我正在创建一个应用程序,在其中我需要扫描所有BLE信标并连接到特定的信标,然后在该外设上执行其他操作。我能够扫描android设备上的外围设备,但无法连接到任何外围设备。在下面的代码中,使用了react-native-ble-plx API。
import React, { Component } from 'react';
import {PermissionsAndroid, Text, View} from 'react-native';
import { BleManager } from 'react-native-ble-plx';
export default class App extends Component{
state = {
permissionStatus:'denied',
bluetoothStatus: 'disabled',
devices:[],
info:''
}
constructor(){
super();
this.manager = new BleManager();
}
info(message) {
this.setState({info: message})
}
error(message) {
this.setState({info: "ERROR: " + message})
}
async requestPermission() {
try {
const granted = await PermissionsAndroid.request(PermissionsAndroid.PERMISSIONS.ACCESS_FINE_LOCATION);
if (granted === PermissionsAndroid.RESULTS.GRANTED) {
this.setState({permissionStatus:'granted'});
}else if(granted === PermissionsAndroid.RESULTS.DENIED) {
this.setState({permissionStatus:'denied'});
}else{
//console.log('never-ask-again');
}
} catch (err) {
console.error(err)
}
}
scanAndConnect(){
this.manager.startDeviceScan(null, null, (error, device) => {
if(error){
console.log('Error occurred while scanning');
return;
}
if(device.id === MAC_ADDRESS){
console.log(device);
console.log(device.isConnectable);
console.log(`info: ${this.state.info}`);
this.manager.stopDeviceScan();
this.manager.connectToDevice(MAC_ADDRESS, {autoConnect:true})
.then((device) => {
this.info("Discovering services and characteristics")
console.log('device');
return device.discoverAllServicesAndCharacteristics();
})
.then((device) => {
this.info("Listening... ")
})
.catch((error) => {
this.manager.isDeviceConnected(device.id).then((res) => console.log(res))
.catch(err=>console.log(err));
this.error(error.message);
device.cancelConnection();
this.scanAndConnect();
});
}
})
}
componentDidMount()
{
this.requestPermission();
const subscription = this.manager.onStateChange((state) => {
if(state === 'PoweredOn'){
this.setState({bluetoothStatus:'enabled'});
this.scanAndConnect();
subscription.remove();
}else{
this.setState({bluetoothStatus:'disabled'});
}
}, true);
}
render(){
return(
<View style={{flex:1, padding:15, justifyContent:'center'}}>
<Text style={{fontSize:20, alignSelf:'center', color:'steelblue'}}>
Location access is {this.state.permissionStatus}
</Text>
<Text style={{fontSize:20, alignSelf:'center', color:'blue'}}>
Bluetooth is {this.state.bluetoothStatus}
</Text>
<Text style={{fontSize:20, alignSelf:'center', color:'black'}}>
Info is {this.state.info}
</Text>
</View>
);
}
}
如果我从connectToDevice()函数中删除了autoConnect选项,则会收到错误消息,即错误:设备MAC_ADDRESS已断开连接。