北京网站改版价格,网站首页效果图怎么做,自适应单页网站模板,wordpress运行时间BluetoothAdapter在Android6.0以上startDiscovery不能发现蓝牙设备问题问题的重要原因之一是Android 6.0#xff0c;Android 7.0的权限问题引起的。在Android 4.0上运行良好的蓝牙代码#xff0c;在高版本运行异常。比如BluetoothAdapter的startDiscovery虽然启动了发现蓝牙任…BluetoothAdapter在Android6.0以上startDiscovery不能发现蓝牙设备问题问题的重要原因之一是Android 6.0Android 7.0的权限问题引起的。在Android 4.0上运行良好的蓝牙代码在高版本运行异常。比如BluetoothAdapter的startDiscovery虽然启动了发现蓝牙任务但是不能发现蓝牙设备。解决问题是针对最新高版本的Android系统增加权限申请。现在给出一个完整例子。activity_main.xmlxmlns:toolshttp://schemas.android.com/toolsandroid:layout_widthmatch_parentandroid:layout_heightmatch_parentandroid:orientationverticaltools:contextzhangphil.bluetooth.MainActivityandroid:idid/initandroid:layout_widthwrap_contentandroid:layout_heightwrap_contentandroid:text初始化蓝牙设备 /android:idid/discoveryandroid:layout_widthwrap_contentandroid:layout_heightwrap_contentandroid:text发现设备 /android:idid/enable_discoveryandroid:layout_widthwrap_contentandroid:layout_heightwrap_contentandroid:text使自身可被其他蓝牙设备发现 /android:layout_widthmatch_parentandroid:layout_heightwrap_contentandroid:idid/listView测试的MainActivity.javapackage zhangphil.bluetooth;import android.Manifest;import android.app.Activity;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 android.content.pm.PackageManager;import android.os.Build;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.ArrayAdapter;import android.widget.ListView;public class MainActivity extends Activity implements View.OnClickListener {private final int REQUEST_ENABLE_BT 0xa01;private final int PERMISSION_REQUEST_COARSE_LOCATION 0xb01;private String TAG zhangphil;private ArrayAdapter mAdapter;private BluetoothAdapter mBluetoothAdapter;// 广播接收发现蓝牙设备private BroadcastReceiver mReceiver new BroadcastReceiver() {Overridepublic void onReceive(Context context, Intent intent) {String action intent.getAction();if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {Log.d(TAG, 开始扫描...);}if (BluetoothDevice.ACTION_FOUND.equals(action)) {BluetoothDevice device intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);if (device ! null) {// 添加到ListView的Adapter。mAdapter.add(设备名: device.getName() \n设备地址: device.getAddress());mAdapter.notifyDataSetChanged();}}if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {Log.d(TAG, 扫描结束.);}}};Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);if (Build.VERSION.SDK_INT Build.VERSION_CODES.M) {if (this.checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) ! PackageManager.PERMISSION_GRANTED) {requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, PERMISSION_REQUEST_COARSE_LOCATION);}}// 注册广播接收器。// 接收蓝牙发现IntentFilter filterFound new IntentFilter(BluetoothDevice.ACTION_FOUND);registerReceiver(mReceiver, filterFound);IntentFilter filterStart new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_STARTED);registerReceiver(mReceiver, filterStart);IntentFilter filterFinish new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);registerReceiver(mReceiver, filterFinish);mAdapter new ArrayAdapter(this, android.R.layout.simple_list_item_1, android.R.id.text1);((ListView) findViewById(R.id.listView)).setAdapter(mAdapter);findViewById(R.id.init).setOnClickListener(this);findViewById(R.id.discovery).setOnClickListener(this);findViewById(R.id.enable_discovery).setOnClickListener(this);}Overridepublic void onClick(View view) {switch (view.getId()) {case R.id.init:init();case R.id.discovery:discovery();case R.id.enable_discovery:enable_discovery();}}// 初始化蓝牙设备private void init() {mBluetoothAdapter BluetoothAdapter.getDefaultAdapter();// 检查设备是否支持蓝牙设备if (mBluetoothAdapter null) {Log.d(TAG, 设备不支持蓝牙);// 不支持蓝牙退出。return;}// 如果用户的设备没有开启蓝牙则弹出开启蓝牙设备的对话框让用户开启蓝牙if (!mBluetoothAdapter.isEnabled()) {Log.d(TAG, 请求用户打开蓝牙);Intent enableBtIntent new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);// 接下去在onActivityResult回调判断}}// 启动蓝牙发现...private void discovery() {if (mBluetoothAdapter null) {init();}mBluetoothAdapter.startDiscovery();}// 可选方法非必需// 此方法使自身的蓝牙设备可以被其他蓝牙设备扫描到// 注意时间阈值。0 - 3600 秒。// 通常设置时间为120秒。private void enable_discovery() {Intent discoverableIntent new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);// 第二个参数可设置的范围是0~3600秒在此时间区间(窗口期)内可被发现// 任何不在此区间的值都将被自动设置成120秒。discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 3600);startActivity(discoverableIntent);}Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {super.onActivityResult(requestCode, resultCode, data);if (requestCode REQUEST_ENABLE_BT) {if (resultCode RESULT_OK) {Log.d(TAG, 打开蓝牙成功);}if (resultCode RESULT_CANCELED) {Log.d(TAG, 放弃打开蓝牙);}} else {Log.d(TAG, 蓝牙异常);}}Overrideprotected void onDestroy() {super.onDestroy();unregisterReceiver(mReceiver);}Overridepublic void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {switch (requestCode) {case PERMISSION_REQUEST_COARSE_LOCATION:if (grantResults[0] PackageManager.PERMISSION_GRANTED) {}break;}}}不要忘记增加权限代码运行结果以上代码运行测试环境硬件设备是三星S7EdgeAndroid版本7.0
