Question

如果有人可以帮助我，我将非常高兴，因为我是对象编程的新手。我的问题是：我正在用蓝牙通信写一些应用程序。我编写了所有方法，并在 MainActivity.class 中的设备之间成功连接和传输数据。我还有一个 SearchActivity.class ，它显示List上范围内的所有设备，因此用户可以选择一个。然后，设备通过Intent传递到 MainActivity ，连接开始。但由于我的应用程序的性质，我必须创建单独的类，仅用于称为 BluetoothService.class 的蓝牙通信。我将蓝牙和其他内容的所有方法都移到 BluetoothService.class。 现在我甚至无法编译我的项目，因为我在为SearchActivity创建Intent时出错，我也得到错误startActivityForResult和onActivityResult方法。

第一个错误是：构造函数Intent（BluetoothService，Class）未定义

第二个错误：方法startActivityForResult（Intent，int）未定义类型BluetoothService

public void startConnection() {
    // Create an intent for SearchActivity 
    Intent intent = new Intent(this, SearchActivity.class);
    //start SearchActivity through intent and expect for result. 
    //The result is based on result code, which is REQUEST_DISCOVERY
    startActivityForResult(intent, REQUEST_DISCOVERY);              
}

当我从MainActivity调用方法 startConnection（）时，一切正常，但现在我还没有。我认为问题是，我无法从非活动类创建新的活动。

onActivityResult方法中出现下一个错误：* RESULT_OK无法解析为变量*

//on ActivityResult method is called, when other activity returns result through intent!
//when user selected device in SearchActivity, result is passed through intent with //requestCode, resultCode (intent data + requestCode + resultCode)
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode != REQUEST_DISCOVERY) {
    Log.d("Debug", ">>intent REQUEST_DISCOVERY failed!");
    return;
    }
    if (resultCode != RESULT_OK) {
    Log.d("Debug", ">>intent RESULT_OK failed!");
    return;
    }
    Log.d("Debug", ">>onActivityResult!");
    final BluetoothDevice device = data.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

    Log.d(device.getName(), "Name of Selected Bluetoothdevice");


    new Thread () {
        public void run() {
        //call connect function with device argument
        connect(device);
        };
    }.start();
    }

请告诉我如何解决这个问题。如果您需要更多信息或代码告诉我。感谢。

public class SearchActivity  extends ListActivity
{
    //name of LxDevices, that will be shown on search
    private String nameOfLxDevice = "DEBUG";

    private Handler handler = new Handler();
    /* Get Default Adapter */
    private BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    /* Storage the BT devices */
    private List<BluetoothDevice> devices = new ArrayList<BluetoothDevice>();
    /* Discovery is Finished */
    private volatile boolean discoveryFinished;


    /* Start search device */ 
    private Runnable discoveryWorker = new Runnable() {
        public void run() 
        {
            //To start discovering devices, simply call startDiscovery(). The process is asynchronous and the method will 
            //immediately return with a boolean indicating whether discovery has successfully started.
            mBluetoothAdapter.startDiscovery();
            Log.d("debug", ">>Starting Discovery");
            for (;;) 
            {
                if (discoveryFinished) 
                {
                    Log.d("debug", ">>Finished");
                    break;
                }
                try 
                {
                    Thread.sleep(100);
                } 
                catch (InterruptedException e){}
            }
        }
    }; 

    /* when discovery is finished, this will be called */
    //Your application must register a BroadcastReceiver for the ACTION_FOUND Intent in order to receive information about each device discovered.
    //For each device, the system will broadcast the ACTION_FOUND Intent. This Intent carries the extra fields EXTRA_DEVICE and EXTRA_CLASS,
    //containing a BluetoothDevice and a BluetoothClass, respectively

    private BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            /* get the search results */
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);               
                //add it on List<BluetoothDevice>
                devices.add(device);
                //show found LxDevice on list
                showDevices();
            }           
        }
    };

    private BroadcastReceiver discoveryReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent)  
        {
            /* unRegister Receiver */
            Log.d("debug", ">>unregisterReceiver");
            unregisterReceiver(mBroadcastReceiver);
            unregisterReceiver(this);
            discoveryFinished = true;
        }
    };

    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);

        /* BT isEnable */
        if (!mBluetoothAdapter.isEnabled())
        {
            Log.w("debug", ">>BT is disable!");
            finish();
            return;
        }
        /* Register Receiver*/
        IntentFilter discoveryFilter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(discoveryReceiver, discoveryFilter);
        IntentFilter foundFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        registerReceiver(mBroadcastReceiver, foundFilter);


        /* show a dialog "Scanning..." */ 
        SamplesUtils.indeterminate(SearchActivity.this, handler, "Scanning for LX devices..", discoveryWorker, new OnDismissListener() {
            public void onDismiss(DialogInterface dialog)
            {
                for (; mBluetoothAdapter.isDiscovering();) {
                    // Discovery is resource intensive.  Make sure it isn't going on when you attempt to connect and pass your message.
                    mBluetoothAdapter.cancelDiscovery();
                }
                discoveryFinished = true;
            }
        }, true); 
    }

    /* Show devices list */
    private void showDevices()
    {
        //Create a list of strings
        List<String> list = new ArrayList<String>();
        for (int i = 0, size = devices.size(); i < size; ++i) {
            StringBuilder b = new StringBuilder();
            BluetoothDevice d = devices.get(i);
            b.append(d.getName());
            b.append('\n');
            b.append(d.getAddress());
            String s = b.toString();
            list.add(s);
        }

        Log.d("debug", ">>showDevices");
        final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, list);
        handler.post(new Runnable() {
            public void run()
            {
                setListAdapter(adapter);
            }
        });
    }

    /* Select device */
    protected void onListItemClick(ListView l, View v, int position, long id) {
        Log.d("debug", ">>Click device");
        Intent result = new Intent();
        result.putExtra(BluetoothDevice.EXTRA_DEVICE, devices.get(position));
        setResult(RESULT_OK, result);
        finish();
    }

}

在MainActivity中我正在做：

// Initialize the BluetoothChatService to perform bluetooth connections
    mBluetoothService = new BluetoothService(this);

BluetoothService中的构造函数是：

 public BluetoothService(Context context) {

    }

连接方法：

protected void connect(BluetoothDevice device) {
    try {
    //Create a Socket connection: need the server's UUID number of registered
    BluetoothSocket socket = null;
    socket = device.createRfcommSocketToServiceRecord(MY_UUID);         
    socket.connect();
        //Create temporary input and output stream
         InputStreamtmpIn=socket.getInputStream();                                                      
    OutputStream tmpOut = socket.getOutputStream();

    //for use purposes
    mmSocket = socket;
    mmOutStream = tmpOut;
    mmInStream = tmpIn;

    tmpOut.write("Device connected..".getBytes());

    //start Thread for receiving data over bluetooth
    //dataReceiveThread.start();

    } catch (IOException e) {
        Log.e("Colibri2BB BT", "", e);
    } 
}

Answer 1

你的BluettoothService课程不是一个上下文，要初始化一个意图，你需要一个上下文。所以尝试创建这样的类：

    public class BluettoothService{

    Activity activity;

    BluettoothService(Activity activity){
    this.activity=activity;
    }
    public void startConnection() {
    // Create an intent for SearchActivity 
    Intent intent = new Intent(activity, SearchActivity.class);
    //start SearchActivity through intent and expect for result. 
    //The result is based on result code, which is REQUEST_DISCOVERY
    activity.startActivityForResult(intent, REQUEST_DISCOVERY);              
    } 


}

您可以通过任何活动以这种方式创建BluettoothService课程：

BluettoothService bluetooth=new BluettoothService(this);

编辑：

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode != REQUEST_DISCOVERY) {
Log.d("Debug", ">>intent REQUEST_DISCOVERY failed!");
return;
}
if (resultCode != Activity.RESULT_OK) {
Log.d("Debug", ">>intent RESULT_OK failed!");
return;
}
Log.d("Debug", ">>onActivityResult!");
final BluetoothDevice device = data.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

Log.d(device.getName(), "Name of Selected Bluetoothdevice");


new Thread () {
    public void run() {
    //call connect function with device argument
    connect(device);
    };
}.start();
}

Answer 2

您无法使用服务的this来启动ActivityForResult

Answer 3

您应该为@override指定onActivityResult()。

您的代码应放入扩展“activity”（android.app.Activity）的类中。这就是你有这个：

Next error is in onActivityResult method: *RESULT_OK cannot be resolved to a variable*

这是无法解决的，因为您的课程没有延伸“活动”

Answer 4

//创建这个包含应用程序上下文的类。

public class Application_Manager extends Application {

    private static Context context;

    public void onCreate() {
        super.onCreate();
        Application_Manager.context = getApplicationContext();

    }

    public static Context getAppContext() {
        return Application_Manager.context;
    }
}

//使用此类getAppcontext（）来获取非活动类中的上下文。

public class BluettoothService{

    static Context context=Application_Manager.getAppContext();
    public void startConnection() {
    Intent intent = new Intent(context, SearchActivity.class);
    context.startActivityForResult(intent, REQUEST_DISCOVERY);//change edited              
    } 


}

无法从类中启动intent startActivityForResult

4 个答案: