【发布时间】：2014-03-10 10:04:11
【问题描述】：
我已经实现了一个能够检测 BLE 信号并将它们显示在 ListView 中的代码（在 List 的每个项目中，它将显示名称、地址和 rssi）但是当我尝试将其保存到 xml 文件中时，它会发生错误并停止应用程序。代码如下：
package com.example.newblescan;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import com.example.newblescan.R;
import android.app.Activity;
import android.app.ListActivity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;
import com.example.newblescan.adapter.BleDevicesAdapter;
/**
* Activity for scanning and displaying available Bluetooth LE devices.
*/
public class DeviceScanActivity extends ListActivity {
private static final int REQUEST_ENABLE_BT = 1;
private static final long SCAN_PERIOD = 500;
private BleDevicesAdapter leDeviceListAdapter;
private BluetoothAdapter bluetoothAdapter;
private Scanner scanner;
private Save save;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getActionBar().setTitle(R.string.title_devices);
// Use this check to determine whether BLE is supported on the device. Then you can
// selectively disable BLE-related features.
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
finish();
return;
}
// Initializes a Bluetooth adapter. For API level 18 and above, get a reference to
// BluetoothAdapter through BluetoothManager.
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
bluetoothAdapter = bluetoothManager.getAdapter();
// Checks if Bluetooth is supported on the device.
if (bluetoothAdapter == null) {
Toast.makeText(this, R.string.error_bluetooth_not_supported, Toast.LENGTH_SHORT).show();
finish();
return;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.gatt_scan, menu);
if (scanner == null || !scanner.isScanning()) {
menu.findItem(R.id.menu_stop).setVisible(false);
menu.findItem(R.id.menu_scan).setVisible(true);
menu.findItem(R.id.menu_refresh).setActionView(null);
} else {
menu.findItem(R.id.menu_stop).setVisible(true);
menu.findItem(R.id.menu_scan).setVisible(false);
menu.findItem(R.id.menu_refresh).setActionView(
R.layout.actionbar_indeterminate_progress);
}
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_scan:
leDeviceListAdapter.clear();
if (scanner == null) {
scanner = new Scanner(bluetoothAdapter, mLeScanCallback);
scanner.startScanning();
invalidateOptionsMenu();
}
break;
case R.id.menu_stop:
if (scanner != null) {
save = new Save(leDeviceListAdapter);
scanner.stopScanning();
try {
save.savedata();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
scanner = null;
invalidateOptionsMenu();
}
break;
}
return true;
}
@Override
protected void onResume() {
super.onResume();
// Ensures Bluetooth is enabled on the device. If Bluetooth is not currently enabled,
// fire an intent to display a dialog asking the user to grant permission to enable it.
if (!bluetoothAdapter.isEnabled()) {
final Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
return;
}
init();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// User chose not to enable Bluetooth.
if (requestCode == REQUEST_ENABLE_BT) {
if (resultCode == Activity.RESULT_CANCELED) {
finish();
} else {
init();
}
}
super.onActivityResult(requestCode, resultCode, data);
}
@Override
protected void onPause() {
super.onPause();
if (scanner != null) {
scanner.stopScanning();
scanner = null;
}
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
final BluetoothDevice device = leDeviceListAdapter.getDevice(position);
if (device == null)
return;
//final Intent intent = new Intent(this, DeviceServicesActivity.class);
//intent.putExtra(DeviceServicesActivity.EXTRAS_DEVICE_NAME, device.getName());
//intent.putExtra(DeviceServicesActivity.EXTRAS_DEVICE_ADDRESS, device.getAddress());
//startActivity(intent);
}
private void init() {
if (leDeviceListAdapter == null) {
leDeviceListAdapter = new BleDevicesAdapter(getBaseContext());
setListAdapter(leDeviceListAdapter);
}
if (scanner == null) {
scanner = new Scanner(bluetoothAdapter, mLeScanCallback);
scanner.startScanning();
}
invalidateOptionsMenu();
}
// Device scan callback.
private BluetoothAdapter.LeScanCallback mLeScanCallback =
new BluetoothAdapter.LeScanCallback() {
@Override
public void onLeScan(final BluetoothDevice device, final int rssi, byte[] scanRecord) {
runOnUiThread(new Runnable() {
@Override
public void run() {
leDeviceListAdapter.addDevice(device, rssi);
leDeviceListAdapter.notifyDataSetChanged();
}
});
}
};
private static class Scanner extends Thread {
private final BluetoothAdapter bluetoothAdapter;
private final BluetoothAdapter.LeScanCallback mLeScanCallback;
private volatile boolean isScanning = false;
Scanner(BluetoothAdapter adapter, BluetoothAdapter.LeScanCallback callback) {
bluetoothAdapter = adapter;
mLeScanCallback = callback;
}
public boolean isScanning() {
return isScanning;
}
public void startScanning() {
synchronized (this) {
isScanning = true;
start();
}
}
public void stopScanning() {
synchronized (this) {
isScanning = false;
bluetoothAdapter.stopLeScan(mLeScanCallback);
}
}
@Override
public void run() {
try {
while (true) {
synchronized (this) {
if (!isScanning)
break;
bluetoothAdapter.startLeScan(mLeScanCallback);
}
sleep(SCAN_PERIOD);
synchronized (this) {
bluetoothAdapter.stopLeScan(mLeScanCallback);
}
}
} catch (InterruptedException ignore) {
} finally {
bluetoothAdapter.stopLeScan(mLeScanCallback);
}
}
}
public class Save implements Serializable {
/**
*
*/
private BleDevicesAdapter leDeviceListAdapter;
private static final long serialVersionUID = 1L;
Save(BleDevicesAdapter BLEList) {
leDeviceListAdapter = BLEList;
}
public void savedata() throws FileNotFoundException{
String filename = "file.txt";
FileOutputStream fos = null;
//Bundle extras = getIntent().getExtras();
//long timestamp = extras.getLong("currentTime");
try {
fos= openFileOutput(filename, Context.MODE_PRIVATE);
ObjectOutputStream out = new ObjectOutputStream(fos);
//out.write((int) timestamp);
out.writeObject(leDeviceListAdapter);
out.close();
Toast.makeText(DeviceScanActivity.this, R.string.list_saved, Toast.LENGTH_SHORT).show();
} catch (FileNotFoundException e){
e.printStackTrace();
} catch (IOException e){
e.printStackTrace();
}
}
}
}
在这里，我希望当我按下按钮时，在 R.id.menu_stop 情况下，它调用类 Save 将列表保存到 xml 文件中。这是我执行应用程序时的 Logcat：
新的 LOGCAT ！！！！！：
03-10 10:33:02.426: D/BluetoothAdapter(21891): startLeScan(): null
03-10 10:33:02.431: D/BluetoothAdapter(21891): onClientRegistered() - status=0 clientIf=4
03-10 10:33:02.441: D/AbsListView(21891): unregisterIRListener() is called
03-10 10:33:02.466: D/AbsListView(21891): unregisterIRListener() is called
03-10 10:33:02.486: D/BluetoothAdapter(21891): stopLeScan()
03-10 10:33:02.521: W/System.err(21891): java.io.NotSerializableException: com.example.newblescan.adapter.BleDevicesAdapter
03-10 10:33:02.521: W/System.err(21891): at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1364)
03-10 10:33:02.521: W/System.err(21891): at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671)
03-10 10:33:02.521: W/System.err(21891): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517)
03-10 10:33:02.521: W/System.err(21891): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481)
03-10 10:33:02.521: W/System.err(21891): at com.example.newblescan.DeviceScanActivity$Save.savedata(DeviceScanActivity.java:295)
03-10 10:33:02.521: W/System.err(21891): at com.example.newblescan.DeviceScanActivity.onOptionsItemSelected(DeviceScanActivity.java:116)
03-10 10:33:02.521: W/System.err(21891): at android.app.Activity.onMenuItemSelected(Activity.java:2640)
03-10 10:33:02.521: W/System.err(21891): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:1171)
03-10 10:33:02.521: W/System.err(21891): at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735)
03-10 10:33:02.521: W/System.err(21891): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:152)
03-10 10:33:02.526: W/System.err(21891): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)
03-10 10:33:02.526: W/System.err(21891): at com.android.internal.view.menu.ActionMenuView.invokeItem(ActionMenuView.java:630)
03-10 10:33:02.526: W/System.err(21891): at com.android.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:200)
03-10 10:33:02.526: W/System.err(21891): at android.view.View.performClick(View.java:4475)
03-10 10:33:02.526: W/System.err(21891): at android.view.View$PerformClick.run(View.java:18786)
03-10 10:33:02.526: W/System.err(21891): at android.os.Handler.handleCallback(Handler.java:730)
03-10 10:33:02.526: W/System.err(21891): at android.os.Handler.dispatchMessage(Handler.java:92)
03-10 10:33:02.526: W/System.err(21891): at android.os.Looper.loop(Looper.java:137)
03-10 10:33:02.526: W/System.err(21891): at android.app.ActivityThread.main(ActivityThread.java:5493)
03-10 10:33:02.526: W/System.err(21891): at java.lang.reflect.Method.invokeNative(Native Method)
03-10 10:33:02.526: W/System.err(21891): at java.lang.reflect.Method.invoke(Method.java:525)
03-10 10:33:02.526: W/System.err(21891): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
03-10 10:33:02.526: W/System.err(21891): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
03-10 10:33:02.531: W/System.err(21891): at dalvik.system.NativeStart.main(Native Method)
03-10 10:33:02.931: D/BluetoothAdapter(21891): stopLeScan()
03-10 10:33:02.931: D/BluetoothAdapter(21891): stopLeScan()
03-10 10:33:07.701: D/AbsListView(21891): unregisterIRListener() is called
03-10 10:33:07.911: D/AbsListView(21891): onDetachedFromWindow
任何人都可以解决错误或将此代码的更正放在它可能丢失的代码上吗？请帮忙！！！！！！！
更新：现在当我按下按钮停止扫描时，它完全停止了，但我不知道为什么它不保存甚至不创建 xml 文件。此外，它不会因为知道它已被保存而弹出吐司。我更新了上面的代码和 logcat。谁能解决这个新问题？？！！！！！！
【问题讨论】：