Question

我尝试实现一个必须搜索蓝牙设备的Android应用程序（具有设备名称的条件）。按下搜索按钮时，必须在搜索时显示进度对话框。第一次，没有进度对话框，应用程序工作但现在当我按下按钮时，有时它运行正常，它显示对话框，然后显示找到的设备，但有时，对话框消失，没有显示结果（或结果显示很长时间后）。这是我的代码：

import android.app.ProgressDialog;
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.os.AsyncTask;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;
import java.util.Set;


public class ConnectionScreen extends ActionBarActivity {
    //Declaration of components
    private static final String TAG = "ConnectionScreen";
    public static final String BROADCAST = "PACKAGE_NAME.android.action.broadcast";
    private static final int REQUEST_ENABLE_BT = 1;
    private Button buttonSearch;
    private CheckBox checkBoxAutoConnect;
    private ListView listOfDevices;
    private TextView statusId;
    private TextView statusConnection;
    private BluetoothAdapter bluetoothadapt;
    private Set<BluetoothDevice> pairedDevices;
    private ArrayAdapter<String> deviceAdapter;
    private ProgressDialog dialog;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_connection_screen);

    linkViewToResources();


    listOfDevices.setAdapter(deviceAdapter);


    bluetoothadapt = BluetoothAdapter.getDefaultAdapter();
    if (bluetoothadapt == null) {
        statusConnection.setText("Not supported");
        Toast.makeText(getApplicationContext(), "Your device does not support Bluetooth", Toast.LENGTH_LONG).show();
        buttonSearch.setEnabled(false);
    } else {
        buttonSearch.setEnabled(true);
    }


}

@Override
protected void onResume() {
    super.onResume();
    registerReceiver(bReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));

}

private void linkViewToResources() {
    buttonSearch = (Button) findViewById(R.id.searchButton);
    buttonSearch.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            find(view);

        }
    });
    checkBoxAutoConnect = (CheckBox) findViewById(R.id.checkBoxAutoconnect);
    listOfDevices = (ListView) findViewById(R.id.listOfDevices);
    deviceAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);
}





final BroadcastReceiver bReceiver = 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 the MAC address of the object to the arrayAdapter
                // get paired devices
                if (device.getName().startsWith("HXM") && device.getName().length() == 9) {
                    deviceAdapter.add(device.getName() + "\n" + device.getAddress());
                    //deviceAdapter.notifyDataSetChanged();
                }
            }
            if(dialog != null && dialog.isShowing()){
                dialog.dismiss();
            }
        }
    };

    public void find(View view) {
        if (bluetoothadapt.isDiscovering()) {
            // the button is pressed when it discovers, so cancel the discovery
            bluetoothadapt.cancelDiscovery();
        }
        else {
            dialog = new ProgressDialog(ConnectionScreen.this);
            this.dialog.setMessage("Searching");
            this.dialog.show();

            deviceAdapter.clear();
            bluetoothadapt.startDiscovery();
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
            sendBroadcast(enableBtIntent);
            //new ProgressTask().execute(null, null, null);
            //////////////////////////
        }


    }



 @Override
    protected void onPause() {
        super.onPause();
        try {
            if (bReceiver != null) {
                unregisterReceiver(bReceiver);
            }
        } catch (IllegalArgumentException e) {
            Log.e(TAG, e.getMessage(), e);
        }
    }



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



 @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            // Handle action bar item clicks here. The action bar will
            // automatically handle clicks on the Home/Up button, so long
            // as you specify a parent activity in AndroidManifest.xml.
            int id = item.getItemId();
            if (id == R.id.action_settings) {
                return true;
            }
            return super.onOptionsItemSelected(item);
        }


    }

有人怎么解决这个问题？感谢。

更新：

我在测试期间遇到的另一个问题是使用搜索按钮：当我第一次按下它时，它会运行，但是当我第二次按下它时，它不会运行，依此类推。当它没有运行时，logcat中没有显示任何内容。当它运行时，这是在logcat中打印的内容：

 07-14 10:34:58.466  22020-22020/com.yast D/ProgressBar﹕ setProgress = 0
07-14 10:34:58.466  22020-22020/com.yast D/ProgressBar﹕ setProgress = 0, fromUser = false
07-14 10:34:58.466  22020-22020/com.yast D/ProgressBar﹕ mProgress = 0mIndeterminate = false, mMin = 0, mMax = 10000
07-14 10:34:58.496  22020-22020/com.yast W/ResourceType﹕ Failure getting entry for 0x010802c9 (t=7 e=713) in package 0 (error -75)
07-14 10:34:59.527  22020-22020/com.yast E/SpannableStringBuilder﹕ SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
07-14 10:34:59.527  22020-22020/com.yast E/SpannableStringBuilder﹕ SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
07-14 10:34:59.777  22020-22020/com.yast E/SpannableStringBuilder﹕ SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
07-14 10:34:59.777  22020-22020/com.yast E/SpannableStringBuilder﹕ SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length

Answer 1

尝试更改代码（当您开始发现并且正在搜索设备时，您的代码不会重新启动发现例程，只需取消它）：

public void find(View view) {
    if (bluetoothadapt.isDiscovering()) {
        // the button is pressed when it discovers, so cancel the discovery
        bluetoothadapt.cancelDiscovery();
    }

    dialog = new ProgressDialog(ConnectionScreen.this);
    this.dialog.setMessage("Searching");
    this.dialog.show();

    deviceAdapter.clear();
    bluetoothadapt.startDiscovery();
    Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
    sendBroadcast(enableBtIntent);
    //new ProgressTask().execute(null, null, null);
    //////////////////////////
}

更新
来自documentation：
发现过程通常涉及大约12秒的查询扫描，然后对每个新设备进行页面扫描以检索其蓝牙名称。
设备发现是一个重量级的过程。

我想你必须等到发现例程完成后才能加速这个过程。

用于搜索蓝牙设备的Android进度对话框

1 个答案: