android - 使用 startDiscovery 扫描蓝牙设备但未找到设备

问题描述

我在 Kotlin 中编写并能够设置一个接收器来处理由 startDiscovery 引起的 ACTION_DISCOVERY_STARTED 和 ACTION_DISCOVERY_FINISHED 事件（我将消息打印到文本视图并查看它们是否有效）。

但是，ACTION_FOUND 永远不会在接收器中被调用（当应该找到设备时，我从未看到我在该例程中更新的文本视图更改）。

我拥有清单中的所有权限（以及更多权限）：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.test_ble">
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/Theme.Test_BLE">
    <activity
        android:name=".MainActivity"
        android:exported="true">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

我有两个文本视图。text_view1 用于报告扫描状态，text_view2 用于放置扫描设备列表。这些设备（目前很粗略）只是连接到一个字符串，然后分配给 text_view2.text。但是，我从未看到该列表得到更新。

我知道房间里还有其他蓝牙设备在做广告，因为我可以在华硕 Nexus 7 平板电脑（Android 6.1）上看到它们，我用它来测试蓝牙设备设置下的代码。

minSdk 在 21 时应该足够低。这是 buildgradle 模块脚本：

plugins {
    id 'com.android.application'
    id 'kotlin-android'
}
android {
    compileSdk 31
    defaultConfig {
        applicationId "com.example.test_ble"
        minSdk 21
        targetSdk 31
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
    buildFeatures{
        viewBinding = true
    }
}
dependencies {
    implementation 'androidx.core:core-ktx:1.6.0'
    implementation 'androidx.appcompat:appcompat:1.3.1'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.1'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
}

这是 MainActivity.kt 文件。

package com.example.test_ble

import android.bluetooth.BluetoothAdapter
import android.bluetooth.BluetoothDevice
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import com.example.test_ble.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {
    private lateinit var binding: ActivityMainBinding
    private lateinit var btAdapter: BluetoothAdapter
    private var deviceList: String = ""
    // *****************************************************
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        // Get the BluetoothAdapter
        btAdapter = BluetoothAdapter.getDefaultAdapter()
        if (btAdapter == null) {
            binding.textView1.text = "No Bt Adapter!"
        } else if (!btAdapter.isEnabled) {
            binding.textView1.text = "Bt Adapter is NOT ENABLED!"
        } else {
            binding.textView1.text = "Bt Adapter is ENABLED!"

            // Build receiver for Device Discovery
            val receiver = object : BroadcastReceiver() {
                override fun onReceive(context: Context, intent: Intent) {
                    when (intent.action) {
                        BluetoothAdapter.ACTION_DISCOVERY_STARTED -> {
                            // Device discovery started, show loading indication
                            binding.textView1.text = "Device discovery started"
                        }
                        BluetoothAdapter.ACTION_DISCOVERY_FINISHED -> {
                            // unregister receiver and hide loading indication
                            binding.textView1.text = "Device discovery finished"
                        }
                        BluetoothDevice.ACTION_FOUND -> {
                            binding.textView1.text = "ACTION_FOUND" // I never see this message
                            val device: BluetoothDevice? =
                                intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE)
                            val deviceName = device?.name
                            val deviceHardwareAddress = device?.address // MAC address
                            deviceList =
                                deviceList + "\n" + deviceName.toString() + " " + deviceHardwareAddress.toString()
                            binding.textView2.text = deviceList // The device list is never updated
                        }
                    }
                }
            }
            // Register for broadcasts when a device is discovered.
            val intentFilter = IntentFilter().apply {
                addAction(BluetoothDevice.ACTION_FOUND)
                addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED)
                addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED)
            }
            if (btAdapter.isDiscovering()) {
                btAdapter.cancelDiscovery();
            }
            registerReceiver(receiver, intentFilter)
            btAdapter.startDiscovery()
        }
    }
}

谁能看到我错过了什么或做错了什么？当我确实看到发现的开始和结束确实发生时，我不明白为什么我没有检测到任何设备。在搜索并尝试了我在网上可以找到的所有内容后，我没有想法。非常感谢帮助。

吉姆

标签： androidkotlinbluetoothandroid-bluetooth

android - 使用 startDiscovery 扫描蓝牙设备但未找到设备

问题描述

解决方案

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