java - 无法使用 OpenCSV 写入文件

Question

我正在尝试将文件写入目录。由于 RxBleClient 将搜索蓝牙低能耗客户端的结果返回到 ArrayList，我使用了 RxJava。然后我需要创建并打开一个具有自定义名称的文件以将结果保存到其中。我在 Android Doc 上搜索以检查我是否已授予所有权限，编写了一些代码以确保这一点 - 全部授予。我不知道如何解决这个问题。下面是代码、堆栈跟踪和清单文件。

    private void scanBleDevicesDelay(int howManyRows, String filename) {
        scanDisposable = rxBleClient.scanBleDevices(
                new ScanSettings.Builder()
                        .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY) // change if needed
                        .setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES) // change if needed
                        .build(),
                new ScanFilter.Builder()
                        .build())
                .doFinally(() -> {
                    dispose();
                    toggleScanBleButton.setEnabled(true);
                    dumpToFileButton.setEnabled(true);

                })
                .subscribe(
                        scanResult -> {
//                            I am not proud of this :-(
                            // Process scan result here.
                            recycleViewBLEAdapter.addScanResult(scanResult);
                            scanResultsCSV.add(scanResult);
                            if (scanResultsCSV.size() == howManyRows) {
//                                CSV file writer
                                try {

                                    if (ContextCompat.checkSelfPermission(
                                            getApplicationContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE) ==
                                            PackageManager.PERMISSION_GRANTED) {
                                        // You can use the API that requires the permission.
//                                        performAction(...);

                                        File pathfile = new File(Environment.getExternalStorageDirectory()
                                                .getAbsolutePath()
                                                + File.separator
                                                + "csvData");
                                        if (!pathfile.isDirectory()) {
//                                            ~~~~~~~~~~~~~~~~~~IS NOT CREATING A DIRECTORY~~~~~~~~~~~~~~~~~~
                                            pathfile.mkdir();
                                        }

                                        File file = new File(pathfile,
                                                File.separator + filename + ".csv");
                                        if (!file.exists()) {
//                                            ~~~~~~~~~~~~~~~~~~IS NOT CREATING A FILE~~~~~~~~~~~~~~~~~~
//                                            ~~~~~~~~~~~~~~~~~~HERE THROWS IOException ~~~~~~~~~~~~~~~~~~
                                            file.createNewFile();
//                                            Files.createFile(file.toPath());
                                            Log.i("File created: ", file.getName());
                                        }
                                        CSVWriter writer = new CSVWriter(new FileWriter(file));
//                                        CSVWriter writer = new CSVWriter(new FileWriter(pathfile + File.separator + filename + ".csv"));

                                        scanResultsCSV.forEach(scan -> {
                                            String[] entries = String.format("%s,%s,%s", scan.getTimestampNanos(), scan.getBleDevice(), scan.getRssi()).split(",");
                                            Log.i("Entries", Arrays.toString(entries));
                                            writer.writeNext(entries);
                                        });
                                        writer.close();
                                        Toast.makeText(this, "Zapisano do pliku", Toast.LENGTH_SHORT).show();
                                    } else if (shouldShowRequestPermissionRationale("Failed")) {
                                        // In an educational UI, explain to the user why your app requires this
                                        // permission for a specific feature to behave as expected. In this UI,
                                        // include a "cancel" or "no thanks" button that allows the user to
                                        // continue using your app without granting the permission.
//                                        showInContextUI(...);
                                        Toast.makeText(this, "Nie przyznano dostępu", Toast.LENGTH_SHORT).show();
                                    } else {
                                        // request a permission
                                        ActivityCompat.requestPermissions(this, new String[]{
                                                Manifest.permission.WRITE_EXTERNAL_STORAGE}, 3);
                                    }

                                } catch (IOException ioException) {
                                    ioException.printStackTrace();
                                    Toast.makeText(this, "Plik istnieje!", Toast.LENGTH_SHORT).show();
                                } catch (Exception e) {
                                    e.printStackTrace();
                                    Toast.makeText(this, "Nieoczekiwany blad", Toast.LENGTH_SHORT).show();
                                } finally {
//                                    Toast.makeText(this, "Zakonczono procedure", Toast.LENGTH_SHORT).show();
                                    scanDisposable.dispose();
                                }
                            }
                        },
                        throwable -> {
                            // Handle an error here.
                            Log.e("BLE search error", Arrays.toString(throwable.getStackTrace()));
                            Toast.makeText(this, "Nieoczekiwany blad", Toast.LENGTH_SHORT).show();
                        }
                );
    }

并在Manifest file：

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

堆栈跟踪：

W/System.err: java.io.IOException: No such file or directory
        at java.io.UnixFileSystem.createFileExclusively0(Native Method)
        at java.io.UnixFileSystem.createFileExclusively(UnixFileSystem.java:317)
W/System.err:     at java.io.File.createNewFile(File.java:1008)
        at com.example.ble_rssi_plotter.MainActivity.lambda$scanBleDevicesDelay$4$MainActivity(MainActivity.java:291)
W/System.err:     at com.example.ble_rssi_plotter.-$$Lambda$MainActivity$k9iEru6y1TGq9ZgTipfCtV0GZ18.accept(Unknown Source:8)
        at io.reactivex.internal.observers.LambdaObserver.onNext(LambdaObserver.java:63)
W/System.err:     at io.reactivex.internal.operators.observable.ObservableDoFinally$DoFinallyObserver.onNext(ObservableDoFinally.java:80)
        at io.reactivex.internal.operators.observable.ObservableFlatMap$MergeObserver.tryEmit(ObservableFlatMap.java:265)
        at io.reactivex.internal.operators.observable.ObservableFlatMap$InnerObserver.onNext(ObservableFlatMap.java:562)
        at io.reactivex.internal.operators.observable.ObservableDoOnEach$DoOnEachObserver.onNext(ObservableDoOnEach.java:101)
W/System.err:     at io.reactivex.internal.operators.observable.ObservableMap$MapObserver.onNext(ObservableMap.java:62)
        at io.reactivex.internal.operators.observable.ObservableUnsubscribeOn$UnsubscribeObserver.onNext(ObservableUnsubscribeOn.java:60)
        at io.reactivex.internal.operators.observable.ObservableCreate$CreateEmitter.onNext(ObservableCreate.java:66)
W/System.err:     at com.polidea.rxandroidble2.internal.serialization.FIFORunnableEntry$1$1.onNext(FIFORunnableEntry.java:68)
        at io.reactivex.internal.operators.observable.ObservableUnsubscribeOn$UnsubscribeObserver.onNext(ObservableUnsubscribeOn.java:60)
        at io.reactivex.internal.operators.observable.ObservableCreate$CreateEmitter.onNext(ObservableCreate.java:66)
W/System.err:     at com.polidea.rxandroidble2.internal.operations.ScanOperationApi21$1.onScanResult(ScanOperationApi21.java:77)
        at android.bluetooth.le.BluetoothLeScanner$BleScanCallbackWrapper$1.run(BluetoothLeScanner.java:492)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:223)
W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:7656)
W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

标签： javaandroidopencsv