
});
});
}

btnBlueToothConnect() {
   if (this.devices.length > 0) {
   //this code connects device which’s position is 0. Change it whatever you 
   //want.
   this.bluetoothSerial.connect(this.devices[0].id).subscribe((data) => {
   console.log(“Connected”, data);
   }, (error) => {
   console.log(“not Connected”, error);
   });
    }
    else {
    console.log(“Device List did not genereted yet.”);
    }
    }

    btnBlueToothPrint() {
    //Attention… Bluetooth printer prints data when whole line filled. For 
    //example in my case printer is 32 colon,
    //“hello world” has 11 characters. so it prints after 3 times clicked 
    //the print button.
        this.bluetoothSerial.write(‘hello world’).then(() => { console.log(“s”); }, () => { console.log(“f”); });
    }