Question

我遇到了奇怪的问题。从活动我请求蓝牙通过意图激活和300s可发现性：

Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);                        
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);

无论蓝牙是否已经激活，我都会使用它。通过这样做，对话框权限显示如预期：

“蓝牙权限请求：手机上的应用程序是请求允许打开蓝牙和...“

但无论我是否加入，对话框仍会多次出现。我不知道为什么。我的代码：

public class Initial extends Activity {

 private Integer REQUEST_ENABLE_BT  = 1;
 private Integer REQUEST_ENABLE_DISCBT  = 2;
 private ListView listView;
 private  ArrayAdapter<String> mArrayAdapter;
 TextView editText;
 private Global global;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_initial);
    this.global= ((Global)this.getApplicationContext());
    editText = (TextView) findViewById(R.id.textView1);     
    global.setAdapter(BluetoothAdapter.getDefaultAdapter());
    if (global.getAdapter() == null) {
        // Device does not support Bluetooth
        editText.setText("Erro: Sistema não suporta Bluetooth!");
        finish();
    }
    listView = (ListView) findViewById(R.id.list);
    mArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1);
    listView.setAdapter(mArrayAdapter);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.initial, menu);
    return true;
}

@Override
public void onResume() {
    super.onResume();  // Always call the superclass method first
    if(!global.getEstado()){
        if (!global.getAdapter().isEnabled()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
        }
        else
            editText.setText("Bluetooth Ligado!");
        global.setReceiver(new BroadcastReceiver() {
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                // When discovery finds a device
                if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                    // Get the BluetoothDevice object from the Intent
                    BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                    // Add the name and address to an array adapter to show in a ListView
                    mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
                    Thread novocliente = new novoCliente(device);
                    novocliente.start();
                }
            }
        });
        // Register the BroadcastReceiver
        IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        registerReceiver(global.getReceiver(), filter); // Don't forget to unregister during onDestroy
        global.getAdapter().startDiscovery();
    }
    else{   
            Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
            discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
            startActivity(discoverableIntent);
    }   
}

@Override
protected void onActivityResult (int requestCode, int resultCode, Intent data){
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode == REQUEST_ENABLE_BT){
        switch(resultCode){
        case RESULT_OK:     editText.setText("Bluetooth Ligado!");break;
        case RESULT_CANCELED:   editText.setText("Impossivel ligar Bluetooth!");finish();break;
        }   
    }
    if(requestCode == REQUEST_ENABLE_DISCBT){
        switch(resultCode){
            case RESULT_CANCELED:   editText.setText("Bluetooth não Detetável!");break;
            default :   editText.setText("Bluetooth Detetável por "+resultCode+" segundos!");
                        Thread servidor = new ServerSocket();
                        servidor.start();
            break;
        }   
    }
}

@Override
public void onStop() {
    super.onStop();  // Always call the superclass method first
    BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
    BluetoothAdapter.getDefaultAdapter().disable(); 
}

@Override
public void onDestroy() {
    super.onDestroy();  // Always call the superclass method first
    unregisterReceiver(global.getReceiver()); // Don't forget to unregister during onDestroy    

}

} 我的可变getEstado（）是一个布尔值，表示应用程序是服务器还是客户端。如果是真的那就是服务器。而在其他方面就是问题。

有人可以帮我吗？

Answer 1

您要启用的代码位于onResume（）中。显示对话框时，您的活动暂停，当它被解除时（正面或负面），您的活动将恢复。如果对话框是肯定的，那么启用BT适配器也需要一些时间，因此global.getAdapter（）。isEnabled（）仍将返回false。这就是您重复显示对话框的原因。

要解决此问题，您需要使用不同的触发器（为什么您需要使用onResume？可以将它放在onCreate中），或者您可以使用存储状态。类似的东西：

private boolean requestedEnable = false;

@Override
public void onResume() {
    super.onResume();  // Always call the superclass method first
    if(!global.getEstado()){
        if (!global.getAdapter().isEnabled()) {
            if(!requestedEnable){
                requestedEnable = true;
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
            }
        }
        else
            editText.setText("Bluetooth Ligado!");
        global.setReceiver(new BroadcastReceiver() {
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                // When discovery finds a device
                if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                    // Get the BluetoothDevice object from the Intent
                    BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                    // Add the name and address to an array adapter to show in a ListView
                    mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
                    Thread novocliente = new novoCliente(device);
                    novocliente.start();
                }
            }
        });
        // Register the BroadcastReceiver
        IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        registerReceiver(global.getReceiver(), filter); // Don't forget to unregister during onDestroy
        global.getAdapter().startDiscovery();
    }
    else{   
            Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
            discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
            startActivity(discoverableIntent);
    }   
}

我希望你觉得这很有用。

Answer 2

查看Bluetooth Chat示例，可能会有所帮助

蓝牙权限对话框乘法

2 个答案: